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A model-based approach to generating annotated pressure support waveforms. J Clin Monit Comput 2022; 36:1739-1752. [PMID: 35142976 PMCID: PMC9637593 DOI: 10.1007/s10877-022-00822-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Accepted: 01/29/2022] [Indexed: 10/19/2022]
Abstract
Large numbers of asynchronies during pressure support ventilation cause discomfort and higher work of breathing in the patient, and are associated with an increased mortality. There is a need for real-time decision support to detect asynchronies and assist the clinician towards lung-protective ventilation. Machine learning techniques have been proposed to detect asynchronies, but they require large datasets with sufficient data diversity, sample size, and quality for training purposes. In this work, we propose a method for generating a large, realistic and labeled, synthetic dataset for training and validating machine learning algorithms to detect a wide variety of asynchrony types. We take a model-based approach in which we adapt a non-linear lung-airway model for use in a diverse patient group and add a first-order ventilator model to generate labeled pressure, flow, and volume waveforms of pressure support ventilation. The model was able to reproduce basic measured lung mechanics parameters. Experienced clinicians were not able to differentiate between the simulated waveforms and clinical data (P = 0.44 by Fisher's exact test). The detection performance of the machine learning trained on clinical data gave an overall comparable true positive rate on clinical data and on simulated data (an overall true positive rate of 94.3% and positive predictive value of 93.5% on simulated data and a true positive rate of 98% and positive predictive value of 98% on clinical data). Our findings demonstrate that it is possible to generate labeled pressure and flow waveforms with different types of asynchronies.
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Umbrello M, Antonucci E, Muttini S. Neurally Adjusted Ventilatory Assist in Acute Respiratory Failure-A Narrative Review. J Clin Med 2022; 11:jcm11071863. [PMID: 35407471 PMCID: PMC9000024 DOI: 10.3390/jcm11071863] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2022] [Revised: 03/10/2022] [Accepted: 03/25/2022] [Indexed: 02/08/2023] Open
Abstract
Maintaining spontaneous breathing has both potentially beneficial and deleterious consequences in patients with acute respiratory failure, depending on the balance that can be obtained between the protecting and damaging effects on the lungs and the diaphragm. Neurally adjusted ventilatory assist (NAVA) is an assist mode, which supplies the respiratory system with a pressure proportional to the integral of the electrical activity of the diaphragm. This proportional mode of ventilation has the theoretical potential to deliver lung- and respiratory-muscle-protective ventilation by preserving the physiologic defense mechanisms against both lung overdistention and ventilator overassistance, as well as reducing the incidence of diaphragm disuse atrophy while maintaining patient–ventilator synchrony. This narrative review presents an overview of NAVA technology, its basic principles, the different methods to set the assist level and the findings of experimental and clinical studies which focused on lung and diaphragm protection, machine–patient interaction and preservation of breathing pattern variability. A summary of the findings of the available clinical trials which investigate the use of NAVA in acute respiratory failure will also be presented and discussed.
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Does Interrupting Self-Induced Lung Injury and Respiratory Drive Expedite Early Spontaneous Breathing in the Setting of Early Severe Diffuse Acute Respiratory Distress Syndrome? Crit Care Med 2021; 50:1272-1276. [PMID: 34369430 DOI: 10.1097/ccm.0000000000005288] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Khan YA, Fan E, Ferguson ND. Precision Medicine and Heterogeneity of Treatment Effect in Therapies for Acute Respiratory Distress Syndrome. Chest 2021; 160:1729-1738. [PMID: 34270967 PMCID: PMC8277554 DOI: 10.1016/j.chest.2021.07.009] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 06/28/2021] [Accepted: 07/05/2021] [Indexed: 12/16/2022] Open
Abstract
Acute respiratory distress syndrome (ARDS) is a clinically heterogenous syndrome, rather than a distinct disease. This heterogeneity at least partially explains the difficulty in studying treatments for these patients and contributes to the numerous trials of therapies for the syndrome that have not shown benefit. Recent studies have identified different subphenotypes within the heterogenous patient population. These different subphenotypes likely have variable clinical responses to specific therapies, a concept known as heterogeneity of treatment effect (HTE). Recognizing different subphenotypes and HTE has important implications for the clinical management of patients with ARDS. In this review, we will present studies that have identified different subphenotypes and discuss how they can modify the effects of therapies evaluated in trials that are commonly considered to have demonstrated no overall benefit in patients with ARDS.
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Affiliation(s)
- Yasin A Khan
- Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, Canada; Department of Medicine, University of Toronto, Toronto, Canada; Institute of Health Policy, Management and Evaluation, University of Toronto, Toronto, Canada
| | - Eddy Fan
- Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, Canada; Department of Medicine, University of Toronto, Toronto, Canada; Institute of Health Policy, Management and Evaluation, University of Toronto, Toronto, Canada; Toronto General Hospital Research Institute, Toronto, Canada; Division of Respirology, Department of Medicine, University Health Network, Toronto, Canada
| | - Niall D Ferguson
- Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, Canada; Department of Medicine, University of Toronto, Toronto, Canada; Institute of Health Policy, Management and Evaluation, University of Toronto, Toronto, Canada; Toronto General Hospital Research Institute, Toronto, Canada; Department of Physiology, University of Toronto, Toronto, Canada; Division of Respirology, Department of Medicine, University Health Network, Toronto, Canada.
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Petitjeans F, Pichot C, Ghignone M, Quintin L. Building on the Shoulders of Giants: Is the use of Early Spontaneous Ventilation in the Setting of Severe Diffuse Acute Respiratory Distress Syndrome Actually Heretical? Turk J Anaesthesiol Reanim 2018; 46:339-347. [PMID: 30263856 DOI: 10.5152/tjar.2018.01947] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Accepted: 06/13/2018] [Indexed: 12/14/2022] Open
Abstract
Acute respiratory distress syndrome (ARDS) is not a failure of the neurological command of the ventilatory muscles or of the ventilatory muscles; it is an oxygenation defect. As positive pressure ventilation impedes the cardiac function, paralysis under general anaesthesia and controlled mandatory ventilation should be restricted to the interval needed to control the acute cardio-ventilatory distress observed upon admission into the critical care unit (CCU; "salvage therapy" during "shock state"). Current management of early severe diffuse ARDS rests on a prolonged interval of controlled mechanical ventilation with low driving pressure, paralysis (48 h, too often overextended), early proning and positive end-expiratory pressure (PEEP). Therefore, the time interval between arrival to the CCU and switching to spontaneous ventilation (SV) is not focused on normalizing the different factors involved in the pathophysiology of ARDS: fever, low cardiac output, systemic acidosis, peripheral shutdown (local acidosis), supine position, hypocapnia (generated by hyperpnea and tachypnea), sympathetic activation, inflammation and agitation. Then, the extended period of controlled mechanical ventilation with paralysis under general anaesthesia leads to CCU-acquired pathology, including low cardiac output, myoneuropathy, emergence delirium and nosocomial infection. The stabilization of the acute cardio-ventilatory distress should primarily itemize the pathophysiological conditions: fever control, improved micro-circulation and normalized local acidosis, 'upright' position, minimized hypercapnia, sympathetic de-activation (normalized sympathetic activity toward baseline levels resulting in improved micro-circulation with alpha-2 agonists administered immediately following optimized circulation and endotracheal intubation), lowered inflammation and 'cooperative' sedation without respiratory depression evoked by alpha-2 agonists. Normalised metabolic, circulatory and ventilatory demands will allow one to single out the oxygenation defect managed with high PEEP (diffuse recruitable ARDS) under early spontaneous ventilation (airway pressure release ventilation+SV or low-pressure support). Assuming an improved overall status, PaO2/FiO2≥150-200 allows for extubation and continuous non-invasive ventilation. Such fast-tracking may avoid most of the CCU-acquired pathologies. Evidence-based demonstration is required.
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Mauri T, Foti G, Fornari C, Constantin JM, Guerin C, Pelosi P, Ranieri M, Conti S, Tubiolo D, Rondelli E, Lovisari F, Fossali T, Spadaro S, Grieco DL, Navalesi P, Calamai I, Becher T, Roca O, Wang YM, Knafelj R, Cortegiani A, Mancebo J, Brochard L, Pesenti A. Pressure support ventilation + sigh in acute hypoxemic respiratory failure patients: study protocol for a pilot randomized controlled trial, the PROTECTION trial. Trials 2018; 19:460. [PMID: 30157955 PMCID: PMC6114230 DOI: 10.1186/s13063-018-2828-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Accepted: 07/28/2018] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND Adding cyclic short sustained inflations (sigh) to assisted ventilation yields optimizes lung recruitment, decreases heterogeneity and reduces inspiratory effort in patients with acute hypoxemic respiratory failure (AHRF). These findings suggest that adding sigh to pressure support ventilation (PSV) might decrease the risk of lung injury, shorten weaning and improve clinical outcomes. Thus, we conceived a pilot trial to test the feasibility of adding sigh to PSV (the PROTECTION study). METHODS PROTECTION is an international randomized controlled trial that will be conducted in 23 intensive care units (ICUs). Patients with AHRF who have been intubated from 24 h to 7 days and undergoing PSV from 4 to 24 h will be enrolled. All patients will first undergo a 30-min sigh test by adding sigh to clinical PSV for 30 min to identify early oxygenation responders. Then, patients will be randomized to PSV or PSV + sigh until extubation, ICU discharge, death or day 28. Sigh will be delivered as a 3-s pressure control breath delivered once per minute at 30 cmH2O. Standardized protocols will guide ventilation settings, switch back to controlled ventilation, use of rescue treatments, performance of spontaneous breathing trial, extubation and reintubation. The primary endpoint of the study will be to verify the feasibility of PSV + sigh evaluated through reduction of failure to remain on assisted ventilation during the first 28 days in the PSV + sigh group versus standard PSV (15 vs. 22%). Failure will be defined by switch back to controlled ventilation for more than 24 h or use of rescue treatments or reintubation within 48 h from elective extubation. Setting the power to 80% and first-risk order to 5%, the computed size of the trial is 129 patients per arm. DISCUSSION PROTECTION is a pilot randomized controlled trial testing the feasibility of adding sigh to PSV. If positive, it will provide physicians with an effective addition to standard PSV for lung protection, able to reduce failure of assisted ventilation. PROTECTION will provide the basis for a future larger trial aimed at verifying the impact of PSV + sigh on 28-day survival and ventilator-free days. TRIAL REGISTRATION ClinicalTrials.gov, NCT03201263 . Registered on 28 June 2017.
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Affiliation(s)
- Tommaso Mauri
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, University of Milan, Milan, Italy
| | - Giuseppe Foti
- ASST Monza, University of Milan-Bicocca, Monza, Italy
| | - Carla Fornari
- Research Centre on Public Health, School of Medicine and Surgery, University of Milan-Bicocca, Monza, Italy
| | - Jean-Michel Constantin
- Department of Preoperative Medicine, University Hospital of Clermont-Ferrand, Clermont-Ferrand, France
| | - Claude Guerin
- Service de Réanimation Médicale, Hôpital de la Croix Rousse, Lyon, France
| | - Paolo Pelosi
- Department of Surgical and Integrated Diagnostics, San Martino Policlinico Hospital, IRCCS for Oncology, University of Genoa, Genoa, Italy
| | - Marco Ranieri
- Department of Anesthesia and Intensive Care Medicine, Sapienza University of Rome, Policlinico Umberto I, Rome, Italy
| | - Sara Conti
- Research Centre on Public Health, School of Medicine and Surgery, University of Milan-Bicocca, Monza, Italy
| | - Daniela Tubiolo
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, University of Milan, Milan, Italy
| | - Egle Rondelli
- ASST Monza, University of Milan-Bicocca, Monza, Italy
| | - Federica Lovisari
- Department of Anesthesia and Critical Care, Niguarda Hospital, University of Milan-Bicocca, Milan, Italy
| | - Tommaso Fossali
- Department of Anesthesiology and Intensive Care, ASST Fatebenefratelli Sacco - Luigi Sacco Hospital, Milan, Italy
| | - Savino Spadaro
- Department of morphology, surgery and experimental medicine, Azienda Ospedaliera-Universitaria Arcispedale Sant'Anna, Ferrara, Italy
| | - Domenico Luca Grieco
- Department of Anesthesiology and Intensive Care Medicine, Catholic University of The Sacred Heart, IRCCS Fondazione Policlinico A. Gemelli, Rome, Italy
| | - Paolo Navalesi
- Dipartimento di Scienze Mediche e Chirurgiche, Università Magna Graecia di Catanzaro, Azienda Ospedaliera Universitaria Mater Domini, Catanzaro, Italy
| | - Italo Calamai
- AUSL Toscana Centro, Unit of Anesthesia and Resuscitation, San Giuseppe Hospital, Empoli, Italy
| | - Tobias Becher
- Department of Anesthesiology and Intensive Care Medicine, University Medical Center Schleswig-Holstein, Campus Kiel, Kiel, Germany
| | - Oriol Roca
- Critical Care Department, Vall d'Hebron University Hospital, Vall d'Hebron Research Institute, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Yu-Mei Wang
- Department of Critical Care Medicine, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Rihard Knafelj
- Center for Internal Intensive medicine (MICU), University Medical Center Ljubljana, Ljubljana, Slovenia
| | - Andrea Cortegiani
- Department of Biopathology and Medical Biotechnologies (DIBIMED), Section of Anesthesia, Analgesia, Intensive Care and Emergency, Policlinico Paolo Giaccone, University of Palermo, Palermo, Italy
| | - Jordi Mancebo
- Servei de Medicina Intensiva, Hospital de la Santa Creu i Sant Pau, Universitat Autònoma de Barcelona (UAB), Barcelona, Spain
| | - Laurent Brochard
- Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, ON, Canada.,Keenan Research Centre, Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, ON, Canada
| | - Antonio Pesenti
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, University of Milan, Milan, Italy. .,Anesthesia and Critical Care, Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy. .,Department of Anesthesia, Critical Care and Emergency, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Via F. Sforza 35, 20122, Milan, Italy.
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Demoule A, Clavel M, Rolland-Debord C, Perbet S, Terzi N, Kouatchet A, Wallet F, Roze H, Vargas F, Guerin C, Dellamonica J, Jaber S, Brochard L, Similowski T. Neurally adjusted ventilatory assist as an alternative to pressure support ventilation in adults: a French multicentre randomized trial. Intensive Care Med 2016; 42:1723-1732. [PMID: 27686347 DOI: 10.1007/s00134-016-4447-8] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2016] [Accepted: 07/05/2016] [Indexed: 02/07/2023]
Abstract
PURPOSE Neurally adjusted ventilatory assist (NAVA) is a ventilatory mode that tailors the level of assistance delivered by the ventilator to the electromyographic activity of the diaphragm. The objective of this study was to compare NAVA and pressure support ventilation (PSV) in the early phase of weaning from mechanical ventilation. METHODS A multicentre randomized controlled trial of 128 intubated adults recovering from acute respiratory failure was conducted in 11 intensive care units. Patients were randomly assigned to NAVA or PSV. The primary outcome was the probability of remaining in a partial ventilatory mode (either NAVA or PSV) throughout the first 48 h without any return to assist-control ventilation. Secondary outcomes included asynchrony index, ventilator-free days and mortality. RESULTS In the NAVA and PSV groups respectively, the proportion of patients remaining in partial ventilatory mode throughout the first 48 h was 67.2 vs. 63.3 % (P = 0.66), the asynchrony index was 14.7 vs. 26.7 % (P < 0.001), the ventilator-free days at day 7 were 1.0 day [1.0-4.0] vs. 0.0 days [0.0-1.0] (P < 0.01), the ventilator-free days at day 28 were 21 days [4-25] vs. 17 days [0-23] (P = 0.12), the day-28 mortality rate was 15.0 vs. 22.7 % (P = 0.21) and the rate of use of post-extubation noninvasive mechanical ventilation was 43.5 vs. 66.6 % (P < 0.01). CONCLUSIONS NAVA is safe and feasible over a prolonged period of time but does not increase the probability of remaining in a partial ventilatory mode. However, NAVA decreases patient-ventilator asynchrony and is associated with less frequent application of post-extubation noninvasive mechanical ventilation. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT02018666.
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Affiliation(s)
- A Demoule
- Service de Pneumologie et Réanimation Médicale (Département "R3S"), Groupe Hospitalier Pitié-Salpêtrière Charles Foix, AP-HP, 75013, Paris, France.
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, UMRS1158 Neurophysiologie Respiratoire Expérimentale et Clinique, Paris, France.
| | - M Clavel
- Réanimation Polyvalente, Hôpital Dupuytren, Limoges, France
| | - C Rolland-Debord
- Service de Pneumologie et Réanimation Médicale (Département "R3S"), Groupe Hospitalier Pitié-Salpêtrière Charles Foix, AP-HP, 75013, Paris, France
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, UMRS1158 Neurophysiologie Respiratoire Expérimentale et Clinique, Paris, France
| | - S Perbet
- Réanimation Médico-Chirurgicale, CHU de Clermont-Ferrand, Clermont-Ferrand, France
- R2D2 EA-7281, Université d'Auvergne, Clermont-Ferrand, France
| | - N Terzi
- INSERM U1042, Université Grenoble-Alpes, HP2, 38000, Grenoble, France
- Service de Réanimation Médicale, CHU Grenoble Alpes, 38000, Grenoble, France
| | - A Kouatchet
- Service de Réanimation Médicale et Médecine Hyperbare, CHU d'Angers, Angers, Angers, France
| | - F Wallet
- Réanimation Médicale et Chirurgicale, Centre Hospitalier Lyon-Sud, Lyon, France
- Laboratoire des Pathogènes Emergents, Centre International de Recherche en Infectiologie, Inserm U1111, CNRS UMR5308, ENS de Lyon, UCBL1, Lyon, France
| | - H Roze
- Anesthésie et Réanimation, CHU de Bordeaux, Pessac, France
| | - F Vargas
- Réanimation Médicale, Hôpital Pellegrin-Tripode, Bordeaux, France
| | - C Guerin
- Réanimation Médicale, Hôpital de la Croix Rousse, Lyon, France
| | - J Dellamonica
- Réanimation Médicale, Hôpital de l'Archet, Centre Hospitalier Universitaire de Nice, Nice, France
- INSERM 1065 Team 3 C3 M, Nice, France
| | - S Jaber
- Anesthésie et Réanimation, Hôpital Saint-Eloi, Montpellier, France
- Montpellier School of Medicine, University of Montpellier, INSERM U1046, CNRS UMR 9214, Montpellier, France
| | - L Brochard
- Keenan Research Centre and Li Ka Shing Institute, Saint-Michael's Hospital, Toronto, ON, Canada
- Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, Canada
| | - T Similowski
- Service de Pneumologie et Réanimation Médicale (Département "R3S"), Groupe Hospitalier Pitié-Salpêtrière Charles Foix, AP-HP, 75013, Paris, France
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, UMRS1158 Neurophysiologie Respiratoire Expérimentale et Clinique, Paris, France
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Goto Y, Katayama S, Shono A, Mori Y, Miyazaki Y, Sato Y, Ozaki M, Kotani T. Roles of neurally adjusted ventilatory assist in improving gas exchange in a severe acute respiratory distress syndrome patient after weaning from extracorporeal membrane oxygenation: a case report. J Intensive Care 2016; 4:26. [PMID: 27057312 PMCID: PMC4823850 DOI: 10.1186/s40560-016-0153-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Accepted: 03/31/2016] [Indexed: 02/06/2023] Open
Abstract
Background Patient-ventilator asynchrony is a major cause of difficult weaning from mechanical ventilation. Neurally adjusted ventilatory assist (NAVA) is reported useful to improve the synchrony in patients with sustained low lung compliance. However, the role of NAVA has not been fully investigated. Case presentation The patient was a 63-year-old Japanese man with acute respiratory distress syndrome secondary to respiratory infection. He was treated with extracorporeal membrane oxygenation for 7 days and survived. Dynamic compliance at withdrawal of extracorporeal membrane oxygenation decreased to 20 ml/cmH2O or less, but gas exchange was maintained by full support with assist/control mode. However, weaning from mechanical ventilation using a flow trigger failed repeatedly because of patient-ventilator asynchrony with hypercapnic acidosis during partial ventilator support despite using different types of ventilators and different trigger levels. Weaning using NAVA restored the regular respiration and stable and normal acid-base balance. Electromyographic analysis of the diaphragm clearly showed improved triggering of both the start and the end of spontaneous inspiration. Regional ventilation monitoring using electrical impedance tomography showed an increase in tidal volume and a ventilation shift to the dorsal regions during NAVA, indicating that NAVA could deliver gas flow to the dorsal regions to adjust for the magnitude of diaphragmatic excursion. NAVA was applied for 31 days, followed by partial ventilatory support with a conventional flow trigger. The patient was discharged from the intensive care unit on day 110 and has recovered enough to be able to live without a ventilatory support for 5 h per day. Conclusion Our experience showed that NAVA improved not only patient-ventilator synchrony but also regional ventilation distribution in an acute respiratory distress patient with sustained low lung compliance.
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Affiliation(s)
- Yuya Goto
- Department of Anesthesiology and Intensive Care Medicine, Tokyo Women's Medical University, Tokyo, 162-8666 Japan
| | - Shinshu Katayama
- Department of Anesthesiology and Intensive Care Medicine, Tokyo Women's Medical University, Tokyo, 162-8666 Japan
| | - Atsuko Shono
- Department of Anesthesiology, Shimane University, Shimane, 693-8501 Japan
| | - Yosuke Mori
- Department of Anesthesiology and Intensive Care Medicine, Tokyo Women's Medical University, Tokyo, 162-8666 Japan
| | - Yuya Miyazaki
- Department of Anesthesiology and Intensive Care Medicine, Tokyo Women's Medical University, Tokyo, 162-8666 Japan
| | - Yoko Sato
- Department of Anesthesiology and Intensive Care Medicine, Tokyo Women's Medical University, Tokyo, 162-8666 Japan
| | - Makoto Ozaki
- Department of Anesthesiology and Intensive Care Medicine, Tokyo Women's Medical University, Tokyo, 162-8666 Japan
| | - Toru Kotani
- Department of Anesthesiology and Intensive Care Medicine, Tokyo Women's Medical University, Tokyo, 162-8666 Japan
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Chen J, Chen G, Xiao D, Peng W, Yu G, Lin Y, Zheng F. Continuous venovenous hemofiltration decreases mortality and ameliorates acute lung injury in canine model of severe salt water drowning. Scand J Trauma Resusc Emerg Med 2016; 24:40. [PMID: 27036317 PMCID: PMC4818413 DOI: 10.1186/s13049-016-0224-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Accepted: 03/10/2016] [Indexed: 11/15/2022] Open
Abstract
Background Pulmonary edema is an important cause of complications and death in severe drowning. Continuous veno-venous hemofiltration (CVVH) may reduce pulmonary edema and thus may be a treatment modality for severe sea water drowning resuscitation. Methos 20 dogs were anesthetized and tracheally intubated. 10 ml/kg of sea water was infused into trachea in a minute. All animals developed signs of respiratory distress and severe hypoxia (PaO2 < 40 mmHg) within 15 minutes after infusion. They were then mechanical ventilated and randomized to receive either CVVH (n = 10) or no additional treatment (control, n = 10) and followed over 4 hours. Arterial gas, hemodynamic parameters, and the levels of circulating inflammatory cytokines including interleukin 6 (IL-6), interleukin 8 (IL-8), and tumor necrosis factor α (TNFα) were determined. Additionally, blood endothelin and the levels of oxidative stress in lung were measured at sacrifice. Results 5 animals in the control group (50 %) died within 4 hours after sea water aspiration, while 10 animals received CVVH all survived (p < 0.05). Importantly, CVVH significantly improved blood gas exchange as evidenced by higher PaO2, normal oxygen saturation, and no carbon dioxide retention after 3 hour of CVVH, while also correcting against acidosis. Levels of circulating IL-6, IL-8, and TNFα were elevated in control but not in CVVH group (p < 0.01). CVVH also reduced plasma endothelin and alleviated oxidative stress. Histology examination further revealed reductions in pulmonary alveolar injury, blood congestion, and inflammation by CVVH. Discussion and conclusions CVVH decreased mortality and pulmonary injury and largely maintained hemodynamic and acid-base balance in animals with severe sea water drowning and thus, may be added as a new measure to aid in resuscitation from severe sea water drowning. Trial registration Animal protocol number: FZG0001859 http://www.fzzyy.com.
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Affiliation(s)
- Jian Chen
- Department of Nephrology, Fuzhou General Hospital, Nanjing Military Command, Fuzhou, China
| | - Guangming Chen
- Department of Nephrology, Fuzhou General Hospital, Nanjing Military Command, Fuzhou, China
| | - Daping Xiao
- Department of Nephrology, Fuzhou General Hospital, Nanjing Military Command, Fuzhou, China
| | - Weihua Peng
- Department of Nephrology, Fuzhou General Hospital, Nanjing Military Command, Fuzhou, China
| | - Guoqing Yu
- Department of Nephrology, Fuzhou General Hospital, Nanjing Military Command, Fuzhou, China
| | - Yueyong Lin
- Department of Nephrology, Fuzhou General Hospital, Nanjing Military Command, Fuzhou, China
| | - Feng Zheng
- Department of Nephrology, The Second Hospital, and Advanced Institute for Medical Sciences, Dalian Medical University, Dalian, 116044, China.
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Sédation légère chez les patients en insuffisance respiratoire aiguë. MEDECINE INTENSIVE REANIMATION 2016. [DOI: 10.1007/s13546-015-1147-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Abstract
Purpose of review Compared with the conventional forms of partial support, neurally adjusted ventilatory assist was repeatedly shown to improve patient–ventilator synchrony and reduce the risk of overassistance, while guaranteeing adequate inspiratory effort and gas exchange. A few animal studies also suggested the potential of neurally adjusted ventilatory assist in averting the risk of ventilator-induced lung injury. Recent work adds new information on the physiological effects of neurally adjusted ventilatory assist. Recent findings Compared with pressure support, neurally adjusted ventilatory assist has been shown to improve patient–ventilator interaction and synchrony in patients with the most challenging respiratory system mechanics, such as very low compliance consequent to severe acute respiratory distress syndrome and high resistance and air trapping due to chronic airflow obstruction; enhance redistribution of the ventilation in the dependent lung regions; avert the risk of patient–ventilator asynchrony due to sedation; avoid central apneas; limit the risk of high (injurious) tidal volumes in patients with acute respiratory distress syndrome of varied severity; and improve patient–ventilator interaction and synchrony during noninvasive ventilation, irrespective of the interface utilized. Summary Several studies nowadays prove the physiological benefits of neurally adjusted ventilatory assist, as opposed to the conventional modes of partial support. Whether these advantages translate into improvement of clinical outcomes remains to be determined.
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Ziebart A, Hartmann EK, Thomas R, Liu T, Duenges B, Schad A, Bodenstein M, Thal SC, David M. Low tidal volume pressure support versus controlled ventilation in early experimental sepsis in pigs. Respir Res 2014; 15:101. [PMID: 25189285 PMCID: PMC4172867 DOI: 10.1186/s12931-014-0101-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2014] [Accepted: 08/18/2014] [Indexed: 11/30/2022] Open
Abstract
Background In moderate acute respiratory distress syndrome (ARDS) several studies support the usage of assisted spontaneous breathing modes. Only limited data, however, focus on the application in systemic sepsis and developing lung injury. The present study examines the effects of immediate initiation of pressure support ventilation (PSV) in a model of sepsis-induced ARDS. Methods 18 anesthetized pigs received a two-staged continuous lipopolysaccharide infusion to induce lung injury. The animals were randomly assigned to PSV or volume controlled (VCV) lung protective ventilation (tidal volume each 6 ml kg-1, n = 2x9) over six hours. Gas exchange parameters, hemodynamics, systemic inflammation, and ventilation distribution by multiple inert gas elimination and electrical impedance tomography were assessed. The post mortem analysis included histopathological scoring, wet to dry ratio, and alveolar protein content. Results Within six hours both groups developed a mild to moderate ARDS with comparable systemic inflammatory response and without signs of improving gas exchange parameters during PSV. The PSV group showed signs of more homogenous ventilation distribution by electrical impedance tomography, but only slightly less hyperinflated lung compartments by multiple inert gas elimination. Post mortem and histopathological assessment yielded no significant intergroup differences. Conclusions In a porcine model of sepsis-induced mild ARDS immediate PSV was not superior to VCV. This contrasts with several experimental studies from non-septic mild to moderate ARDS. The present study therefore assumes that not only severity, but also etiology of lung injury considerably influences the response to early initiation of PSV.
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Glover G, Connolly B, Di Gangi S, Ayers L, Terblanche M, Beale R, Hart N. An observational cohort study to determine efficacy, adherence and outcome of the early initiation of pressure support ventilation during mechanical ventilation. BMJ Open Respir Res 2014; 1:e000028. [PMID: 25478179 PMCID: PMC4212705 DOI: 10.1136/bmjresp-2014-000028] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2014] [Revised: 03/30/2014] [Accepted: 04/05/2014] [Indexed: 12/23/2022] Open
Abstract
Background Timely initiation of weaning from mechanical ventilation (MV) is important. Non-validated screening criteria may delay weaning if too prescriptive. This study observed physician-led utilisation of pressure support ventilation (PSV), referenced to four reported conventional screening criteria hypothesising that these criteria would have delayed the weaning progress. Methods A prospective observational cohort study of adult patients receiving MV in a 30-bed university hospital intensive care unit (ICU). Logistic regression analysis identified factors associated with PSV failure. Outcome is reported according to adherence to the screening criteria. Results 209 patients were included (age 62.6±15.9 years, male:female 115:94, Acute Physiology and Chronic Health Evaluation (APACHE) II 16.7±6.1). Median (IQR) time to initiate PSV was 11.0 (5.0–22.0) h, and duration of weaning to extubation was 43.0 (13.0–121.5) h. PSV weaning was initiated despite significant hypoxia (partial pressure of arterial oxygen to fraction of inspired oxygen ratio (PaO2:FiO2) 35.8±15.9 kPa), moderate positive end-expiratory pressure levels (7.5±2.5 cm H2O), deep sedation (44% Richmond Agitation and Sedation Scale (RASS) ≤−3) and cardiovascular instability (48.8%). At PSV initiation, 85% of patients violated at least one screening criterion, yet 74.6% of patients remained stable for 24 h and 25.4% of patients were successfully extubated within 12 h. There was no association between individual screening criteria and PSV failure. Failure to sustain a PSV trial was associated with ventilation >7 days (RR=2.12 (1.33 to 3.38), p=0.002) and ICU mortality (RR=2.94 (1.46 to 5.94), p=0.002). Conclusions Physician-led transition to PSV and weaning was often initiated early and successfully before patients fulfilled conventional screening criteria. Failure to sustain a PSV trial could be an early indicator of prolonged MV and ICU mortality and warrants further investigation. These data support the view that current screening criteria may delay initiation of weaning.
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Affiliation(s)
- Guy Glover
- Department of Critical Care , Guy's and St Thomas' NHS Foundation Trust , London , UK
| | - Bronwen Connolly
- Division of Asthma, Allergy and Lung Biology , King's College London , London , UK ; Lane Fox Respiratory Unit , Guy's and St Thomas' NHS Foundation Trust , London , UK ; Guy's and St Thomas' NHS Foundation Trust and King's College London, National Institute of Health Research Biomedical Research Centre , London , UK
| | - Stefania Di Gangi
- Department of Critical Care , Guy's and St Thomas' NHS Foundation Trust , London , UK
| | - Lisa Ayers
- Department of Critical Care , Guy's and St Thomas' NHS Foundation Trust , London , UK
| | - Marius Terblanche
- Department of Critical Care , Guy's and St Thomas' NHS Foundation Trust , London , UK ; Division of Health & Social Care Research, King's College London , London , UK
| | - Richard Beale
- Department of Critical Care , Guy's and St Thomas' NHS Foundation Trust , London , UK
| | - Nicholas Hart
- Division of Asthma, Allergy and Lung Biology , King's College London , London , UK ; Lane Fox Respiratory Unit , Guy's and St Thomas' NHS Foundation Trust , London , UK ; Guy's and St Thomas' NHS Foundation Trust and King's College London, National Institute of Health Research Biomedical Research Centre , London , UK
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Impact of ventilator adjustment and sedation-analgesia practices on severe asynchrony in patients ventilated in assist-control mode. Crit Care Med 2013; 41:2177-87. [PMID: 23782972 DOI: 10.1097/ccm.0b013e31828c2d7a] [Citation(s) in RCA: 103] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
OBJECTIVES Breath-stacking asynchrony during assist-control-mode ventilation may be associated with increased tidal volume and alveolar pressure that could contribute to ventilator-induced lung injury. Methods to reduce breath stacking have not been well studied. The objective of this investigation was to evaluate 1) which interventions were used by managing clinicians to address severe breath stacking; and 2) how effective these measures were. SETTING Sixteen-bed medical ICU. PATIENTS AND INTERVENTIONS Physiological study in consecutively admitted patients without severe brain injury, who had severe breath stacking defined as an asynchrony index greater than or equal to 10% of total breaths. During 30 minutes before (baseline) and after any intervention employed by the managing clinician, the ventilator flow, airway pressure, and volume/time waveforms were continuously recorded and analyzed to detect normal and stacked breaths. The initial approach taken was assigned to one of three categories: no intervention, increase of sedation-analgesia, or change of ventilator setting. Nonparametric Wilcoxon-Mann-Whitney tests and multiple regression were used for statistical analysis. Quantitative data are presented as median [25-75]. MAIN RESULTS Sixty-six of 254 (26%) mechanically ventilated patients exhibited severe breath-stacking asynchrony. A total of 100 30-minute sequences were recorded and analyzed in 30 patients before and after 50 clinical decisions for ongoing management (no intervention, n=8; increasing sedation/analgesia, n=16; ventilator adjustment, n=26). Breath-stacking asynchrony index was 44 [27-87]% at baseline. Compared with baseline, the decrease of asynchrony index was greater after changing the ventilator setting (-99 [-92, -100]%) than after increasing the sedation-analgesia (-41 [-66, 7]%, p<0.001) or deciding to tolerate the asynchrony (4 [-4, 12]%, p<0.001). Pressure-support ventilation and increased inspiratory time were independently associated with the reduction of asynchrony index. CONCLUSIONS Compared with increasing sedation-analgesia, adapting the ventilator to patient breathing effort reduces breath-stacking asynchrony significantly and often dramatically. These results support an algorithm beginning with ventilator adjustment to rationalize the management of severe breath-stacking asynchrony in ICU patients.
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Aguirre-Bermeo H, Bottiroli M, Italiano S, Roche-Campo F, Santos JA, Alonso M, Mancebo J. [Pressure support ventilation and proportional assist ventilation during weaning from mechanical ventilation]. Med Intensiva 2013; 38:363-70. [PMID: 24144679 DOI: 10.1016/j.medin.2013.08.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2013] [Revised: 08/07/2013] [Accepted: 08/28/2013] [Indexed: 11/17/2022]
Abstract
OBJECTIVES To compare tolerance, duration of mechanical ventilation (MV) and clinical outcomes during weaning from MV in patients subjected to either pressure support ventilation (PSV) or proportional assist ventilation (PAV). DESIGN A prospective, observational study was carried out. SETTING Intensive Care Unit. PATIENTS A total of 40 consecutive subjects were allocated to either the PSV or the PAV group until each group contained 20 patients. Patients were included in the study when they met the criteria to begin weaning and the attending physician decided to initiate the weaning process. The physician selected the modality and set the ventilatory parameters. INTERVENTIONS None. VARIABLES OF INTEREST Demographic data, respiratory mechanics, ventilatory parameters, duration of MV, and clinical outcomes (reintubation, tracheostomy, mortality). RESULTS Baseline characteristics were similar in both groups. No significant differences were observed between the PSV and PAV groups in terms of the total duration of MV (10 [5-18] vs. 9 [7-19] days; P=.85), reintubation (5 [31%] vs. 3 [19%]; P=.69), or mortality (4 [20%] vs. 5 [25%] deaths; P=1). Eight patients (40%) in the PSV group and 6 patients (30%) in the PAV group (P=.74) required a return to volume assist-control ventilation due to clinical deterioration. CONCLUSIONS Tolerance, duration of MV and clinical outcomes during weaning from mechanical ventilation were similar in PSV and PAV.
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Affiliation(s)
- H Aguirre-Bermeo
- Servicio de Medicina Intensiva, Hospital de la Santa Creu i Sant Pau, Universidad Autónoma de Barcelona (UAB), Barcelona, España; Servicio de Medicina Intensiva, Hospital Sant Joan de Reus, Reus, Tarragona, España.
| | - M Bottiroli
- Servicio de Medicina Intensiva, Hospital de la Santa Creu i Sant Pau, Universidad Autónoma de Barcelona (UAB), Barcelona, España; Anestesia e Rianimazione 3, Ospedale Niguarda Ca' Granda, Milán, Italia
| | - S Italiano
- Servicio de Medicina Intensiva, Hospital de la Santa Creu i Sant Pau, Universidad Autónoma de Barcelona (UAB), Barcelona, España; Servicio de Medicina Intensiva, Hospital Verge de la Cinta, Tortosa, Tarragona, España
| | - F Roche-Campo
- Servicio de Medicina Intensiva, Hospital de la Santa Creu i Sant Pau, Universidad Autónoma de Barcelona (UAB), Barcelona, España; Servicio de Medicina Intensiva, Hospital Sant Joan de Reus, Reus, Tarragona, España
| | - J A Santos
- Servicio de Medicina Intensiva, Hospital de la Santa Creu i Sant Pau, Universidad Autónoma de Barcelona (UAB), Barcelona, España
| | - M Alonso
- Servicio de Farmacología Clínica, Hospital de la Santa Creu i Sant Pau, Universidad Autónoma de Barcelona (UAB), Barcelona, España
| | - J Mancebo
- Servicio de Medicina Intensiva, Hospital de la Santa Creu i Sant Pau, Universidad Autónoma de Barcelona (UAB), Barcelona, España
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Pressure Support in Acute Respiratory Distress Syndrome. Crit Care Med 2013; 41:1811-2. [DOI: 10.1097/ccm.0b013e31828c261a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Topographic Distribution of Tidal Ventilation in Acute Respiratory Distress Syndrome. Crit Care Med 2013; 41:1664-73. [DOI: 10.1097/ccm.0b013e318287f6e7] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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Pichot C, Petitjeans F, Ghignone M, Quintin L. Is there a place for pressure-support ventilation and high positive end-expiratory pressure combined to alpha-2 agonists early in severe diffuse acute respiratory distress syndrome? Med Hypotheses 2013; 80:732-7. [PMID: 23561575 DOI: 10.1016/j.mehy.2013.02.023] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2012] [Revised: 01/16/2013] [Accepted: 02/28/2013] [Indexed: 11/20/2022]
Abstract
Acute respiratory distress syndrome (ARDS) is associated with a high mortality linked primarily to co-morbidities (sepsis, cardiac failure, multiple organ failure, etc.). When the lung is the single failing organ, quick resolution of ARDS should skip some complications arising from a prolonged stay in the critical care unit. In severe ARDS (PaO2/FIO2=P/F<100 with positive end-expiratory pressure (PEEP) ≥ 5 cm H2O), current recommendations are to intubate the trachea of the patient and use mechanical ventilation, low tidal volume, high PEEP, prone positioning and possibly neuromuscular blockade in association with intravenous sedation. Another strategy is possible. Firstly, spontaneous ventilation (SV) coupled with pressure support (PS) ventilation and high PEEP is possible from tracheal intubation onwards, with the possible exception of the short period following immediately tracheal intubation. Secondly, using alpha-2 adrenergic agonists (e.g. clonidine, dexmedetomidine) can provide first-line sedation from the beginning of mechanical ventilation, as they preserve respiratory drive, lower oxygen consumption and pulmonary hypertension and increase diuresis. Alpha-2 agonists are to be supplemented, if appropriate, by drugs devoid of effect on respiratory drive (neuroleptics, etc.). The expected benefits would be to prevent acquired diaphragmatic weakness, accumulation of sedation, cognitive dysfunction, and presumably improved outcome. This hypothesis should be tested in a double blind randomized controlled trial.
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Affiliation(s)
- C Pichot
- Department of Physiology, University of Lyon, EA 4612: Neurocardiology, Lyon, France
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Mauri T, Bellani G, Grasselli G, Confalonieri A, Rona R, Patroniti N, Pesenti A. Patient–ventilator interaction in ARDS patients with extremely low compliance undergoing ECMO: a novel approach based on diaphragm electrical activity. Intensive Care Med 2012. [DOI: 10.1007/s00134-012-2755-1] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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McMullen SM, Meade M, Rose L, Burns K, Mehta S, Doyle R, Henzler D. Partial ventilatory support modalities in acute lung injury and acute respiratory distress syndrome-a systematic review. PLoS One 2012; 7:e40190. [PMID: 22916094 PMCID: PMC3420868 DOI: 10.1371/journal.pone.0040190] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2012] [Accepted: 06/02/2012] [Indexed: 01/21/2023] Open
Abstract
PURPOSE The efficacy of partial ventilatory support modes that allow spontaneous breathing in patients with acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) is unclear. The objective of this scoping review was to assess the effects of partial ventilatory support on mortality, duration of mechanical ventilation, and both hospital and intensive care unit (ICU) lengths of stay (LOS) for patients with ALI and ARDS; the secondary objective was to describe physiologic effects on hemodynamics, respiratory system and other organ function. METHODS MEDLINE (1966-2009), Cochrane, and EmBase (1980-2009) databases were searched using common ventilator modes as keywords and reference lists from retrieved manuscripts hand searched for additional studies. Two researchers independently reviewed and graded the studies using a modified Oxford Centre for Evidence-Based Medicine grading system. Studies in adult ALI/ARDS patients were included for primary objectives and pre-clinical studies for supporting evidence. RESULTS Two randomized controlled trials (RCTs) were identified, in addition to six prospective cohort studies, one retrospective cohort study, one case control study, 41 clinical physiologic studies and 28 pre-clinical studies. No study was powered to assess mortality, one RCT showed shorter ICU length of stay, and the other demonstrated more ventilator free days. Beneficial effects of preserved spontaneous breathing were mainly physiological effects demonstrated as improvement of gas exchange, hemodynamics and non-pulmonary organ perfusion and function. CONCLUSIONS The use of partial ventilatory support modalities is often feasible in patients with ALI/ARDS, and may be associated with short-term physiological benefits without appreciable impact on clinically important outcomes.
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Affiliation(s)
- Sarah M. McMullen
- Department of Anesthesiology and Critical Care Medicine, Dalhousie University, Halifax, Canada
| | - Maureen Meade
- Departments of Medicine and Clinical Epidemiology & Biostatistics, McMaster University, Hamilton, Canada
| | - Louise Rose
- Lawrence S. Bloomberg Faculty of Nursing, University of Toronto, Toronto, Canada
| | - Karen Burns
- Interdepartmental Division of Critical Care, University of Toronto and St Michael's Hospital, and Li Ka Shing Knowledge Institute, Toronto, Canada
| | - Sangeeta Mehta
- Department of Medicine and Interdepartmental Division of Critical Care Medicine, Mount Sinai Hospital, University of Toronto, Toronto, Canada
| | - Robert Doyle
- Department of Anesthesiology and Critical Care Medicine, Dalhousie University, Halifax, Canada
| | - Dietrich Henzler
- Department of Anesthesiology and Critical Care Medicine, Dalhousie University, Halifax, Canada
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Terzi N, Piquilloud L, Rozé H, Mercat A, Lofaso F, Delisle S, Jolliet P, Sottiaux T, Tassaux D, Roesler J, Demoule A, Jaber S, Mancebo J, Brochard L, Richard JCM. Clinical review: Update on neurally adjusted ventilatory assist--report of a round-table conference. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2012; 16:225. [PMID: 22715815 PMCID: PMC3580602 DOI: 10.1186/cc11297] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Conventional mechanical ventilators rely on pneumatic pressure and flow sensors and controllers to detect breaths. New modes of mechanical ventilation have been developed to better match the assistance delivered by the ventilator to the patient's needs. Among these modes, neurally adjusted ventilatory assist (NAVA) delivers a pressure that is directly proportional to the integral of the electrical activity of the diaphragm recorded continuously through an esophageal probe. In clinical settings, NAVA has been chiefly compared with pressure-support ventilation, one of the most popular modes used during the weaning phase, which delivers a constant pressure from breath to breath. Comparisons with proportional-assist ventilation, which has numerous similarities, are lacking. Because of the constant level of assistance, pressure-support ventilation reduces the natural variability of the breathing pattern and can be associated with asynchrony and/or overinflation. The ability of NAVA to circumvent these limitations has been addressed in clinical studies and is discussed in this report. Although the underlying concept is fascinating, several important questions regarding the clinical applications of NAVA remain unanswered. Among these questions, determining the optimal NAVA settings according to the patient's ventilatory needs and/or acceptable level of work of breathing is a key issue. In this report, based on an investigator-initiated round table, we review the most recent literature on this topic and discuss the theoretical advantages and disadvantages of NAVA compared with other modes, as well as the risks and limitations of NAVA.
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Lim B, Pawar D, Ng O. Pressure support ventilation vs spontaneous ventilation via ProSeal™ laryngeal mask airway in pediatric patients undergoing ambulatory surgery: a randomized controlled trial. Paediatr Anaesth 2012; 22:360-4. [PMID: 22380745 DOI: 10.1111/j.1460-9592.2012.03819.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
AIM To investigate the advantages of using pressure support ventilation (PSV) vs spontaneous ventilation via ProSeal™ laryngeal mask airway in children undergoing ambulatory surgery. BACKGROUND In our ambulatory surgical unit, the use of unassisted spontaneous breathing via laryngeal mask airway is a common anesthetic technique during general anesthesia. However, this may be associated with inadequate ventilation. PSV is a ventilatory mode that is synchronized with the patient's respiratory effort and may improve gaseous exchange under general anesthesia. MATERIALS AND METHODS After the approval from the ethics committee, a randomized controlled trial involving 24 pediatric patients was conducted in our ambulatory surgical unit. They were randomized into two groups, namely Group PSV (receiving PSV) and Group SV (unassisted spontaneous ventilation). Outcome measures included intraoperative respiratory and hemodynamic parameters as well as recovery room data. RESULTS There were no significant differences in baseline characteristics between the two groups. Patients in Group PSV had lower ETCO(2) (42.8 ± 5.8 vs 50.4 ± 4.0, P = 0.001) and higher expiratory tidal volume per kg bodyweight (8.3 ± 1.8 ml kg(-1) vs 5.8 ± 0.8 ml kg(-1), P = 0.001) compared with patients in Group SV. There were no significant differences in other respiratory and hemodynamic parameters or recovery room data between the two groups. CONCLUSION Pressure support ventilation via ProSeal™ laryngeal mask airway during general anesthesia improves ventilation in pediatric patients undergoing ambulatory surgery. However, this did not translate to a difference in clinical outcome among our study patients.
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Affiliation(s)
- Beatrice Lim
- Department of Pediatrics Anesthesia, KK Women's and Children's Hospital, Singapore.
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Effect of pressure support on end-expiratory lung volume and lung diffusion for carbon monoxide. Crit Care Med 2011; 39:2283-9. [DOI: 10.1097/ccm.0b013e3182227fce] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Influence of lung collapse distribution on the physiologic response to recruitment maneuvers during noninvasive continuous positive airway pressure. Intensive Care Med 2011; 37:1095-102. [PMID: 21567113 DOI: 10.1007/s00134-011-2239-8] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2010] [Accepted: 03/14/2011] [Indexed: 10/18/2022]
Abstract
PURPOSE Noninvasive continuous positive airway pressure (n-CPAP) has been proposed for the treatment of hypoxemic acute respiratory failure (h-ARF). Recruitment maneuvers were shown to improve oxygenation, i.e., the ratio of arterial oxygen tension to inspiratory oxygen fraction (PaO2/FiO2), during either invasive mechanical ventilation, and n-CPAP, with a response depending on the distribution of lung collapse. We hypothesized that, during n-CPAP, early h-ARF patients with bilateral (B(L)) distribution of lung involvement would benefit from recruitment maneuvers more than those with unilateral (U(L)) involvement. METHODS To perform a recruitment maneuver, once a minute we increased the pressure applied to the airway from 10 cmH2O to 25 cmH2O for 8 s (SIGH). We enrolled 24 patients with h-ARF (12 B(L) and 12 U(L)) who underwent four consecutive trials: (1) 30 min breathing through a Venturi mask (V(MASK)), (2) 1 h n-CPAP (n-CPAP1), (3) 1 h n-CPAP plus SIGH (n-CPAP(SIGH)), and (4) 1 h n-CPAP (n-CPAP2). RESULTS Compared to V(MASK), n-CPAP at 10 cmH2O delivered via a helmet, increased PaO2/FiO2 and decreased dyspnea in both B(L) and U(L); furthermore, it reduced the respiratory rate and brought PaCO2 up to normal in B(L) only. Compared to n-CPAP, n-CPAP(SIGH) significantly improved PaO2/FiO2 in B(L) (225 ± 88 vs. 308 ± 105, respectively), whereas it produced no further improvement in PaO2/FiO2 in U(L) (232 ± 72 vs. 231 ± 77, respectively). SIGH did not affect hemodynamics in both groups. CONCLUSIONS Compared to n-CPAP, n-CPAP(SIGH) further improved arterial oxygenation in B(L) patients, whereas it produced no additional benefit in those with U(L).
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Pressure support improves oxygenation and lung protection compared to pressure-controlled ventilation and is further improved by random variation of pressure support*. Crit Care Med 2011; 39:746-55. [DOI: 10.1097/ccm.0b013e318206bda6] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Carvalho AR, Spieth PM, Güldner A, Cuevas M, Carvalho NC, Beda A, Spieth S, Stroczynski C, Wiedemann B, Koch T, Pelosi P, de Abreu MG. Distribution of regional lung aeration and perfusion during conventional and noisy pressure support ventilation in experimental lung injury. J Appl Physiol (1985) 2011; 110:1083-92. [PMID: 21270348 DOI: 10.1152/japplphysiol.00804.2010] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In acute lung injury (ALI), pressure support ventilation (PSV) may improve oxygenation compared with pressure-controlled ventilation (PCV), and benefit from random variation of pressure support (noisy PSV). We investigated the effects of PCV, PSV, and noisy PSV on gas exchange as well as the distribution of lung aeration and perfusion in 12 pigs with ALI induced by saline lung lavage in supine position. After injury, animals were mechanically ventilated with PCV, PSV, and noisy PSV for 1 h/mode in random sequence. The driving pressure was set to a mean tidal volume of 6 ml/kg and positive end-expiratory pressure to 8 cmH₂O in all modes. Functional variables were measured, and the distribution of lung aeration was determined by static and dynamic computed tomography (CT), whereas the distribution of pulmonary blood flow (PBF) was determined by intravenously administered fluorescent microspheres. PSV and noisy PSV improved oxygenation and reduced venous admixture compared with PCV. Mechanical ventilation with PSV and noisy PSV did not decrease nonaerated areas but led to a redistribution of PBF from dorsal to ventral lung regions and reduced tidal reaeration and hyperinflation compared with PCV. Noisy PSV further improved oxygenation and redistributed PBF from caudal to cranial lung regions compared with conventional PSV. We conclude that assisted ventilation with PSV and noisy PSV improves oxygenation compared with PCV through redistribution of PBF from dependent to nondependent zones without lung recruitment. Random variation of pressure support further redistributes PBF and improves oxygenation compared with conventional PSV.
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Affiliation(s)
- Alysson R Carvalho
- Clinic of Anesthesiology and Intensive Care Therapy, Univ. Hospital Dresden, Dresden, Germany
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Successful use of neurally adjusted ventilatory assist in a patient with extremely low respiratory system compliance undergoing ECMO. Intensive Care Med 2010; 37:166-7. [PMID: 20845028 DOI: 10.1007/s00134-010-2030-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/30/2010] [Indexed: 12/12/2022]
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Neurally adjusted ventilatory assist in patients recovering spontaneous breathing after acute respiratory distress syndrome: Physiological evaluation*. Crit Care Med 2010; 38:1830-7. [DOI: 10.1097/ccm.0b013e3181eb3c51] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Yoshida T, Rinka H, Kaji A, Yoshimoto A, Arimoto H, Miyaichi T, Kan M. The impact of spontaneous ventilation on distribution of lung aeration in patients with acute respiratory distress syndrome: airway pressure release ventilation versus pressure support ventilation. Anesth Analg 2009; 109:1892-900. [PMID: 19923518 DOI: 10.1213/ane.0b013e3181bbd918] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND In this study, we sought to determine which mode, airway pressure release ventilation (APRV) or pressure support ventilation (PSV), decreases atelectasis more in patients with acute lung injury/acute respiratory distress syndrome (ARDS). METHODS This was a retrospective study in the intensive care unit. Between 2006 and 2007, we identified 18 patients with acute lung injury/ARDS who received either APRV or PSV and had a helical computed tomography scan twice in 3 days. RESULTS Computed tomography data from the APRV and PSV groups (n = 9 each) were analyzed for 3-dimensional reconstruction and volumetry. Aerated lung regions (normally aerated, poorly aerated, nonaerated, and hyperinflated) were identified by their densities in Hounsfield units. The Pao(2)/Fio(2) ratio and alveolar-arteriolar oxygen gradient after ventilation were improved in both groups (P = 0.008); however, the improvements in the APRV group exceeded those in the PSV group when delivered with equal mean airway pressure (P = 0.018 and 0.015, respectively). Atelectasis decreased significantly from 41% (range, 17%-68%) to 19% (range, 6%-40%) (P = 0.008) and normally aerated volume increased significantly from 29% (range, 13%-41%) to 43% (range, 25%-56%) (P = 0.008) in the APRV group, whereas lung volume did not change in the PSV group. CONCLUSIONS Spontaneous ventilation during APRV improves lung aeration by decreasing atelectasis. PSV for gas exchange is effective but not sufficient to improve lung aeration. These results indicate that APRV is more efficient than PSV as a mode of primary ventilatory support to decrease atelectasis in patients with ARDS.
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Affiliation(s)
- Takeshi Yoshida
- Intensive Care Unit, Osaka University Hospital, 2-15 Yamadaoka, Suita, Osaka 565-0871, Japan.
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Carvalho AR, Spieth PM, Pelosi P, Beda A, Lopes AJ, Neykova B, Heller AR, Koch T, Gama de Abreu M. Pressure Support Ventilation and Biphasic Positive Airway Pressure Improve Oxygenation by Redistribution of Pulmonary Blood Flow. Anesth Analg 2009; 109:856-65. [DOI: 10.1213/ane.0b013e3181aff245] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Abstract
Health-care providers are increasingly faced with the possibility of needing to care for people injured in explosions, but can often, however, feel undertrained for the unique aspects of the patient's presentation and management. Although most blast-related injuries (eg, fragmentation injuries from improvised explosive devices and standard military explosives) can be managed in a similar manner to typical penetrating or blunt traumatic injuries, injuries caused by the blast pressure wave itself cannot. The blast pressure wave exerts forces mainly at air-tissue interfaces within the body, and the pulmonary, gastrointestinal, and auditory systems are at greatest risk. Arterial air emboli arising from severe pulmonary injury can cause ischaemic complications-especially in the brain, heart, and intestinal tract. Attributable, in part, to the scene chaos that undoubtedly exists, poor triage and missed diagnosis of blast injuries are substantial concerns because injuries can be subtle or their presentation can be delayed. Management of these injuries can be a challenge, compounded by potentially conflicting treatment goals. This Seminar aims to provide a thorough overview of these unique primary blast injuries and their management.
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Affiliation(s)
- Stephen J Wolf
- Department of Emergency Medicine, Denver Health Medical Center, Denver, CO 80204, USA.
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Fick IWF, Tijdink MM, Halbertsma FJJ, van der Hoeven JG, Pickkers P. Risk factors for the deterioration of oxygenation ratio in ventilated intensive care unit patients: a retrospective cohort study. J Crit Care 2009; 25:3-9. [PMID: 19592207 DOI: 10.1016/j.jcrc.2009.04.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2008] [Revised: 04/23/2009] [Accepted: 04/28/2009] [Indexed: 10/20/2022]
Abstract
PURPOSE The aim of the study is to determine which factors are associated with the deterioration of Pao(2)/fraction of inspired oxygen (Fio(2)) ratio in patients with normal oxygenation at admission and ventilated according to a lung protective ventilation strategy. MATERIALS AND METHODS Retrospective cohort study of ventilated (>/=3 days) intensive care unit patients with an admission Pao(2)/Fio(2) ratio of 300 mm Hg or higher (n = 105). Patients who developed lung injury (Pao(2)/Fio(2) ratio, <300 mm Hg) on day 7 (n = 37) were compared to those who did not (n = 68), with regard to ventilator settings, gas exchange variables, and lung injury risk factors. RESULTS Mean +/- SD of administered tidal volume was 7.9 +/- 1.3 mL/kg. Patients who developed lung injury were older (P = .019), had lower Pao(2) (P = .009), higher Paco(2) (P = .045), and lower Pao(2)/Fio(2) ratio (P = .002) at admission. Postoperative state (Hazard risk [HR], 5.1) and controlled ventilation mode (HR, 4.3) were identified as independent risk factors. Lung injury-free time was shorter in patients with low initial Pao(2)/Fio(2) ratio (odds ratio, 1.7; P = .039). This effect was not only caused by the baseline difference, as the decrease in Pao(2)/Fio(2) ratio was more pronounced in patients who developed lung injury compared to those who did not (P = .008). CONCLUSIONS Lung injury exacerbates during mechanical ventilation. In patients treated with a mean tidal volume of 7.9 mL/kg, controlled ventilation is a major risk factor.
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Affiliation(s)
- Ilma W F Fick
- Radboud University Nijmegen Medical Center, PO-Box 9101, 6500HB Nijmegen, The Netherlands
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33
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Physiologic response to varying levels of pressure support and neurally adjusted ventilatory assist in patients with acute respiratory failure. Intensive Care Med 2008; 34:2010-8. [DOI: 10.1007/s00134-008-1208-3] [Citation(s) in RCA: 140] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2008] [Accepted: 05/26/2008] [Indexed: 10/21/2022]
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34
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Xirouchaki N, Kondili E, Vaporidi K, Xirouchakis G, Klimathianaki M, Gavriilidis G, Alexandopoulou E, Plataki M, Alexopoulou C, Georgopoulos D. Proportional assist ventilation with load-adjustable gain factors in critically ill patients: comparison with pressure support. Intensive Care Med 2008; 34:2026-34. [PMID: 18607562 DOI: 10.1007/s00134-008-1209-2] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2008] [Accepted: 06/16/2008] [Indexed: 11/24/2022]
Abstract
OBJECTIVES It is not known if proportional assist ventilation with load-adjustable gain factors (PAV+) may be used as a mode of support in critically ill patients. The aim of this study was to examine the effectiveness of sustained use of PAV+ in critically ill patients and compare it with pressure support ventilation (PS). DESIGN AND SETTING Randomized study in the intensive care unit of a university hospital. METHODS A total of 208 critically ill patients mechanically ventilated on controlled modes for at least 36 h and meeting certain criteria were randomized to receive either PS (n = 100) or PAV+ (n = 108). Specific written algorithms were used to adjust the ventilator settings in each mode. PAV+ or PS was continued for 48 h unless the patients met pre-defined criteria either for switching to controlled modes (failure criteria) or for breathing without ventilator assistance. RESULTS Failure rate was significantly lower in PAV+ than that in PS (11.1 vs. 22.0%, P = 0.040, OR 0.443, 95% CI 0.206-0.952). The proportion of patients exhibiting major patient-ventilator dyssynchronies at least during one occasion and after adjusting the initial ventilator settings, was significantly lower in PAV+ than in PS (5.6 vs. 29.0%, P < 0.001, OR 0.1, 95% CI 0.06-0.4). The proportion of patients meeting criteria for unassisted breathing did not differ between modes. CONCLUSIONS PAV+ may be used as a useful mode of support in critically ill patients. Compared to PS, PAV+ increases the probability of remaining on spontaneous breathing, while it considerably reduces the incidence of patient-ventilator asynchronies.
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Affiliation(s)
- Nektaria Xirouchaki
- Intensive Care Medicine Department, University Hospital of Heraklion, Medical School, University of Crete, Heraklion, Crete, Greece
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Gattinoni L, Carlesso E, Caironi P. Mechanical Ventilation in Acute Respiratory Distress Syndrome. Crit Care Med 2008. [DOI: 10.1016/b978-032304841-5.50013-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Garcia-Fernandez J, Tusman G, Suarez-Sipmann F, Llorens J, Soro M, Belda JF. Programming pressure support ventilation in pediatric patients in ambulatory surgery with a laryngeal mask airway. Anesth Analg 2007; 105:1585-91, table of contents. [PMID: 18042854 DOI: 10.1213/01.ane.0000287674.64086.f1] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND Anesthesia workstations with pressure support ventilation (PSV) are available, but there are few studies published on how to program flow-triggered PSV using a laryngeal mask airway (LMA) under general anesthesia in pediatric patients. METHODS We studied 60 ASA I and II patients, from 2 mo to 14 yr, scheduled for ambulatory surgery under combined general and regional anesthesia with a LMA. Patients were classified according to their body weight as follows: Group A < or =10 kg, Group B 11-20 kg, and Group C >20 kg. All were ventilated in PSV using the following settings: positive end-expiratory pressure of 4 cm H2O, the minimum flow-trigger without provoking auto-triggering, and the minimum level of pressure support to obtain 10 mL/kg of tidal volume. RESULTS The flow-trigger most frequently used in our study was 0.4 L/min, ranging from 0.2 to 0.6 L/min. We found no correlation between the flow-trigger setting and the patient's age, weight, compliance, resistance, or respiratory rate. There was a good correlation between the level of pressure support (Group A = 15 cm H2O, Group B = 10 cm H2O and Group C = 9 cm H2O) and age (P < 0.001), weight (P < 0.001), dynamic compliance (P < 0.001), and airway resistances (P < 0.001). CONCLUSIONS PSV with a Proseal LMA in outpatient pediatric anesthesia can be programmed simply using the common clinical noninvasive variables studied. However, more studies are needed to estimate the level of pressure support that may be required in other clinical situations (respiratory pathology, endotracheal tubes, or other types of surgeries) or with other anesthesia workstations.
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Affiliation(s)
- Javier Garcia-Fernandez
- Pediatric Anesthesiology and Postsurgical Critical Care Department, La Paz Universitary Hospital, Madrid, Spain.
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Alexopoulou C, Kondili E, Vakouti E, Klimathianaki M, Prinianakis G, Georgopoulos D. Sleep during proportional-assist ventilation with load-adjustable gain factors in critically ill patients. Intensive Care Med 2007; 33:1139-1147. [PMID: 17458541 DOI: 10.1007/s00134-007-0630-2] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2006] [Accepted: 03/19/2007] [Indexed: 02/02/2023]
Abstract
BACKGROUND Proportional-assist ventilation with load-adjustable gain factors (PAV+) automatically adjusts the flow and volume assist to represent constant fractions of resistance and elastance of the respiratory system, respectively. Resistance and elastance are calculated at random intervals of 4-10 breaths, by applying a 300 ms pause maneuver at the end of selected inspirations. OBJECTIVES To determine whether the large number of end-inspiratory occlusions during PAV+ operation influences sleep quality in critically ill patients who exhibited good patient-ventilator synchrony during pressure support (PS, baseline). METHODS One and two nights' polysomnography was performed in sedated (protocol A, n=11) and non-sedated (protocol B, n=9) patients, respectively, while respiratory variables were continuously recorded. In each protocol the patients were ventilated with PAV+ and PS at two levels of assist (baseline and high). RESULTS In both protocols sleep quality did not differ between the modes of support or the assist levels. In sedated patients sleep efficiency was slightly but significantly higher with PAV+ than with high PS, while it did not differ between modes in non-sedated patients. The two modes of support had comparable effects on respiratory variables. Independent of the mode of support and particularly at high assist, a significant proportion of patients developed periodic breathing during sleep (27% in protocol A and 44% in protocol B). CONCLUSION In patients exhibiting good patient-ventilator synchrony during PS, the large number of short-term end-inspiratory occlusions with PAV+ operation did not adversely influence sleep quality. With both modes high assist may cause unstable breathing during sleep.
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Affiliation(s)
- C Alexopoulou
- Department of Intensive Care Medicine, University Hospital of Heraklion, University of Crete, Heraklion, 711 10, Crete, Greece
| | - E Kondili
- Department of Intensive Care Medicine, University Hospital of Heraklion, University of Crete, Heraklion, 711 10, Crete, Greece
| | - E Vakouti
- Department of Intensive Care Medicine, University Hospital of Heraklion, University of Crete, Heraklion, 711 10, Crete, Greece
| | - M Klimathianaki
- Department of Intensive Care Medicine, University Hospital of Heraklion, University of Crete, Heraklion, 711 10, Crete, Greece
| | - G Prinianakis
- Department of Intensive Care Medicine, University Hospital of Heraklion, University of Crete, Heraklion, 711 10, Crete, Greece
| | - D Georgopoulos
- Department of Intensive Care Medicine, University Hospital of Heraklion, University of Crete, Heraklion, 711 10, Crete, Greece.
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van Heerde M, van Genderingen HR, Leenhoven T, Roubik K, Plötz FB, Markhorst DG. Imposed work of breathing during high-frequency oscillatory ventilation: a bench study. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2006; 10:R23. [PMID: 16469130 PMCID: PMC1550789 DOI: 10.1186/cc3988] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/24/2005] [Revised: 12/22/2005] [Accepted: 01/11/2006] [Indexed: 01/04/2023]
Abstract
Introduction The ventilator and the endotracheal tube impose additional workload in mechanically ventilated patients breathing spontaneously. The total work of breathing (WOB) includes elastic and resistive work. In a bench test we assessed the imposed WOB using 3100 A/3100 B SensorMedics high-frequency oscillatory ventilators. Methods A computer-controlled piston-driven test lung was used to simulate a spontaneously breathing patient. The test lung was connected to a high-frequency oscillatory ventilation (HFOV) ventilator by an endotracheal tube. The inspiratory and expiratory airway flows and pressures at various places were sampled. The spontaneous breath rate and volume, tube size and ventilator settings were simulated as representative of the newborn to adult range. The fresh gas flow rate was set at a low and a high level. The imposed WOB was calculated using the Campbell diagram. Results In the simulations for newborns (assumed body weight 3.5 kg) and infants (assumed body weight 10 kg) the imposed WOB (mean ± standard deviation) was 0.22 ± 0.07 and 0.87 ± 0.25 J/l, respectively. Comparison of the imposed WOB in low and high fresh gas flow rate measurements yielded values of 1.63 ± 0.32 and 0.96 ± 0.24 J/l (P = 0.01) in small children (assumed body weight 25 kg), of 1.81 ± 0.30 and 1.10 ± 0.27 J/l (P < 0.001) in large children (assumed body weight 40 kg), and of 1.95 ± 0.31 and 1.12 ± 0.34 J/l (P < 0.01) in adults (assumed body weight 70 kg). High peak inspiratory flow and low fresh gas flow rate significantly increased the imposed WOB. Mean airway pressure in the breathing circuit decreased dramatically during spontaneous breathing, most markedly at the low fresh gas flow rate. This led to ventilator shut-off when the inspiratory flow exceeded the fresh gas flow. Conclusion Spontaneous breathing during HFOV resulted in considerable imposed WOB in pediatric and adult simulations, explaining the discomfort seen in those patients breathing spontaneously during HFOV. The level of imposed WOB was lower in the newborn and infant simulations, explaining why these patients tolerate spontaneous breathing during HFOV well. A high fresh gas flow rate reduced the imposed WOB. These findings suggest the need for a demand flow system based on patient need allowing spontaneous breathing during HFOV.
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Affiliation(s)
- Marc van Heerde
- Fellow of Pediatric Intensive Care, Pediatric Intensive Care, Department of Pediatric Intensive Care, VU University Medical Center, Amsterdam, The Netherlands
| | - Huib R van Genderingen
- Medical Physicist, Department of Physics and Medical Technology, VU University Medical Center, Amsterdam, The Netherlands
| | - Tom Leenhoven
- Biomedical Engineer, Department of Pediatric Intensive Care, Wilhelmina Children's Hospital/University Medical Center, Utrecht, The Netherlands
| | - Karel Roubik
- Biomedical Engineer, Faculty of Biomedical Engineering, Czech Technical University, Prague, Czech Republic
| | - Frans B Plötz
- Pediatric Intensivist, Department of Pediatric Intensive Care, VU University Medical Center, Amsterdam, The Netherlands
| | - Dick G Markhorst
- Pediatric Intensivist, Department of Pediatric Intensive Care, VU University Medical Center, Amsterdam, The Netherlands
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van Heerde M, Roubik K, Kopelent V, Plötz FB, Markhorst DG. Unloading work of breathing during high-frequency oscillatory ventilation: a bench study. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2006; 10:R103. [PMID: 16848915 PMCID: PMC1750967 DOI: 10.1186/cc4968] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/20/2006] [Revised: 06/14/2006] [Accepted: 06/22/2006] [Indexed: 11/18/2022]
Abstract
Introduction With the 3100B high-frequency oscillatory ventilator (SensorMedics, Yorba Linda, CA, USA), patients' spontaneous breathing efforts result in a high level of imposed work of breathing (WOB). Therefore, spontaneous breathing often has to be suppressed during high-frequency oscillatory ventilation (HFOV). A demand-flow system was designed to reduce imposed WOB. Methods An external gas flow controller (demand-flow system) accommodates the ventilator fresh gas flow during spontaneous breathing simulation. A control algorithm detects breathing effort and regulates the demand-flow valve. The effectiveness of this system has been evaluated in a bench test. The Campbell diagram and pressure time product (PTP) are used to quantify the imposed workload. Results Using the demand-flow system, imposed WOB is considerably reduced. The demand-flow system reduces inspiratory imposed WOB by 30% to 56% and inspiratory imposed PTP by 38% to 59% compared to continuous fresh gas flow. Expiratory imposed WOB was decreased as well by 12% to 49%. In simulations of shallow to normal breathing for an adult, imposed WOB is 0.5 J l-1 at maximum. Fluctuations in mean airway pressure on account of spontaneous breathing are markedly reduced. Conclusion The use of the demand-flow system during HFOV results in a reduction of both imposed WOB and fluctuation in mean airway pressure. The level of imposed WOB was reduced to the physiological range of WOB. Potentially, this makes maintenance of spontaneous breathing during HFOV possible and easier in a clinical setting. Early initiation of HFOV seems more possible with this system and the possibility of weaning of patients directly on a high-frequency oscillatory ventilator is not excluded either.
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Affiliation(s)
- Marc van Heerde
- Department of Pediatric Intensive Care, VU University Medical Center, Amsterdam, The Netherlands
| | - Karel Roubik
- Faculty of Biomedical Engineering, Czech Technical University in Prague, Kladno, Czech Republic
| | - Vitek Kopelent
- Faculty of Biomedical Engineering, Czech Technical University in Prague, Kladno, Czech Republic
| | - Frans B Plötz
- Department of Pediatric Intensive Care, VU University Medical Center, Amsterdam, The Netherlands
| | - Dick G Markhorst
- Department of Pediatric Intensive Care, VU University Medical Center, Amsterdam, The Netherlands
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40
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Brander L, Slutsky AS. Assisted spontaneous breathing during early acute lung injury. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2006; 10:102. [PMID: 16420654 PMCID: PMC1550866 DOI: 10.1186/cc3953] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In the early phase of their disease process, patients with acute lung injury are often ventilated with strategies that control the tidal volume or airway pressure, while modes employing spontaneous breathing are applied later to wean the patient from the ventilator. Spontaneous breathing modes may integrate intrinsic feedback mechanisms that should help prevent ventilator-induced lung injury, and should improve synchrony between the ventilator and the patient's demand. Airway pressure release ventilation with spontaneous breathing was shown to decrease cyclic collapse/recruitment of dependent, juxtadiaphragmatic lung areas compared with airway pressure release ventilation without spontaneous breathing. Combined with previous data demonstrating improved cardiorespiratory variables, airway pressure release ventilation with spontaneous breathing may turn out to be a less injurious ventilatory strategy.
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Affiliation(s)
- Lukas Brander
- Postdoctoral research fellow, Interdepartmental Division of Critical Care, Division of Respiratory Medicine, University of Toronto, St Michael's Hospital, Toronto, Ontario, Canada
| | - Arthur S Slutsky
- Professor of Medicine, Surgery and Biomedical Engineering and Director of Interdepartmental Division of Critical Care, University of Toronto, and Vice President (Research), St Michael's Hospital, University of Toronto, St Michael's Hospital, Toronto, Ontario, Canada
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Henzler D, Pelosi P, Bensberg R, Dembinski R, Quintel M, Pielen V, Rossaint R, Kuhlen R. Effects of partial ventilatory support modalities on respiratory function in severe hypoxemic lung injury. Crit Care Med 2006; 34:1738-45. [PMID: 16625116 DOI: 10.1097/01.ccm.0000218809.49883.54] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
OBJECTIVE The early phase of acute respiratory distress syndrome (ARDS) is characterized by impaired respiratory mechanics, ventilation-perfusion mismatch, and severe hypoxemia. Partial ventilatory support can effectively unload the respiratory workload and improve pulmonary gas exchange with less hemodynamic compromise. The partial ventilatory support mode most indicated in early phases of ARDS has not been determined. This study compares the effects of assisted ventilatory techniques on breathing pattern, gas exchange, hemodynamic function, and respiratory effort with those of controlled mechanical ventilation in similarly sedated subjects. DESIGN Prospectively randomized crossover animal study. SETTING Animal research laboratory. SUBJECTS Eleven anesthetized and mechanically ventilated pigs. INTERVENTIONS Acute lung injury was induced by lung lavage. Pressure-controlled ventilation (PCV), pressure-controlled assisted ventilation (P-ACV), bilevel positive airway pressure (BIPAP), and pressure support ventilation (PSV) with equal airway pressures and sedation were applied in random order. MEASUREMENTS AND MAIN RESULTS Gas exchange, respiratory effort, and hemodynamic function were measured, and ventilation-perfusion distributions were calculated by multiple inert-gas-elimination techniques. The results revealed that partial ventilatory support was superior to PCV in maintaining adequate oxygenation and hemodynamic function with reduced sedation. The effects of P-ACV, BIPAP, and PSV were comparable with respect to gas exchange and hemodynamic function, except for a more pronounced reduction in shunt during BIPAP. P-ACV and PSV were superior to BIPAP to reduce respiratory drive and work of breathing. PSV affected the pattern of breathing and deadspace to a greater degree than did P-ACV. CONCLUSIONS In acute lung injury, P-ACV preserves oxygenation and hemodynamic function with less respiratory effort compared with BIPAP and reduces the need for sedation compared with PCV.
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Affiliation(s)
- Dietrich Henzler
- Department of Anesthesiology, Aachen University Hospital, Germany.
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42
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Kondili E, Prinianakis G, Alexopoulou C, Vakouti E, Klimathianaki M, Georgopoulos D. Respiratory load compensation during mechanical ventilation—proportional assist ventilation with load-adjustable gain factors versus pressure support. Intensive Care Med 2006; 32:692-9. [PMID: 16523329 DOI: 10.1007/s00134-006-0110-0] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2006] [Accepted: 02/10/2006] [Indexed: 10/24/2022]
Abstract
RATIONALE In mechanically ventilated patients respiratory system impedance may vary from time to time, resulting, with pressure modalities of ventilator support, in changes in the level of assistance. Recently, implementation of a closed-loop adjustment to continuously adapt the level of assistance to changes in respiratory mechanics has been designed to operate with proportional assist ventilation (PAV+). OBJECTIVES The aim of this study was to assess, in critically ill patients, the short-term steady-state response of respiratory motor output to added mechanical respiratory load during PAV+ and during pressure support (PS). PATIENTS AND INTERVENTIONS In 10 patients respiratory workload was increased and the pattern of respiratory load compensation was examined during both modes of support. MEASUREMENTS AND RESULTS Airway and transdiaphragmatic pressures, volume and flow were measured breath by breath. Without load, both modes provided an equal support as indicated by a similar pressure-time product of the diaphragm per breath, per minute and per litre of ventilation. With load, these values were significantly lower (p<0.05) with PAV+ than those with PS (5.1+/-3.7 vs 6.1+/-3.4 cmH2O.s, 120.9+/-77.6 vs 165.6+/-77.5 cmH2O.s/min, and 18.7+/-15.1 vs 24.4+/-16.4 cmH2O.s/l, respectively). Contrary to PS, with PAV+ the ratio of tidal volume (VT) to pressure-time product of the diaphragm per breath (an index of neuroventilatory coupling) remained relatively independent of load. With PAV+ the magnitude of load-induced VT reduction and breathing frequency increase was significantly smaller than that during PS. CONCLUSION In critically ill patients the short-term respiratory load compensation is more efficient during proportional assist ventilation with adjustable gain factors than during pressure support.
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Affiliation(s)
- Eumorfia Kondili
- Intensive Care Medicine Department, University Hospital of Heraklion, Heraklion, 711 10, Crete, Greece
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Putensen C, Hering R, Muders T, Wrigge H. Assisted breathing is better in acute respiratory failure. Curr Opin Crit Care 2005; 11:63-8. [PMID: 15659947 DOI: 10.1097/00075198-200502000-00010] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
PURPOSE OF REVIEW Mechanical ventilation is usually provided in acute lung injury to ensure alveolar ventilation and reduce the patients' work of breathing without further damaging the lungs by the treatment itself. Although partial ventilatory support modalities were initially developed for weaning from mechanical ventilation, they are increasingly used as primary modes of ventilation, even in patients in the acute phase of pulmonary dysfunction. The aim of this paper is to review the role of spontaneous breathing ventilatory modalities with respect to their physiologic or clinical evidence. RECENT FINDINGS By allowing patients with acute lung injury to breathe spontaneously, one can expect improvement in gas exchange and in systemic blood flow, on the basis of both experimental and clinical trials. In addition, by increasing end-expiratory lung volume, as will occur when airway pressure release ventilation is used, recruitment of collapsed or consolidated lung is likely to occur, especially in juxtadiaphragmatic lung regions. Until recently, traditional approaches to mechanical ventilatory support of patients with acute lung injury have called for adaptation of the patient to the mechanical ventilator using heavy sedation and administration of neuromuscular blocking agents. Recent investigations have questioned the utility of sedation, muscle paralysis, and mechanical control of ventilation. Further, evidence exists that lowering sedation levels will decrease the duration of mechanical ventilatory support, the length of stay in the intensive care unit, and the overall costs of hospitalization. SUMMARY On the basis of currently available data, the authors suggest the use of techniques of mechanical ventilatory support that maintain, rather than suppress, spontaneous ventilatory effort, especially in patients with severe pulmonary dysfunction.
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Affiliation(s)
- Christian Putensen
- Department of Anesthesiology and Intensive Care Medicine, University of Bonn, Germany.
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Putensen C, Wrigge H. Clinical review: biphasic positive airway pressure and airway pressure release ventilation. Crit Care 2004; 8:492-7. [PMID: 15566621 PMCID: PMC1065046 DOI: 10.1186/cc2919] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
This review focuses on mechanical ventilation strategies that allow unsupported spontaneous breathing activity in any phase of the ventilatory cycle. By allowing patients with the acute respiratory distress syndrome to breathe spontaneously, one can expect improvements in gas exchange and systemic blood flow, based on findings from both experimental and clinical trials. In addition, by increasing end-expiratory lung volume, as occurs when using biphasic positive airway pressure or airway pressure release ventilation, recruitment of collapsed or consolidated lung is likely to occur, especially in juxtadiaphragmatic lung legions. Traditional approaches to mechanical ventilatory support of patients with acute respiratory distress syndrome require adaptation of the patient to the mechanical ventilator using heavy sedation and even muscle relaxation. Recent investigations have questioned the utility of sedation, muscle paralysis and mechanical control of ventilation. Furthermore, evidence exists that lowering sedation levels will decrease the duration of mechanical ventilatory support, length of stay in the intensive care unit, and overall costs of hospitalization. Based on currently available data, we suggest considering the use of techniques of mechanical ventilatory support that maintain, rather than suppress, spontaneous ventilatory effort, especially in patients with severe pulmonary dysfunction.
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Affiliation(s)
- Christian Putensen
- Department of Anaesthesiology and Intensive Care Medicine, University of Bonn, Bonn, Germany.
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Granton J, Granton J. 8th Annual Toronto Critical Care Medicine Symposium, 30 October-1 November 2003, Toronto, Ontario, Canada. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2004; 8:58-66. [PMID: 14975048 PMCID: PMC420071 DOI: 10.1186/cc2429] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 12/18/2003] [Accepted: 12/18/2003] [Indexed: 11/10/2022]
Affiliation(s)
- Jeff Granton
- Programme Director, Critical Care Medicine Programme, University of Toronto, Canada.
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Zinserling J, Wrigge H, Varelmann D, Hering R, Putensen C. Measurement of functional residual capacity by nitrogen washout during partial ventilatory support. Intensive Care Med 2003; 29:720-6. [PMID: 12595980 DOI: 10.1007/s00134-003-1677-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2002] [Accepted: 01/16/2003] [Indexed: 12/21/2022]
Abstract
OBJECTIVE Evaluation of an open circuit multiple breath nitrogen washout (MBNW) technique for measurement of functional residual capacity (FRC) during partial ventilatory support using corrections for gas viscosity, sampling delay time, and re-inspired nitrogen. DESIGN Measurements in a lung model with known reference volume simulating spontaneous breathing and duplicate measurements in patients breathing spontaneously with partial ventilatory support. SETTING. Experimental laboratory and intensive care units of a university hospital. PATIENTS Eighteen patients with acute respiratory failure. INTERVENTIONS Change of FiO(2) from baseline to 1.0. MEASUREMENTS AND MAIN RESULTS FRC was measured by MBNW during spontaneous breathing with continuous positive airway pressure, pressure support ventilation, proportional assist ventilation, automatic tube compensation, and airway pressure release ventilation. In the lung model, repeated measurements at three volumes were done with all partial ventilatory support modalities, and baseline FiO(2 )was varied with one mode and FRC. The mean of differences between MBNW (FRC(MBNW)) and reference was 28 ml (1.6%), and the 2.SD-interval was 84 ml (4.9%) for all modes. Measurements up to a baseline FiO(2) of 0.8 showed differences of 5 ml (-0.3%) and the 2.SD-interval of 38 ml (2.2%) between reference and FRC(MBNW). In 18 patients, 66 duplicate measurements revealed a mean difference of 30 ml (0.9%) with a coefficient of repeatability of 358 ml (13%) independent of ventilatory mode and chronological order. CONCLUSION This study suggests that, using corrections for gas viscosity, sampling delay time, and re-inspired nitrogen, FRC can be determined with good repeatability in patients and good accuracy in a lung model during partial ventilatory support.
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Affiliation(s)
- Jörg Zinserling
- Klinik und Poliklinik für Anästhesiologie und Spezielle Intensivmedizin, Rheinische Friedrich-Wilhelms-Universität Bonn, Sigmund-Freud-Strasse 25, 53105 Bonn, Germany.
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Dembinski R, Max M, Bensberg R, Rossaint R, Kuhlen R. Pressure Support Compared with Controlled Mechanical Ventilation in Experimental Lung Injury. Anesth Analg 2002. [DOI: 10.1213/00000539-200206000-00037] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Dembinski R, Max M, Bensberg R, Rossaint R, Kuhlen R. Pressure support compared with controlled mechanical ventilation in experimental lung injury. Anesth Analg 2002; 94:1570-6, table of contents. [PMID: 12032029 DOI: 10.1097/00000539-200206000-00037] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
UNLABELLED It has been suggested that, in acute lung injury (ALI), spontaneous breathing activity may increase oxygenation because of an improvement of ventilation-perfusion distribution. Pressure support ventilation (PSV) is one of the assisted spontaneous breathing modes often used in critical care medicine. We sought to determine the prolonged effects of PSV on gas exchange in experimental ALI. We hypothesized that PSV may increase oxygenation because of an improvement in ventilation-perfusion distribution. Thus, ALI was induced in 20 pigs by using repetitive lung lavage. Thereafter, the animals were randomized to receive either PSV with a pressure level set to achieve a tidal volume >4 mL/kg and a respiratory rate <40 min(-1) (n = 10) or controlled mechanical ventilation (CMV) with a tidal volume of 10 mL/kg and a respiratory rate of 20 min(-1) (n = 10). Positive end-expiratory pressure was set at 10 cm H(2)O in both groups. Blood gas analyses and determination of ventilation-perfusion (.V(A)/.Q) distribution were performed at the onset of ALI and after 2, 4, 8, and 12 h. The main result was an improvement of oxygenation because of a decrease of pulmonary shunt and an increase of areas with normal .V(A)/.Q ratios during PSV (P < 0.005). However, during CMV, a more pronounced reduction of shunt was observed compared with PSV (P < 0.005). We conclude that, in this model of ALI, PSV improves gas exchange because of a reduction of .V(A)/.Q inequality. However, improvements in .V(A)/.Q distribution may be more effective with CMV than with PSV. IMPLICATIONS Assisted spontaneous breathing may have beneficial effects on gas exchange in acute lung injury. We tested this hypothesis for pressure support ventilation in an animal model of acute lung injury. Our results demonstrate that pressure support does not necessarily provide better gas exchange than controlled mechanical ventilation.
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Affiliation(s)
- Rolf Dembinski
- Department of Anesthesiology, Universitaetsklinikum der RWTH Aachen, Pauwelsstrasse 30, 52074 Aachen, Germany.
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Abstract
On the basis of currently available data, it can be suggested that maintained spontaneous breathing during mechanical ventilation should not be suppressed even in patients with severe pulmonary dysfunction if no contraindications, such as increased intracranial pressure, are present. Improvements in pulmonary gas exchange, systemic blood flow, and oxygen supply to tissues, which have been observed when spontaneous breathing was allowed during ventilatory support, are reflected in the clinical improvement in the patient's condition, as indicated by significantly fewer days with ventilation, earlier extubation, and shorter stays in the intensive care unit. The positive effects of spontaneous breathing have been documented only for some of the available partial ventilatory support modalities. If ventilatory modalities are limited to those whose positive effects have been documented, then partial ventilatory support can be used as a primary modality even in patients with severe pulmonary dysfunction. Whereas controlled mechanical ventilation followed by weaning with partial ventilatory support modalities has been the earlier standard in ventilation therapy, this approach should be reconsidered in view of the available data.
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Affiliation(s)
- Christian Putensen
- Department of Anesthesiology and Intensive Care Medicine, University of Bonn, Germany.
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