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Silva PL, Ball L, Rocco PRM, Pelosi P. Physiological and Pathophysiological Consequences of Mechanical Ventilation. Semin Respir Crit Care Med 2022; 43:321-334. [PMID: 35439832 DOI: 10.1055/s-0042-1744447] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Mechanical ventilation is a life-support system used to ensure blood gas exchange and to assist the respiratory muscles in ventilating the lung during the acute phase of lung disease or following surgery. Positive-pressure mechanical ventilation differs considerably from normal physiologic breathing. This may lead to several negative physiological consequences, both on the lungs and on peripheral organs. First, hemodynamic changes can affect cardiovascular performance, cerebral perfusion pressure (CPP), and drainage of renal veins. Second, the negative effect of mechanical ventilation (compression stress) on the alveolar-capillary membrane and extracellular matrix may cause local and systemic inflammation, promoting lung and peripheral-organ injury. Third, intra-abdominal hypertension may further impair lung and peripheral-organ function during controlled and assisted ventilation. Mechanical ventilation should be optimized and personalized in each patient according to individual clinical needs. Multiple parameters must be adjusted appropriately to minimize ventilator-induced lung injury (VILI), including: inspiratory stress (the respiratory system inspiratory plateau pressure); dynamic strain (the ratio between tidal volume and the end-expiratory lung volume, or inspiratory capacity); static strain (the end-expiratory lung volume determined by positive end-expiratory pressure [PEEP]); driving pressure (the difference between the respiratory system inspiratory plateau pressure and PEEP); and mechanical power (the amount of mechanical energy imparted as a function of respiratory rate). More recently, patient self-inflicted lung injury (P-SILI) has been proposed as a potential mechanism promoting VILI. In the present chapter, we will discuss the physiological and pathophysiological consequences of mechanical ventilation and how to personalize mechanical ventilation parameters.
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Affiliation(s)
- Pedro Leme Silva
- Laboratory of Pulmonary Investigation, Institute of Biophysics Carlos Chagas Filho, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Lorenzo Ball
- Department of Surgical Sciences and Integrated Diagnostics, University of Genoa, Genoa, Italy.,Department of Anesthesia and Critical Care, San Martino Policlinico Hospital, IRCCS for Oncology and Neuroscience, Genoa, Italy
| | - Patricia R M Rocco
- Laboratory of Pulmonary Investigation, Institute of Biophysics Carlos Chagas Filho, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Paolo Pelosi
- Department of Surgical Sciences and Integrated Diagnostics, University of Genoa, Genoa, Italy.,Department of Anesthesia and Critical Care, San Martino Policlinico Hospital, IRCCS for Oncology and Neuroscience, Genoa, Italy
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Al-Ruweidi MKAA, Ali FH, Shurbaji S, Popelka A, Yalcin HC. Dexamethasone and transdehydroandrosterone significantly reduce pulmonary epithelial cell injuries associated with mechanical ventilation. J Appl Physiol (1985) 2021; 130:1143-1151. [PMID: 33600286 PMCID: PMC8384562 DOI: 10.1152/japplphysiol.00574.2020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Many patients who suffer from pulmonary diseases cannot inflate their lungs normally, as they need mechanical ventilation (MV) to assist them. The stress associated with MV can damage the delicate epithelium in small airways and alveoli, which can cause complications resulting in ventilation-induced lung injuries (VILIs) in many cases, especially in patients with acute respiratory distress syndrome (ARDS). Therefore, efforts were directed to develop safe modes for MV. In our work, we propose a different approach to decrease injuries of epithelial cells (EpCs) upon MV. We alter EpCs’ cytoskeletal structure to increase their survival rate during airway reopening conditions associated with MV. We tested two anti-inflammatory drugs dexamethasone (DEX) and transdehydroandrosterone (DHEA) to alter the cytoskeleton. Cultured rat L2 alveolar EpCs were exposed to airway reopening conditions using a parallel-plate perfusion chamber. Cells were exposed to a single bubble propagation to simulate stresses associated with mechanical ventilation in both control and study groups. Cellular injury and cytoskeleton reorganization were assessed via fluorescence microscopy, whereas cell topography was studied via atomic force microscopy (AFM). Our results indicate that culturing cells in media, DEX solution, or DHEA solution did not lead to cell death (static cultures). Bubble flows caused significant cell injury. Preexposure to DEX or DHEA decreased cell death significantly. The AFM verified alteration of cell mechanics due to actin fiber depolymerization. These results suggest potential beneficial effects of DEX and DHEA for ARDS treatment for patients with COVID-19. They are also critical for VILIs and applicable to future clinical studies. NEW & NOTEWORTHY Preexposure of cultured cells to either dexamethasone or transdehydroandrosterone significantly decreases cellular injuries associated with mechanical ventilation due to their ability to alter the cell mechanics. This is an alternative protective method against VILIs instead of common methods that rely on modification of mechanical ventilator modes.
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Affiliation(s)
- Mahmoud Khatib A A Al-Ruweidi
- Biomedical Research Centre, Qatar University, Doha, Qatar.,Department of Chemistry and Earth Sciences, Qatar University, Doha, Qatar
| | | | - Samar Shurbaji
- Biomedical Research Centre, Qatar University, Doha, Qatar
| | - Anton Popelka
- Center of Advanced Materials, Qatar University, Doha, Qatar
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Kheyfets VO, Lammers SR, Wagner J, Bartels K, Piccoli J, Smith BJ. PEEP/ FIO2 ARDSNet Scale Grouping of a Single Ventilator for Two Patients: Modeling Tidal Volume Response. Respir Care 2020; 65:1094-1103. [PMID: 32712582 DOI: 10.4187/respcare.07931] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
BACKGROUND The COVID-19 pandemic is creating ventilator shortages in many countries that is sparking a conversation about placing multiple patients on a single ventilator. However, on March 26, 2020, six leading medical organizations released a joint statement warning clinicians that attempting this technique could lead to poor outcomes and high mortality. Nevertheless, hospitals around the United States and abroad are considering this technique out of desperation (eg, New York), but there is little data to guide their approach. The overall objective of this study is to utilize a computational model of mechanically ventilated lungs to assess how patient-specific lung mechanics and ventilator settings impact lung tidal volume (VT). METHODS We developed a lumped-parameter computational model of multiple patients connected to a shared ventilator and validated it against a similar experimental study. We used this model to evaluate how patient-specific lung compliance and resistance would impact VT under 4 ventilator settings of pressure control level, PEEP, breathing frequency, and inspiratory:expiratory ratio. RESULTS Our computational model predicts VT within 10% of experimental measurements. Using this model to perform a parametric study, we provide proof-of-concept for an algorithm to better match patients in different hypothetical scenarios of a single ventilator shared by > 1 patient. CONCLUSIONS Assigning patients to preset ventilators based on their required level of support on the lower PEEP/higher [Formula: see text] scale of the National Institute of Health's National Heart, Lung, and Blood Institute ARDS Clinical Network (ARDSNet), secondary to lung mechanics, could be used to overcome some of the legitimate concerns of placing multiple patients on a single ventilator. We emphasize that our results are currently based on a computational model that has not been validated against any preclinical or clinical data. Therefore, clinicians considering this approach should not look to our study as an exact estimate of predicted patient VT values.
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Affiliation(s)
- Vitaly O Kheyfets
- Department of Bioengineering, University of Colorado Denver, Anschutz Medical Campus, Aurora, Colorado.
| | - Steven R Lammers
- Department of Bioengineering, University of Colorado Denver, Anschutz Medical Campus, Aurora, Colorado
| | - Jennifer Wagner
- Department of Bioengineering, University of Colorado Denver, Anschutz Medical Campus, Aurora, Colorado
| | - Karsten Bartels
- Department of Anesthesiology, Psychiatry, Medicine, and Surgery, University of Colorado School of Medicine, Aurora, Colorado
| | - Jerome Piccoli
- University of Colorado School of Medicine, Aurora, Colorado
| | - Bradford J Smith
- Department of Bioengineering, University of Colorado Denver, Anschutz Medical Campus, Aurora, Colorado
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JAK2/STAT1-mediated HMGB1 translocation increases inflammation and cell death in a ventilator-induced lung injury model. J Transl Med 2019; 99:1810-1821. [PMID: 31467427 DOI: 10.1038/s41374-019-0308-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2018] [Revised: 06/03/2019] [Accepted: 06/14/2019] [Indexed: 01/06/2023] Open
Abstract
Janus kinase 2/signal transducer and activators of transcription 1 (JAK2/STAT1) signaling is a common pathway that contributes to numerous inflammatory disorders, including different forms of acute lung injury (ALI). However, the role of JAK2/STAT1 in ventilator-induced lung injury (VILI) and its underlying mechanism remain unclear. In this study, using lipopolysaccharide (LPS) inhalation plus mechanical ventilation as VILI mouse model, we found that the administration of JAK2 inhibitor AZD1480 markedly attenuated lung destruction, diminished protein leakage, and inhibited cytokine release. In addition, when mouse macrophage-like RAW 264.7 cells were exposed to LPS and cyclic stretch (CS), AZD1480 prevented cell autophagy, reduced apoptosis, and suppressed lactate dehydrogenase release by downregulating JAK2/STAT1 phosphorylation levels and inducing HMGB1 translocation from the nucleus to the cytoplasm. Furthermore, HMGB1 and STAT1 knockdown attenuated LPS+CS-induced autophagy and apoptosis in RAW 264.7 cells. In conclusion, these findings reveal the connection between the JAK2/STAT1 pathway and HMGB1 translocation in mediating lung inflammation and cell death in VILI, suggesting that these molecules may serve as novel therapeutic targets for VILI.
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Russotto V, Bellani G, Foti G. Respiratory mechanics in patients with acute respiratory distress syndrome. ANNALS OF TRANSLATIONAL MEDICINE 2018; 6:382. [PMID: 30460256 DOI: 10.21037/atm.2018.08.32] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Despite the recognition of its iatrogenic potential, mechanical ventilation remains the mainstay of respiratory support for patients with acute respiratory distress syndrome (ARDS). The low volume ventilation has been recognized as the only method to reduce mortality of ARDS patients and plateau pressure as the lighthouse for delivering safe ventilation. Recent investigations suggest that a ventilation based on lung mechanics (tidal ventilation tailored to the available lung volume able to receive it, i.e., driving pressure) is a successful approach to improve outcome. However, currently available bedside mechanical variables do not consider regional mechanical properties of ARDS affected lungs, which include the role of local stress risers at the boundaries of areas with different aeration. A unifying approach considers lung-related causes and ventilation-related causes of lung injury. These last may be incorporated in the mechanical power (i.e., amount of mechanical energy transferred per unit of time). Ventilation-induced lung injury (which includes the self-inflicted lung injury of a spontaneously breathing patient) can therefore be prevented by the adoption of measures promoting an increase of ventilable lung and its homogeneity and by delivering lower levels of mechanical power. Prone position promotes lung homogeneity without increasing the delivered mechanical power. This review describes the recent developments on respiratory mechanics in ARDS patients, providing both bedside and research insights from the most updated evidence.
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Affiliation(s)
- Vincenzo Russotto
- Department of Emergency and Intensive Care, University Hospital San Gerardo, Monza, Italy
| | - Giacomo Bellani
- Department of Emergency and Intensive Care, University Hospital San Gerardo, Monza, Italy.,University of Milano Bicocca, Milano, Italy
| | - Giuseppe Foti
- Department of Emergency and Intensive Care, University Hospital San Gerardo, Monza, Italy.,University of Milano Bicocca, Milano, Italy
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Abstract
Even after many years of intensive research acute respiratory distress syndrome (ARDS) is still associated with a high mortality. Epidemiologically, ARDS represents a central challenge for modern intensive care treatment. The multifactorial etiology of ARDS complicates the clear identification and evaluation of new therapeutic interventions. Lung protective mechanical ventilation and adjuvant therapies, such as the prone position and targeted extracorporeal lung support are of particular importance in the treatment of ARDS, depending on the severity of the disease. In order to guarantee an individualized and needs-adapted treatment, ARDS patients benefit from treatment in specialized centers.
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8
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Differential Effects of Intraoperative Positive End-expiratory Pressure (PEEP) on Respiratory Outcome in Major Abdominal Surgery Versus Craniotomy. Ann Surg 2017; 264:362-369. [PMID: 26496082 DOI: 10.1097/sla.0000000000001499] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
OBJECTIVES In this study, we examined whether (1) positive end-expiratory pressure (PEEP) has a protective effect on the risk of major postoperative respiratory complications in a cohort of patients undergoing major abdominal surgeries and craniotomies, and (2) the effect of PEEP is differed by surgery type. BACKGROUND Protective mechanical ventilation with lower tidal volumes and PEEP reduces compounded postoperative complications after abdominal surgery. However, data regarding the use of intraoperative PEEP is conflicting. METHODS In this observational study, we included 5915 major abdominal surgery patients and 5063 craniotomy patients. Analysis was performed using multivariable logistic regression. The primary outcome was a composite of major postoperative respiratory complications (respiratory failure, reintubation, pulmonary edema, and pneumonia) within 3 days of surgery. RESULTS Within the entire study population (major abdominal surgeries and craniotomies), we found an association between application of PEEP ≥5 cmH2O and a decreased risk of postoperative respiratory complications compared with PEEP <5 cmH2O. Application of PEEP >5 cmH2O was associated with a significant lower odds of respiratory complications in patients undergoing major abdominal surgery (odds ratio 0.53, 95% confidence interval 0.39 - 0.72), effects that translated to deceased hospital length of stay [median hospital length of stay : 6 days (4-9 days), incidence rate ratios for each additional day: 0.91 (0.84 - 0.98)], whereas PEEP >5 cmH2O was not significantly associated with reduced odds of respiratory complications or hospital length of stay in patients undergoing craniotomy. CONCLUSIONS The protective effects of PEEP are procedure specific with meaningful effects observed in patients undergoing major abdominal surgery. Our data suggest that default mechanical ventilator settings should include PEEP of 5-10 cmH2O during major abdominal surgery.
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Biological Impact of Transpulmonary Driving Pressure in Experimental Acute Respiratory Distress Syndrome. Anesthesiology 2015; 123:423-33. [DOI: 10.1097/aln.0000000000000716] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Abstract
Background:
Ventilator-induced lung injury has been attributed to the interaction of several factors: tidal volume (VT), positive end-expiratory pressure (PEEP), transpulmonary driving pressure (difference between transpulmonary pressure at end-inspiration and end-expiration, ΔP,L), and respiratory system plateau pressure (Pplat,rs).
Methods:
Forty-eight Wistar rats received Escherichia coli lipopolysaccharide intratracheally. After 24 h, animals were randomized into combinations of VT and PEEP, yielding three different ΔP,L levels: ΔP,LLOW (VT = 6 ml/kg, PEEP = 3 cm H2O); ΔP,LMEAN (VT = 13 ml/kg, PEEP = 3 cm H2O or VT = 6 ml/kg, PEEP = 9.5 cm H2O); and ΔP,LHIGH (VT = 22 ml/kg, PEEP = 3 cm H2O or VT = 6 ml/kg, PEEP = 11 cm H2O). In other groups, at low VT, PEEP was adjusted to obtain a Pplat,rs similar to that achieved with ΔP,LMEAN and ΔP,LHIGH at high VT.
Results:
At ΔP,LLOW, expressions of interleukin (IL)-6, receptor for advanced glycation end products (RAGE), and amphiregulin were reduced, despite morphometric evidence of alveolar collapse. At ΔP,LHIGH (VT = 6 ml/kg and PEEP = 11 cm H2O), lungs were fully open and IL-6 and RAGE were reduced compared with ΔP,LMEAN (27.4 ± 12.9 vs. 41.6 ± 14.1 and 0.6 ± 0.2 vs. 1.4 ± 0.3, respectively), despite increased hyperinflation and amphiregulin expression. At ΔP,LMEAN (VT = 6 ml/kg and PEEP = 9.5 cm H2O), when PEEP was not high enough to keep lungs open, IL-6, RAGE, and amphiregulin expression increased compared with ΔP,LLOW (41.6 ± 14.1 vs. 9.0 ± 9.8, 1.4 ± 0.3 vs. 0.6 ± 0.2, and 6.7 ± 0.8 vs. 2.2 ± 1.0, respectively). At Pplat,rs similar to that achieved with ΔP,LMEAN and ΔP,LHIGH, higher VT and lower PEEP reduced IL-6 and RAGE expression.
Conclusion:
In the acute respiratory distress syndrome model used in this experiment, two strategies minimized ventilator-induced lung injury: (1) low VT and PEEP, yielding low ΔP,L and Pplat,rs; and (2) low VT associated with a PEEP level sufficient to keep the lungs open.
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Aschner Y, Zemans RL, Yamashita CM, Downey GP. Matrix metalloproteinases and protein tyrosine kinases: potential novel targets in acute lung injury and ARDS. Chest 2014; 146:1081-1091. [PMID: 25287998 DOI: 10.1378/chest.14-0397] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Acute lung injury (ALI) and ARDS fall within a spectrum of pulmonary disease that is characterized by hypoxemia, noncardiogenic pulmonary edema, and dysregulated and excessive inflammation. While mortality rates have improved with the advent of specialized ICUs and lung protective mechanical ventilation strategies, few other therapies have proven effective in the management of ARDS, which remains a significant clinical problem. Further development of biomarkers of disease severity, response to therapy, and prognosis is urgently needed. Several novel pathways have been identified and studied with respect to the pathogenesis of ALI and ARDS that show promise in bridging some of these gaps. This review will focus on the roles of matrix metalloproteinases and protein tyrosine kinases in the pathobiology of ALI in humans, and in animal models and in vitro studies. These molecules can act independently, as well as coordinately, in a feed-forward manner via activation of tyrosine kinase-regulated pathways that are pivotal in the development of ARDS. Specific signaling events involving proteolytic processing by matrix metalloproteinases that contribute to ALI, including cytokine and chemokine activation and release, neutrophil recruitment, transmigration and activation, and disruption of the intact alveolar-capillary barrier, will be explored in the context of these novel molecular pathways.
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Affiliation(s)
- Yael Aschner
- Division of Pulmonary, Critical Care, and Sleep Medicine, Departments of Medicine and Pediatrics, National Jewish Health, Denver, CO; Division of Pulmonary Sciences and Critical Care Medicine, Departments of Medicine, University of Colorado Denver, Aurora, CO
| | - Rachel L Zemans
- Division of Pulmonary, Critical Care, and Sleep Medicine, Departments of Medicine and Pediatrics, National Jewish Health, Denver, CO; Division of Pulmonary Sciences and Critical Care Medicine, Departments of Medicine, University of Colorado Denver, Aurora, CO
| | - Cory M Yamashita
- Department of Medicine, University of Western Ontario, London, ON, Canada
| | - Gregory P Downey
- Division of Pulmonary, Critical Care, and Sleep Medicine, Departments of Medicine and Pediatrics, National Jewish Health, Denver, CO; Division of Pulmonary Sciences and Critical Care Medicine, Departments of Medicine, University of Colorado Denver, Aurora, CO; Immunology, University of Colorado Denver, Aurora, CO.
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Yamashita CM, Radisky DC, Aschner Y, Downey GP. The importance of matrix metalloproteinase-3 in respiratory disorders. Expert Rev Respir Med 2014; 8:411-21. [DOI: 10.1586/17476348.2014.909288] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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12
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Abstract
Mechanical ventilation (MV) is, by definition, the application of external forces to the lungs. Depending on their magnitude, these forces can cause a continuum of pathophysiological alterations ranging from the stimulation of inflammation to the disruption of cell-cell contacts and cell membranes. These side effects of MV are particularly relevant for patients with inhomogeneously injured lungs such as in acute lung injury (ALI). These patients require supraphysiological ventilation pressures to guarantee even the most modest gas exchange. In this situation, ventilation causes additional strain by overdistension of the yet non-injured region, and additional stress that forms because of the interdependence between intact and atelectatic areas. Cells are equipped with elaborate mechanotransduction machineries that respond to strain and stress by the activation of inflammation and repair mechanisms. Inflammation is the fundamental response of the host to external assaults, be they of mechanical or of microbial origin and can, if excessive, injure the parenchymal tissue leading to ALI. Here, we will discuss the forces generated by MV and how they may injure the lungs mechanically and through inflammation. We will give an overview of the mechanotransduction and how it leads to inflammation and review studies demonstrating that ventilator-induced lung injury can be prevented by blocking pathways of mechanotransduction or inflammation.
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Affiliation(s)
- Ulrike Uhlig
- Department of Pharmacology & Toxicology, Medical Faculty, RWTH Aachen University, Aachen, Germany
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Vahdat Shariatpanahi Z, Mokhtari M, Taleban FA, Alavi F, Salehi Surmaghi MH, Mehrabi Y, Shahbazi S. Effect of enteral feeding with ginger extract in acute respiratory distress syndrome. J Crit Care 2013; 28:217.e1-6. [PMID: 22884532 DOI: 10.1016/j.jcrc.2012.04.017] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2011] [Revised: 04/16/2012] [Accepted: 04/22/2012] [Indexed: 10/28/2022]
Abstract
PURPOSE The purpose of this study is to evaluate the effects of an enteral diet enriched with ginger extract on inflammatory factors, respiratory profile, and outcome of patients with acute respiratory distress syndrome (ARDS). MATERIALS AND METHODS Thirty-two patients with ARDS were randomized to receive a high-protein enteral diet enriched with ginger or placebo. Serum levels of interleukin (IL) 1, IL-6, tumor necrosis factor α, and leukotriene B4; red blood cell glutathione; oxygenation; and static compliance were measured on days 0, 5, and 10. RESULTS Patients fed enteral diet enriched with ginger had significantly lower serum levels of IL-1, IL-6, and tumor necrosis factor α and higher level of RBC glutathione on days 5 and 10 compared with control group (P < .05). Significant improvement in oxygenation was observed on day 5 (P = .02) and 10 (P = .003) in ginger group compared with control group. Static compliance was increased on day 5 (P = .01) in ginger group compared with control group. A significant difference was found in duration of mechanical ventilation (P = .02) and length of intensive care unit stay (P = .04) in favor of ginger group. We did not find any difference in barotraumas, organ failure, and mortality between the study groups. CONCLUSIONS An enteral diet supplemented with ginger in patients with ARDS may be beneficial for gas exchange and could decrease duration of mechanical ventilation and length of stay in intensive care unit.
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Affiliation(s)
- Zahra Vahdat Shariatpanahi
- National Nutrition and Food Technology Research Institute, Faculty of Nutrition and Food Technology, Shahid Beheshti University of Medical Science, Tehran, Iran.
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14
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Models and mechanisms of acute lung injury caused by direct insults. Eur J Cell Biol 2012; 91:590-601. [PMID: 22284832 DOI: 10.1016/j.ejcb.2011.11.004] [Citation(s) in RCA: 122] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2011] [Revised: 11/18/2011] [Accepted: 11/30/2011] [Indexed: 11/22/2022] Open
Abstract
Acute lung injury (ALI) and its more severe form acute respiratory distress syndrome (ARDS) are life-threatening diseases that are characterized by acute onset, pulmonary inflammation, oedema due to increased vascular permeability and severe hypoxemia. Clinically, ARDS can be divided into ARDS due to direct causes such as pneumonia, aspiration or injurious ventilation, and due to extrapulmonary indirect causes such as sepsis, severe burns or pancreatitis. In order to identify potential therapeutic targets, we asked here whether common molecular mechanisms can be identified that are relevant in different models of the direct form of ALI/ARDS. To this end, we reviewed three widely used models: (a) one based on a biological insult, i.e. instillation of bacterial endotoxins; (b) one based on a chemical insult, i.e. instillation of acid; and (c) one based on a mechanical insult, i.e. injurious ventilation. Studies were included only if the mediator or mechanism of interest was studied in at least two of the three animal models listed above. As endpoints, we selected neutrophil sequestration, permeability, hypoxemia (physiological dysfunction) and survival. Our analysis showed that most studies have focused on mechanisms of pulmonary neutrophil sequestration and models with moderate forms of oedema. The underlying mechanisms that involve canonical inflammatory pathways such as MAP kinases, CXCR2 chemokines, PAF, leukotrienes, adhesions molecules (CD18, ICAM-1) and elastase have been defined relatively well. Further mechanisms including TNF, DARC, HMGB1, PARP, GADD45 and collagenase are under investigation. Such mechanisms that are shared between the three ALI models may represent viable therapeutic targets. However, only few studies have linked these pathways to hypoxemia, the most important clinical aspect of ALI/ARDS. Since moderate oedema does not necessarily lead to hypoxemia, we suggest that the clinical relevance of experimental studies can be further improved by putting greater emphasis on gas exchange.
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Reiss LK, Kowallik A, Uhlig S. Recurrent recruitment manoeuvres improve lung mechanics and minimize lung injury during mechanical ventilation of healthy mice. PLoS One 2011; 6:e24527. [PMID: 21935418 PMCID: PMC3174196 DOI: 10.1371/journal.pone.0024527] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2011] [Accepted: 08/12/2011] [Indexed: 11/18/2022] Open
Abstract
INTRODUCTION Mechanical ventilation (MV) of mice is increasingly required in experimental studies, but the conditions that allow stable ventilation of mice over several hours have not yet been fully defined. In addition, most previous studies documented vital parameters and lung mechanics only incompletely. The aim of the present study was to establish experimental conditions that keep these parameters within their physiological range over a period of 6 h. For this purpose, we also examined the effects of frequent short recruitment manoeuvres (RM) in healthy mice. METHODS Mice were ventilated at low tidal volume V(T) = 8 mL/kg or high tidal volume V(T) = 16 mL/kg and a positive end-expiratory pressure (PEEP) of 2 or 6 cm H(2)O. RM were performed every 5 min, 60 min or not at all. Lung mechanics were followed by the forced oscillation technique. Blood pressure (BP), electrocardiogram (ECG), heart frequency (HF), oxygen saturation and body temperature were monitored. Blood gases, neutrophil-recruitment, microvascular permeability and pro-inflammatory cytokines in bronchoalveolar lavage (BAL) and blood serum as well as histopathology of the lung were examined. RESULTS MV with repetitive RM every 5 min resulted in stable respiratory mechanics. Ventilation without RM worsened lung mechanics due to alveolar collapse, leading to impaired gas exchange. HF and BP were affected by anaesthesia, but not by ventilation. Microvascular permeability was highest in atelectatic lungs, whereas neutrophil-recruitment and structural changes were strongest in lungs ventilated with high tidal volume. The cytokines IL-6 and KC, but neither TNF nor IP-10, were elevated in the BAL and serum of all ventilated mice and were reduced by recurrent RM. Lung mechanics, oxygenation and pulmonary inflammation were improved by increased PEEP. CONCLUSIONS Recurrent RM maintain lung mechanics in their physiological range during low tidal volume ventilation of healthy mice by preventing atelectasis and reduce the development of pulmonary inflammation.
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Affiliation(s)
- Lucy Kathleen Reiss
- Institute of Pharmacology and Toxicology, Medical Faculty of RWTH Aachen University, Aachen, Germany.
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Taniguchi LU, Caldini EG, Velasco IT, Negri EM. Cytoskeleton and mechanotransduction in the pathophysiology of ventilator-induced lung injury. J Bras Pneumol 2010; 36:363-71. [PMID: 20625675 DOI: 10.1590/s1806-37132010000300015] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2009] [Accepted: 01/26/2010] [Indexed: 01/27/2023] Open
Abstract
Although mechanical ventilation is an important therapy, it can result in complications. One major complication is ventilator-induced lung injury, which is caused by alveolar hyperdistension, leading to an inflammatory process, with neutrophilic infiltration, hyaline membrane formation, fibrogenesis and impaired gas exchange. In this process, cellular mechanotransduction of the overstretching stimulus is mediated by means of the cytoskeleton and its cell-cell and cell-extracellular matrix interactions, in such a way that the mechanical stimulus of ventilation is translated into an intracellular biochemical signal, inducing endothelial activation, pulmonary vascular permeability, leukocyte chemotaxis, cytokine production and, possibly, distal organ failure. Clinical studies have shown the relationship between pulmonary distension and mortality in patients with ventilator-induced lung injury. However, although the cytoskeleton plays a fundamental role in the pathogenesis of ventilator-induced lung injury, there have been few in vivo studies of alterations in the cytoskeleton and in cytoskeleton-associated proteins during this pathological process.
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Affiliation(s)
- Leandro Utino Taniguchi
- Faculdade de Medicina da Universidade de São Paulo, Hospital das Clínicas da Universidade de São Paulo, São Paulo, Brazil.
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Truscott EA, McCaig LA, Yao LJ, Veldhuizen RAW, Lewis JF. Surfactant protein-A reduces translocation of mediators from the lung into the circulation. Exp Lung Res 2010; 36:431-9. [PMID: 20715984 DOI: 10.3109/01902141003721440] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The objective of this study was to characterize a mouse model of lung inflammation and determine the effect of surfactant protein A (SP-A, or sftpa) on the transfer of inflammatory mediators from these injured lungs into the systemic circulation. Lung inflammation was induced in either sftpa-deficient (-/-) or wild-type (+/+) spontaneously breathing, adult mice via intranasal lipopolysaccharide (LPS). Four hours later, lungs were isolated, perfused, and mechanically ventilated for 2 hours. Perfusate was collected for analysis over the duration of ventilation and lung lavage was obtained in groups of animals immediately before and after mechanical ventilation (MV). Lavage analysis showed an increase in interleukin-6 (IL6) and tumor necrosis factor-alpha (TNFalpha) 4 hours after LPS, with a further increase in IL6 following MV. LPS and MV also caused an increase in total cell and neutrophil numbers as well as total protein in the lavage compared to controls. Perfusate analysis revealed a significant increase in IL6 and TNFalpha after LPS and MV, with significantly greater levels of these mediators in sftpa (-/-) versus (+/+) mice. The authors conclude that LPS followed by MV resulted in lung inflammation and injury, and that SP-A significantly influenced inflammatory mediator release from these inflamed lungs into the perfusate.
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Affiliation(s)
- Emily A Truscott
- Department of Physiology and Pharmacology, Lawson Health Research Institute, University of Western Ontario, London, Ontario, Canada
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De Robertis E, Uttman L, Jonson B. Re-inspiration of CO(2) from ventilator circuit: effects of circuit flushing and aspiration of dead space up to high respiratory rate. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2010; 14:R73. [PMID: 20420671 PMCID: PMC2887196 DOI: 10.1186/cc8986] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/27/2009] [Revised: 11/24/2009] [Accepted: 04/26/2010] [Indexed: 02/05/2023]
Abstract
Introduction Dead space negatively influences carbon dioxide (CO2) elimination, particularly at high respiratory rates (RR) used at low tidal volume ventilation in acute respiratory distress syndrome (ARDS). Aspiration of dead space (ASPIDS), a known method for dead space reduction, comprises two mechanisms activated during late expiration: aspiration of gas from the tip of the tracheal tube and gas injection through the inspiratory line - circuit flushing. The objective was to study the efficiency of circuit flushing alone and of ASPIDS at wide combinations of RR and tidal volume (VT) in anaesthetized pigs. The hypothesis was tested that circuit flushing and ASPIDS are particularly efficient at high RR. Methods In Part 1 of the study, RR and VT were, with a computer-controlled ventilator, modified for one breath at a time without changing minute ventilation. Proximal dead space in a y-piece and ventilator tubing (VDaw, prox) was measured. In part two, changes in CO2 partial pressure (PaCO2) during prolonged periods of circuit flushing and ASPIDS were studied at RR 20, 40 and 60 minutes-1. Results In Part 1, VDaw, prox was 7.6 ± 0.5% of VT at RR 10 minutes-1 and 16 ± 2.5% at RR 60 minutes-1. In Part 2, circuit flushing reduced PaCO2 by 20% at RR 40 minutes-1 and by 26% at RR 60 minutes-1. ASPIDS reduced PaCO2 by 33% at RR 40 minutes-1 and by 41% at RR 60 minutes-1. Conclusions At high RR, re-breathing of CO2 from the y-piece and tubing becomes important. Circuit flushing and ASPIDS, which significantly reduce tubing dead space and PaCO2, merit further clinical studies.
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Affiliation(s)
- Edoardo De Robertis
- Department of Surgical, Anaesthesiological, and Intensive Care Medicine Sciences, University of Napoli Federico II, Via S, Pansini 5, Naples, Italy.
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Muellenbach RM, Kredel M, Wilhelm J, Küstermann J, Fink L, Siebenliest G, Klosterhalfen B, Foerster CY, Kranke P, Wunder C, Roewer N, Brederlau J. High-frequency oscillation combined with arteriovenous extracorporeal lung assist reduces lung injury. Exp Lung Res 2010; 36:148-58. [DOI: 10.3109/01902140903214683] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Doroszko A, Hurst TS, Polewicz D, Sawicka J, Fert-Bober J, Johnson DH, Sawicki G. Effects of MMP-9 inhibition by doxycycline on proteome of lungs in high tidal volume mechanical ventilation-induced acute lung injury. Proteome Sci 2010; 8:3. [PMID: 20205825 PMCID: PMC2824689 DOI: 10.1186/1477-5956-8-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2009] [Accepted: 01/29/2010] [Indexed: 12/20/2022] Open
Abstract
Background Although mechanical ventilation (MV) is a major supportive therapy for patients with acute respiratory distress syndrome, it may result in side effects including lung injury. In this study we hypothesize that MMP-9 inhibition by doxycycline might reduce MV-related lung damage. Using a proteomic approach we identified the pulmonary proteins altered in high volume ventilation-induced lung injury (VILI). Forty Wistar rats were randomized to an orally pretreated with doxycycline group (n = 20) or to a placebo group (n = 20) each of which was followed by instrumentation prior to either low or high tidal volume mechanical ventilation. Afterwards, animals were euthanized and lungs were harvested for subsequent analyses. Results Mechanical function and gas exchange parameters improved following treatment with doxycycline in the high volume ventilated group as compared to the placebo group. Nine pulmonary proteins have shown significant changes between the two biochemically analysed (high volume ventilated) groups. Treatment with doxycycline resulted in a decrease of pulmonary MMP-9 activity as well as in an increase in the levels of soluble receptor for advanced glycation endproduct, apoliporotein A-I, peroxiredoxin II, four molecular forms of albumin and two unnamed proteins. Using the pharmacoproteomic approach we have shown that treatment with doxycycline leads to an increase in levels of several proteins, which could potentially be part of a defense mechanism. Conclusion Administration of doxycycline might be a significant supportive therapeutic strategy in prevention of VILI.
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Affiliation(s)
- Adrian Doroszko
- Department of Pharmacology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
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Pinheiro de Oliveira R, Hetzel MP, dos Anjos Silva M, Dallegrave D, Friedman G. Mechanical ventilation with high tidal volume induces inflammation in patients without lung disease. Crit Care 2010; 14:R39. [PMID: 20236550 PMCID: PMC2887148 DOI: 10.1186/cc8919] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2009] [Revised: 10/26/2009] [Accepted: 03/18/2010] [Indexed: 11/10/2022] Open
Abstract
INTRODUCTION Mechanical ventilation (MV) with high tidal volumes may induce or aggravate lung injury in critical ill patients. We compared the effects of a protective versus a conventional ventilatory strategy, on systemic and lung production of tumor necrosis factor-alpha (TNF-alpha) and interleukin-8 (IL-8) in patients without lung disease. METHODS Patients without lung disease and submitted to mechanical ventilation admitted to one trauma and one general adult intensive care unit of two different university hospitals were enrolled in a prospective randomized-control study. Patients were randomized to receive MV either with tidal volume (VT) of 10 to 12 ml/kg predicted body weight (high VT group) (n = 10) or with VT of 5 to 7 ml/kg predicted body weight (low VT group) (n = 10) with an oxygen inspiratory fraction (FIO2) enough to keep arterial oxygen saturation >90% with positive end-expiratory pressure (PEEP) of 5 cmH2O during 12 hours after admission to the study. TNF-alpha and IL-8 concentrations were measured in the serum and in the bronchoalveolar lavage fluid (BALF) at admission and after 12 hours of study observation time. RESULTS Twenty patients were enrolled and analyzed. At admission or after 12 hours there were no differences in serum TNF-alpha and IL-8 between the two groups. While initial analysis did not reveal significant differences, standardization against urea of logarithmic transformed data revealed that TNF-alpha and IL-8 levels in bronchoalveolar lavage (BAL) fluid were stable in the low VT group but increased in the high VT group (P = 0.04 and P = 0.03). After 12 hours, BALF TNF-alpha (P = 0.03) and BALF IL-8 concentrations (P = 0.03) were higher in the high VT group than in the low VT group. CONCLUSIONS The use of lower tidal volumes may limit pulmonary inflammation in mechanically ventilated patients even without lung injury. CLINICAL TRIAL REGISTRATION NCT00935896.
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Affiliation(s)
- Roselaine Pinheiro de Oliveira
- Central Intensive Care Unit, Complexo Hospitalar Santa Casa, Rua Prof. Annes Dias, 295, Porto Alegre, 90020-090, Brazil
- Hospital de Clínicas de Porto Alegre, Universidade Federal do Rio Grande do Sul, Ramiro Barcelos n° 2.350, Porto Alegre, 90035-903, Brazil
| | - Marcio Pereira Hetzel
- Central Intensive Care Unit, Complexo Hospitalar Santa Casa, Rua Prof. Annes Dias, 295, Porto Alegre, 90020-090, Brazil
| | - Mauro dos Anjos Silva
- Central Intensive Care Unit, Complexo Hospitalar Santa Casa, Rua Prof. Annes Dias, 295, Porto Alegre, 90020-090, Brazil
| | - Daniele Dallegrave
- Central Intensive Care Unit, Complexo Hospitalar Santa Casa, Rua Prof. Annes Dias, 295, Porto Alegre, 90020-090, Brazil
| | - Gilberto Friedman
- Central Intensive Care Unit, Complexo Hospitalar Santa Casa, Rua Prof. Annes Dias, 295, Porto Alegre, 90020-090, Brazil
- Hospital de Clínicas de Porto Alegre, Universidade Federal do Rio Grande do Sul, Ramiro Barcelos n° 2.350, Porto Alegre, 90035-903, Brazil
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Pedreira PR, García-Prieto E, Parra D, Astudillo A, Diaz E, Taboada F, Albaiceta GM. Effects of melatonin in an experimental model of ventilator-induced lung injury. Am J Physiol Lung Cell Mol Physiol 2008; 295:L820-7. [DOI: 10.1152/ajplung.90211.2008] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Melatonin is a free radical scavenger and a broad-spectrum antioxidant and has well-documented immunomodulatory effects. We studied the effects of this hormone on lung damage, oxidative stress, and inflammation in a model of ventilator-induced lung injury (VILI), using 8- to 12-wk-old Swiss mice ( n = 48). Animals were randomized into three experimental groups: control (not ventilated); low-pressure ventilation [peak inspiratory pressure 15 cmH2O, positive end-expiratory pressure (PEEP) 2 cmH2O], and high-pressure ventilation (peak inspiratory pressure 25 cmH2O, PEEP 0 cmH2O). Each group was divided into two subgroups: eight animals were treated with melatonin (10 mg/kg ip, 30 min before the onset of ventilation) and the remaining eight with vehicle. After 2 h of ventilation, lung injury was evaluated by gas exchange, wet-to-dry weight ratio, and histological analysis. Levels of malondialdehyde, glutathione peroxidase, interleukins IL-1β, IL-6, TNF-α, and IL-10, and matrix metalloproteinases 2 and 9 in lung tissue were measured as indicators of oxidation status, pro-/anti-inflammatory cytokines, and matrix turnover, respectively. Ventilation with high pressures induced severe lung damage and release of TNF-α, IL-6, and matrix metalloproteinase-9. Treatment with melatonin improved oxygenation and decreased histological lung injury but significantly increased oxidative stress quantified by malondialdehyde levels. There were no differences in TNF-α, IL-1β, IL-6, or matrix metalloproteinases caused by melatonin treatment, but IL-10 levels were significantly higher in treated animals. These results suggest that melatonin decreases VILI by increasing the anti-inflammatory response despite an unexpected increase in oxidative stress.
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MacIntyre NR. Is there a best way to set tidal volume for mechanical ventilatory support? Clin Chest Med 2008; 29:225-31, v. [PMID: 18440432 DOI: 10.1016/j.ccm.2008.01.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Tidal breaths are an important component of mechanical ventilation. However, an inappropriate tidal volume setting can overstretch and injure the lung. Maximal stretch, tidal stretch, frequency of stretch, and rate of stretch are all implicated in such injury. Clinical trials have shown that limiting maximal and tidal stretch improves outcomes, even if gas exchange is partially compromised. Thus, current strategies should focus on limiting tidal and maximal stretch as much as possible.
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Affiliation(s)
- Neil R MacIntyre
- Division of Pulmonary and Critical Care Medicine, Duke University Medical Center, Room 1120, Box 3911, Erwin Road, Durham, NC 27710, USA.
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Almendros I, Gutierrez PT, Closa D, Navajas D, Farre R. One-lung overventilation does not induce inflammation in the normally ventilated contralateral lung. Respir Physiol Neurobiol 2008; 162:100-2. [DOI: 10.1016/j.resp.2008.04.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2008] [Revised: 04/16/2008] [Accepted: 04/16/2008] [Indexed: 11/29/2022]
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Abstract
Among ventilated children, the incidence of acute lung injury (ALI) was 9%; of that latter group 80% developed the acute respiratory distress syndrome (ARDS). The population-based prevalence of pediatric ARDS was 5.5 cases/100.000 inhabitants. Underlying diseases in children were septic shock (34%), respiratory syncytial virus infections (16%), bacterial pneumonia (15%), near-drowning 9%, and others. Mortality ranged from 18% to 27% for ALI (including ALI-non ARDS and ARDS) and from 29% to 50% for ARDS. Mortality was only 3%-11% in children with ALI-non ARDS. As risk factors, oxygenation indices and multi-organ failure have been identified. New insights into the pathophysiology (for example the interplay between intraalveolar coagulation/fibrinolysis and inflammation and the genetic polymorphism for the angiotensin-converting enzyme) offer new therapeutic options. Lung protective mechanical ventilation with optimal lung recruitment is the mainstay of supportive therapy. New therapeutic modalities refer to corticosteroid and surfactant treatment. Well-designed follow up studies are needed.
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Pugin J, Dunn-Siegrist I, Dufour J, Tissières P, Charles PE, Comte R. Cyclic stretch of human lung cells induces an acidification and promotes bacterial growth. Am J Respir Cell Mol Biol 2007; 38:362-70. [PMID: 17921360 DOI: 10.1165/rcmb.2007-0114oc] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
The reasons for bacterial proliferation in the lungs of mechanically ventilated patients are poorly understood. We hypothesized that prolonged cyclic stretch of lung cells influenced bacterial growth. Human alveolar type II-like A549 cells were submitted in vitro to prolonged cyclic stretch. Bacteria were cultured in conditioned supernatants from cells submitted to stretch and from control static cells. Escherichia coli had a marked growth advantage in conditioned supernatants from stretched A549 cells, but also from stretched human bronchial BEAS-2B cells, human MRC-5 fibroblasts, and murine RAW 264.7 macrophages. Stretched cells compared with control static cells acidified the milieu by producing increased amounts of lactic acid. Alkalinization of supernatants from stretched cells blocked E. coli growth. In contrast, acidification of supernatants from control cells stimulated bacterial growth. The effect of various pharmacological inhibitors of metabolic pathways was tested in this system. Treatment of A549 cells and murine RAW 264.7 macrophages with the Na(+)/K(+)-ATPase pump inhibitor ouabain during cyclic stretch blocked both the acidification of the milieu and bacterial growth. Several pathogenic bacteria originating from lungs of patients with ventilator-associated pneumonia (VAP) also grow better in vitro at slightly acidic pH (pH 6-7.2), pH similar to those measured in the airways from ventilated patients. This novel metabolic pathway stimulated by cyclic stretch may represent an important pathogenic mechanism of VAP. Alkalinization of the airways may represent a promising preventive strategy in ventilated critically ill patients.
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Affiliation(s)
- Jérôme Pugin
- Soins Intensifs, Hôpitaux Universitaires de Genève, 1211 Genève 14, Switzerland.
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Papadakos PJ, Lachmann B. The open lung concept of mechanical ventilation: the role of recruitment and stabilization. Crit Care Clin 2007; 23:241-50, ix-x. [PMID: 17368168 DOI: 10.1016/j.ccc.2006.12.001] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
This article describes the pathophysiologic basis and clinical role for lung recruitment maneuvers. It reviews the literature and presents the authors' clinical experience of over 15 years in the collaboration between Erasmus MC and the University of Rochester. The authors are hopeful that these lung-protective strategies are presented in a useful format that may be useful to the practicing intensivist, thus bringing laboratory and clinical research to bedside practice.
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Affiliation(s)
- Peter J Papadakos
- Department of Anesthesiology, University of Rochester School of Medicine and Dentistry, Box 604, 601 Elmwood Avenue, Rochester, NY 14642, USA.
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Wilson MR, Goddard ME, O'Dea KP, Choudhury S, Takata M. Differential roles of p55 and p75 tumor necrosis factor receptors on stretch-induced pulmonary edema in mice. Am J Physiol Lung Cell Mol Physiol 2007; 293:L60-8. [PMID: 17435079 DOI: 10.1152/ajplung.00284.2006] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Ventilator-induced lung injury plays a crucial role in the outcome of patients with acute lung injury. Previous studies have shown a role for the cytokine tumor necrosis factor-alpha (TNF) in stretch-induced alveolar neutrophil recruitment, but the involvement of TNF in stretch-induced pulmonary edema is unclear. We investigated the effects of TNF through its individual p55 and p75 receptors on early pulmonary edema formation during high stretch ventilation, before neutrophil infiltration. Anesthetized wild-type or TNF receptor single/double knockout mice were ventilated with high tidal volume ( approximately 38 ml/kg) for 2 h or until they developed arterial hypotension. Pulmonary edema was assessed by physiological parameters including respiratory mechanics and blood gases, and by lavage fluid protein, lung wet:dry weight ratio, and lung permeability measurements using fluorescence-labeled albumin. High stretch ventilation in wild-type and TNF receptor double knockout animals induced similar pulmonary edema, and only 25-30% of mice completed the protocol. In contrast, the p55 receptor knockout mice were strongly protected from edema formation, with all animals completing the protocol. Myeloperoxidase assay indicated that this protective effect was not associated with decreased pulmonary neutrophil sequestration. The p75 receptor knockout mice, however, displayed increased susceptibility to edema formation, and no animals survived the full 2 h. These results demonstrate a novel role for TNF signaling (independent from its effects on neutrophil recruitment) specifically through the p55 receptor, in promoting high stretch-induced pulmonary edema, whereas p75 signaling may play an opposing role.
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Affiliation(s)
- Michael R Wilson
- Department of Anaesthetics, Pain Medicine, and Intensive Care, Faculty of Medicine, Imperial College London, Chelsea and Westminster Hospital, London, United Kingdom
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Pedreira PR, García-Prieto E, Albaiceta GM, Taboada F. Respuesta inflamatoria y apoptosis en la lesión pulmonar aguda. Med Intensiva 2006; 30:268-75. [PMID: 16949001 DOI: 10.1016/s0210-5691(06)74523-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
One of the principal mechanisms of pulmonary injury in acute respiratory distress is due to the effects of the precipitated inflammatory response. The damage produced to the alveolar epithelium and underlying endothelium depends on the sequestration and activation of inflammatory cells, which in turn exert their actions through mediators. On the other hand, apoptosis is a mechanism responsible for epithelial damage and regulation of inflammation. Response of the lung tissue subjected to mechanical ventilation stimulus is added to the previous mechanisms. All these processes flow into a series of common pathways of cellular activation. Knowledge of these mechanisms could serve to identify which patients would benefit from a specific treatment before applying therapies that act indiscriminately in the inflammatory response.
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Affiliation(s)
- P R Pedreira
- Servicio de Medicina Intensiva, Hospital Universitario Central de Asturias, Oviedo, España
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Abstract
Patients with severe acute respiratory distress syndrome who die usually succumb to multiorgan failure as opposed to hypoxia. Despite appropriate resuscitation, some patients' symptoms persist on a downward spiral, apparently propagated by an uncontained systemic inflammatory response. This phenomenon is not well understood. However, a novel hypothesis to explain this observation proposes that it is related to the life-saving ventilatory support used to treat the respiratory failure. According to this hypothesis, mechanical ventilation per se, by altering both the magnitude and the pattern of lung stretch, can cause changes in gene expression and/or cellular metabolism that ultimately can lead to the development of an overwhelming inflammatory response-even in the absence of overt structural damage. This mechanism of injury has been termed biotrauma. In this review we explore the biotrauma hypothesis, the causal relationship between biophysical injury and organ failure, and its implications for the future therapy and management of critically ill patients.
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Affiliation(s)
- Claudia C dos Santos
- Department of Medicine, St. Michael's Hospital, Toronto, Ontario M5B 1W8, Canada.
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Steingrub JS. Adding up the zeros. J Intensive Care Med 2006; 21:188-90. [PMID: 16672641 DOI: 10.1177/0885066606287049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Matthay MA, Zimmerman GA. Acute lung injury and the acute respiratory distress syndrome: four decades of inquiry into pathogenesis and rational management. Am J Respir Cell Mol Biol 2005; 33:319-27. [PMID: 16172252 PMCID: PMC2715340 DOI: 10.1165/rcmb.f305] [Citation(s) in RCA: 439] [Impact Index Per Article: 23.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Affiliation(s)
- Michael A Matthay
- Department of Medicine, Cardiovascular Research and Training Institute, University of California at San Francisco, San Francisco, California 94143-0130, USA.
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Jin Y, Kim HP, Ifedigbo E, Lau LF, Choi AMK. Cyr61 Protects against Hyperoxia-Induced Cell Death via Akt Pathway in Pulmonary Epithelial Cells. Am J Respir Cell Mol Biol 2005; 33:297-302. [PMID: 15961723 DOI: 10.1165/rcmb.2005-0144oc] [Citation(s) in RCA: 39] [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
We have used gene expression profiling approaches to identify new molecular targets in various models of lung injury and human lung diseases. Among the many genes that are significantly induced in these studies, cysteine-rich61 (Cyr61) consistently ranks as one of the most significant genes. Here, we use the well-established model of hyperoxia to better understand the function of Cyr61 in acute lung injury. Cyr61, a stress-related immediate-early response gene, has known diverse functions involving angiogenesis, tumorigenesis, and wound repair. It belongs to the newly discovered "CCN" family containing six growth and regulatory factors. We showed that hyperoxia induces Cyr61 expression in a variety of pulmonary cells and in lung tissue in vivo. Loss of function studies, by suppressing Cyr61 expression by siRNA, accelerated lung epithelial cell death after hyperoxia. Gain of function studies, by overexpressing Cyr61, significantly conferred increased resistance to hyperoxia-induced cell death. Moreover, cells overexpressing Cyr61 induce Akt activation. Inhibition of Akt by siRNA abrogated the protective effects of Cyr61-overexpressing cells in response to hyperoxia. Taken together, our data demonstrate that Cyr61 expression provides cytoprotection in hyperoxia-induced pulmonary epithelial cell death and that this effect was in part mediated via the Akt signaling pathway.
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Affiliation(s)
- Yang Jin
- Division of Pulmonary, Allergy and Critical Care Medicine, 628 NW MUH, University of Pittsburgh Medical Center, 3459 5th Ave., Pittsburgh, PA 15213, USA
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Plötz FB. Is Interleukin-6 Clinically Relevant? Crit Care Med 2005; 33:1893-4; author reply 1894. [PMID: 16096492 DOI: 10.1097/01.ccm.0000174108.08539.5f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Gattinoni L, Caironi P, Carlesso E. How to ventilate patients with acute lung injury and acute respiratory distress syndrome. Curr Opin Crit Care 2005; 11:69-76. [PMID: 15659948 DOI: 10.1097/00075198-200502000-00011] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE OF REVIEW The purpose of this paper is to review the mechanisms of ventilator-induced lung injury as a basis for providing the less damaging mechanical ventilation in patients with acute respiratory failure. RECENT FINDINGS In normal lungs, high tidal volume causes an immediate gene upregulation and downregulation. Although the importance of alveolar inflammatory reaction is well known, recent findings suggest the potential role of airway distension in causing ventilator-induced lung injury. The initial activation has been shown to occur in the airways, accounting for the damages induced by high peak flow. The healthier lung regions are more exposed to the injury, since they may be subjected to strain. Challenge with endotoxin enhances in a synergistic manner the pulmonary inflammation induced by mechanical ventilation. However, mechanical strain and endotoxin seem to trigger lung inflammation through two different pathways. Despite convincing experimental and clinical evidences of lung injury, the clinical implementation of low tidal volume ventilation is still limited and has not yet become part of standard clinical practice. Setting positive end-expiratory pressure remains an open problem because the ALVEOLI study did not provide any exhaustive answers, likely because of methodologic problems and, unphysiologic design. SUMMARY Gentle lung ventilation must be standard practice. Because stress and strain are the triggers of ventilator-induced lung injury, their clinical equivalents should be measured (transpulmonary pressure and the ratio between tidal volume and end-expiratory lung volume). For a rational application of positive end-expiratory pressure, the potential for recruitment in any single patient should be estimated.
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Affiliation(s)
- Luciano Gattinoni
- Istituto di Anestesia e Rianimazione, Ospedale Maggiore di Milano-IRCCS, Università degli Studi di Milano, Milano, Italy.
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Abstract
OBJECTIVE To review the current literature on possible mechanisms by which mechanical ventilation may initiate or aggravate acute renal failure. DATA SOURCE A Medline database and references from identified articles were used to perform a literature search relating to mechanical ventilation and acute renal failure. DATA SYNTHESIS Acute renal failure may be initiated or aggravated by mechanical ventilation through three different mechanisms. First, strategies such as permissive hypercapnia or permissive hypoxemia may compromise renal blood flow. Second, through effects on cardiac output, mechanical ventilation affects systemic and renal hemodynamics. Third, mechanical ventilation may cause biotrauma-a pulmonary inflammatory reaction that may generate systemic release of inflammatory mediators. The harmful effects of mechanical ventilation may become more significant when a comorbidity is present. In these situations, it is more difficult to maintain normal gas exchange, and moderate arterial hypoxemia and hypercapnia are often accepted. Renal blood flow is compromised due to a decreased cardiac output as a consequence of high intrathoracic pressures. Furthermore, the effects of biotrauma are not limited to the lungs but may lead to a systemic inflammatory reaction. CONCLUSIONS The development of acute renal failure during mechanical ventilation likely represents a multifactorial process that may become more important in the presence of comorbidities. Development of optimal interventional strategies requires an understanding of physiologic principles and greater insight into the precise molecular and cellular mechanisms that may also play a role.
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Affiliation(s)
- Jan Willem Kuiper
- Department of Pediatric Intensive Care, VU Medical Center, Amsterdam, The Netherlands
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Tremblay LN, Slutsky AS. Pathogenesis of ventilator-induced lung injury: trials and tribulations. Am J Physiol Lung Cell Mol Physiol 2005; 288:L596-8. [PMID: 15757952 DOI: 10.1152/ajplung.00438.2004] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
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Yoshikawa S, Miyahara T, Reynolds SD, Stripp BR, Anghelescu M, Eyal FG, Parker JC. Clara cell secretory protein and phospholipase A2activity modulate acute ventilator-induced lung injury in mice. J Appl Physiol (1985) 2005; 98:1264-71. [PMID: 15608088 DOI: 10.1152/japplphysiol.01150.2004] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Lung vascular permeability is acutely increased by high-pressure and high-volume ventilation. To determine the roles of mechanically activated cytosolic PLA2(cPLA2) and Clara cell secretory protein (CCSP), a modulator of cPLA2activity, we compared lung injury with and without a PLA2inhibitor in wild-type mice and CCSP-null mice (CCSP−/−) ventilated with high and low peak inflation pressures (PIP) for 2- or 4-h periods. After ventilation with high PIP, we observed significant increases in the bronchoalveolar lavage albumin concentrations, lung wet-to-dry weight ratios, and lung myeloperoxidase in both genotypes compared with unventilated controls and low-PIP ventilated mice. All injury variables except myeloperoxidase were significantly greater in the CCSP−/−mice relative to wild-type mice. Inhibition of cPLA2in wild-type and CCSP−/−mice ventilated at high PIP for 4 h significantly reduced bronchoalveolar lavage albumin and total protein and lung wet-to-dry weight ratios compared with vehicle-treated mice of the same genotype. Membrane phospho-cPLA2and cPLA2activities were significantly elevated in lung homogenates of high-PIP ventilated mice of both genotypes but were significantly higher in the CCSP−/−mice relative to the wild-type mice. Inhibition of cPLA2significantly attenuated both the phospho-cPLA2increase and increased cPLA2activity due to high-PIP ventilation. We propose that mechanical activation of the cPLA2pathway contributes to acute high PIP-induced lung injury and that CCSP may reduce this injury through inhibition of the cPLA2pathway and reduction of proinflammatory products produced by this pathway.
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Affiliation(s)
- Sawako Yoshikawa
- Dept. of Physiology, MSB 3074, Univ. of South Alabama, Mobile, AL 36688, USA
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Abstract
PURPOSE OF REVIEW Mechanical ventilation is the main supportive therapy for patients with acute respiratory distress syndrome. As with any therapy, mechanical ventilation has side effects and may induce lung injury. This review will focus on stretch-dependent activation of alveolar epithelial and endothelial cells and polymorphonuclear leukocytes, and apoptosis/necrosis balance. RECENT FINDINGS The past year has seen important research in the area of mechanotransduction and lung native immunity, suggesting further mechanisms of lung inflammation and injury in ventilator-induced lung injury. Research in the past year has also stressed the importance of inflammatory response by alveolar cells and role of polymorphonuclear leukocytes in stretch-induced lung injury and has suggested a role for apoptosis in the maintenance of the alveolar epithelium. SUMMARY The proportion of patients receiving protective ventilatory strategies remains modest. If efforts to minimize the iatrogenic consequences of mechanical ventilation are to succeed, there must be a greater understanding of the signal transduction mechanisms and the development of potential pharmacologic targets to modulate the molecular and cellular effects of lung stretch.
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Affiliation(s)
- Vincenzo Lionetti
- Laboratorio di Fisiologia e Biologia Molecolare, Classe di Scienze Sperimentali, Settore di Scienze Mediche, Pisa, Italy
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Farre R, Granell S, Rotger M, Serrano-Mollar A, Closa D, Navajas D. Animal model of unilateral ventilator-induced lung injury. Intensive Care Med 2005; 31:487-90. [PMID: 15668763 DOI: 10.1007/s00134-004-2534-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2004] [Accepted: 12/08/2004] [Indexed: 10/25/2022]
Abstract
OBJECTIVE To design, implement, and test a selective lung ventilator for setting a rat model of unilateral ventilator-induced lung injury (VILI). DESIGN AND SETTING Interventional animal study in a university laboratory for animal research. SUBJECTS Anesthetized and paralyzed male Wistar rats. INTERVENTIONS A selective ventilator designed to apply varying tidal volume, PEEP, and breathing gas to each lung of the rat was implemented and evaluated. Five control animals were ventilated at 7 ml/kg (3.5 ml/kg each lung). Unilateral VILI was induced in six animals subjected to selective ventilation (3.5 ml/kg in one lung and 15 ml/kg in the other lung). After 3 h of ventilation the animals were killed and the lungs excised. MEASUREMENTS AND RESULTS Lung edema was assessed by means of the ratio between wet and dry lung weights. No significant differences were found in lungs of control animals (5.16+/-0.22 and 4.96+/-0.25), but the W/D ratio in the over ventilated lung (8.98+/-3.80) was significantly greater than that in the normally ventilated lung (4.76+/-0.15), indicating selective induction of lung edema by over stretch. CONCLUSIONS This selective ventilator can be implemented into a rat model of unilateral VILI to gain further insight into the mechanisms of pulmonary injury induced by different ventilatory strategies.
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Affiliation(s)
- Ramon Farre
- Unitat de Biofisica i Bioenginyeria, Facultat de Medicina, Universitat de Barcelona-IDIBAPS, Spain.
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Choudhury S, Wilson MR, Goddard ME, O'Dea KP, Takata M. Mechanisms of early pulmonary neutrophil sequestration in ventilator-induced lung injury in mice. Am J Physiol Lung Cell Mol Physiol 2004; 287:L902-10. [PMID: 15257987 DOI: 10.1152/ajplung.00187.2004] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Polymorphonuclear leukocytes (PMN) play an important role in ventilator-induced lung injury (VILI), but the mechanisms of pulmonary PMN recruitment, particularly early intravascular PMN sequestration during VILI, have not been elucidated. We investigated the physiological and molecular mechanisms of pulmonary PMN sequestration in an in vivo mouse model of VILI. Anesthetized C57/BL6 mice were ventilated for 1 h with high tidal volume (injurious ventilation), low tidal volume and high positive end-expiratory pressure (protective ventilation), or normal tidal volume (control ventilation). Pulmonary PMN sequestration analyzed by flow cytometry of lung cell suspensions was substantially enhanced in injurious ventilation compared with protective and control ventilation, preceding development of physiological signs of lung injury. Anesthetized, spontaneously breathing mice with continuous positive airway pressure demonstrated that raised alveolar pressure alone does not induce PMN entrapment. In vitro leukocyte deformability assay indicated stiffening of circulating leukocytes in injurious ventilation compared with control ventilation. PMN sequestration in injurious ventilation was markedly inhibited by administration of anti-L-selectin antibody, but not by anti-CD18 antibody. These results suggest that mechanical ventilatory stress initiates pulmonary PMN sequestration early in the course of VILI, and this phenomenon is associated with stretch-induced inflammatory events leading to PMN stiffening and mediated by L-selectin-dependent but CD18-independent mechanisms.
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Affiliation(s)
- Sharmila Choudhury
- Department of Anaesthetics and Intensive Care, Faculty of Medicine, Imperial College London, Chelsea and Westminster Hospital, London SW10 9NH, United Kingdom
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Wilson MR, Choudhury S, Takata M. Pulmonary inflammation induced by high-stretch ventilation is mediated by tumor necrosis factor signaling in mice. Am J Physiol Lung Cell Mol Physiol 2004; 288:L599-607. [PMID: 15489373 DOI: 10.1152/ajplung.00304.2004] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Although high-stretch mechanical ventilation has been demonstrated to induce lung inflammation, the roles of soluble mediators, in particular TNF, remain controversial. We have previously shown in mice that high-stretch ventilation, in the absence of preceding lung injury, induces expression of bioactive TNF in lung lavage fluid early in the course of injury, but the biological significance of this, if any, has yet to be determined. We therefore investigated the pulmonary inflammatory response to a transient period of high-stretch ventilation in anesthetized mice lacking TNF receptors and mice treated with anti-TNF antibodies. A standardized stretch-induced lung injury (assessed by lung mechanics, blood gases, and lavage protein content), followed by noninjurious low-stretch ventilation for 3 h, produced significant alveolar neutrophil infiltration in wild-type mice. However, neutrophil recruitment was substantially attenuated in TNF receptor double knockout mice and in wild-type mice treated with intratracheal anti-TNF antibody. This attenuation was not associated with decreased concentrations of neutrophil attractant CXC chemokines (macrophage inflammatory protein-2 and keratinocyte-derived chemokine) in lavage fluid. In contrast to intratracheal antibody, intravenous anti-TNF antibody did not reduce neutrophil infiltration, suggesting that the role of TNF signaling is localized within the alveolar space and does not require decompartmentalization of TNF into the circulation. These findings provide the first direct evidence that pulmonary inflammation induced by high-stretch ventilation without underlying lung injury possesses a significant TNF-dependent component. The results suggest a potential for regional anti-TNF treatment in attenuating stretch-induced pulmonary inflammation.
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Affiliation(s)
- Michael R Wilson
- Department of Anaesthetics and Intensive Care, Imperial College London, Chelsea and Westminster Hospital, 369 Fulham Road, London SW10 9NH, United Kingdom
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Lapinsky SE, Mehta S. Bench-to-bedside review: Recruitment and recruiting maneuvers. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2004; 9:60-5. [PMID: 15693985 PMCID: PMC1065091 DOI: 10.1186/cc2934] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
In patients with acute respiratory distress syndrome (ARDS), the lung comprises areas of aeration and areas of alveolar collapse, the latter producing intrapulmonary shunt and hypoxemia. The currently suggested strategy of ventilation with low lung volumes can aggravate lung collapse and potentially produce lung injury through shear stress at the interface between aerated and collapsed lung, and as a result of repetitive opening and closing of alveoli. An 'open lung strategy' focused on alveolar patency has therefore been recommended. While positive end-expiratory pressure prevents alveolar collapse, recruitment maneuvers can be used to achieve alveolar recruitment. Various recruitment maneuvers exist, including sustained inflation to high pressures, intermittent sighs, and stepwise increases in positive end-expiratory pressure or peak inspiratory pressure. In animal studies, recruitment maneuvers clearly reverse the derecruitment associated with low tidal volume ventilation, improve gas exchange, and reduce lung injury. Data regarding the use of recruitment maneuvers in patients with ARDS show mixed results, with increased efficacy in those with short duration of ARDS, good compliance of the chest wall, and in extrapulmonary ARDS. In this review we discuss the pathophysiologic basis for the use of recruitment maneuvers and recent evidence, as well as the practical application of the technique.
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Affiliation(s)
- Stephen E Lapinsky
- Intensive Care Unit, Mount Sinai Hospital, and Interdepartmental Division of Critical Care, University of Toronto,Toronto, Canada.
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Gattinoni L, Carlesso E, Valenza F, Chiumello D, Caspani ML. Acute respiratory distress syndrome, the critical care paradigm: what we learned and what we forgot. Curr Opin Crit Care 2004; 10:272-8. [PMID: 15258499 DOI: 10.1097/01.ccx.0000135511.75998.22] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
In the last several years, we definitely learned that the acute respiratory distress syndrome lung is small, nonhomogeneous, and that mechanical ventilation in this baby lung may cause physical damage as well as inflammatory reaction. The clinical benefit of the gentle lung treatment, based on a decrease of global/regional stress and strain into the lung, has been finally proved. However, we forgot the importance of lung perfusion and its distribution in this syndrome and, besides a low tidal volume, we still do not know how to handle the other variables of mechanical ventilation. Measurements of variables as transpulmonary pressure and end expiratory lung volume, for a rational setting of mechanical ventilation, should be introduced in routine clinical practice.
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Affiliation(s)
- Luciano Gattinoni
- Istituto di Anestesia e Rianimazione, Universita' degli Studi di Milano, Ospedale Policlinico IRCCS, Milano, Italy.
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Plötz FB, Slutsky AS, van Vught AJ, Heijnen CJ. Ventilator-induced lung injury and multiple system organ failure: a critical review of facts and hypotheses. Intensive Care Med 2004; 30:1865-72. [PMID: 15221129 DOI: 10.1007/s00134-004-2363-9] [Citation(s) in RCA: 149] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2004] [Accepted: 06/01/2004] [Indexed: 01/01/2023]
Abstract
OBJECTIVE To review how biotrauma leads to the development of multiple system organ failure (MSOF). DESIGN AND SETTING Published articles on experimental and clinical studies and review articles in the English language were collected and analyzed. RESULTS The concept that ventilation strategies using "large" tidal volumes and zero PEEP of injured lungs can enhance injury by the release of inflammatory mediators into the lungs and circulation, a mechanism that has been called biotrauma, is supported by evidence from experimental models ranging from mechanically stressed cell systems, to isolated lungs, intact animals, and humans. Biotrauma may lead to MSOF via spillover of lung-borne inflammatory mediators into the systemic circulation. However, spillover of other agents such as bacteria and soluble proapoptotic factors may also contribute to the onset of MSOF. Other less well studied mechanisms such as peripheral immunosuppression and translocation of bacteria and/or products from the gut may play an important role. Finally, genetic variability is a crucial factor. CONCLUSIONS The development of MSOF is a multifactorial process. Our proposed mechanisms linking mechanical ventilation and MSOF suggest several novel therapeutic approaches. However, it will first be necessary to study the mechanisms described above to delineate more precisely the contribution of each proposed factor, their interrelationships, and their time course. We suggest that scientific advances in immunology may offer novel approaches for prevention of MSOF secondary to ventilator-induced lung injury.
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Affiliation(s)
- Frans B Plötz
- Department of Pediatric Intensive Care, VU Medical Center, P.O. Box 7057, 1007 MB Amsterdam, The Netherlands.
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