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Sakr Y, Midega T, Antoniazzi J, Solé-Violán J, Bauer PR, Ostermann M, Pellis T, Szakmany T, Zacharowski K, Ñamendys-Silva SA, Pham T, Ferrer R, Taccone FS, van Haren F, Brochard L. Do ventilatory parameters influence outcome in patients with severe acute respiratory infection? Secondary analysis of an international, multicentre14-day inception cohort study. J Crit Care 2021; 66:78-85. [PMID: 34461380 PMCID: PMC8394083 DOI: 10.1016/j.jcrc.2021.08.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 07/13/2021] [Accepted: 08/16/2021] [Indexed: 11/06/2022]
Abstract
Purpose To investigate the possible association between ventilatory settings on the first day of invasive mechanical ventilation (IMV) and mortality in patients admitted to the intensive care unit (ICU) with severe acute respiratory infection (SARI). Materials and methods In this pre-planned sub-study of a prospective, multicentre observational study, 441 patients with SARI who received controlled IMV during the ICU stay were included in the analysis. Results ICU and hospital mortality rates were 23.1 and 28.1%, respectively. In multivariable analysis, tidal volume and respiratory rate on the first day of IMV were not associated with an increased risk of death; however, higher driving pressure (DP: odds ratio (OR) 1.05; 95% confidence interval (CI): 1.01–1.1, p = 0.011), plateau pressure (Pplat) (OR 1.08; 95% CI: 1.04–1.13, p < 0.001) and positive end-expiratory pressure (PEEP) (OR 1.13; 95% CI: 1.03–1.24, p = 0.006) were independently associated with in-hospital mortality. In subgroup analysis, in hypoxemic patients and in patients with acute respiratory distress syndrome (ARDS), higher DP, Pplat, and PEEP were associated with increased risk of in-hospital death. Conclusions In patients with SARI receiving IMV, higher DP, Pplat and PEEP, and not tidal volume, were associated with a higher risk of in-hospital death, especially in those with hypoxemia or ARDS.
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Affiliation(s)
- Yasser Sakr
- Department of Anaesthesiology and Intensive Care, Uniklinikum Jena, Jena, Germany.
| | - Thais Midega
- Department of Anaesthesiology and Intensive Care, Uniklinikum Jena, Jena, Germany; Department of intensive care, Instituto de Assistência Médicaao Servidor Público Estadual, São Paulo, Brazil
| | - Julia Antoniazzi
- Department of Anaesthesiology and Intensive Care, Uniklinikum Jena, Jena, Germany; Intensive Care Unit at Hospital das Clínicas da Faculdade de Medicina de Ribeirão Preto, Brazil
| | - Jordi Solé-Violán
- Intensive Care Medicine Department, Hospital Universitario Dr Negrín, Las Palmas de Gran Canaria, Spain
| | - Philippe R Bauer
- Mayo Clinic, Division of Pulmonary and Critical Care Medicine, Saint Mary's Hospital, Rochester, USA
| | | | - Tommaso Pellis
- Department of Anaesthesia and Intensive Care, AAS 5 Friuli Occidentale Pordenone Hospital, Pordenone, Italy
| | - Tamas Szakmany
- Department of Anaesthesia, Intensive Care, and Pain Medicine, Division of Population Medicine, Cardiff University, UK
| | - Kai Zacharowski
- Department of Anesthesiology, Intensive Care Medicine and Pain Therapy, University Hospital Frankfurt, Frankfurt am Main, Germany
| | - Silvio A Ñamendys-Silva
- Department of Critical Care Medicine, Instituto Nacional de Cancerología, Instituto Nacional de Ciencias Medicas y Nutricion Salvador Zubiran, & Hospital Medica Sur, Mexico City, Mexico
| | - Tài Pham
- Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, Ontario, Canada; Keenan Research Centre, Li KaShing Knowledge Institute, St. Michael's Hospital, Toronto, Ontario, Canada
| | - Ricard Ferrer
- Intensive Care Department, Valld'Hebron University Hospital, Shock, Organ Dysfunction and Resuscitation Research Group, Valld'Hebron Research Institute, Barcelona, Spain
| | - Fabio S Taccone
- Department of Intensive Care, Hôpital Erasme, Université Libre de Bruxelles (ULB), Brussels, Belgium
| | - Frank van Haren
- Intensive Care Unit, the Canberra Hospital, Canberra, Australia
| | - Laurent Brochard
- Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, Ontario, Canada; Keenan Research Centre, Li KaShing Knowledge Institute, St. Michael's Hospital, Toronto, Ontario, Canada
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Umbrello M, Marino A, Chiumello D. Tidal volume in acute respiratory distress syndrome: how best to select it. ANNALS OF TRANSLATIONAL MEDICINE 2017; 5:287. [PMID: 28828362 DOI: 10.21037/atm.2017.06.51] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Mechanical ventilation is the type of organ support most widely provided in the intensive care unit. However, this form of support does not constitute a cure for acute respiratory distress syndrome (ARDS), as it mainly works by buying time for the lungs to heal while contributing to the maintenance of vital gas exchange. Moreover, it can further damage the lung, leading to the development of a particular form of lung injury named ventilator-induced lung injury (VILI). Experimental evidence accumulated over the last 30 years highlighted the factors associated with an injurious form of mechanical ventilation. The present paper illustrates the physiological effects of delivering a tidal volume to the lungs of patients with ARDS, and suggests an approach to tidal volume selection. The relationship between tidal volume and the development of VILI, the so called volotrauma, will be reviewed. The still actual suggestion of a lung-protective ventilatory strategy based on the use of low tidal volumes scaled to the predicted body weight (PBW) will be presented, together with newer strategies such as the use of airway driving pressure as a surrogate for the amount of ventilatable lung tissue or the concept of strain, i.e., the ratio between the tidal volume delivered relative to the resting condition, that is the functional residual capacity (FRC). An ultra-low tidal volume strategy with the use of extracorporeal carbon dioxide removal (ECCO2R) will be presented and discussed. Eventually, the role of other ventilator-related parameters in the generation of VILI will be considered (namely, plateau pressure, airway driving pressure, respiratory rate (RR), inspiratory flow), and the promising unifying framework of mechanical power will be presented.
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Affiliation(s)
- Michele Umbrello
- UOC Anestesia e Rianimazione, Ospedale San Paolo-ASST Santi Paolo e Carlo, Milano, Italy
| | - Antonella Marino
- Dipartimento di Scienze della Salute, Università degli Studi di Milano, Milano, Italy
| | - Davide Chiumello
- UOC Anestesia e Rianimazione, Ospedale San Paolo-ASST Santi Paolo e Carlo, Milano, Italy.,Dipartimento di Scienze della Salute, Università degli Studi di Milano, Milano, Italy
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Current Concepts of ARDS: A Narrative Review. Int J Mol Sci 2016; 18:ijms18010064. [PMID: 28036088 PMCID: PMC5297699 DOI: 10.3390/ijms18010064] [Citation(s) in RCA: 85] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Revised: 12/18/2016] [Accepted: 12/23/2016] [Indexed: 01/20/2023] Open
Abstract
Acute respiratory distress syndrome (ARDS) is characterized by the acute onset of pulmonary edema of non-cardiogenic origin, along with bilateral pulmonary infiltrates and reduction in respiratory system compliance. The hallmark of the syndrome is refractory hypoxemia. Despite its first description dates back in the late 1970s, a new definition has recently been proposed. However, the definition remains based on clinical characteristic. In the present review, the diagnostic workup and the pathophysiology of the syndrome will be presented. Therapeutic approaches to ARDS, including lung protective ventilation, prone positioning, neuromuscular blockade, inhaled vasodilators, corticosteroids and recruitment manoeuvres will be reviewed. We will underline how a holistic framework of respiratory and hemodynamic support should be provided to patients with ARDS, aiming to ensure adequate gas exchange by promoting lung recruitment while minimizing the risk of ventilator-induced lung injury. To do so, lung recruitability should be considered, as well as the avoidance of lung overstress by monitoring transpulmonary pressure or airway driving pressure. In the most severe cases, neuromuscular blockade, prone positioning, and extra-corporeal life support (alone or in combination) should be taken into account.
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BLOCKADE OF ENDOTHELIAL GROWTH FACTOR, ANGIOPOIETIN-2, REDUCES INDICES OF ARDS AND MORTALITY IN MICE RESULTING FROM THE DUAL-INSULTS OF HEMORRHAGIC SHOCK AND SEPSIS. Shock 2016; 45:157-65. [PMID: 26529660 DOI: 10.1097/shk.0000000000000499] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
We have demonstrated hemorrhagic shock "priming" for the development of indirect acute respiratory distress syndrome (iARDS) in mice following subsequent septic challenge, and show pathology characteristic of patients with iARDS, including increased lung microvascular permeability and arterial PO2/FI02 reduced to levels comparable to mild/moderate ARDS during the 48 h following hemorrhage. Loss of endothelial cell (EC) barrier function is a major component in the development of iARDS. EC growth factors, Angiopoietin (Ang)-1 and 2, maintain vascular homeostasis via tightly regulated competitive interaction with tyrosine kinase receptor, Tie2, expressed on ECs. Ang-2/Tie2 binding, in contrast to Ang-1, is believed to produce vessel destabilization, pulmonary leakage, and inflammation. Recent clinical findings from our trauma/surgical intensive care units and others have reported elevated Ang-2 in the plasma from patients that develop ARDS. We have previously described similarly elevated Ang-2 in plasma and lung tissue in our shock/sepsis model for the development of iARDS, and demonstrated effective reduction in indices of inflammation and lung tissue injury following siRNA inhibition of Ang-2 protein synthesis. In this study we show that Ang-2 in lung tissue and plasma spikes following hemorrhage (priming) and remain elevated at sepsis induction. In addition, that transient inhibition of Ang-2 function immediately following hemorrhage, suppressing priming, but not following sepsis, impacts the development of iARDS in our model. Our data demonstrate that selective temporal blockade of Ang-2 function following hemorrhagic shock priming significantly improved PO2/FIO2, decreased lung protein leak and indices of inflammation, and improved 10-day survival in our murine model for the development iARDS.
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Abstract
This article reviews aspects of mechanical ventilation in patients without lung injury, patients in the perioperative period, and those with neurologic injury or disease including spinal cord injury. Specific emphasis is placed on ventilator strategies, including timing and indications for tracheostomy. Lung protective ventilation, using low tidal volumes and modest levels of positive end-expiratory pressure, should be the default consideration in all patients requiring mechanical ventilatory support. The exception may be the patient with high cervical spinal cord injuries who requires mechanical ventilatory support. There is no consensus on the timing of tracheostomy in patients with neurologic diseases.
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Abstract
This article describes the gas exchange abnormalities occurring in the acute respiratory distress syndrome seen in adults and children and in the respiratory distress syndrome that occurs in neonates. Evidence is presented indicating that the major gas exchange abnormality accounting for the hypoxemia in both conditions is shunt, and that approximately 50% of patients also have lungs regions in which low ventilation-to-perfusion ratios contribute to the venous admixture. The various mechanisms by which hypercarbia may develop and by which positive end-expiratory pressure improves gas exchange are reviewed, as are the effects of vascular tone and airway narrowing. The mechanisms by which surfactant abnormalities occur in the two conditions are described, as are the histological findings that have been associated with shunt and low ventilation-to-perfusion.
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Affiliation(s)
- Richard K Albert
- Chief of Medicine, Denver Health, Professor of Medicine, University of Colorado, Adjunct Professor of Engineering and Computer Science, University of Denver, Denver, Colorado, USA.
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Sakuramoto H, Shimojo N, Jesmin S, Unoki T, Kamiyama J, Oki M, Miya K, Kawano S, Mizutani T. Repeated open endotracheal suctioning causes gradual desaturation but does not exacerbate lung injury compared to closed endotracheal suctioning in a rabbit model of ARDS. BMC Anesthesiol 2013; 13:47. [PMID: 24308643 PMCID: PMC3878988 DOI: 10.1186/1471-2253-13-47] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Accepted: 11/25/2013] [Indexed: 12/01/2022] Open
Abstract
Background Although endotracheal suctioning induces alveolar derecruitment during mechanical ventilation, it is not clear whether repeated endotracheal suctioning exacerbates lung injuries. The present study aimed to determine whether repeated open endotracheal suctioning (OS) exacerbates lung injury compared to closed endotracheal suctioning (CS) during mechanical ventilation in an animal model of acute respiratory distress syndrome (ARDS). Methods Briefly, thirty six Japanese white rabbits were initially ventilated in pressure-controlled mode with a constant tidal volume (6 mL/kg). Then, lung injury was induced by repeated saline lavage. The rabbits were divided into four groups, namely: a) OS; b) CS; c) control with ARDS only; d) and healthy control (HC) without ARDS. Animals in all the groups were then ventilated with positive end expiratory pressure (PEEP) at 10 cm H2O. CS was performed using 6 French-closed suctioning catheters connected to endotracheal tube under the following conditions: a) a suctioning time and pressure of 10 sec and 140 mm Hg, respectively; and b) a suction depth of 2 cm (length of adapter) plus tracheal tube. OS was performed using the same conditions described for CS, except the ventilator was disconnected from the animals. Each endotracheal suctioning was performed at an interval of 30 min. Results PaO2/FIO2 (P/F) ratio for CS, control and HC groups remained at >400 for 6 hours, whereas that of the OS group progressively declined to 300 (p < 0.05), with each suctioning. However, no difference was observed either in lung injury score (histology) or in the expression pattern of inflammatory cytokines (tumor necrosis factor-α and interleukin-6) after 6 hours between the OS and CS groups in the circulatory as well as the pulmonary tissues. Conclusions Progressive arterial desaturation under conditions of repeated endotracheal suctioning is greater in OS than in CS time-dependently. However, OS does not exacerbate lung injury during mechanical ventilation when observed over a longer time span (6 hours) of repeated endotracheal suctioning, based on morphological and molecular analysis.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Taro Mizutani
- Department of Emergency and Critical Care Medicine, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki 305-8575, Japan.
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Unilateral acid aspiration augments the effects of ventilator lung injury in the contralateral lung. Anesthesiology 2013; 119:642-51. [PMID: 23681142 DOI: 10.1097/aln.0b013e318297d487] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Mechanical ventilation is necessary during acute respiratory distress syndrome, but it promotes lung injury because of the excessive stretch applied to the aerated parenchyma. The authors' hypothesis was that after a regional lung injury, the noxious effect of mechanical ventilation on the remaining aerated parenchyma would be more pronounced. METHODS Mice, instilled with hydrochloric acid (HCl) in the right lung, was assigned to one of the following groups: mechanical ventilation with tidal volumes (VT) 25 ml/kg (HCl-VILI25, n = 12), or VT 15 ml/kg (HCl-VILI15, n = 9), or spontaneous breathing (HCl-SB, n = 14). Healthy mice were ventilated with VT 25 ml/kg (VILI25, n = 11). Arterial oxygenation, lung compliance, bronchoalveolar lavage inflammatory cells, albumin, and cytokines concentration were measured. RESULTS After 7 h, oxygenation and lung compliance resulted lower in HCl-VILI25 than in VILI25 (P < 0.05, 210 ± 54 vs. 479 ± 83 mmHg, and 32 ± 3.5 vs. 45 ± 4.1 µl/cm H2O, mean ± SD, respectively). After right lung injury, the left lung of HCl-VILI25 group received a greater fraction of the VT than the VILI25 group, despite an identical global VT. The number of total and polymorphonuclear cells in bronchoalveolar lavage resulted significantly higher in HCl-VILI25, compared with the other groups, in not only the right lung, but also in the left lung. The albumin content in the left lung resulted higher in HCl-VILI25 than in VILI25 (224 ± 85 vs. 33 ± 6 µg/ml; P < 0.05). Cytokines levels did not differ between groups. CONCLUSION Aggressive mechanical ventilation aggravates the preexisting lung injury, which is noxious for the contralateral, not previously injured lung, possibly because of a regional redistribution of VT.
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MEADE MO, COOK DJ. The aetiology, consequences and prevention of barotrauma: a critical review of the literature. ACTA ACUST UNITED AC 2011. [DOI: 10.3109/tcic.6.4.166.173] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Abstract
PURPOSE OF REVIEW Peripheral airways are less than 2 mm in diameter and comprise a relatively large cross-sectional area, which allows for slower, laminar airflow. They include both membranous bronchioles and gas exchange ducts, and have been referred to in the past as the 'quiet zone', partly because these structures were felt to contribute little to lung mechanics, and partly because they are difficult to study directly. RECENT FINDINGS Recent studies suggest that peripheral airway dysfunction plays a significant role in acute respiratory distress syndrome, which may be exacerbated by injurious mechanical ventilation strategies. The presence of elevated airways resistance, intrinsic positive end-expiratory pressure or a lower inflection point on a pressure-volume curve of the respiratory system may indicate presence of impaired peripheral airway function. In-vitro animal and human studies have begun to elucidate the signaling mechanisms responsible for stretch and shear mediated cellular injury. SUMMARY Understanding the pathophysiology of peripheral airway dysfunction in acute respiratory distress syndrome and mechanical ventilation continues to evolve. Greater insight into the signaling mechanisms involved in cellular injury and repair will lead to further alterations in mechanical ventilation strategies, and may lead to specific treatment options.
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Jain M, Sznajder JI. Bench-to-bedside review: distal airways in acute respiratory distress syndrome. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2007; 11:206. [PMID: 17306039 PMCID: PMC2151900 DOI: 10.1186/cc5159] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Distal airways are less than 2 mm in diameter, comprising a relatively large cross-sectional area that allows for slower, laminar airflow. The airways include both membranous bronchioles and gas exchange ducts, and have been referred to in the past as the 'quiet zone', in part because these structures were felt to contribute little to lung mechanics and in part because they were difficult to study directly. More recent data suggest that distal airway dysfunction plays a significant role in acute respiratory distress syndrome. In addition, injurious mechanical ventilation strategies may contribute to distal airway dysfunction. The presence of elevated airway resistance, intrinsic positive end-expiratory pressure or a lower inflection point on a pressure–volume curve of the respiratory system may indicate the presence of impaired distal airway function. There are no proven specific treatments for distal airway dysfunction, and protective ventilation strategies to minimize distal airway injury may be the best therapeutic approach at this time.
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Affiliation(s)
- Manu Jain
- Division of Pulmonary and Critical Care, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA.
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Conrad SA, Zhang S, Arnold TC, Scott LK, Carden DL. Protective effects of low respiratory frequency in experimental ventilator-associated lung injury*. Crit Care Med 2005; 33:835-40. [PMID: 15818113 DOI: 10.1097/01.ccm.0000159532.56865.8a] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
OBJECTIVE To determine whether ventilator-associated lung hyperinflation injury can be attenuated by a reduction in respiratory frequency. DESIGN Prospective comparative laboratory investigation. SETTING University medical center research laboratory. SUBJECTS Male Sprague-Dawley rats. INTERVENTIONS Eight groups of isolated, perfused rat lungs were exposed to cyclic ventilation at different respiratory frequencies and tidal volumes. Each group of six to eight lung preparations was assigned to one of four respiratory frequencies (10, 20, 40, or 80 breaths/min) and one of two tidal volumes (5 or 20 mL.kg). Measurement of capillary filtration coefficient (Kf,c), a sensitive index of lung microvascular permeability and injury, was made at baseline and at 30, 60, and 90 mins of the experimental conditions. MEASUREMENTS AND MAIN RESULTS Lungs exposed to 5 mL.kg tidal volume had no elevation in Kf,c at any time point regardless of respiratory frequency. Lungs exposed to 20 mL. kg tidal volume and a respiratory frequency of 80 had significant elevations in Kf,c at all times after baseline compared with lungs exposed to respiratory frequencies of 10, 20, or 40 (0.14 +/- 0.03, 0.16 +/- 0.02, 0.31 +/- 0.05 vs. 0.76 +/- 0.16). Furthermore, the Kf,c at 90 mins was significantly higher than permeability at baseline in this group (1.53 +/- 0.45 vs. 0.12 +/- 0.02 mL.min.cm H2O.100 g of lung tissue). CONCLUSIONS Reduction in respiratory frequency to values much lower than normal ameliorated experimental ventilator-induced hyperinflation lung injury as determined by pulmonary capillary filtration coefficient.
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Affiliation(s)
- Steven A Conrad
- Department of Emergency Medicine, Louisiana State University Health Sciences Center, 1541 Kings Highway, PO Box 33932, Shreveport, LA 71130-3932, USA.
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13
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Chu EK, Whitehead T, Slutsky AS. Effects of cyclic opening and closing at low- and high-volume ventilation on bronchoalveolar lavage cytokines. Crit Care Med 2004; 32:168-74. [PMID: 14707576 DOI: 10.1097/01.ccm.0000104203.20830.ae] [Citation(s) in RCA: 124] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To examine the mechanisms of ventilator-induced lung injury at low and high lung volumes. DESIGN Prospective, randomized, laboratory study. SETTING University research laboratory. SUBJECTS Eighty-eight adult male Sprague-Dawley rats. INTERVENTIONS Mechanical ventilation using low and high lung volumes. MEASUREMENTS AND MAIN RESULTS An ex vivo rat lung model was used. In study I (ventilation at low lung volumes), rat lungs (n = 40) were randomly assigned to various modes of ventilation: a) opening and closing with positive end-expiratory pressure (PEEP; control): tidal volume 7 mL/kg and PEEP 5 cm H2O; b) opening and closing from zero end-expiratory pressure (ZEEP): tidal volume 7 mL/kg and PEEP 0; or c) atelectasis. Peak inspiratory pressure was monitored at the beginning and end of 3 hrs of ventilation. At the end of 3 hrs of ventilation, the lungs were lavaged, and the concentrations of tumor necrosis factor-alpha, macrophage inflammatory protein-2, and interleukin-6 cytokines were measured in the lavage. In study II (ventilation at high volumes), rat lungs (n = 45) were randomly assigned to a) cyclic lung stretch: pressure-controlled ventilation, peak inspiratory pressure 50 cm H2O, and PEEP 8 cm H2O; b) continuous positive airway pressure at 50 cm H2O (CPAP50); or c) CPAP at the mean airway pressure of the cyclic stretch group (CPAP 31 cm H2O). Bronchoalveolar lavage cytokine concentrations (tumor necrosis factor-alpha, macrophage inflammatory protein-2, and interleukin-6) were measured at the end of 3 hrs of ventilation. In the low volume study, there was no difference in bronchoalveolar lavage cytokine concentrations between the PEEP group and the atelectatic group. All cytokines were significantly higher in the ZEEP group compared with the atelectasis group. Macrophage inflammatory protein-2 was significantly higher in the ZEEP group compared with the PEEP group. Lung compliance, as reflected by change in peak inspiratory pressure, was also significantly worse in the ZEEP compared with the PEEP group. In the high-volume study, tumor necrosis factor-alpha and interleukin-6 were significantly higher in the cyclic stretch group compared with the CPAP 31 group. There was no significant difference between the cytokine concentrations in the cyclic stretch group compared with the CPAP 50 group. CONCLUSION We conclude that at low lung volumes, cyclic opening and closing from ZEEP leads to greater increases in bronchoalveolar lavage cytokines than atelectasis. With high-volume ventilation, over time, the degree of overdistension is more associated with increases in bronchoalveolar lavage cytokines than cyclic opening and closing alone.
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Affiliation(s)
- Eric K Chu
- Department of Medicine and Critical Care Medicine, St. Michael's Hospital, University of Toronto, Ontario, Canada
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Moloney ED, Griffiths MJD. Protective ventilation of patients with acute respiratory distress syndrome. Br J Anaesth 2004; 92:261-70. [PMID: 14722180 DOI: 10.1093/bja/aeh031] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The majority of patients with acute respiratory distress syndrome (ARDS) require mechanical ventilation. This support provides time for the lungs to heal, but the adverse effects of mechanical ventilation significantly influence patient outcome. Traditionally, these were ascribed to mechanical effects, such as haemodynamic compromise from decreased venous return or gross air leaks induced by large transpulmonary pressures. More recently, however, the ARDS Network study has established the clinical importance of lowering the tidal volume to limit overdistension of the lung when ventilating patients with ARDS. This study suggests that ventilator-associated lung injury (VALI) caused by overdistension of the lung contributes to the mortality of patients with ARDS. Moreover, the results from clinical and basic research have revealed more subtle types of VALI, including upregulation of the inflammatory response in the injured and overdistended lung. This not only damages the lung, but the overflow of inflammatory mediators into the systemic circulation may explain why most patients who die with ARDS succumb to multi-organ failure rather than respiratory failure. The results of these studies, the present understanding of the pathophysiology of VALI, and protective ventilatory strategies are reviewed.
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Affiliation(s)
- E D Moloney
- Imperial College School of Medicine at the National Heart and Lung Institute, Royal Brompton Hospital, London, UK
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Abstract
Although ALI/ARDS mortality rates have improved over the last several decades, they remain high, particularly in the geriatric patient population. Although considerable progress has been made in understanding the pathogenesis of the disease, a large number of promising treatments have proven unsuccessful. One exception has been in the area of ventilator management, where a strategy of protective ventilation with low tidal volumes has demonstrated a significant mortality benefit. Basic research continues to help advance our understanding of this complex syndrome and identify interesting new directions of investigation. The results of several large, randomized trials of new ventilatory and pharmacologic strategies currently underway may help identify successful methods of treating this important disease.
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Affiliation(s)
- Ivan W Cheng
- University of California, San Francisco, Cardiovascular Research Institute, 505 Parnassus Avenue, Box 0130, San Francisco, CA 94143-0624, USA.
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Steinberg J, Schiller HJ, Halter JM, Gatto LA, Dasilva M, Amato M, McCann UG, Nieman GF. Tidal volume increases do not affect alveolar mechanics in normal lung but cause alveolar overdistension and exacerbate alveolar instability after surfactant deactivation. Crit Care Med 2002; 30:2675-83. [PMID: 12483058 DOI: 10.1097/00003246-200212000-00011] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE We utilized microscopy to measure the impact of increasing tidal volume on individual alveolar mechanics (i.e., the dynamic change in alveolar size during tidal ventilation) in the living porcine lung. DESIGN In three anesthetized, mechanically ventilated pigs, we observed normal alveoli (n = 27) and alveoli after surfactant deactivation by Tween 20 lavage (n = 26) at three different tidal volumes (6, 12, and 15 mL/kg). Alveolar area was measured at peak inspiration (I) and at end expiration (E) by image analysis and I minus E was calculated as an index of alveolar stability (I-Edelta). MEASUREMENTS AND MAIN RESULTS In normal alveoli, increasing tidal volume did not change alveolar area at I (6 mL/kg = 9726 +/- 848 microm; 15 mL/kg = 9,637 +/- 884 microm ), E (6 mL/kg = 9747 +/- 800 microm; 15 mL/kg = 9742 +/- 853 microm ), or I-Edelta (6 mL/kg = -21 +/- 240 microm; 15 mL/kg = -105 +/- 229 microm ). In contrast, with surfactant deactivation, increasing tidal volume significantly increased alveolar area at I (6 mL/kg = 11,413 +/- 1032 microm; 15 mL/kg = 13,917 +/- 1214 microm ), at E (6 mL/kg = 10,462 +/- 906 microm; 15 mL/kg = 12,000 +/- 1066 microm ), and I-Edelta (6 mL/kg = 825 +/- 276 microm; 15 mL/kg = 1917 +/- 363 microm ). Moreover, alveolar instability (increased I-Edelta) was significantly increased at all tidal volumes with altered surface tension when compared with normal alveoli. CONCLUSIONS We conclude that high tidal volume ventilation does not alter alveolar mechanics in the normal lung; however, in the surfactant-deactivated lung, it causes alveolar overdistension and exacerbates alveolar instability.
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Affiliation(s)
- Jay Steinberg
- Department of Surgery, SUNY Upstate Medical University, Syracuse, NY, USA
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Whitehead T, Slutsky AS. The pulmonary physician in critical care * 7: ventilator induced lung injury. Thorax 2002; 57:635-42. [PMID: 12096209 PMCID: PMC1746372 DOI: 10.1136/thorax.57.7.635] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- T Whitehead
- Department of Critical Care, St Michael's Hospital, Interdepartmental Division of Critical Care, University of Toronto, Toronto, Ontario, Canada
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Conrad SA, Bidani A. Management of the acute respiratory distress syndrome. CHEST SURGERY CLINICS OF NORTH AMERICA 2002; 12:325-54. [PMID: 12122828 DOI: 10.1016/s1052-3359(02)00012-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Significant advances have occurred in the knowledge of the pathogenesis of ARDS. It is now recognized that ARDS is a manifestation of a diffuse process that results from a complicated cascade of events following an initial insult or injury. Mechanical ventilation and PEEP are still important components of supportive therapy. To avoid ventilator-associated lung injury there is emphasis on targeting ventilator management based on measurement of pulmonary mechanics. For those with resistant hypoxia and severe pulmonary hypertension adjunctive modalities, such as prone positioning and low-dose iNO, may provide important benefit. Alternative modes of supporting gas exchange, such as with partial liquid ventilation and extracorporeal gas-exchange, may serve as rescue therapies. Advances in cell and molecular biology have contributed to a better understanding of the role of inflammatory cells and mediators that contribute to the acute lung injury and the pathophysiology of the syndrome that manifests as ARDS. Based on this new understanding, the potential targets for intervention to ameliorate the systemic inflammatory response have proliferated. Examples include the cytokine network and its receptors, antioxidants, and endothelins. Apart from the challenge of testing these agents in experimental models, it seems likely that determination of the optimum combination of agents will become an equally important endeavor. A particular challenge is to develop better methods of predicting which of the many at-risk patients will go on to full-blown ARDS and MODS, thereby targeting subgroups of patients most likely to benefit from anti-inflammatory therapies. Similarly, the adverse effects of immunosuppressive therapy may be diminished by improved, perhaps molecular, techniques to detect microbial pathogens and permit differentiation between Systemic inflammatory response syndrome and sepsis.
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Affiliation(s)
- Steven A Conrad
- Departments of Medicine and Emergency Medicine, Critical Care Service, Louisiana State University Health Sciences Center, 1501 Kings Highway, Shreveport, LA 71103-4228, USA.
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19
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Rotta AT, Gunnarsson B, Fuhrman BP, Hernan LJ, Steinhorn DM. Comparison of lung protective ventilation strategies in a rabbit model of acute lung injury. Crit Care Med 2001; 29:2176-84. [PMID: 11700418 DOI: 10.1097/00003246-200111000-00021] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To determine the impact of different protective and nonprotective mechanical ventilation strategies on the degree of pulmonary inflammation, oxidative damage, and hemodynamic stability in a saline lavage model of acute lung injury. DESIGN A prospective, randomized, controlled, in vivo animal laboratory study. SETTING Animal research facility of a health sciences university. SUBJECTS Forty-six New Zealand White rabbits. INTERVENTIONS Mature rabbits were instrumented with a tracheostomy and vascular catheters. Lavage-injured rabbits were randomized to receive conventional ventilation with either a) low peak end-expiratory pressure (PEEP; tidal volume of 10 mL/kg, PEEP of 2 cm H2O); b) high PEEP (tidal volume of 10 mL/kg, PEEP of 10 cm H2O); c) low tidal volume with PEEP above Pflex (open lung strategy, tidal volume of 6 mL/kg, PEEP set 2 cm H2O > Pflex); or d) high-frequency oscillatory ventilation. Animals were ventilated for 4 hrs. Lung lavage fluid and tissue samples were obtained immediately after animals were killed. Lung lavage fluid was assayed for measurements of total protein, elastase activity, tumor necrosis factor-alpha, and malondialdehyde. Lung tissue homogenates were assayed for measurements of myeloperoxidase activity and malondialdehyde. The need for inotropic support was recorded. MEASUREMENTS AND MAIN RESULTS Animals that received a lung protective strategy (open lung or high-frequency oscillatory ventilation) exhibited more favorable oxygenation and lung mechanics compared with the low PEEP and high PEEP groups. Animals ventilated by a lung protective strategy also showed attenuation of inflammation (reduced tracheal fluid protein, tracheal fluid elastase, tracheal fluid tumor necrosis factor-alpha, and pulmonary leukostasis). Animals treated with high-frequency oscillatory ventilation had attenuated oxidative injury to the lung and greater hemodynamic stability compared with the other experimental groups. CONCLUSIONS Both lung protective strategies were associated with improved oxygenation, attenuated inflammation, and decreased lung damage. However, in this small-animal model of acute lung injury, an open lung strategy with deliberate hypercapnia was associated with significant hemodynamic instability.
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Affiliation(s)
- A T Rotta
- Division of Pediatric Critical Care, The Children's Hospital of Buffalo, State University of New York at Buffalo, Buffalo, NY 14222, USA.
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20
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Martin-Lefèvre L, Ricard JD, Roupie E, Dreyfuss D, Saumon G. Significance of the changes in the respiratory system pressure-volume curve during acute lung injury in rats. Am J Respir Crit Care Med 2001; 164:627-32. [PMID: 11520727 DOI: 10.1164/ajrccm.164.4.2008018] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
UNLABELLED The hypothesis that the changes in the respiratory system pressure- volume (PV) curve during pulmonary edema mainly reflect distal airway obstruction was investigated in rats. Normal rats had a well-defined upper inflection point (UIP) at low airway pressure. Airway occlusion by liquid instillation decreased compliance (Crs) and the volume (Vuip) of the UIP, and increased end-inspiratory pressure. The same changes were observed during the progression of edema produced by high volume ventilation (HV). Changes in Vuip and in Crs produced by HV were correlated with edema severity in normal rats or rats with lungs preinjured with alpha-naphthylthiourea. Vuip and Crs changes were proportional, reflecting compression of the PV curve on the volume axis and suggesting reduction of the amount of ventilatable lung at low airway pressure. In keeping with this explanation, the lower Vuip and Crs were before HV, the more severe HV-induced edema was in alpha-naphthylthiourea-injected rats. When edema was profuse, PV curves displayed a marked lower inflection point (LIP), the UIP at low pressure disappeared but another was seen at high volume above the LIP, and the correlation between Vuip changes and edema severity was lost. These observations may have clinical relevance in the context of the "open lung" strategy. KEYWORDS ventilator-induced lung injury; respiratory mechanics; acute respiratory distress syndrome
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Affiliation(s)
- L Martin-Lefèvre
- Service de Réanimation Médicale, Hôpital Louis Mourier (Assistance Publique-Hôpitaux de Paris), Colombes, France
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21
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Kerr CL, Veldhuizen RA, Lewis JF. Effects of high-frequency oscillation on endogenous surfactant in an acute lung injury model. Am J Respir Crit Care Med 2001; 164:237-42. [PMID: 11463594 DOI: 10.1164/ajrccm.164.2.2007144] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
This study evaluated the effects of high-frequency oscillation (HFO) and conventional mechanical ventilation (CMV) on gas exchange and the pulmonary surfactant system in an acute lung injury model. Following induction of lung injury with N-nitroso-n-methylurethane, adult rabbits were anesthetized and randomized to one of the following ventilatory strategies: HFO for 120 min, CMV for 120 min, HFO for 60 min, followed by CMV for 60 min, CMV for 60 min followed by HFO for 60 min or CMV for 60 min. Separate animals were ventilated using CMV with a lower tidal volume and a positive end-expiratory pressure level that was increased throughout the experimental period. Oxygenation was significantly greater in animals ventilated with HFO compared with animals ventilated with CMV. The proportion of surfactant in large aggregate forms was significantly greater following ventilatory support with HFO compared with CMV. Surfactant aggregate conversion was also significantly lower during HFO compared with CMV. We conclude that in our model of acute lung injury, HFO was a superior mode of ventilation and reduced the conversion of alveolar surfactant large aggregates into small aggregate forms, resulting in a greater percentage of large aggregate forms in the alveolar space.
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Affiliation(s)
- C L Kerr
- Department of Physiology, Lawson Research Institute, St. Joseph's Health Centre, The University of Western Ontario, 268 Grosvenor Street, London, Ontario, N6A 4V2, Canada
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Kloot TE, Blanch L, Melynne Youngblood A, Weinert C, Adams AB, Marini JJ, Shapiro RS, Nahum A. Recruitment maneuvers in three experimental models of acute lung injury. Effect on lung volume and gas exchange. Am J Respir Crit Care Med 2000; 161:1485-94. [PMID: 10806143 DOI: 10.1164/ajrccm.161.5.9809014] [Citation(s) in RCA: 169] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Recruitment maneuvers (RM), consisting of sustained inflations at high airway pressures, have been advocated as an adjunct to mechanical ventilation in acute respiratory distress syndrome (ARDS). We studied the effect of baseline ventilatory strategy and RM on end-expiratory lung volume (EELV) and oxygenation in 18 dogs, using three models of acute lung injury (ALI; n = 6 in each group): saline lavage (LAV), oleic acid injury (OAI), and intratracheal instillation of Escherichia coli (pneumonia; PNM). All three models exhibited similar degrees of lung injury. The PNM model was less responsive to positive end-expiratory pressure (PEEP) than was the LAV or OAI model. Only the LAV model showed an oxygenation response to increasing tidal volume (VT). After RM, there were transient increases in Pa(O(2)) and EELV when ventilating with PEEP = 10 cm H(2)O. At PEEP = 20 cm H(2)O the lungs were probably fully recruited, since the plateau airway pressures were relatively high ( approximately 45 cm H(2)O) and the oxygenation was similar to preinjury values, thus making the system unresponsive to RM. Sustained improvement in oxygenation after RM was seen in the LAV model when ventilating with PEEP = 10 cm H(2)O and VT = 15 ml/kg. Changes in EELV correlated with changes in Pa(O(2)) only in the OAI model with PEEP = 10 cm H(2)O. We conclude that responses to PEEP, VT, and RM differ among these models of ALI. RM may have a role in some patients with ARDS who are ventilated with low PEEP and low VT.
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Affiliation(s)
- T E Kloot
- Department of Pulmonary and Critical Care Medicine, University of Minnesota, Regions Hospital, St. Paul, Minnesota, USA
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23
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Fraisse A, Paut O, Viard L, Camboulives J. [Recent developments in the treatment of pediatric acute respiratory distress syndrome]. Arch Pediatr 1998; 5:1107-21. [PMID: 9809155 DOI: 10.1016/s0929-693x(99)80009-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Acute respiratory distress syndrome (ARDS) is a severe condition with a high mortality rate, despite conventional treatment using mechanical ventilation. Better understanding of the pathophysiology and awareness of important iatrogenic lung injury secondary to mechanical ventilation has led to new therapeutic principles. Mechanical ventilation strategy during ARDS is characterized by positive end-expiratory pressure, increase in the inspiratory time, high inspiratory oxygen concentration and, more recently, use of permissive hypercapnia. High frequency ventilation allows optimal lung recruitment under small tidal volume. The effectiveness of extracorporeal oxygenation techniques is demonstrated, but because of their cost and morbidity these therapies are rational only in patients who seem likely to die. Partial liquid ventilation and inhaled nitric oxide have great potential but require further studies. Intratracheal exogenous surfactant might be beneficial but controlled trials are needed to confirm the usefulness of this expensive therapy. Finally, a number of adjuncts to mechanical ventilation are currently available to minimize iatrogenic lung injury and improve the outcome. The role of these new treatments must be defined with randomized and controlled clinical trials using homogenous inclusion criteria.
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Affiliation(s)
- A Fraisse
- Service de cardiologie A, hôpital de la Timone, Marseille, France
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Artigas A, Bernard GR, Carlet J, Dreyfuss D, Gattinoni L, Hudson L, Lamy M, Marini JJ, Matthay MA, Pinsky MR, Spragg R, Suter PM. The American-European Consensus Conference on ARDS, part 2: Ventilatory, pharmacologic, supportive therapy, study design strategies, and issues related to recovery and remodeling. Acute respiratory distress syndrome. Am J Respir Crit Care Med 1998; 157:1332-47. [PMID: 9563759 DOI: 10.1164/ajrccm.157.4.ats2-98] [Citation(s) in RCA: 240] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The acute respiratory distress syndrome (ARDS) continues as a contributor to the morbidity and mortality of patients in intensive care units throughout the world, imparting tremendous human and financial costs. During the last 10 years there has been a decline in ARDS mortality without a clear explanation. The American-European Consensus Committee on ARDS was formed to re-evaluate the standards for the ICU care of patients with acute lung injury (ALI), with regard to ventilatory strategies, the more promising pharmacologic agents, and the definition and quantification of pathologic features of ALI that require resolution. It was felt that the definition of strategies for the clinical design and coordination of studies between centers and continents was becoming increasingly important to facilitate the study of various new therapies for ARDS.
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Artigas A, Bernard GR, Carlet J, Dreyfuss D, Gattinoni L, Hudson L, Lamy M, Marini JJ, Matthay MA, Pinsky MR, Spragg R, Suter PM. The American-European Consensus Conference on ARDS, part 2. Ventilatory, pharmacologic, supportive therapy, study design strategies and issues related to recovery and remodeling. Intensive Care Med 1998; 24:378-98. [PMID: 9609420 DOI: 10.1007/s001340050585] [Citation(s) in RCA: 132] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The acute respiratory distress syndrome (ARDS) continues as a contributor to the morbidity and mortality of patients in intensive care units throughout the world, imparting tremendous human and financial costs. During the last ten years there has been a decline in ARDS mortality without a clear explanation. The American-European Consensus Committee on ARDS was formed to re-evaluate the standards for the ICU care of patients with acute lung injury (ALI), with regard to ventilatory strategies, the more promising pharmacologic agents, and the definition and quantification of pathological features of ALI that require resolution. It was felt that the definition of strategies for the clinical design and coordination of studies between centers and continents was becoming increasingly important to facilitate the study of various new therapies for ARDS.
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Dreyfuss D, Saumon G. Ventilator-induced lung injury: lessons from experimental studies. Am J Respir Crit Care Med 1998; 157:294-323. [PMID: 9445314 DOI: 10.1164/ajrccm.157.1.9604014] [Citation(s) in RCA: 1399] [Impact Index Per Article: 53.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Affiliation(s)
- D Dreyfuss
- Service de Réanimation Médicale, Hôpital Louis Mourier, Colombes (Assistance Publique-Hôpitaux de Paris), France
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Affiliation(s)
- L D Hudson
- Harborview Medical Center, Seattle, WA 98104-2499, USA
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Abstract
Recent advances in mechanical ventilation, accompanied with a better understanding of the pathophysiology of ARDS, have resulted in a brighter outlook for the child who acquires this still dreaded disease. A greater understanding of the pathophysiology of ARDS has led to a heightened awareness that the care of these patients should be more than just supportive. The potential for exacerbation of lung injury by mechanical ventilation is real. Many new therapies are being evaluated for the treatment of ARDS; all are intended to reduce ventilator-induced injury. With the recognition of "volutrauma" as a serious complication of mechanical ventilation in ARDS, the mode of ventilation used should minimize the potential for this complication in a child with signs of progressive lung disease requiring mechanical ventilation. Optimal integration of the many new techniques into the treatment of pediatric ARDS will require more research and experience. Surfactant replacement in ARDS as an adjunct to the basic care of these patients may be beneficial. Liquid ventilation is another exciting new ventilation technique that has a significant protective effect in animal models of ARDS. Other therapies, such as tracheal gas insufflation, or other new modes of ventilation may also improve outcome. Techniques of high-frequency ventilation and ECMO in the treatment of children already show potential for improved outcome. The decision between using ECMO or "nonconventional" forms of mechanical ventilation should be considered carefully, after the morbidity of the procedures, the duration of therapy, and the cost have been weighed. Centers with experience using ECMO in the setting of pediatric ARDS have better results than those where ECMO is infrequently used for this purpose. It is imperative that future studies of both mechanical ventilation and ECMO describe ventilation strategy and prospectively identify protocols or algorithms for ventilator management. Coupled with severity scores, ventilator techniques and ECMO can then be systematically compared in children with ARDS.
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Affiliation(s)
- T E Paulson
- Department of Critical Care, San Diego Children's Hospital, California, USA
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29
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Gilmour IJ, Gove K. Safety and efficacy of a ventilator database interface. J Clin Monit Comput 1995; 11:183-5. [PMID: 7623058 DOI: 10.1007/bf01617720] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
This report describes a ventilator dysfunction that arose during the mechanical ventilation of a lung transplant recipient. The problem was discovered because the data on the computer-based information management system (CIMS) was different from that on the ventilator's dials. This incident is important because of the continued extensive use of analog mechanical ventilators, the increasing popularity of CIMS, and the patient safety implications of the incident.
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Affiliation(s)
- I J Gilmour
- Department of Anesthesiology, University of Minnesota Medical School, Minneapolis, USA
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Maarek JM, Grimbert F. Segmental pulmonary vascular resistances during oleic acid lung injury in rabbits. RESPIRATION PHYSIOLOGY 1994; 98:179-91. [PMID: 7817049 DOI: 10.1016/0034-5687(94)00053-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
We studied in isolated rabbit lungs the effects of oleic acid (OA) injury on the segmental distribution of vascular resistance. Vascular occlusion pressures were measured in control and OA-injured preparations over 90 min. Capillary filtration coefficient KF,C increased from 0.61 (+/- 0.10) to 0.91 (+/- 0.14) g.min-1.mmHg-1.(100 g)-1 in OA-injured lungs whereas it remained constant in control lungs. Total pulmonary vascular resistance changed little in both control and OA-injured lungs. OA injury resulted in a 15% increase of the double occlusion capillary pressure. In addition, the contribution of the microvascular to the total vascular resistance rose from 8% to 22%. The increase in microvascular resistance was significant 15 min after OA on the arteriolar side and became significant 30 min later on the venular side. Oleic acid injury does not change the total pulmonary vascular resistance but alters the distribution of segmental resistances in the isolated rabbit lung, thereby contributing to the accumulation of lung water in this model of low pressure permeability edema.
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Affiliation(s)
- J M Maarek
- Department of Biomedical Engineering, University of Southern California, Los Angeles 90089-1451
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31
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Ely EW, Bowton DL, Reed JC, Case LD, Haponik EF. Portable chest radiographs identify mechanical ventilator-associated hyperinflation. Chest 1994; 106:545-51. [PMID: 7774335 DOI: 10.1378/chest.106.2.545] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
OBJECTIVE Portable chest radiographs (CRs) are obtained routinely in mechanically ventilated patients, but little is known about relationships between CR findings and ventilator parameters. It is unclear whether radiographically apparent hyperinflation correlates with tidal volume (VT), body weight (BW), VT/kg, or levels of peak airway pressure (PAP), positive end-expiratory pressure (PEEP), or pressure support (PS). DESIGN Prospective comparison of CR and ventilator parameters in 62 mechanically ventilated patients in surgical and medical intensive care units of a university hospital. PATIENT SELECTION All mechanically ventilated adults with portable CR on four separate dates. METHODS Chest radiographs were classified by subjective assessments as hyperinflated (H+) or nonhyperinflated (H-), independent of knowledge of patients or their mechanical ventilation. Chest radiographs were reclassified independently as H+, H-, or indeterminate by a radiologist using objective criteria. Ventilator parameters recorded at the time of the CR were obtained and compared. RESULTS Patients with CRs classified subjectively as H+ compared with patients with CRs classified as H- had a larger VT/kg (12.0 +/- 0.4 ml/kg [mean +/- SEM] vs 10.2 +/- 0.4; p = 0.004), lower BW (70.8 +/- 2.9 kg vs 81.5 +/- 3.8; p = 0.03), higher PEEP (6.5 +/- 0.5 cm H2O vs 5.0 +/- 0.4; p = 0.01), and higher PAP (38.2 +/- 2.1 cm H2O vs. 33.4 +/- 1.8; p = 0.06). Using objective CR classifications, patients with H+ CRs had a VT/kg of 12.6 +/- 0.4, larger than in the indeterminate (11.1 +/- 0.8) and H- (9.9 +/- 0.3) groups (p < 0.001). The BW differed among objectively classified groups (66.5 +/- 2.7 H+, 68.9 +/- 5.1 indeterminate, and 85.2 +/- 3.7 H-; p < 0.001), but other ventilator parameters did not correlate univariately with the degree of inflation on CR. Multivariate analysis showed that higher VT was predictive of H+ after adjusting for BW in subjective (p = 0.076) and objective (p = 0.017) classifications. PEEP (p = 0.004) and older age (p = 0.021) were also associated with H+ in multivariate analysis. Four of 25 (16 percent) patients with objectively H+ CRs developed barotrauma, while no patient with H- CR had this complication (p = 0.037). CONCLUSIONS In mechanically ventilated patients, hyperinflation seen on portable CR is associated with higher VT, VT/kg, and lower BW, and may help predict subsequent barotrauma.
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Affiliation(s)
- E W Ely
- Department of Internal Medicine, Bowman Gray School of Medicine of Wake Forest University, Winston-Salem, N.C., USA
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Affiliation(s)
- M J Chapman
- Department of Anaesthesia and Intensive Care, Royal Adelaide Hospital, S.A
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Dreyfuss D, Saumon G. Role of tidal volume, FRC, and end-inspiratory volume in the development of pulmonary edema following mechanical ventilation. THE AMERICAN REVIEW OF RESPIRATORY DISEASE 1993; 148:1194-203. [PMID: 8239153 DOI: 10.1164/ajrccm/148.5.1194] [Citation(s) in RCA: 293] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Mechanical ventilation with high peak inspiratory pressure and large tidal volume (VT) produces permeability pulmonary edema. Whether it is mean or peak inspiratory pressure (i.e., mean or end-inspiratory volume) that is the major determinant of ventilation-induced lung injury is unsettled. Rats were ventilated with increasing tidal volumes starting from different degrees of FRC that were set by increasing end-expiratory pressure during positive-pressure ventilation. Pulmonary edema was assessed by the measurement of extravascular lung water content. The importance of permeability alterations was evaluated by measurement of dry lung weight and determination of albumin distribution space. Pulmonary edema with permeability alterations occurred regardless of the value of positive end-expiratory pressure (PEEP), provided the increase in VT was large enough. Similarly, edema occurred even during normal VT ventilation provided the increase in PEEP was large enough. Furthermore, moderate increases in VT or PEEP that were innocuous when applied alone, produced edema when combined. The effect of PEEP was not the consequence of raised airway pressure but of the increase in FRC since similar observations were made in animals ventilated with negative inspiratory pressure. However, although permeability alterations were similar, edema was less marked in animals ventilated with PEEP than in those ventilated with zero end-expiratory pressure (ZEEP) with the same end-inspiratory pressure. This "beneficial" effect of PEEP was probably the consequence of hemodynamic alterations. Indeed, infusion of dopamine to correct the drop in systemic arterial pressure that occurred during PEEP ventilation resulted in a significant increase in pulmonary edema. In conclusion, rather than VT or FRC value, the end-inspiratory volume is probably the main determinant of ventilation-induced edema. Hemodynamic status plays an important role in modulating the amount of edema during lung overinflation but does not fundamentally modify the characteristics of this edema which is consistently associated with major permeability alterations. These results may be relevant for ventilatory strategies during acute respiratory failure.
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Affiliation(s)
- D Dreyfuss
- Service de Réanimation Médicale, Hôpital Louis Mourier, Colombes, France
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34
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Lykens MG, Bowton DL. Aspiration and acute lung injury. Int J Obstet Anesth 1993; 2:236-40. [PMID: 15636897 DOI: 10.1016/0959-289x(93)90053-k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Aspiration is a common clinical entity whose consequences range from the relatively benign to fulminant acute respiratory failure and death. Clinical situations in which airway protection is lost or compromised predispose patients to aspiration. Treatment of aspiration, while generally supportive, depends in part upon the material aspirated and the resulting clinical syndrome. When mechanical ventilatory support is required, the avoidance of iatrogenic complications, including worsening lung injury, becomes especially important. Preventative measures, either to minimize the chances of aspiration, or to reduce the potential for injury consequent to aspiration may be highly effective in reducing the incidence of aspiration syndromes.
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Affiliation(s)
- M G Lykens
- Department of Medicine, The Bowman Gray School of Medicine of Wake Forest University, Winston-Salem, NC, USA
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35
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Dreyfuss D, Saumon G. Barotrauma is volutrauma, but which volume is the one responsible? Intensive Care Med 1992; 18:139-41. [PMID: 1644960 DOI: 10.1007/bf01709236] [Citation(s) in RCA: 166] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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Tsuno K, Miura K, Takeya M, Kolobow T, Morioka T. Histopathologic pulmonary changes from mechanical ventilation at high peak airway pressures. THE AMERICAN REVIEW OF RESPIRATORY DISEASE 1991; 143:1115-20. [PMID: 2024823 DOI: 10.1164/ajrccm/143.5_pt_1.1115] [Citation(s) in RCA: 207] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
We investigated the histopathologic pulmonary changes induced by mechanical pulmonary ventilation (MV) with a high peak airway pressure and a large tidal volume in healthy baby pigs. Eleven animals were mechanically ventilated at a peak inspiratory pressure (PIP) of 40 cm H2O, a respiratory rate (RR) of 20 min-1, a positive end-expiratory pressure (PEEP) of 3 to 5 cm H2O, and an FIO2 of 0.4. High airway pressure MV was terminated in 22 +/- 11 h because of severe hypoxemia in the animals. Five of the baby pigs were killed for gross and light microscope studies. The pulmonary changes consisted of alveolar hemorrhage, alveolar neutrophil infiltration, alveolar macrophage and type II pneumocyte proliferation, interstitial congestion and thickening, interstitial lymphocyte infiltration, emphysematous change, and hyaline membrane formation. Those lesions were similar to that seen in the early stage of the adult respiratory distress syndrome (ARDS). The remaining six animals were treated for 3 to 6 days with conventional respiratory care with appropriate ventilator settings. Prominent organized alveolar exudate in addition to lesions was also found in the five animals. These findings were indistinguishable from the clinical late stage of ARDS. Six control animals were mechanically ventilated at a PIP of less than 18 cm H2O, a RR of 20 min-1, a PEEP of 3 to 5 cm H2O, and an FIO2 of 0.4 for 48 h. They showed no notable changes in lung functions and histopathologic findings. Aggressive MV with a high PIP is often applied to patients with respiratory distress to attain adequate pulmonary gas exchange.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- K Tsuno
- Department of Anesthesiology, Kumamoto University Medical School, Japan
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37
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Leatherman JW, Lari RL, Iber C, Ney AL. Tidal volume reduction in ARDS. Effect on cardiac output and arterial oxygenation. Chest 1991; 99:1227-31. [PMID: 2019183 DOI: 10.1378/chest.99.5.1227] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
During continuous positive pressure ventilation (CPPV), mean airway pressure and lung volume will be influenced both by the tidal volume (VT) employed and the amount of positive end-expiratory pressure (PEEP). The effect of varying levels of CPPV on PaO2 and cardiac output (Q) has been previously assessed by adjusting the level of PEEP at constant VT. This study examined the influence of a 200-ml reduction in VT, at a constant PEEP of 15 cm H2O, on the PaO2 and Q of 21 patients with adult respiratory distress syndrome (ARDS). The relationship between change in Q and change in total respiratory system compliance (Cst) after VT reduction was also examined. VT reduction from 14.1 +/- 0.8 ml/kg to 11.2 +/- 0.9 ml/kg yielded an increase in Q (+ 15 +/- 12 percent, p less than 0.01) without a significant change in PaO2 (-6.3 +/- 15.0 mm Hg, p = 0.08). Cst increased with VT reduction (+ 3.1 +/- 1.8 ml/cm H2O). There was only a modest correlation (r = +0.42, p = 0.06) between delta Q percent and delta Cst following VT reduction. VT reduction at high level PEEP may yield a significant improvement in Q and net O2 delivery, but the degree of hemodynamic improvement is variable and is not reliably predicted noninvasively by measurement of Cst.
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