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Lundquist J, Shams N, Wallin M, Hallbäck M, Lönnqvist PA, Karlsson J. Capnodynamic end-expiratory lung volume assessment in anesthetized healthy children. Paediatr Anaesth 2024; 34:251-258. [PMID: 38055609 DOI: 10.1111/pan.14804] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 10/18/2023] [Accepted: 11/21/2023] [Indexed: 12/08/2023]
Abstract
BACKGROUND Capnodynamic lung function monitoring generates variables that may be useful for pediatric perioperative ventilation. AIMS Establish normal values for end-expiratory lung volume CO2 in healthy children undergoing anesthesia and to compare these values to previously published values obtained with alternative end-expiratory lung volume methods. The secondary aim was to investigate the ability of end-expiratory lung volume CO2 to react to positive end-expiratory pressure-induced changes in end-expiratory lung volume. In addition, normal values for associated volumetric capnography lung function variables were examined. METHODS Fifteen pediatric patients with healthy lungs (median age 8 months, range 1-36 months) undergoing general anesthesia were examined before start of surgery. Tested variables were recorded at baseline positive end-expiratory pressure 3 cmH2 O, 1 and 3 min after positive end-expiratory pressure 10 cmH2 O and 3 min after returning to baseline positive end-expiratory pressure 3 cmH2 O. RESULTS Baseline end-expiratory lung volume CO2 was 32 mL kg-1 (95% CI 29-34 mL kg-1 ) which increased to 39 mL kg-1 (95% CI 35-43 mL kg-1 , p < .0001) and 37 mL kg-1 (95% CI 34-41 mL kg-1 , p = .0003) 1 and 3 min after positive end-expiratory pressure 10 cmH2 O, respectively. End-expiratory lung volume CO2 returned to baseline, 33 mL kg-1 (95% CI 29-37 mL kg-1 , p = .72) 3 min after re-establishing positive end-expiratory pressure 3 cmH2 O. Airway dead space increased from 1.1 mL kg-1 (95% CI 0.9-1.4 mL kg-1 ) to 1.4 (95% CI 1.1-1.8 mL kg-1 , p = .003) and 1.5 (95% CI 1.1-1.8 mL kg-1 , p < .0001) 1 and 3 min after positive end-expiratory pressure 10 cmH2 O, respectively, and 1.2 mL kg-1 (95% CI 0.9-1.4 mL kg-1 , p = .08) after 3 min of positive end-expiratory pressure 3 cmH2 O. Additional volumetric capnography and lung function variables showed no major changes in response to positive end-expiratory pressure variations. CONCLUSIONS Capnodynamic noninvasive and continuous end-expiratory lung volume CO2 values assessed during anesthesia in children were in close agreement with previously reported end-expiratory lung volume values generated by alternative methods. Furthermore, positive end-expiratory pressure changes resulted in physiologically expected end-expiratory lung volume CO2 responses in a timely manner, suggesting that it can be used to trend end-expiratory lung volume changes during anesthesia.
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Affiliation(s)
- Johanna Lundquist
- Pediatric perioperative medicine and Intensive Care, Karolinska University Hospital, Stockholm, Sweden
| | - Niki Shams
- Pediatric perioperative medicine and Intensive Care, Karolinska University Hospital, Stockholm, Sweden
| | - Mats Wallin
- Department of Physiology and Pharmacology (FYFA), C3, Eriksson I Lars, PA Lönnqvist group, Section of Anesthesiology and Intensive Care, Anestesi- och Intensivvårdsavdelningen, Karolinska Institute, Stockholm, Sweden
| | | | - Per-Arne Lönnqvist
- Pediatric perioperative medicine and Intensive Care, Karolinska University Hospital, Stockholm, Sweden
- Department of Physiology and Pharmacology (FYFA), C3, Eriksson I Lars, PA Lönnqvist group, Section of Anesthesiology and Intensive Care, Anestesi- och Intensivvårdsavdelningen, Karolinska Institute, Stockholm, Sweden
| | - Jacob Karlsson
- Pediatric perioperative medicine and Intensive Care, Karolinska University Hospital, Stockholm, Sweden
- Department of Physiology and Pharmacology (FYFA), C3, Eriksson I Lars, PA Lönnqvist group, Section of Anesthesiology and Intensive Care, Anestesi- och Intensivvårdsavdelningen, Karolinska Institute, Stockholm, Sweden
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2
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Keleher E, Iftikhar H, Schulz LF, McCanny P, Austin D, Stewart A, O'Regan W, Hallbäck M, Wallin M, Aneman A. Capnodynamic monitoring of lung volume and pulmonary blood flow during alveolar recruitment: a prospective observational study in postoperative cardiac patients. J Clin Monit Comput 2023; 37:1463-1472. [PMID: 37243954 DOI: 10.1007/s10877-023-01033-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Accepted: 05/08/2023] [Indexed: 05/29/2023]
Abstract
Alveolar recruitment manoeuvres may mitigate ventilation and perfusion mismatch after cardiac surgery. Monitoring the efficacy of recruitment manoeuvres should provide concurrent information on pulmonary and cardiac changes. This study in postoperative cardiac patients applied capnodynamic monitoring of changes in end-expiratory lung volume and effective pulmonary blood flow. Alveolar recruitment was performed by incremental increases in positive end-expiratory pressure (PEEP) to a maximum of 15 cmH2O from a baseline of 5 cmH2O over 30 min. The change in systemic oxygen delivery index after the recruitment manoeuvre was used to identify responders (> 10% increase) with all other changes (≤ 10%) denoting non-responders. Mixed factor ANOVA using Bonferroni correction for multiple comparisons was used to denote significant changes (p < 0.05) reported as mean differences and 95% CI. Changes in end-expiratory lung volume and effective pulmonary blood flow were correlated using Pearson's regression. Twenty-seven (42%) of 64 patients were responders increasing oxygen delivery index by 172 (95% CI 61-2984) mL min-1 m-2 (p < 0.001). End-expiratory lung volume increased by 549 (95% CI 220-1116) mL (p = 0.042) in responders associated with an increase in effective pulmonary blood flow of 1140 (95% CI 435-2146) mL min-1 (p = 0.012) compared to non-responders. A positive correlation (r = 0.79, 95% CI 0.5-0.90, p < 0.001) between increased end-expiratory lung volume and effective pulmonary blood flow was only observed in responders. Changes in oxygen delivery index after lung recruitment were correlated to changes in end-expiratory lung volume (r = 0.39, 95% CI 0.16-0.59, p = 0.002) and effective pulmonary blood flow (r = 0.60, 95% CI 0.41-0.74, p < 0.001). Capnodynamic monitoring of end-expiratory lung volume and effective pulmonary blood flow early in postoperative cardiac patients identified a characteristic parallel increase in both lung volume and perfusion after the recruitment manoeuvre in patients with a significant increase in oxygen delivery.Trial registration This study was registered on ClinicalTrials.gov (NCT05082168, 18th of October 2021).
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Affiliation(s)
- E Keleher
- Faculty of Medicine, University of New South Wales, Sydney, NSW, Australia
| | - H Iftikhar
- Faculty of Medicine, University of New South Wales, Sydney, NSW, Australia
| | - L F Schulz
- Intensive Care Unit, Liverpool Hospital, South Western Sydney Local Health District, Sydney, NSW, Australia
| | - P McCanny
- Intensive Care Unit, Liverpool Hospital, South Western Sydney Local Health District, Sydney, NSW, Australia
| | - D Austin
- Intensive Care Unit, Liverpool Hospital, South Western Sydney Local Health District, Sydney, NSW, Australia
| | - A Stewart
- Intensive Care Unit, Liverpool Hospital, South Western Sydney Local Health District, Sydney, NSW, Australia
| | - W O'Regan
- Intensive Care Unit, Liverpool Hospital, South Western Sydney Local Health District, Sydney, NSW, Australia
| | | | - M Wallin
- Department of Physiology and Pharmacology, Karolinska Institute, Stockholm, Sweden
| | - A Aneman
- Intensive Care Unit, Liverpool Hospital, South Western Sydney Local Health District, Sydney, NSW, Australia.
- Southwestern Clinical School, University of New South Wales, Sydney, NSW, Australia.
- Ingham Institute for Applied Medical Research, Sydney, NSW, Australia.
- Intensive Care Unit, Liverpool Hospital, Locked Bag 7103, Liverpool BC, NSW, 1871, Australia.
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3
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Mehmood R, Mansoor Z, Atanasov GP, Cheian A, Davletova A, Patel A, Ahmed D. High-Flow Nasal Oxygenation and Its Applicability in COVID Patients. SN Compr Clin Med 2022; 4:49. [PMID: 35128319 PMCID: PMC8801314 DOI: 10.1007/s42399-022-01132-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Accepted: 01/26/2022] [Indexed: 11/24/2022]
Abstract
High-flow nasal oxygenation (HFNO) is a type of oxygen therapy that provides humidified and heated oxygen through a nasal cannula at much higher flow rates than standard oxygen therapy, while also allowing control over the fraction of inspired oxygen (FIO2). Compared to standard oxygen therapy, it is much more comfortable for the patient and seems to alleviate most of the problems associated with standard oxygen therapy, such as dry nose, dry throat and nasal pain. It also provides a variety of benefits that can reduce the incidence of escalating treatment and initiating mechanical ventilation in COVID patients with acute hypoxemic respiratory failure (AHRF). This article provides an overview of HFNO and its current applications in COVID patients during the pandemic.
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Affiliation(s)
- Raafay Mehmood
- First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Zainab Mansoor
- First Faculty of Medicine, Charles University, Prague, Czech Republic
| | | | - Alexei Cheian
- First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Alina Davletova
- First Faculty of Medicine, Charles University, Prague, Czech Republic
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4
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Andrews P, Shiber J, Madden M, Nieman GF, Camporota L, Habashi NM. Myths and Misconceptions of Airway Pressure Release Ventilation: Getting Past the Noise and on to the Signal. Front Physiol 2022; 13:928562. [PMID: 35957991 PMCID: PMC9358044 DOI: 10.3389/fphys.2022.928562] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Accepted: 06/21/2022] [Indexed: 12/16/2022] Open
Abstract
In the pursuit of science, competitive ideas and debate are necessary means to attain knowledge and expose our ignorance. To quote Murray Gell-Mann (1969 Nobel Prize laureate in Physics): “Scientific orthodoxy kills truth”. In mechanical ventilation, the goal is to provide the best approach to support patients with respiratory failure until the underlying disease resolves, while minimizing iatrogenic damage. This compromise characterizes the philosophy behind the concept of “lung protective” ventilation. Unfortunately, inadequacies of the current conceptual model–that focuses exclusively on a nominal value of low tidal volume and promotes shrinking of the “baby lung” - is reflected in the high mortality rate of patients with moderate and severe acute respiratory distress syndrome. These data call for exploration and investigation of competitive models evaluated thoroughly through a scientific process. Airway Pressure Release Ventilation (APRV) is one of the most studied yet controversial modes of mechanical ventilation that shows promise in experimental and clinical data. Over the last 3 decades APRV has evolved from a rescue strategy to a preemptive lung injury prevention approach with potential to stabilize the lung and restore alveolar homogeneity. However, several obstacles have so far impeded the evaluation of APRV’s clinical efficacy in large, randomized trials. For instance, there is no universally accepted standardized method of setting APRV and thus, it is not established whether its effects on clinical outcomes are due to the ventilator mode per se or the method applied. In addition, one distinctive issue that hinders proper scientific evaluation of APRV is the ubiquitous presence of myths and misconceptions repeatedly presented in the literature. In this review we discuss some of these misleading notions and present data to advance scientific discourse around the uses and misuses of APRV in the current literature.
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Affiliation(s)
- Penny Andrews
- R Adams Cowley Shock Trauma Center, University of Maryland School of Medicine, Baltimore, MD, United States
- *Correspondence: Penny Andrews,
| | - Joseph Shiber
- University of Florida College of Medicine, Jacksonville, FL, United States
| | - Maria Madden
- R Adams Cowley Shock Trauma Center, University of Maryland School of Medicine, Baltimore, MD, United States
| | - Gary F. Nieman
- Department of Surgery, SUNY Upstate Medical University, Syracuse, NY, United States
| | - Luigi Camporota
- Department of Adult Critical Care, Guy’s and St Thomas’ NHS Foundation Trust, Health Centre for Human and Applied Physiological Sciences, London, United Kingdom
| | - Nader M. Habashi
- R Adams Cowley Shock Trauma Center, University of Maryland School of Medicine, Baltimore, MD, United States
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5
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Rezoagli E, Laffey JG, Bellani G. Monitoring Lung Injury Severity and Ventilation Intensity during Mechanical Ventilation. Semin Respir Crit Care Med 2022; 43:346-368. [PMID: 35896391 DOI: 10.1055/s-0042-1748917] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
Acute respiratory distress syndrome (ARDS) is a severe form of respiratory failure burden by high hospital mortality. No specific pharmacologic treatment is currently available and its ventilatory management is a key strategy to allow reparative and regenerative lung tissue processes. Unfortunately, a poor management of mechanical ventilation can induce ventilation induced lung injury (VILI) caused by physical and biological forces which are at play. Different parameters have been described over the years to assess lung injury severity and facilitate optimization of mechanical ventilation. Indices of lung injury severity include variables related to gas exchange abnormalities, ventilatory setting and respiratory mechanics, ventilation intensity, and the presence of lung hyperinflation versus derecruitment. Recently, specific indexes have been proposed to quantify the stress and the strain released over time using more comprehensive algorithms of calculation such as the mechanical power, and the interaction between driving pressure (DP) and respiratory rate (RR) in the novel DP multiplied by four plus RR [(4 × DP) + RR] index. These new parameters introduce the concept of ventilation intensity as contributing factor of VILI. Ventilation intensity should be taken into account to optimize protective mechanical ventilation strategies, with the aim to reduce intensity to the lowest level required to maintain gas exchange to reduce the potential for VILI. This is further gaining relevance in the current era of phenotyping and enrichment strategies in ARDS.
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Affiliation(s)
- Emanuele Rezoagli
- School of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy.,Department of Emergency and Intensive Care, San Gerardo University Hospital, Monza, Italy
| | - John G Laffey
- School of Medicine, National University of Ireland, Galway, Ireland.,Department of Anaesthesia and Intensive Care Medicine, Galway University Hospitals, Saolta University Hospital Group, Galway, Ireland.,Lung Biology Group, Regenerative Medicine Institute (REMEDI) at CÚRAM Centre for Research in Medical Devices, National University of Ireland Galway, Galway, Ireland
| | - Giacomo Bellani
- School of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy.,Department of Emergency and Intensive Care, San Gerardo University Hospital, Monza, Italy
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Rollas K, Hanci P, Topeli A. Effects of end-expiratory lung volume versus PaO 2 guided PEEP determination on respiratory mechanics and oxygenation in moderate to severe ARDS. Exp Lung Res 2021; 48:12-22. [PMID: 34957895 DOI: 10.1080/01902148.2021.2021326] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
There is no ideal method for determination of positive end-expiratory pressure (PEEP) in acute respiratory distress syndrome (ARDS) patients. We compared the effects of end-expiratory lung volume (EELV)-guided versus PaO2-guided PEEP determination on respiratory mechanics and oxygenation during the first 48 hours in moderate to severe ARDS. Twenty-two patients with moderate to severe ARDS admitted to an academic medical ICU were assigned to PaO2-guided (n = 11) or to EELV-guided PEEP determination (n = 11) group. First, an incremental PEEP trial was performed by increasing PEEP by 3 cmH2O steps from 8 to 20 cmH2O and in each step EELV and lung mechanics were measured in both groups. Then, oxygenation and respiratory mechanics were measured under the determined PEEP at 4, 12, 24, and 48th hours. After the incremental PEEP trial, over the 48 hours of the study period, in the EELV-guided group PaO2 and PaO2/FiO2 increased (p = 0.04 and p = 0.02; respectively), whereas they did not change in PaO2-guided group (p = 0.09 and p = 0.27; respectively). In all patients, the median value of EELV change (ΔEELV) during incremental PEEP trial was 25%. In patients with ΔEELV > 25% (n = 11) PaO2, PaO2/FiO2 and Cs increased over time in 48 hours (p = 0.03, p < 0.01, and p = 0.04; respectively), whereas they did not change in those with ΔEELV ≤ 25% (n = 11) (p = 0.73, p = 0.51, and p = 0.73; respectively). Compared to PaO2-guided PEEP determination, EELV-guided PEEP determination resulted in greater improvement in oxygenation over time. Patients who had > 25% improvement in EELV during a PEEP trial had greater improvement in oxygenation and compliance over 48 hours. Supplemental data for this article is available online at.
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Affiliation(s)
- Kazim Rollas
- Division of Intensive Care Medicine, Department of Anaesthesiology, Tepecik Training and Research Hospital, Izmir, Turkey
| | - Pervin Hanci
- Division of Intensive Care Medicine, Department of Pulmonology, Trakya University Faculty of Medicine, Edirne, Turkey
| | - Arzu Topeli
- Division of Intensive Care Medicine, Department of Internal Medicine, Faculty of Medicine, Hacettepe University, Ankara, Turkey
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7
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Cheng JC, Chen HC, Jerng JS, Kuo PH, Wu HD. End-Expiratory Lung Volumes During Spontaneous Breathing Trials in Tracheostomized Subjects on Prolonged Mechanical Ventilation. Respir Care 2021; 66:1704-1712. [PMID: 34465570 PMCID: PMC9993541 DOI: 10.4187/respcare.08957] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND The role of end-expiratory lung volume (EELV) during a spontaneous breathing trial (SBT) in patients who were tracheostomized and on prolonged mechanical ventilation is unclear. This study aimed to assess EELV during a 60-min SBT and its correlation with weaning success. METHODS Enrolled subjects admitted to a weaning unit were measured for EELV and relevant parameters before and after the SBT. RESULTS Of the 44 enrolled subjects, 29 (66%) were successfully liberated, defined as not needing mechanical ventilation for 5 d. The success group had fewer subjects with chronic kidney disease (41% vs 73%, P = .044), stronger mean ± SD maximum inspiratory pressure (41.6 ± 10.4 vs 34.1 ± 7.1 cm H2O; P = .02) and mean ± SD maximum expiratory pressure (46.9 ± 11.7 vs 35.3 ± 16.9 cm H2O; P = .01) versus the failure group. Toward the end of the SBT, the success group had a significant increase in the mean ± SD EELV (before vs after: 1,278 ± 744 vs 1,493 ± 867 mL; P = .040) and a decrease in the mean ± SD rapid shallow breathing index (83.8 ± 39.4 vs 66.3 ± 29.4; P = .02), whereas there were no significant changes in these 2 parameters in the failure group. The Cox regression analysis showed that, at the beginning of SBT, a greater difference between EELV with a PEEP of 0 cm H2O and with a PEEP of 5 cm H2O was significantly correlated to a higher likelihood of weaning success. Toward the end of the SBT, a greater EELV level at a PEEP of 0 cm H2O was also correlated with weaning success. Also, the greater difference of EELV at a PEEP of 0 cm H2O between the beginning and the end of the SBT was also correlated with a shorter duration to weaning success. CONCLUSIONS The change in EELV during a 60-min SBT may be of prognostic value for liberation from prolonged mechanical ventilation in patients who had a tracheostomy. Our findings suggest a model to understand the underlying mechanism of failure of liberation from mechanical ventilation in these patients.
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Affiliation(s)
- Jui-Chen Cheng
- Division of Respiratory Therapy, Department of Integrated Diagnostics and Therapeutics, National Taiwan University Hospital, Taipei, Taiwan
| | - Hui-Chuan Chen
- Division of Respiratory Therapy, Department of Integrated Diagnostics and Therapeutics, National Taiwan University Hospital, Taipei, Taiwan
| | - Jih-Shuin Jerng
- Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan.
| | - Ping-Hung Kuo
- Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan
| | - Huey-Dong Wu
- Division of Respiratory Therapy, Department of Integrated Diagnostics and Therapeutics, National Taiwan University Hospital, Taipei, Taiwan
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8
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Radhakrishnan S, Nair SG, Isaac J. Multilayer perceptron neural network model development for mechanical ventilator parameters prediction by real time system learning. Biomed Signal Process Control 2021; 71:103170. [PMID: 34567236 PMCID: PMC8450520 DOI: 10.1016/j.bspc.2021.103170] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Revised: 08/17/2021] [Accepted: 09/07/2021] [Indexed: 02/02/2023]
Abstract
Background and objective In pandemic situations like COVID 19, real time monitoring of patient condition and continuous delivery of inspired oxygen can be made possible only through artificial intelligence-based system modeling. Even now manual control of mechanical ventilator parameters is continuing despite the ever-increasing number of patients in critical epidemic conditions. Here a suggestive multi-layer perceptron neural network model is developed to predict the level of inspired oxygen delivered by the mechanical ventilator along with mode and positive end expiratory pressure (PEEP) changes for reducing the effort of health care professionals. Methods The artificial neural network model is developed by Python programming using real time data. Parameter identification for model inputs and outputs is done by in corporating consistent real time patient data including periodical arterial blood gas analysis, continuous pulse oximetry readings and mechanical ventilator settings using statistical pairwise analysis using R programming. Results Mean square error values and R values of the model are calculated and found to be an average of 0.093 and 0.81 respectively for various data sets. Accuracy loss will be in good fit with validation loss for a comparable number of epochs. Conclusions Comparison of the model output is undertaken with physician’s prediction using statistical analysis and shows an accuracy error of 4.11 percentages which is permissible for a good predictive system.
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Affiliation(s)
- Sita Radhakrishnan
- Department of Instrumentation, Cochin University of Science and Technology, Kochi, Kerala 682022, India
| | - Suresh G Nair
- Anesthesia and Critical Care, Aster Medcity, Kochi, Kerala 682034, India
| | - Johney Isaac
- Department of Instrumentation, Cochin University of Science and Technology, Kochi, Kerala 682022, India
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9
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McAlinden B, Kuys S, Schibler A, Hough JL. Chest physiotherapy improves regional lung volume in ventilated children. Crit Care 2020; 24:440. [PMID: 32677990 PMCID: PMC7364137 DOI: 10.1186/s13054-020-03156-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Accepted: 07/05/2020] [Indexed: 11/24/2022]
Affiliation(s)
- Bronagh McAlinden
- School of Allied Health, Australian Catholic University, Banyo, QLD, 4014, Australia.,Mater Health, South Brisbane, 4101, Australia
| | - Suzanne Kuys
- School of Allied Health, Australian Catholic University, Banyo, QLD, 4014, Australia
| | - Andreas Schibler
- Paediatric Critical Care Research Group, Children's Health Research Centre - The University of Queensland, South Brisbane, 4101, Australia
| | - Judith L Hough
- School of Allied Health, Australian Catholic University, Banyo, QLD, 4014, Australia. .,Mater Health, South Brisbane, 4101, Australia. .,Paediatric Critical Care Research Group, Children's Health Research Centre - The University of Queensland, South Brisbane, 4101, Australia.
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Webb JB, Bray A, Clipp RB. Parameterization of Respiratory Physiology and Pathophysiology for Real-Time Simulation. Annu Int Conf IEEE Eng Med Biol Soc 2020; 2020:2274-2278. [PMID: 33018461 DOI: 10.1109/embc44109.2020.9176364] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We have refactored the Pulse Physiology Engine respiratory software with enhanced parameterization for improved simulation functionality and results. Realistic patient variability can be applied using discretized lumped-parameters that define lung volumes, compliances, and resistances. A new sigmoid compliance waveform helps meet validation of compartment pressures, flows, volumes, and substance values. Further parameterization and enhanced logic for the application of pathophysiology allows for more accurate modeling of both restrictive and obstructive diseases for mild, moderate, and severe cases.Clinical Relevance- This free and open model provides a well-validated respiratory system for integration with medical simulations and research. It improves the Pulse modeling software and allows for new, low-cost training and in silico testing use-cases. Applications include virtual/augmented environments, manikin-based simulations, and clinical explorations.
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11
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Chen HC, Ruan SY, Huang CT, Huang PY, Chien JY, Kuo LC, Kuo PH, Wu HD. Pre-extubation functional residual capacity and risk of extubation failure among patients with hypoxemic respiratory failure. Sci Rep 2020; 10:937. [PMID: 31969674 PMCID: PMC6976564 DOI: 10.1038/s41598-020-58008-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2019] [Accepted: 01/09/2020] [Indexed: 11/29/2022] Open
Abstract
Hypoxemic respiratory failure is usually accompanied with a certain extent of consolidation and alveolar derecruitment, which may still be present even after the patients have achieved the status of readiness to extubate. Functional residual capacity (FRC) is an indicator of lung aeration. This study aimed to evaluate whether pre-extubation FRC is associated with the risk of extubation failure in patients with hypoxemic respiratory failure. We prospectively included 92 patients intubated for hypoxemic respiratory failure. We used a technique based on a nitrogen multiple breath washout method to measure FRC before the planned extubation. The median FRC before extubation was 25 mL/kg (Interquartile range, 20–32 mL/Kg) per predicted body weight (pBW). After extubation, 20 patients (21.7%) were reintubated within 48 hours. The median FRC was higher in the extubation success group than in the extubation failure group (27 versus 21 mL/Kg, p < 0.001). Reduced FRC was associated with higher risk of extubation failure (odds ratio, 1.14 per each decreased of 1 mL/Kg of FRC/pBW, 95% CI, 1.05–1.23, p = 0.002). In conclusion, pre-extubation FRC is associated with the risk of extubation failure. Reduced FRC may be incorporated into the traditional risk factors to identify patients at high risk for extubation failure.
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Affiliation(s)
- Hui-Chuan Chen
- Division of Respiratory Therapy, Department of Integrated Diagnostic and Therapeutics, National Taiwan University Hospital, Taipei, Taiwan
| | - Sheng-Yuan Ruan
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, National Taiwan University Hospital and College of Medicine, Taipei, Taiwan.
| | - Chun-Ta Huang
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, National Taiwan University Hospital and College of Medicine, Taipei, Taiwan
| | - Pei-Yu Huang
- Division of Respiratory Therapy, Department of Integrated Diagnostic and Therapeutics, National Taiwan University Hospital, Taipei, Taiwan
| | - Jung-Yien Chien
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, National Taiwan University Hospital and College of Medicine, Taipei, Taiwan
| | - Lu-Cheng Kuo
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, National Taiwan University Hospital and College of Medicine, Taipei, Taiwan
| | - Ping-Hung Kuo
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, National Taiwan University Hospital and College of Medicine, Taipei, Taiwan
| | - Huey-Dong Wu
- Division of Respiratory Therapy, Department of Integrated Diagnostic and Therapeutics, National Taiwan University Hospital, Taipei, Taiwan.,Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, National Taiwan University Hospital and College of Medicine, Taipei, Taiwan
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Marchioni A, Tonelli R, Fantini R, Tabbì L, Castaniere I, Livrieri F, Bedogni S, Ruggieri V, Pisani L, Nava S, Clini E. Respiratory Mechanics and Diaphragmatic Dysfunction in COPD Patients Who Failed Non-Invasive Mechanical Ventilation. Int J Chron Obstruct Pulmon Dis 2019; 14:2575-2585. [PMID: 31819395 PMCID: PMC6879385 DOI: 10.2147/copd.s219125] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Accepted: 09/23/2019] [Indexed: 01/10/2023] Open
Abstract
Background Although non-invasive mechanical ventilation (NIV) is the gold standard treatment for patients with acute exacerbation of COPD (AECOPD) developing respiratory acidosis, failure rates still range from 5% to 40%. Recent studies have shown that the onset of severe diaphragmatic dysfunction (DD) during AECOPD increases risk of NIV failure and mortality in this subset of patients. Although the imbalance between the load and the contractile capacity of inspiratory muscles seems the main cause of AECOPD-induced hypercapnic respiratory failure, data regarding the influence of mechanical derangement on DD in this acute phase are lacking. With this study, we investigate the impact of respiratory mechanics on diaphragm function in AECOPD patients experiencing NIV failure. Methods Twelve AECOPD patients with respiratory acidosis admitted to the Respiratory ICU of the University Hospital of Modena from 2017 to 2018 undergoing mechanical ventilation (MV) due to NIV failure were enrolled. Static respiratory mechanics and end-expiratory lung volume (EELV) were measured after 30 mins of volume control mode MV. Subsequently, transdiaphragmatic pressure (Pdi) was calculated by means of a sniff maneuver (Pdisniff) after 30 mins of spontaneous breathing trial. Linear regression analysis and Pearson’s correlation coefficient served to assess associations. Results Average Pdisniff was 23.3 cmH2O (standard deviation 29 cmH2O) with 3 patients presenting bilateral diaphragm palsy. Pdisniff was directly correlated with static lung elastance (r=0.69, p=0.001) while inverse correlation was found with dynamic intrinsic PEEP (r=−0.73, p=0.007). No significant correlation was found with static intrinsic PEEP (r=−0.55, p=0.06), EELV (r=−0.4, p=0.3), airway resistance (r=−0.2, p=0.54), chest wall, and total elastance (r=−0-01, p=0.96 and r=0.3, p=0.36, respectively). Significant linear inverse correlation was found between Pdisniff and the ratio between Pdi assessed at tidal volume and Pdi sniff (r=−0.82, p=0.02). Conclusion The causes of extreme DD in AECOPD patients who experienced NIV failure might be predominantly mechanical, driven by a severe dynamic hyperinflation that overlaps on an elastic lung substrate favoring volume overload.
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Affiliation(s)
- Alessandro Marchioni
- University Hospital of Modena, Pneumology Unit and Center for Rare Lung Diseases, Department of Medical and Surgical Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Roberto Tonelli
- University Hospital of Modena, Pneumology Unit and Center for Rare Lung Diseases, Department of Medical and Surgical Sciences, University of Modena and Reggio Emilia, Modena, Italy.,PhD Course in Clinical and Experimental Medicine, University of Modena and Reggio Emilia, Modena, Italy
| | - Riccardo Fantini
- University Hospital of Modena, Pneumology Unit and Center for Rare Lung Diseases, Department of Medical and Surgical Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Luca Tabbì
- University Hospital of Modena, Pneumology Unit and Center for Rare Lung Diseases, Department of Medical and Surgical Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Ivana Castaniere
- University Hospital of Modena, Pneumology Unit and Center for Rare Lung Diseases, Department of Medical and Surgical Sciences, University of Modena and Reggio Emilia, Modena, Italy.,PhD Course in Clinical and Experimental Medicine, University of Modena and Reggio Emilia, Modena, Italy
| | - Francesco Livrieri
- University Hospital of Modena, Pneumology Unit and Center for Rare Lung Diseases, Department of Medical and Surgical Sciences, University of Modena and Reggio Emilia, Modena, Italy.,Respiratory Disease Unit, Hospital Carlo Poma, Mantova, Italy
| | - Sabrina Bedogni
- School of Medicine, University of Modena and Reggio Emilia, Modena, Italy
| | - Valentina Ruggieri
- University Hospital of Modena, Pneumology Unit and Center for Rare Lung Diseases, Department of Medical and Surgical Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Lara Pisani
- Department of Specialistic, Diagnostic and Experimental Medicine (DIMES), University of Bologna, Bologna, Italy
| | - Stefano Nava
- Department of Specialistic, Diagnostic and Experimental Medicine (DIMES), University of Bologna, Bologna, Italy
| | - Enrico Clini
- University Hospital of Modena, Pneumology Unit and Center for Rare Lung Diseases, Department of Medical and Surgical Sciences, University of Modena and Reggio Emilia, Modena, Italy
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Muders T, Hentze B, Simon P, Girrbach F, Doebler MRG, Leonhardt S, Wrigge H, Putensen C. A Modified Method to Assess Tidal Recruitment by Electrical Impedance Tomography. J Clin Med 2019; 8:jcm8081161. [PMID: 31382559 PMCID: PMC6723902 DOI: 10.3390/jcm8081161] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2019] [Revised: 07/29/2019] [Accepted: 08/01/2019] [Indexed: 12/11/2022] Open
Abstract
Avoiding tidal recruitment and collapse during mechanical ventilation should reduce the risk of lung injury. Electrical impedance tomography (EIT) enables detection of tidal recruitment by measuring regional ventilation delay inhomogeneity (RVDI) during a slow inflation breath with a tidal volume (VT) of 12 mL/kg body weight (BW). Clinical applicability might be limited by such high VTs resulting in high end-inspiratory pressures (PEI) during positive end-expiratory pressure (PEEP) titration. We hypothesized that RVDI can be obtained with acceptable accuracy from reduced slow inflation VTs. In seven ventilated pigs with experimental lung injury, tidal recruitment was quantified by computed tomography at PEEP levels changed stepwise between 0 and 25 cmH2O. RVDI was measured by EIT during slow inflation VTs of 12, 9, 7.5, and 6 mL/kg BW. Linear correlation of tidal recruitment and RVDI was excellent for VTs of 12 (R2 = 0.83, p < 0.001) and 9 mL/kg BW (R2 = 0.83, p < 0.001) but decreased for VTs of 7.5 (R2 = 0.76, p < 0.001) and 6 mL/kg BW (R2 = 0.71, p < 0.001). With any reduction in slow inflation VT, PEI decreased at all PEEP levels. Receiver-Operator-Characteristic curve analyses revealed that RVDI-thresholds to predict distinct amounts of tidal recruitment differ when obtained from different slow inflation VTs. In conclusion, tidal recruitment can sufficiently be monitored by EIT-based RVDI-calculation with a slow inflation of 9 mL/kg BW.
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Affiliation(s)
- Thomas Muders
- Department of Anesthesiology and Intensive Care Medicine, University Hospital Bonn, Bonn 53127, Germany.
| | - Benjamin Hentze
- Department of Anesthesiology and Intensive Care Medicine, University Hospital Bonn, Bonn 53127, Germany
- Chair for Medical Information Technology, RWTH Aachen University, Aachen 52074, Germany
| | - Philipp Simon
- Department of Anesthesiology and Intensive Care Medicine, University of Leipzig, Leipzig 04103, Germany
| | - Felix Girrbach
- Department of Anesthesiology and Intensive Care Medicine, University of Leipzig, Leipzig 04103, Germany
| | - Michael R G Doebler
- Department of Anesthesiology and Intensive Care Medicine, University Hospital Bonn, Bonn 53127, Germany
| | - Steffen Leonhardt
- Chair for Medical Information Technology, RWTH Aachen University, Aachen 52074, Germany
| | - Hermann Wrigge
- Department of Anesthesiology, Intensive Care and Emergency Medicine, Pain Therapy, Bergmannstrost Hospital Halle, Halle 06112, Germany
| | - Christian Putensen
- Department of Anesthesiology and Intensive Care Medicine, University Hospital Bonn, Bonn 53127, Germany
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Magalhães PAF, Padilha GA, Moraes L, Santos CL, Maia LA, Braga CL, Duarte MDCMB, Andrade LB, Schanaider A, Capellozzi VL, Huhle R, Gama de Abreu M, Pelosi P, Rocco PRM, Silva PL. Effects of pressure support ventilation on ventilator-induced lung injury in mild acute respiratory distress syndrome depend on level of positive end-expiratory pressure: A randomised animal study. Eur J Anaesthesiol 2018; 35:298-306. [PMID: 29324568 DOI: 10.1097/EJA.0000000000000763] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Harmful effects of spontaneous breathing have been shown in experimental severe acute respiratory distress syndrome (ARDS). However, in the clinical setting, spontaneous respiration has been indicated only in mild ARDS. To date, no study has compared the effects of spontaneous assisted breathing with those of fully controlled mechanical ventilation at different levels of positive end-expiratory pressure (PEEP) on lung injury in ARDS. OBJECTIVE To compare the effects of assisted pressure support ventilation (PSV) with pressure-controlled ventilation (PCV) on lung function, histology and biological markers at two different PEEP levels in mild ARDS in rats. DESIGN Randomised controlled experimental study. SETTING Basic science laboratory. PARTICIPANTS Thirty-five Wistar rats (weight ± SD, 310 ± 19) g received Escherichia coli lipopolysaccharide (LPS) intratracheally. After 24 h, the animals were anaesthetised and randomly allocated to either PCV (n=14) or PSV (n=14) groups. Each group was further assigned to PEEP = 2 cmH2O or PEEP = 5 cmH2O. Tidal volume was kept constant (≈6 ml kg). Additional nonventilated animals (n=7) were used as a control for postmortem analysis. MAIN OUTCOME MEASURES Ventilatory and mechanical parameters, arterial blood gases, diffuse alveolar damage score, epithelial integrity measured by E-cadherin tissue expression, and biological markers associated with inflammation (IL-6 and cytokine-induced neutrophil chemoattractant, CINC-1) and type II epithelial cell damage (surfactant protein-B) were evaluated. RESULTS In both PCV and PSV, peak transpulmonary pressure was lower, whereas E-cadherin tissue expression, which is related to epithelial integrity, was higher at PEEP = 5 cmH2O than at PEEP = 2 cmH2O. In PSV, PEEP = 5 cmH2O compared with PEEP = 2 cmH2O was associated with significantly reduced diffuse alveolar damage score [median (interquartile range), 11 (8.5 to 13.5) vs. 23 (19 to 26), P = 0.005] and expressions of IL-6 and CINC-1 (P = 0.02 for both), whereas surfactant protein-B mRNA expression increased (P = 0.03). These changes suggested less type II epithelial cell damage at a PEEP of 5 cmH2O. Peak transpulmonary pressure correlated positively with IL-6 [Spearman's rho (ρ) = 0.62, P = 0.0007] and CINC-1 expressions (ρ = 0.50, P = 0.01) and negatively with E-cadherin expression (ρ = -0.67, P = 0.0002). CONCLUSION During PSV, PEEP of 5 cmH2O, but not a PEEP of 2 cmH2O, reduced lung damage and inflammatory markers while maintaining epithelial cell integrity.
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Grieco DL, Russo A, Romanò B, Anzellotti GM, Ciocchetti P, Torrini F, Barelli R, Eleuteri D, Perilli V, Dell'Anna AM, Bongiovanni F, Sollazzi L, Antonelli M. Lung volumes, respiratory mechanics and dynamic strain during general anaesthesia. Br J Anaesth 2018; 121:1156-1165. [PMID: 30336861 DOI: 10.1016/j.bja.2018.03.022] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2018] [Revised: 03/11/2018] [Accepted: 03/28/2018] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Driving pressure (ΔP) represents tidal volume normalised to respiratory system compliance (CRS) and is a novel parameter to target ventilator settings. We conducted a study to determine whether CRS and ΔP reflect aerated lung volume and dynamic strain during general anaesthesia. METHODS Twenty non-obese patients undergoing open abdominal surgery received three PEEP levels (2, 7, or 12 cm H2O) in random order with constant tidal volume ventilation. Respiratory mechanics, lung volumes, and alveolar recruitment were measured to assess end-expiratory aerated volume, which was compared with the patient's individual predicted functional residual capacity in supine position (FRCp). RESULTS CRS was linearly related to aerated volume and ΔP to dynamic strain at PEEP of 2 cm H2O (intraoperative FRC) (r=0.72 and r=0.73, both P<0.001). These relationships were maintained with higher PEEP only when aerated volume did not overcome FRCp (r=0.73, P<0.001; r=0.54, P=0.004), with 100 ml lung volume increases accompanied by 1.8 ml cm H2O-1 (95% confidence interval [1.1-2.5]) increases in CRS. When aerated volume was greater or equal to FRCp (35% of patients at PEEP 2 cm H2O, 55% at PEEP 7 cm H2O, and 75% at PEEP 12 cm H2O), CRS and ΔP were independent from aerated volume and dynamic strain, with CRS weakly but significantly inversely related to alveolar dead space fraction (r=-0.47, P=0.001). PEEP-induced alveolar recruitment yielded higher CRS and reduced ΔP only at aerated volumes below FRCp (P=0.015 and 0.008, respectively). CONCLUSIONS During general anaesthesia, respiratory system compliance and driving pressure reflect aerated lung volume and dynamic strain, respectively, only if aerated volume does not exceed functional residual capacity in supine position, which is a frequent event when PEEP is used in this setting.
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Affiliation(s)
- D L Grieco
- Department of Anesthesiology and Intensive Care Medicine, Catholic University of the Sacred Heart, Fondazione "Policlinico Universitario A. Gemelli", Rome, Italy.
| | - A Russo
- Department of Anesthesiology and Intensive Care Medicine, Catholic University of the Sacred Heart, Fondazione "Policlinico Universitario A. Gemelli", Rome, Italy
| | - B Romanò
- Department of Anesthesiology and Intensive Care Medicine, Catholic University of the Sacred Heart, Fondazione "Policlinico Universitario A. Gemelli", Rome, Italy
| | - G M Anzellotti
- Department of Anesthesiology and Intensive Care Medicine, Catholic University of the Sacred Heart, Fondazione "Policlinico Universitario A. Gemelli", Rome, Italy
| | - P Ciocchetti
- Department of Anesthesiology and Intensive Care Medicine, Catholic University of the Sacred Heart, Fondazione "Policlinico Universitario A. Gemelli", Rome, Italy
| | - F Torrini
- Department of Anesthesiology and Intensive Care Medicine, Catholic University of the Sacred Heart, Fondazione "Policlinico Universitario A. Gemelli", Rome, Italy
| | - R Barelli
- Department of Anesthesiology and Intensive Care Medicine, Catholic University of the Sacred Heart, Fondazione "Policlinico Universitario A. Gemelli", Rome, Italy
| | - D Eleuteri
- Department of Anesthesiology and Intensive Care Medicine, Catholic University of the Sacred Heart, Fondazione "Policlinico Universitario A. Gemelli", Rome, Italy
| | - V Perilli
- Department of Anesthesiology and Intensive Care Medicine, Catholic University of the Sacred Heart, Fondazione "Policlinico Universitario A. Gemelli", Rome, Italy
| | - A M Dell'Anna
- Department of Anesthesiology and Intensive Care Medicine, Catholic University of the Sacred Heart, Fondazione "Policlinico Universitario A. Gemelli", Rome, Italy
| | - F Bongiovanni
- Department of Anesthesiology and Intensive Care Medicine, Catholic University of the Sacred Heart, Fondazione "Policlinico Universitario A. Gemelli", Rome, Italy
| | - L Sollazzi
- Department of Anesthesiology and Intensive Care Medicine, Catholic University of the Sacred Heart, Fondazione "Policlinico Universitario A. Gemelli", Rome, Italy
| | - M Antonelli
- Department of Anesthesiology and Intensive Care Medicine, Catholic University of the Sacred Heart, Fondazione "Policlinico Universitario A. Gemelli", Rome, Italy
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Abstract
INTRODUCTION The mortality of patients with respiratory failure has steadily decreased with the advancements in protective ventilation and treatment options. Although respiratory monitoring per se has not been proven to affect the mortality of critically ill patients, it plays a crucial role in patients' care, as it helps to titrate the ventilatory support. Several new monitoring techniques have recently been made available at the bedside. The goals of monitoring comprise alerting physicians to detect the change in the patients' conditions, to improve the understanding of pathophysiology to guide the diagnosis and provide cost-effective clinical management. Areas covered: We performed a review of the recent scientific literature to provide an overview of the different methods used for respiratory monitoring in adult intensive care units, including bedside imaging techniques such as ultrasound and electrical impedance tomography. Expert commentary: Appropriate respiratory monitoring plays an important role in patients with and without respiratory failure as a guiding tool for the optimization of ventilation support, avoiding further complications and decreasing morbidity and mortality. The physician should tailor the monitoring strategy for each individual patient and know how to correctly interpret the data.
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Affiliation(s)
- Pongdhep Theerawit
- a Division of Pulmonary and Critical Care Medicine, Department of Medicine, Faculty of Medicine Ramathibodi Hospital , Mahidol University , Bangkok , Thailand
| | - Yuda Sutherasan
- a Division of Pulmonary and Critical Care Medicine, Department of Medicine, Faculty of Medicine Ramathibodi Hospital , Mahidol University , Bangkok , Thailand
| | - Lorenzo Ball
- b IRCCS AOU San Martino-IST, Department of Surgical Sciences and Integrated Diagnostics , University of Genoa , Genoa , Italy
| | - Paolo Pelosi
- b IRCCS AOU San Martino-IST, Department of Surgical Sciences and Integrated Diagnostics , University of Genoa , Genoa , Italy
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17
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Nakstad ER, Opdahl H, Heyerdahl F, Borchsenius F, Skjønsberg OH. Manual ventilation and open suction procedures contribute to negative pressures in a mechanical lung model. BMJ Open Respir Res 2017; 4:e000176. [PMID: 28725445 PMCID: PMC5501241 DOI: 10.1136/bmjresp-2016-000176] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Revised: 02/22/2017] [Accepted: 03/03/2017] [Indexed: 11/03/2022] Open
Abstract
INTRODUCTION Removal of pulmonary secretions in mechanically ventilated patients usually requires suction with closed catheter systems or flexible bronchoscopes. Manual ventilation is occasionally performed during such procedures if clinicians suspect inadequate ventilation. Suctioning can also be performed with the ventilator entirely disconnected from the endotracheal tube (ETT). The aim of this study was to investigate if these two procedures generate negative airway pressures, which may contribute to atelectasis. METHODS The effects of device insertion and suctioning in ETTs were examined in a mechanical lung model with a pressure transducer inserted distal to ETTs of 9 mm, 8 mm and 7 mm internal diameter (ID). A 16 Fr bronchoscope and 12, 14 and 16 Fr suction catheters were used at two different vacuum levels during manual ventilation and with the ETTs disconnected. RESULTS During manual ventilation with ETTs of 9 mm, 8 mm and 7 mm ID, and bronchoscopic suctioning at moderate suction level, peak pressure (PPEAK) dropped from 23, 22 and 24.5 cm H2O to 16, 16 and 15 cm H2O, respectively. Maximum suction reduced PPEAK to 20, 17 and 11 cm H2O, respectively, and the end-expiratory pressure fell from 5, 5.5 and 4.5 cm H2O to -2, -6 and -17 cm H2O. Suctioning through disconnected ETTs (open suction procedure) gave negative model airway pressures throughout the duration of the procedures. CONCLUSIONS Manual ventilation and open suction procedures induce negative end-expiratory pressure during endotracheal suctioning, which may have clinical implications in patients who need high PEEP (positive end-expiratory pressure).
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Affiliation(s)
- Espen Rostrup Nakstad
- Department of Acute Medicine, Oslo University Hospital, Ullevaal, Norway.,Department of Pulmonary Medicine, Oslo University Hospital, Ullevaal, Norway
| | - Helge Opdahl
- Department of Acute Medicine, Oslo University Hospital, Ullevaal, Norway
| | - Fridtjof Heyerdahl
- Department of Anesthesiology, Oslo University Hospital, Ullevaal, Norway
| | - Fredrik Borchsenius
- Department of Pulmonary Medicine, Oslo University Hospital, Ullevaal, Norway
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Motta-Ribeiro GC, Jandre FC, Wrigge H, Giannella-Neto A. Generalized estimation of the ventilatory distribution from the multiple-breath nitrogen washout. Biomed Eng Online 2016; 15:89. [PMID: 27480332 PMCID: PMC4970303 DOI: 10.1186/s12938-016-0213-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Accepted: 07/24/2016] [Indexed: 11/23/2022] Open
Abstract
BACKGROUND This work presents a generalized technique to estimate pulmonary ventilation-to-volume (v/V) distributions using the multiple-breath nitrogen washout, in which both tidal volume (V T ) and the end-expiratory lung volume (EELV) are allowed to vary during the maneuver. In addition, the volume of the series dead space (v d ), unlike the classical model, is considered a common series unit connected to a set of parallel alveolar units. METHODS The numerical solution for simulated data, either error-free or with the N2 measurement contaminated with the addition of Gaussian random noise of 3 or 5 % standard deviation was tested under several conditions in a computational model constituted by 50 alveolar units with unimodal and bimodal distributions of v/V. Non-negative least squares regression with Tikhonov regularization was employed for parameter retrieval. The solution was obtained with either unconstrained or constrained (V T , EELV and v d ) conditions. The Tikhonov gain was fixed or estimated and a weighting matrix (WM) was considered. The quality of estimation was evaluated by the sum of the squared errors (SSE) (between reference and recovered distributions) and by the deviations of the first three moments calculated for both distributions. Additionally, a shape classification method was tested to identify the solution as unimodal or bimodal, by counting the number of shape agreements after 1000 repetitions. RESULTS The accuracy of the results showed a high dependence on the noise amplitude. The best algorithm for SSE and moments included the constrained and the WM solvers, whereas shape agreement improved without WM, resulting in 97.2 % for unimodal and 90.0 % for bimodal distributions in the highest noise condition. CONCLUSIONS In conclusion this generalized method was able to identify v/V distributions from a lung model with a common series dead space even with variable V T . Although limitations remain in presence of experimental noise, appropriate combination of processing steps were also found to reduce estimation errors.
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Affiliation(s)
- Gabriel Casulari Motta-Ribeiro
- Pulmonary Engineering Laboratory, Biomedical Engineering Programme, COPPE, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Frederico Caetano Jandre
- Pulmonary Engineering Laboratory, Biomedical Engineering Programme, COPPE, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Hermann Wrigge
- Department of Anesthesiology and Intensive Care Medicine, University of Leipzig, Leipzig, Germany
| | - Antonio Giannella-Neto
- Pulmonary Engineering Laboratory, Biomedical Engineering Programme, COPPE, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
- Department of Anesthesiology and Intensive Care Medicine, University of Leipzig, Leipzig, Germany
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Nakstad ER, Opdahl H, Heyerdahl F, Borchsenius F, Skjønsberg OH. Can ventilator settings reduce the negative effects of endotracheal suctioning? Investigations in a mechanical lung model. BMC Anesthesiol 2016; 16:30. [PMID: 27350249 PMCID: PMC4924309 DOI: 10.1186/s12871-016-0196-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2015] [Accepted: 05/13/2016] [Indexed: 11/17/2022] Open
Abstract
Background The insertion of suction devices through endotracheal tubes (ETTs) increases airway resistance and the subsequent suctioning may reduce airway pressures and facilitate atelectasis. The aim of this study was to investigate how airway pressures and tidal volumes change when different combinations of suction equipment and ETT sizes are used, and to what extent unfavorable effects can be ameliorated by choice of ventilator settings. Methods A mechanical ventilator was connected to a lung model by ETTs of 9 mm, 8 mm or 7 mm internal diameter (ID) with a pressure transducer inserted distal to the ETT. The effects of suction procedures with bronchoscope and closed catheter systems were investigated during pressure controlled ventilation (PCV) and volume controlled ventilation (VCV). In each mode, the effects of changes in inspiration:expiration (I:E) ratio, trigger sensitivity and suction pressure were examined. Results The variables that contributed most to negative model airway pressures and loss of tidal volume during suctioning were (in descending order); 1) Small-size ETTs (7–8 mm ID) combined with large diameter suction devices (14–16 Fr); 2) inverse I:E ratio ventilation (in VCV); 3) negative ventilator trigger sensitivity; and 4) strong suction pressure. The pressure changes observed distal to the ETTs were not identical to those detected by the ventilator. Conclusions Negative model airway pressure was induced by suctioning through small-size ETTs. The most extreme pressure and volume changes were ameliorated when conventional ventilator settings were used, such as PCV mode with short inspiration time and a trigger function sensitive to flow changes. Electronic supplementary material The online version of this article (doi:10.1186/s12871-016-0196-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Espen R Nakstad
- Department of Acute Medicine, Oslo University Hospital, Ullevaal, Oslo, Norway. .,Department of Pulmonary Medicine, Oslo University Hospital, Ullevaal, Oslo, Norway.
| | - Helge Opdahl
- Department of Acute Medicine, Oslo University Hospital, Ullevaal, Oslo, Norway
| | - Fridtjof Heyerdahl
- Department of Acute Medicine, Oslo University Hospital, Ullevaal, Oslo, Norway
| | - Fredrik Borchsenius
- Department of Pulmonary Medicine, Oslo University Hospital, Ullevaal, Oslo, Norway
| | - Ole H Skjønsberg
- Department of Pulmonary Medicine, Oslo University Hospital, Ullevaal, Oslo, Norway.,University of Oslo, Oslo, Norway
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Kalenka A, Gruner F, Weiß C, Viergutz T. End-Expiratory Lung Volume in Patients with Acute Respiratory Distress Syndrome: A Time Course Analysis. Lung 2016; 194:527-34. [PMID: 27169535 DOI: 10.1007/s00408-016-9892-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Accepted: 05/02/2016] [Indexed: 10/21/2022]
Abstract
PURPOSE Lung injury can be caused by ventilation and non-physiological lung stress (transpulmonary pressure) and strain [inflated volume over functional residual capacity ratio (FRC)]. FRC is severely decreased in patients with acute respiratory distress syndrome (ARDS). End-expiratory lung volume (EELV) is FRC plus lung volume increased by the applied positive end-expiratory pressure (PEEP). Measurement using the modified nitrogen multiple breath washout technique may help titrating PEEP during ARDS and allow determining dynamic lung strain (tidal volume over EELV) in patients ventilated with PEEP. In this observational study, we measured EELV for up to seven consecutive days in patients with ARDS at different PEEP levels. RESULTS Thirty sedated patients with ARDS (10 mild, 14 moderate, 6 severe) underwent decremental PEEP testing (20, 15, 10, 5 cm H2O) for up to 7 days after inclusion. At all PEEP levels examined, over a period of 7 days the measured absolute EELVs showed no significant change over time [PEEP 20 cm H2O 2464 ml at day 1 vs. 2144 ml at day 7 (p = 0.78), PEEP 15 cm H2O 2226 ml vs. 1990 ml (p = 0.36), PEEP 10 1835 ml vs. 1858 ml (p = 0.76) and PEEP 5 cm H2O 1487 ml vs. 1612 ml (p = 0.37)]. In relation to the predicted body weight (pbw), no significant change in EELV/kg pbw over time could be detected either at any PEEP level or over time [PEEP 20 36 ml/kg pbw at day 1 vs. 33 ml/kg pbw at day 7 (p = 0.66); PEEP 15 33 vs. 29 ml/kg pbw (p = 0.32); PEEP 10 27 vs. 27 ml/kg pbw (p = 0.70) and PEEP 5 22 vs. 24 ml/kg pbw (p = 0.70)]. Oxygenation significantly improved over time from PaO2/FiO2 of 169 mmHg at day 1 to 199 mmHg at day 7 (p < 0.01). CONCLUSIONS EELV did not change significantly for up to 7 days in patients with ARDS. By contrast, PaO2/FiO2 improved significantly. Bedside measurement of EELV may be a novel approach to individualise lung-protective ventilation on the basis of calculation of dynamic strain as the ratio of VT to EELV.
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Sutt AL, Caruana LR, Dunster KR, Cornwell PL, Anstey CM, Fraser JF. Speaking valves in tracheostomised ICU patients weaning off mechanical ventilation--do they facilitate lung recruitment? Crit Care 2016; 20:91. [PMID: 27038617 PMCID: PMC4818462 DOI: 10.1186/s13054-016-1249-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/17/2015] [Accepted: 02/19/2016] [Indexed: 11/10/2022]
Abstract
BACKGROUND Patients who require positive pressure ventilation through a tracheostomy are unable to phonate due to the inflated tracheostomy cuff. Whilst a speaking valve (SV) can be used on a tracheostomy tube, its use in ventilated ICU patients has been inhibited by concerns regarding potential deleterious effects to recovering lungs. The objective of this study was to assess end expiratory lung impedance (EELI) and standard bedside respiratory parameters before, during and after SV use in tracheostomised patients weaning from mechanical ventilation. METHODS A prospective observational study was conducted in a cardio-thoracic adult ICU. 20 consecutive tracheostomised patients weaning from mechanical ventilation and using a SV were recruited. Electrical Impedance Tomography (EIT) was used to monitor patients' EELI. Changes in lung impedance and standard bedside respiratory data were analysed pre, during and post SV use. RESULTS Use of in-line SVs resulted in significant increase of EELI. This effect grew and was maintained for at least 15 minutes after removal of the SV (p < 0.001). EtCO2 showed a significant drop during SV use (p = 0.01) whilst SpO2 remained unchanged. Respiratory rate (RR (breaths per minute)) decreased whilst the SV was in situ (p <0.001), and heart rate (HR (beats per minute)) was unchanged. All results were similar regardless of the patients' respiratory requirements at time of recruitment. CONCLUSIONS In this cohort of critically ill ventilated patients, SVs did not cause derecruitment of the lungs when used in the ventilator weaning period. Deflating the tracheostomy cuff and restoring the airflow via the upper airway with a one-way valve may facilitate lung recruitment during and after SV use, as indicated by increased EELI. TRIAL REGISTRATION Anna-Liisa Sutt, Australian New Zealand Clinical Trials Registry (ANZCTR). ACTRN ACTRN12615000589583. 4/6/2015.
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Affiliation(s)
- Anna-Liisa Sutt
- Critical Care Research Group, The Prince Charles Hospital, Brisbane, Australia. .,School of Medicine, University of Queensland, Brisbane, Australia. .,Speech Pathology Department, The Prince Charles Hospital, Brisbane, Australia.
| | - Lawrence R Caruana
- Critical Care Research Group, The Prince Charles Hospital, Brisbane, Australia.,Physiotherapy Department, The Prince Charles Hospital, Brisbane, Australia
| | - Kimble R Dunster
- Critical Care Research Group, The Prince Charles Hospital, Brisbane, Australia.,Science & Engineering Faculty, Queensland University of Technology, Brisbane, Australia
| | - Petrea L Cornwell
- Allied Health Collaborative, Metro North HHS, Brisbane, Australia.,School of Applied Psychology, Menzies Health Institute Queensland, Griffith University, Brisbane, Australia
| | - Chris M Anstey
- School of Medicine, University of Queensland, Brisbane, Australia.,Critical Care Research Group, Sunshine Coast University Hospital, Brisbane, Australia
| | - John F Fraser
- Critical Care Research Group, The Prince Charles Hospital, Brisbane, Australia.,School of Medicine, University of Queensland, Brisbane, Australia
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Blankman P, Hasan D, Bikker IG, Gommers D. Lung stress and strain calculations in mechanically ventilated patients in the intensive care unit. Acta Anaesthesiol Scand 2016; 60:69-78. [PMID: 26192561 PMCID: PMC6191648 DOI: 10.1111/aas.12589] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2014] [Revised: 04/18/2015] [Accepted: 06/08/2015] [Indexed: 11/28/2022]
Abstract
Background Stress and strain are parameters to describe respiratory mechanics during mechanical ventilation. Calculations of stress require invasive and difficult to perform esophageal pressure measurements. The hypothesis of the present study was: Can lung stress be reliably calculated based on non‐invasive lung volume measurements, during a decremental Positive end‐expiratory pressure (PEEP) trial in mechanically ventilated patients with different diseases? Methods Data of 26 pressure‐controlled ventilated patients admitted to the ICU with different lung conditions were retrospectively analyzed: 11 coronary artery bypass graft (CABG), 9 neurology, and 6 lung disorders. During a decremental PEEP trial (from 15 to 0 cmH2O in three steps) end‐expiratory lung volume (EELV) measurements were performed at each PEEP step, without interruption of mechanical ventilation. Strain, specific elastance, and stress were calculated for each PEEP level. Elastance was calculated as delta PEEP divided by delta PEEP volume, whereas specific elastance is elastance times the FRC. Stress was calculated as specific elastance times the strain. Global strain was divided into dynamic (tidal volume) and static (PEEP) strain. Results Strain calculations based on FRC showed mainly changes in static component, whereas calculations based on EELV showed changes in both the static and dynamic component of strain. Stress calculated from EELV measurements was 24.0 ± 2.7 and 13.1 ± 3.8 cmH2O in the lung disorder group at 15 and 5 cmH2O PEEP. For the normal lungs, the stress values were 19.2 ± 3.2 and 10.9 ± 3.3 cmH2O, respectively. These values are comparable to earlier publications. Specific elastance calculations were comparable in patients with neurologic and lung disorders, and lower in the CABG group due to recruitment in this latter group. Conclusion Stress and strain can reliably be calculated at the bedside based on non‐invasive EELV measurements during a decremental PEEP trial in patients with different diseases.
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Affiliation(s)
- P. Blankman
- Department of Adult Intensive Care; Erasmus MC Rotterdam; Rotterdam The Netherlands
| | - D. Hasan
- Department of Adult Intensive Care; Erasmus MC Rotterdam; Rotterdam The Netherlands
| | - I. G. Bikker
- Department of Adult Intensive Care; Erasmus MC Rotterdam; Rotterdam The Netherlands
| | - D. Gommers
- Department of Adult Intensive Care; Erasmus MC Rotterdam; Rotterdam The Netherlands
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Ramsi MA, Henry M, Milla CE, Cornfield DN. Inhaled β2-Agonist Therapy Increases Functional Residual Capacity in Mechanically Ventilated Children With Respiratory Failure. Pediatr Crit Care Med 2015; 16:e189-93. [PMID: 25901546 DOI: 10.1097/pcc.0000000000000448] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVES To test the hypothesis that in mechanically ventilated children with respiratory failure, aerosolized albuterol modifies functional residual capacity, lung mechanics, oxygen consumption, and hemodynamics. DESIGN Prospective, self-control clinical trial. SETTING A 24-bed PICU in a quaternary care, academic children's hospital. PATIENTS 25 children (age range, 1-18 yr) undergoing mechanical ventilation to treat respiratory failure. Entry criteria included previously prescribed inhaled β2 agonists. Physiologic measurements were performed prior to and 20 minutes after administration of aerosolized albuterol solution. Functional residual capacity was determined via nitrogen washout. INTERVENTIONS Functional residual capacity, oxygen consumption, respiratory mechanics, and vital signs were measured were measured prior to and 20 minutes after administration of aerosolized albuterol solution. Functional residual capacity was determined via nitrogen washout. MEASUREMENT AND MAIN RESULTS At baseline, functional residual capacity is only 53% of predicted. After aerosolized albuterol, functional residual capacity increased by 18.3% (p = 0.008). Overall, aerosolized albuterol had no effect on airway resistance. However, in patients with an endotracheal tube size of more than or equal to 4.0 mm, resistance decreased from 33 ± 3 to 25 ± 3 (p < 0.02). Inhaled albuterol administration had no effect on oxygen consumption despite an increase in heart rate from 116 ± 2 to 128 ± 2 beats/min (p < 0.0001). CONCLUSIONS In pediatric patients with respiratory failure, aerosolized albuterol increases functional residual capacity without a decrease in resistance. In infants and children, aerosolized albuterol might favorably enhance pulmonary mechanics and thereby represent a novel strategy for lung recruitment in children with respiratory failure.
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Affiliation(s)
- Musaab A Ramsi
- 1Division of Pediatric Critical Care Medicine, Sheikh Khalifa Medical City (SKMC) in affiliation with Cleveland Clinic, Abu Dhabi, United Arab Emirates. 2Respiratory Therapy Department, Lucile Packard Children's Hospital at Stanford University, Palo Alto, CA. 3Division of Pulmonary Medicine, Center for Excellence in Pulmonary Biology, Stanford University School of Medicine, Stanford, CA. 4Department of Pediatrics, Center for Excellence in Pulmonary Biology, Stanford University School of Medicine, Stanford, CA
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Abstract
PURPOSE OF REVIEW To discuss the role of measuring functional residual capacity (FRC) during mechanical ventilation to improve patient ventilator settings in order to prevent ventilator-induced lung injury. RECENT FINDINGS Nowadays, FRC can be measured without the use of tracer gases and without disconnection from the ventilator. It is shown that FRC can provide additional information to optimize the ventilator setting; for example, FRC measurements can differentiate between responders and nonresponders after a recruitment maneuver, and in combination with dynamic compliance one can differentiate between recruitment and overdistention during a positive end-expiratory pressure trial. In addition, FRC measurements enable not only to estimate stress and strain at the bedside, but also to estimate ventilation inhomogeneity. SUMMARY In conclusion, measuring FRC could be extremely valuable during mechanical ventilation, but clinical studies are needed to prove whether this technique will improve outcome.
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Ball L, Sutherasan Y, Pelosi P. Monitoring respiration: what the clinician needs to know. Best Pract Res Clin Anaesthesiol 2014; 27:209-23. [PMID: 24012233 DOI: 10.1016/j.bpa.2013.06.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Revised: 05/07/2013] [Accepted: 06/12/2013] [Indexed: 10/26/2022]
Abstract
A recent large prospective cohort study showed an unexpectedly high in-hospital mortality after major non-cardiac surgery in Europe, as well as a high incidence of postoperative pulmonary complications. The direct effect of postoperative respiratory complications on mortality is still under investigation, for intensive care unit (ICU) and in the perioperative period. Although respiratory monitoring has not been actually proven to affect in-hospital mortality, it plays an important role in patient care, leading to appropriate setting of ventilatory support as well as risk stratification. The aim of this article is to provide an overview of various respiratory monitoring techniques including the role of conventional and most recent methods in the perioperative period and in critically ill patients. The most recent techniques proposed for bedside respiratory monitoring, including lung imaging, are presented and discussed, comparing them to those actually considered as gold standards.
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Affiliation(s)
- Lorenzo Ball
- IRCCS AOU San Martino-IST, Department of Surgical Sciences and Integrated Diagnostics, University of Genoa, Genoa, Italy.
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Bikker IG, Holland W, Specht P, Ince C, Gommers D. Assessment of ventilation inhomogeneity during mechanical ventilation using a rapid-response oxygen sensor-based oxygen washout method. Intensive Care Med Exp 2014; 2:14. [PMID: 26266910 PMCID: PMC4512997 DOI: 10.1186/2197-425x-2-14] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2014] [Accepted: 03/23/2014] [Indexed: 11/16/2022] Open
Abstract
Purpose Ventilatory inhomogeneity indexes in critically ill mechanically ventilated patients could be of importance to optimize ventilator settings in order to reduce additional lung injury. The present study compared six inhomogeneity indexes calculated from the oxygen washout curves provided by the rapid oxygen sensor of the LUFU end-expiratory lung volume measurement system. Methods Inhomogeneity was tested in a porcine model before and after induction of acute lung injury (ALI) at four different levels of positive end-expiratory pressure (PEEP; 15, 10, 5 and 0 cm H2O). The following indexes were assessed: lung clearance index (LCI), mixing ratio, Becklake index, multiple breath alveolar mixing inefficiency, moment ratio and pulmonary clearance delay. Results LCI, mixing ratio, Becklake index and moment ratio were comparable with previous reported values and showed acceptable variation coefficients at baseline with and without ALI. Moment ratio had the highest precision, as calculated by the variation coefficients. LCI, Becklake index and moment ratio showed comparable increases in inhomogeneity during decremental PEEP steps before and after ALI. Conclusions The advantage of the method we introduce is the combined measurement of end-expiratory lung volume (EELV) and inhomogeneity of lung ventilation with the LUFU fast-response medical-grade oxygen sensor, without the need for external tracer gases. This can be combined with conventional breathing systems. The moment ratio and LCI index appeared to be the most favourable for integration with oxygen washout curves as judged by high precision and agreement with previous reported findings. Studies are under way to evaluate the indexes in critically ill patients.
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Affiliation(s)
- Ido G Bikker
- Department of Anaesthesiology, Erasmus Medical Center, Rotterdam, 3000 CA, the Netherlands,
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Henderson WR, Barnbrook J, Dominelli PB, Griesdale DE, Arndt T, Molgat-Seon Y, Foster G, Ackland GL, Xu J, Ayas NT, Sheel AW. Administration of intrapulmonary sodium polyacrylate to induce lung injury for the development of a porcine model of early acute respiratory distress syndrome. Intensive Care Med Exp 2014; 2:5. [PMID: 26266906 PMCID: PMC4513039 DOI: 10.1186/2197-425x-2-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2013] [Accepted: 01/10/2014] [Indexed: 12/15/2022] Open
Abstract
Background The loss of alveolar epithelial and endothelial integrity is a central component in acute respiratory distress syndrome (ARDS); however, experimental models investigating the mechanisms of epithelial injury are lacking. The purpose of the present study was to design and develop an experimental porcine model of ARDS by inducing lung injury with intrapulmonary administration of sodium polyacrylate (SPA). Methods The present study was performed at the Centre for Comparative Medicine, University of British Columbia, Vancouver, British Columbia. Human alveolar epithelial cells were cultured with several different concentrations of SPA; a bioluminescence technique was used to assess cell death associated with each concentration. In the anesthetized pig model (female Yorkshire X pigs (n = 14)), lung injury was caused in 11 animals (SPA group) by injecting sequential aliquots (5 mL) of 1% SPA gel in aqueous solution into the distal airway via a rubber catheter through an endotracheal tube. The SPA was dispersed throughout the lungs by manual bag ventilation. Three control animals (CON group) underwent all experimental procedures and measurements with the exception of SPA administration. Results The mean (± SD) ATP concentration after incubation of human alveolar epithelial cells with 0.1% SPA (0.92 ± 0.27 μM/well) was approximately 15% of the value found for the background control (6.30 ± 0.37 μM/well; p < 0.001). Elastance of the respiratory system (ERS) and the lung (EL) increased in SPA-treated animals after injury (p = 0.003 and p < 0.001, respectively). Chest wall elastance (ECW) did not change in SPA-treated animals. There were no differences in ERS,EL, or ECW in the CON group when pre- and post-injury values were compared. Analysis of bronchoalveolar lavage fluid showed a significant shift toward neutrophil predominance from before to after injury in SPA-treated animals (p < 0.001) but not in the CON group (p = 0.38). Necropsy revealed marked consolidation and congestion of the dorsal lung lobes in SPA-treated animals, with light-microscopy evidence of bronchiolar and alveolar spaces filled with neutrophilic infiltrate, proteinaceous debris, and fibrin deposition. These findings were absent in animals in the CON group. Electron microscopy of lung tissue from SPA-treated animals revealed injury to the alveolar epithelium and basement membranes, including intra-alveolar neutrophils and fibrin on the alveolar surface and intravascular fibrin (microthrombosis). Conclusions In this particular porcine model, the nonimmunogenic polymer SPA caused a rapid exudative lung injury. This model may be useful to study ARDS caused by epithelial injury and inflammation.
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Affiliation(s)
- William R Henderson
- Wolfson Institute for Biomedical Research, Department of Medicine, University College London, London, WC1E 6BT, UK,
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ter Haar H. Teugvolumes onder de loep. Crit Care 2014; 11:12-13. [DOI: 10.1007/s12426-014-0013-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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Caruana LR, Paratz J, Chang AT, Fraser JF. Electrical impedance tomography in the clinical assessment of lung volumes following recruitment manoeuvres. Physical Therapy Reviews 2013. [DOI: 10.1179/1743288x10y.0000000021] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
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Dellamonica J, Lerolle N, Sargentini C, Hubert S, Beduneau G, Di Marco F, Mercat A, Diehl JL, Richard JC, Bernardin G, Brochard L. Effect of different seated positions on lung volume and oxygenation in acute respiratory distress syndrome. Intensive Care Med 2013; 39:1121-7. [PMID: 23344832 DOI: 10.1007/s00134-013-2827-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2012] [Accepted: 01/07/2013] [Indexed: 10/27/2022]
Abstract
RATIONALE Lung volume available for ventilation is markedly decreased during acute respiratory distress syndrome. Body positioning may contribute to increase lung volume and partial verticalization is simple to perform. This study evaluated whether verticalization had parallel effects on oxygenation and end expiratory lung volume (EELV). METHODS Prospective multicenter study in 40 mechanically ventilated patients with ALI/ARDS in five university hospital MICUs. We evaluated four 45-min successive trunk position epochs (supine slightly elevated at 15°; semi recumbent with trunk elevated at 45°; seated with trunk elevated at 60° and legs down at 45°; back to supine). Arterial blood gases, EELV measured using the nitrogen washin/washout, and static compliance were measured. Responders were defined by a PaO₂/FiO₂ increase >20 % between supine and seated position. Results are median [25th-75th percentiles]. RESULTS With median PEEP = 10 cmH₂O, verticalization increased lung volume but only responders (13 patients, 32 %) had a significant increase in EELV/PBW (predicted body weight) compared to baseline. This increase persisted at least partially when patients were positioned back to supine. Responders had a lower EELV/PBW supine [14 mL/kg (13-15) vs. 18 mL/kg (15-27) (p = 0.005)] and a lower compliance [30 mL/cmH₂O (22-38) vs. 42 (30-46) (p = 0.01)] than non-responders. Strain decreased with verticalization for responders. EELV/PBW increase and PaO₂/FiO₂ increase were not correlated. DISCUSSION Verticalization is easily achieved and improves oxygenation in approximately 32 % of the patients together with an increase in EELV. Nonetheless, effect of verticalization on EELV/PBW is not predictable by PaO₂/FiO₂ increase, its monitoring may be helpful for strain optimization.
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Nakahashi S, Gando S, Ishikawa T, Wada T, Yanagida Y, Kubota N, Uegaki S, Hayakawa M, Sawamura A. Effectiveness of end-expiratory lung volume measurements during the lung recruitment maneuver for patients with atelectasis. J Crit Care 2013; 28:534.e1-5. [PMID: 23337480 DOI: 10.1016/j.jcrc.2012.11.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2012] [Revised: 10/26/2012] [Accepted: 11/11/2012] [Indexed: 11/15/2022]
Abstract
PURPOSE The aim of this study was to determine whether the relative change in the end-expiratory lung volume (EELV) obtained by the recruitment maneuver (RM) can serve as an indicator of the change in the P/F ratio. MATERIALS AND METHODS The effects of the intermittent stepwise increases in the RM (peak inspiratory pressure, 45, 50, and 55 cm H2O) were compared in 21 patients with atelectasis under mechanical ventilation. The EELV, the ratio of arterial oxygen concentration to the fraction of inspired oxygen P/F ratio, and relative change rate (Δ) in these parameters were evaluated after each RM. RESULTS A greater improvement in the EELV (1157 ± 344 mL vs 1469 ± 396 mL) and P/F ratio (250 ± 99 vs 320 ± 92) was observed after the RM. The ΔEELV was correlated with the ΔP/F ratio (ρ = 0.73, P < .01) and was identified as an accurate predictor of the improvement of the ΔP/F ratio by the receiver operating characteristic curve (the area under the curve, 0.93; P < .01). CONCLUSIONS These results suggest that the ΔEELV obtained by intermittent stepwise RM can serve as an indicator of the change in the P/F ratio.
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Affiliation(s)
- Susumu Nakahashi
- Division of Acute and Critical Care Medicine, Department of Anesthesiology and Critical Care Medicine, Hokkaido University Graduate School of Medicine, N15W7 Kita-ku, Sapporo 060-8638, Japan.
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Brochard L, Martin GS, Blanch L, Pelosi P, Belda FJ, Jubran A, Gattinoni L, Mancebo J, Ranieri VM, Richard JCM, Gommers D, Vieillard-Baron A, Pesenti A, Jaber S, Stenqvist O, Vincent JL. Clinical review: Respiratory monitoring in the ICU - a consensus of 16. Crit Care 2012; 16:219. [PMID: 22546221 PMCID: PMC3681336 DOI: 10.1186/cc11146] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Monitoring plays an important role in the current management of patients with acute respiratory failure but sometimes lacks definition regarding which 'signals' and 'derived variables' should be prioritized as well as specifics related to timing (continuous versus intermittent) and modality (static versus dynamic). Many new techniques of respiratory monitoring have been made available for clinical use recently, but their place is not always well defined. Appropriate use of available monitoring techniques and correct interpretation of the data provided can help improve our understanding of the disease processes involved and the effects of clinical interventions. In this consensus paper, we provide an overview of the important parameters that can and should be monitored in the critically ill patient with respiratory failure and discuss how the data provided can impact on clinical management.
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Affiliation(s)
- Laurent Brochard
- Department of Intensive Care, Hôpitaux Universitaires de Genève, Rue
Gabrielle-Perret-Gentil 4, 1211 Geneva, Switzerland; and Université de
Genève, Switzerland
| | - Greg S Martin
- Division of Pulmonary, Allergy and Critical Care, Emory University School of
Medicine, Grady Memorial Hospital, 615 Michael Street, Suite 205, Atlanta, GA
30322, USA
| | - Lluis Blanch
- Critical Care Center, Corporacio Sanitaria Universitària Parc Tauli,
Universitat Autònoma de Barcelona, 08208 Sabadell, Spain, CIBER Enfermedades
Respiratorias, ISCiii, Madrid, Spain
| | - Paolo Pelosi
- Department of Surgical Sciences and Integrated Diagnostics, University of Genoa,
San Martino Hospital, Largo Rosanna Benzi 8 16132, Genoa, Italy
| | - F Javier Belda
- Department of Anesthesia and Surgical Critical Care, Hospital Clínico
Universitario, Avda Blasco Ibañez 17, 46010 Valencia, Spain
| | - Amal Jubran
- Division of Pulmonary and Critical Care Medicine, Edward Hines Jr. VA Hospital,
111N, 5th Avenue and Roosevelt Road, Hines, IL 60141, USA
| | - Luciano Gattinoni
- Dipartimento di Anestesiologia, Terapia Intensive e Scienze Dermatologiche, and
Dipartimento do Anestesia, Rianimazione (Intensive e Subintensiva) e Terapia del
Dolore, Fondazione IRCCS Ca' Granda - Ospedale Maggiore Policlinico,
Università degli Studi di Milano, via F, Sforza 35, 20122, Milan, Italy
| | - Jordi Mancebo
- Servicio Medicina Intensiva, Hospital de la Santa Creu i Sant Pau, Carrer St.
Quintí 89, 08041 Barcelona, Spain
| | - V Marco Ranieri
- Department of Anesthesia and Intensive Care Medicine, University of Turin, S.
Giovanni Battista, Molinette Hospital, Corso Dogliotti 14, 10126 Turin, Italy
| | - Jean-Christophe M Richard
- Department of Intensive Care, Hôpitaux Universitaires de Genève, Rue
Gabrielle-Perret-Gentil 4, 1211 Geneva, Switzerland; and Université de
Genève, Switzerland
| | - Diederik Gommers
- Adult Intensive Care, Erasmus MC, Room H623, 's Gravendijkwal 230, 3015CE
Rotterdam, The Netherlands
| | - Antoine Vieillard-Baron
- Intensive Care Unit, Section Thorax - Vascular disease - Abdomen - Metabolism, CHU
Ambroise Paré, 9 avenue Charles-de-Gaulle, 92104 Boulogne, France
| | - Antonio Pesenti
- Anesthesia and Intensive Care, University of Milan-Bicocca, A.O. Ospedale S.
Gerardo, Via Pergolesi 33, 20900 Monza, Italy
| | - Samir Jaber
- Department of Critical Care Medicine and Anesthesiology, Saint Eloi University
Hospital and Montpellier School of Medicine, 80 Avenue Augustin Fliche, 34295
Montpellier - Cedex 5, France
| | - Ola Stenqvist
- Department of Anesthesiology and Intensive Care, Sahlgrenska University Hospital,
Bla Straket 5, Gothenburg, SE 413 45, Sweden
| | - Jean-Louis Vincent
- Department of Intensive Care, Erasme Hospital, Université Libre de Bruxelles,
808 route de Lennik, 1070 Brussels, Belgium
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Dellamonica J, Lerolle N, Sargentini C, Beduneau G, Di Marco F, Mercat A, Richard JCM, Diehl JL, Mancebo J, Rouby JJ, Lu Q, Bernardin G, Brochard L. Accuracy and precision of end-expiratory lung-volume measurements by automated nitrogen washout/washin technique in patients with acute respiratory distress syndrome. Crit Care 2011; 15:R294. [PMID: 22166727 PMCID: PMC3388680 DOI: 10.1186/cc10587] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2011] [Revised: 12/04/2011] [Accepted: 12/07/2011] [Indexed: 11/10/2022] Open
Abstract
Introduction End-expiratory lung volume (EELV) is decreased in acute respiratory distress
syndrome (ARDS), and bedside EELV measurement may help to set positive
end-expiratory pressure (PEEP). Nitrogen washout/washin for EELV measurement is
available at the bedside, but assessments of accuracy and precision in real-life
conditions are scant. Our purpose was to (a) assess EELV measurement precision in
ARDS patients at two PEEP levels (three pairs of measurements), and (b) compare
the changes (Δ) induced by PEEP for total EELV with the PEEP-induced changes
in lung volume above functional residual capacity measured with passive spirometry
(ΔPEEP-volume). The minimal predicted increase in lung volume was calculated
from compliance at low PEEP and ΔPEEP to ensure the validity of lung-volume
changes. Methods Thirty-four patients with ARDS were prospectively included in five
university-hospital intensive care units. ΔEELV and ΔPEEP volumes were
compared between 6 and 15 cm H2O of PEEP. Results After exclusion of three patients, variability of the nitrogen technique was less
than 4%, and the largest difference between measurements was 81 ± 64 ml.
ΔEELV and ΔPEEP-volume were only weakly correlated (r2
= 0.47); 95% confidence interval limits, -414 to 608 ml). In four
patients with the highest PEEP (≥ 16 cm H2O), ΔEELV was
lower than the minimal predicted increase in lung volume, suggesting flawed
measurements, possibly due to leaks. Excluding those from the analysis markedly
strengthened the correlation between ΔEELV and ΔPEEP volume (r2
= 0.80). Conclusions In most patients, the EELV technique has good reproducibility and accuracy, even
at high PEEP. At high pressures, its accuracy may be limited in case of leaks. The
minimal predicted increase in lung volume may help to check for accuracy.
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Affiliation(s)
- Jean Dellamonica
- Réanimation Médicale, AP-HP, Centre Hospitalier Albert Chenevier, Henri Mondor, avenue Marechal de Lattre de Tassigny, Créteil, 94000, France.
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Henderson WR, Sheel AW. Pulmonary mechanics during mechanical ventilation. Respir Physiol Neurobiol 2011; 180:162-72. [PMID: 22154694 DOI: 10.1016/j.resp.2011.11.014] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2011] [Revised: 11/16/2011] [Accepted: 11/23/2011] [Indexed: 10/14/2022]
Abstract
The use of mechanical ventilation has become widespread in the management of hypoxic respiratory failure. Investigations of pulmonary mechanics in this clinical scenario have demonstrated that there are significant differences in compliance, resistance and gas flow when compared with normal subjects. This paper will review the mechanisms by which pulmonary mechanics are assessed in mechanically ventilated patients and will review how the data can be used for investigative research purposes as well as to inform rational ventilator management.
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Affiliation(s)
- William R Henderson
- Program of Critical Care Medicine, University of British Columbia, Vancouver, BC, Canada.
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Brewer L, Orr J, Fulcher E, Markewitz B. Evaluation of a CO2 partial rebreathing functional residual capacity measurement method for use during mechanical ventilation. J Clin Monit Comput 2011; 25:397-404. [PMID: 22057246 DOI: 10.1007/s10877-011-9318-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2011] [Accepted: 10/24/2011] [Indexed: 10/15/2022]
Abstract
OBJECTIVE There is a need for an automated bedside functional residual capacity (FRC) measurement method that does not require a step change in inspired oxygen fraction. Such a method can be used for patients who require a high inspired oxygen fraction to maintain arterial oxygenation and for patients ventilated using a circle breathing system commonly found in operating rooms, which is not capable of step changes in oxygen. We developed a CO(2) rebreathing method for FRC measurement that is based on the change in partial pressure of end-tidal carbon dioxide and volume of CO(2) eliminated at the end of a partial rebreathing period. This study was designed to assess the accuracy and precision of the proposed FRC measurement system compared to body plethysmography and nitrogen washout FRC. METHODS Accuracy and precision of measurements were assessed by comparing the CO(2) rebreathing FRC values to the gold standard, body plethysmography FRC, in twenty spontaneously breathing volunteers. The CO(2) rebreathing FRC measurements were then compared to nitrogen washout FRC in twenty intensive care patients whose lungs were mechanically ventilated. For each subject, an average value of CO(2) rebreathing FRC was compared to the average gold standard method. Measurements were accepted for statistical analysis if they had been recorded from periods of stable tidal ventilation, defined as a coefficient of variation of tidal volume of <0.13. RESULTS Compared to body plethysmography, the accuracy (average error) for the CO(2) rebreathing method during stable ventilation (n = 8) was 0.03 L and precision (1 standard deviation of the error) was 0.29 L (0.8 ± 7.6% of body plethysmography). During stable mechanical ventilation (n = 9), the accuracy was -0.02 L and precision was 0.26 L (-1.1 ± 12.6% of nitrogen washout). CONCLUSIONS The CO(2) rebreathing method for FRC measurement provides acceptable accuracy and precision during stable ventilation compared to the gold standards of body plethysmography and nitrogen washout. The results based on periods of stable ventilation best approximate the performance of the system in the likely areas of application during controlled mechanical ventilation. Further study of the CO(2) rebreathing method is needed to evaluate accuracy in a larger group of controlled mechanical ventilation patients, including patients with respiratory insufficiency and significant lung injury.
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Bikker IG, Preis C, Egal M, Bakker J, Gommers D. Electrical impedance tomography measured at two thoracic levels can visualize the ventilation distribution changes at the bedside during a decremental positive end-expiratory lung pressure trial. Crit Care 2011; 15:R193. [PMID: 21834953 PMCID: PMC3387635 DOI: 10.1186/cc10354] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2010] [Revised: 07/12/2011] [Accepted: 08/11/2011] [Indexed: 11/29/2022] Open
Abstract
Introduction Computed tomography of the lung has shown that ventilation shifts from dependent to nondependent lung regions. In this study, we investigated whether, at the bedside, electrical impedance tomography (EIT) at the cranial and caudal thoracic levels can be used to visualize changes in ventilation distribution during a decremental positive end-expiratory pressure (PEEP) trial and the relation of these changes to global compliance in mechanically ventilated patients. Methods Ventilation distribution was calculated on the basis of EIT results from 12 mechanically ventilated patients after cardiac surgery at a cardiothoracic ICU. Measurements were taken at four PEEP levels (15, 10, 5 and 0 cm H2O) at both the cranial and caudal lung levels, which were divided into four ventral-to-dorsal regions. Regional compliance was calculated using impedance and driving pressure data. Results We found that tidal impedance variation divided by tidal volume significantly decreased on caudal EIT slices, whereas this measurement increased on the cranial EIT slices. The dorsal-to-ventral impedance distribution, expressed according to the center of gravity index, decreased during the decremental PEEP trial at both EIT levels. Optimal regional compliance differed at different PEEP levels: 10 and 5 cm H2O at the cranial level and 15 and 10 cm H2O at the caudal level for the dependent and nondependent lung regions, respectively. Conclusions At the bedside, EIT measured at two thoracic levels showed different behavior between the caudal and cranial lung levels during a decremental PEEP trial. These results indicate that there is probably no single optimal PEEP level for all lung regions.
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Affiliation(s)
- Ido G Bikker
- Department of Intensive Care Medicine, Erasmus MC, 's-Gravendijkwal 230, NL-3015GE Rotterdam, The Netherlands
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Brewer LM, Orr JA, Sherman MR, Fulcher EH, Markewitz BA. Measurement of functional residual capacity by modified multiple breath nitrogen washout for spontaneously breathing and mechanically ventilated patients. Br J Anaesth 2011; 107:796-805. [PMID: 21752798 DOI: 10.1093/bja/aer220] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND There is a need for a bedside functional residual capacity (FRC) measurement method that performs well in intensive care patients during many modes of ventilation including controlled, assisted, spontaneous, and mixed. We developed a modified multiple breath nitrogen washout method for FRC measurement that relies on end-tidal gas fractions and alveolar tidal volume measurements as inputs but does not require the traditional measurements of volume of nitrogen or oxygen. Using end-tidal measurements, not volume, reduces errors from signal synchronization. This study was designed to assess the accuracy, precision, and repeatability of the proposed FRC system in subjects with variable ventilation patterns including some spontaneous effort. METHODS The accuracy and precision of measurements were assessed by comparing the novel N₂ washout FRC values to the gold standard, body plethysmography, in 20 spontaneously breathing volunteers. Repeatability was assessed by comparing subsequent measurements in 20 intensive care patients whose lungs were under controlled and assisted mechanical ventilation. RESULTS Compared with body plethysmography, the accuracy (mean bias) of the novel method was -0.004 litre and precision [1 standard deviation (sd)] was 0.209 litre [mean (sd)] [-0.1 (5.9)% of body plethysmography]. The difference between repeated measurements was 0.009 (0.15) litre [mean (sd)] [0.4 (6.4)%]. The coefficient of repeatability was 0.31 litre (12.7%). CONCLUSIONS The modified multiple breath nitrogen washout method for FRC measurement provides improved precision and equivalent accuracy and repeatability compared with existing methods during ventilation with variable ventilation patterns. Further study of the novel N₂ washout method is needed.
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Affiliation(s)
- L M Brewer
- University of Utah Health Sciences Center, Salt Lake City, UT 84132, USA.
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Bikker IG, Leonhardt S, Reis Miranda D, Bakker J, Gommers D. Bedside measurement of changes in lung impedance to monitor alveolar ventilation in dependent and non-dependent parts by electrical impedance tomography during a positive end-expiratory pressure trial in mechanically ventilated intensive care unit patients. Crit Care 2010; 14:R100. [PMID: 20509966 PMCID: PMC2911738 DOI: 10.1186/cc9036] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/26/2009] [Revised: 02/14/2010] [Accepted: 05/30/2010] [Indexed: 12/28/2022]
Abstract
Introduction As it becomes clear that mechanical ventilation can exaggerate lung injury, individual titration of ventilator settings is of special interest. Electrical impedance tomography (EIT) has been proposed as a bedside, regional monitoring tool to guide these settings. In the present study we evaluate the use of ventilation distribution change maps (ΔfEIT maps) in intensive care unit (ICU) patients with or without lung disorders during a standardized decremental positive end-expiratory pressure (PEEP) trial. Methods Functional EIT (fEIT) images and PaO2/FiO2 ratios were obtained at four PEEP levels (15 to 10 to 5 to 0 cm H2O) in 14 ICU patients with or without lung disorders. Patients were pressure-controlled ventilated with constant driving pressure. fEIT images made before each reduction in PEEP were subtracted from those recorded after each PEEP step to evaluate regional increase/decrease in tidal impedance in each EIT pixel (ΔfEIT maps). Results The response of regional tidal impedance to PEEP showed a significant difference from 15 to 10 (P = 0.002) and from 10 to 5 (P = 0.001) between patients with and without lung disorders. Tidal impedance increased only in the non-dependent parts in patients without lung disorders after decreasing PEEP from 15 to 10 cm H2O, whereas it decreased at the other PEEP steps in both groups. Conclusions During a decremental PEEP trial in ICU patients, EIT measurements performed just above the diaphragm clearly visualize improvement and loss of ventilation in dependent and non-dependent parts, at the bedside in the individual patient.
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Affiliation(s)
- Ido G Bikker
- Department of Intensive Care Medicine, Erasmus MC, 's-Gravendijkwal 230, Rotterdam, 3015 GE, The Netherlands.
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Abstract
Original research contributions published in Critical Care in 2008 in the fields of respirology and critical care medicine are summarized. Eighteen articles were grouped into the following categories: acute lung injury and acute respiratory distress syndrome, mechanical ventilation, mechanisms of ventilator-induced lung injury, and tracheotomy decannulation and non-invasive ventilation.
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Affiliation(s)
- Haibo Zhang
- Keenan Research Centre at the Li Ka Shing Knowledge Institute of St Michael's Hospital, Bond Street, Toronto, ON, Canada.
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Heinze H, Eichler W. Measurements of functional residual capacity during intensive care treatment: the technical aspects and its possible clinical applications. Acta Anaesthesiol Scand 2009; 53:1121-30. [PMID: 19681779 DOI: 10.1111/j.1399-6576.2009.02076.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Direct measurement of lung volume, i.e. functional residual capacity (FRC) has been recommended for monitoring during mechanical ventilation. Mostly due to technical reasons, FRC measurements have not become a routine monitoring tool, but promising techniques have been presented. We performed a literature search of studies with the key words 'functional residual capacity' or 'end expiratory lung volume' and summarize the physiology and patho-physiology of FRC measurements in ventilated patients, describe the existing techniques for bedside measurement, and provide an overview of the clinical questions that can be addressed using an FRC assessment. The wash-in or wash-out of a tracer gas in a multiple breath maneuver seems to be best applicable at bedside, and promising techniques for nitrogen or oxygen wash-in/wash-out with reasonable accuracy and repeatability have been presented. Studies in ventilated patients demonstrate that FRC can easily be measured at bedside during various clinical settings, including positive end-expiratory pressure optimization, endotracheal suctioning, prone position, and the weaning from mechanical ventilation. Alveolar derecruitment can easily be monitored and improvements of FRC without changes of the ventilatory setting could indicate alveolar recruitment. FRC seems to be insensitive to over-inflation of already inflated alveoli. Growing evidence suggests that FRC measurements, in combination with other parameters such as arterial oxygenation and respiratory compliance, could provide important information on the pulmonary situation in critically ill patients. Further studies are needed to define the exact role of FRC in monitoring and perhaps guiding mechanical ventilation.
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Affiliation(s)
- H Heinze
- Department of Anesthesiology, University of Lübeck, Lübeck, Germany.
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Reske A, Seiwerts M. Qualitative und quantitative CT-Analysen beim akuten Lungenversagen. Radiologe 2009; 49:687-697. [DOI: 10.1007/s00117-009-1878-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Bikker IG, Scohy TV, Ad J J C Bogers, Bakker J, Gommers D. Measurement of end-expiratory lung volume in intubated children without interruption of mechanical ventilation. Intensive Care Med 2009; 35:1749-53. [PMID: 19626312 PMCID: PMC2749178 DOI: 10.1007/s00134-009-1579-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2008] [Accepted: 06/20/2009] [Indexed: 11/22/2022]
Abstract
Purpose Monitoring end-expiratory lung volume (EELV) is a valuable tool to optimize respiratory settings that could be of particular importance in mechanically ventilated pediatric patients. We evaluated the feasibility and precision of an intensive care unit (ICU) ventilator with an in-built nitrogen washout/washin technique in mechanically ventilated pediatric patients. Methods Duplicate EELV measurements were performed in 30 patients between 5 kg and 43 kg after cardiac surgery (age, median + range: 26, 3–141 months). All measurements were taken during pressure-controlled ventilation at 0 cm H2O of positive end-expiratory pressure (PEEP). Results Linear regression between duplicate measurements was excellent (R2 = 0.99). Also, there was good agreement between duplicate measurements, bias ± SD: −0.3% (−1.5 mL) ± 5.9% (19.2 mL). Mean EELV ± SD was 19.6 ± 5.1 mL/kg at 0 cm H2O PEEP. EELV correlated with age (p < 0.001, r = 0.92, R2 = 0.78), body weight (p < 0.001, r = 0.91, R2 = 0.82) and height (p < 0.001, r = 0.94, R2 = 0.75). Conclusion This ICU ventilator with an in-built nitrogen washout/washin EELV technique can measure EELV with precision, and can easily be used for mechanically ventilated pediatric patients.
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Affiliation(s)
- Ido G Bikker
- Department of Intensive Care Medicine, Erasmus MC, Room H602, 's-Gravendijkwal 230, 3015 CE, Rotterdam, The Netherlands
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Rieder MDM, Costa ADD, Vieira SRR. Short-term effects of positive expiratory airway pressure in patients being weaned from mechanical ventilation. Clinics (Sao Paulo) 2009; 64:403-8. [PMID: 19488605 PMCID: PMC2694243 DOI: 10.1590/s1807-59322009000500006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2008] [Accepted: 02/09/2009] [Indexed: 11/22/2022] Open
Abstract
OBJECTIVE To investigate the feasibility and the cardiorespiratory effects of using positive expiratory airway pressure, a physiotherapeutic tool, in comparison with a T-tube, to wean patients from mechanical ventilation. METHODS/DESIGN A prospective, randomized, cross-over study. SETTING Two intensive care units. PATIENTS AND INTERVENTIONS We evaluated forty patients who met weaning criteria and had been mechanically-ventilated for more than 48 hours, mean age 59 years, including 23 males. All patients were submitted to the T-tube and Expiratory Positive Airway Pressure devices, at 7 cm H2O, during a 30-minute period. Cardiorespiratory variables including work of breathing, respiratory rate (rr), peripheral oxygen saturation (SpO2), heart rate (hr), systolic, diastolic and mean arterial pressures (SAP, DAP, MAP) were measured in the first and thirtieth minutes. The condition was analyzed as an entire sample set (n=40) and was also divided into subconditions: chronic obstructive pulmonary disease (n=14) and non-chronic obstructive pulmonary disease (non- chronic obstructive pulmonary disease) (n=26) categories. Comparisons were made using a t-test and Analysis of Variance. The level of significance was p < 0.05. RESULTS Our data showed an increase in work of breathing in the first and thirtieth minutes in the EPAP condition (0.86+ 0.43 and 1.02+1.3) as compared with the T-tube condition (0.25+0.26 and 0.26+0.35) (p<0.05), verified by the flow-sensor monitor (values in J/L). No statistical differences were observed when comparing the Expiratory Positive Airway Pressure and T-tube conditions with regard to cardiorespiratory measurements. The same result was observed for both chronic obstructive pulmonary disease and non- chronic obstructive pulmonary disease subconditions. CONCLUSIONS Our study demonstrated that, in weaning patients from mechanical ventilation, the use of a fixed level of Expiratory Positive Airway Pressure caused an increase in work of breathing that was not accompanied by any other significant cardiorespiratory changes. Therefore, we have to be cautious when using Expiratory Positive Airway Pressure as a physiotherapeutic tool during weaning from mechanical ventilation.
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