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Andrews P, Shiber J, Madden M, Nieman GF, Camporota L, Habashi NM. Myths and Misconceptions of Airway Pressure Release Ventilation: Getting Past the Noise and on to the Signal. Front Physiol 2022; 13:928562. [PMID: 35957991 PMCID: PMC9358044 DOI: 10.3389/fphys.2022.928562] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Accepted: 06/21/2022] [Indexed: 12/16/2022] Open
Abstract
In the pursuit of science, competitive ideas and debate are necessary means to attain knowledge and expose our ignorance. To quote Murray Gell-Mann (1969 Nobel Prize laureate in Physics): “Scientific orthodoxy kills truth”. In mechanical ventilation, the goal is to provide the best approach to support patients with respiratory failure until the underlying disease resolves, while minimizing iatrogenic damage. This compromise characterizes the philosophy behind the concept of “lung protective” ventilation. Unfortunately, inadequacies of the current conceptual model–that focuses exclusively on a nominal value of low tidal volume and promotes shrinking of the “baby lung” - is reflected in the high mortality rate of patients with moderate and severe acute respiratory distress syndrome. These data call for exploration and investigation of competitive models evaluated thoroughly through a scientific process. Airway Pressure Release Ventilation (APRV) is one of the most studied yet controversial modes of mechanical ventilation that shows promise in experimental and clinical data. Over the last 3 decades APRV has evolved from a rescue strategy to a preemptive lung injury prevention approach with potential to stabilize the lung and restore alveolar homogeneity. However, several obstacles have so far impeded the evaluation of APRV’s clinical efficacy in large, randomized trials. For instance, there is no universally accepted standardized method of setting APRV and thus, it is not established whether its effects on clinical outcomes are due to the ventilator mode per se or the method applied. In addition, one distinctive issue that hinders proper scientific evaluation of APRV is the ubiquitous presence of myths and misconceptions repeatedly presented in the literature. In this review we discuss some of these misleading notions and present data to advance scientific discourse around the uses and misuses of APRV in the current literature.
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Affiliation(s)
- Penny Andrews
- R Adams Cowley Shock Trauma Center, University of Maryland School of Medicine, Baltimore, MD, United States
- *Correspondence: Penny Andrews,
| | - Joseph Shiber
- University of Florida College of Medicine, Jacksonville, FL, United States
| | - Maria Madden
- R Adams Cowley Shock Trauma Center, University of Maryland School of Medicine, Baltimore, MD, United States
| | - Gary F. Nieman
- Department of Surgery, SUNY Upstate Medical University, Syracuse, NY, United States
| | - Luigi Camporota
- Department of Adult Critical Care, Guy’s and St Thomas’ NHS Foundation Trust, Health Centre for Human and Applied Physiological Sciences, London, United Kingdom
| | - Nader M. Habashi
- R Adams Cowley Shock Trauma Center, University of Maryland School of Medicine, Baltimore, MD, United States
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2
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Yehya N. Lessons learned in acute respiratory distress syndrome from the animal laboratory. ANNALS OF TRANSLATIONAL MEDICINE 2019; 7:503. [PMID: 31728356 DOI: 10.21037/atm.2019.09.33] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Since the description of the acute respiratory distress syndrome (ARDS) in 1967, investigators have struggled to reproduce the syndrome in the animal laboratory. While several different models of experimental acute lung injury (ALI) have been developed, none completely capture the inciting etiologies, initial inflammation, heterogeneity, and resolution of human ARDS. This potentially has contributed to the poor translation of potential therapeutics between animal ALI models and human ARDS. It was only recently that standardized criteria were suggested for what makes an ALI model comparable to human ARDS. Nevertheless, despite model heterogeneity, these models have contributed substantially to our understanding of the syndrome. From the initial studies identifying the risks of mechanical ventilation to the identification of potentially targetable inflammatory mediators, to modern studies focusing on regional heterogeneity and novel molecular pathways, animal models continue to inform our understanding of ARDS. This review will cover several major lessons learned from animal models of ALI, and provide some direction for future studies in this field.
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Affiliation(s)
- Nadir Yehya
- Department of Anesthesiology and Critical Care Medicine, Children's Hospital of Philadelphia and University of Pennsylvania, Philadelphia, PA, USA
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3
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Mahajan M, DiStefano D, Satalin J, Andrews P, Al-Khalisy H, Baker S, Gatto LA, Nieman GF, Habashi NM. Time-controlled adaptive ventilation (TCAV) accelerates simulated mucus clearance via increased expiratory flow rate. Intensive Care Med Exp 2019; 7:27. [PMID: 31098761 PMCID: PMC6522588 DOI: 10.1186/s40635-019-0250-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Accepted: 04/29/2019] [Indexed: 01/31/2023] Open
Abstract
Background Ventilator-associated pneumonia (VAP) is the most common nosocomial infection in intensive care units. Distal airway mucus clearance has been shown to reduce VAP incidence. Studies suggest that mucus clearance is enhanced when the rate of expiratory flow is greater than inspiratory flow. The time-controlled adaptive ventilation (TCAV) protocol using the airway pressure release ventilation (APRV) mode has a significantly increased expiratory relative to inspiratory flow rate, as compared with the Acute Respiratory Distress Syndrome Network (ARDSnet) protocol using the conventional ventilation mode of volume assist control (VAC). We hypothesized the TCAV protocol would be superior to the ARDSnet protocol at clearing mucus by a mechanism of net flow in the expiratory direction. Methods Preserved pig lungs fitted with an endotracheal tube (ETT) were used as a model to study the effect of multiple combinations of peak inspiratory (IPF) and peak expiratory flow rate (EPF) on simulated mucus movement within the ETT. Mechanical ventilation was randomized into 6 groups (n = 10 runs/group): group 1—TCAV protocol settings with an end-expiratory pressure (PLow) of 0 cmH2O and PHigh 25 cmH2O, group 2—modified TCAV protocol with increased PLow 5 cmH2O and PHigh 25 cmH2O, group 3—modified TCAV with PLow 10 cmH2O and PHigh 25 cmH2O, group 4—ARDSnet protocol using low tidal volume (LTV) and PEEP 0 cmH2O, group 5—ARDSnet protocol using LTV and PEEP 10 cmH2O, and group 6—ARDSnet protocol using LTV and PEEP 20 cmH2O. PEEP of ARDSnet is analogous to PLow of TCAV. Proximal (towards the ventilator) mucus movement distance was recorded after 1 min of ventilation in each group. Results The TCAV protocol groups 1, 2, and 3 generated significantly greater peak expiratory flow (EPF 51.3 L/min, 46.8 L/min, 36.8 L/min, respectively) as compared to the ARDSnet protocol groups 4, 5, and 6 (32.9 L/min, 23.5 L/min, and 23.2 L/min, respectively) (p < 0.001). The TCAV groups also demonstrated the greatest proximal mucus movement (7.95 cm/min, 5.8 cm/min, 1.9 cm/min) (p < 0.01). All ARDSnet protocol groups (4–6) had zero proximal mucus movement (0 cm/min). Conclusions The TCAV protocol groups promoted the greatest proximal movement of simulated mucus as compared to the ARDSnet protocol groups in this excised lung model. The TCAV protocol settings resulted in the highest EPF and the greatest proximal movement of mucus. Increasing PLow reduced proximal mucus movement. We speculate that proximal mucus movement is driven by EPF when EPF is greater than IPF, creating a net force in the proximal direction.
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Affiliation(s)
- Melissa Mahajan
- Department of Surgery, SUNY Upstate Medical University, 750 East Adams St., 766 Irving Avenue, Syracuse, NY, 13210, USA
| | - David DiStefano
- Department of Surgery, SUNY Upstate Medical University, 750 East Adams St., 766 Irving Avenue, Syracuse, NY, 13210, USA
| | - Joshua Satalin
- Department of Surgery, SUNY Upstate Medical University, 750 East Adams St., 766 Irving Avenue, Syracuse, NY, 13210, USA.
| | - Penny Andrews
- Department of Trauma Critical Care Medicine, R Adams Cowley Shock Trauma Center, University of Maryland School of Medicine, 22 S. Greene Street, Baltimore, MD, 21201, USA
| | - Hassan Al-Khalisy
- Department of Surgery, SUNY Upstate Medical University, 750 East Adams St., 766 Irving Avenue, Syracuse, NY, 13210, USA
| | - Sarah Baker
- Department of Surgery, SUNY Upstate Medical University, 750 East Adams St., 766 Irving Avenue, Syracuse, NY, 13210, USA
| | - Louis A Gatto
- Department of Biological Sciences, SUNY Cortland, 22 Graham Avenue, Cortland, NY, 13045, USA
| | - Gary F Nieman
- Department of Surgery, SUNY Upstate Medical University, 750 East Adams St., 766 Irving Avenue, Syracuse, NY, 13210, USA
| | - Nader M Habashi
- Department of Trauma Critical Care Medicine, R Adams Cowley Shock Trauma Center, University of Maryland School of Medicine, 22 S. Greene Street, Baltimore, MD, 21201, USA
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Prunet B, Bourenne J, David JS, Bouzat P, Boutonnet M, Cordier PY, Renaudin P, Meaudre E, Michelet P. Patterns of invasive mechanical ventilation in patients with severe blunt chest trauma and lung contusion: A French multicentric evaluation of practices. J Intensive Care Soc 2018; 20:46-52. [PMID: 30792762 DOI: 10.1177/1751143718767060] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Introduction This study investigated invasive mechanical ventilation modalities used in severe blunt chest trauma patients with pulmonary contusion. Occurrence, risk factors, and outcomes of early onset acute respiratory distress syndrome were also evaluated. Methods We performed a retrospective multicenter observational study including 115 adult patients hospitalized in six level 1 trauma intensive care units between April and September of 2014. Independent predictors of early onset acute respiratory distress syndrome were determined by multiple logistic regression analysis based on clinical characteristics and initial management. Results Protective ventilation principles were highly implemented, even prophylactically before acute respiratory distress syndrome occurrence. Early onset acute respiratory distress syndrome appeared to be associated with lung contusion of >20% of total lung volume and early onset pneumonia. Conclusions Predictors of early onset acute respiratory distress syndrome could help with identifying high-risk populations, potentially improving case management through specific protocol development for these patients.
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Affiliation(s)
- Bertrand Prunet
- Department of Critical Care, Sainte Anne Military Teaching Hospital, Toulon, France.,UMR MD2, Aix-Marseille University, School of Medicine, Marseille, France
| | - Jérémy Bourenne
- Department of Critical Care, Timone University Hospital, Marseille, France
| | - Jean-Stéphane David
- Department of Critical Care, Lyon-Sud University Hospital, Pierre-Bénite, France
| | - Pierre Bouzat
- Department of Critical Care, Grenoble University Hospital, France
| | - Mathieu Boutonnet
- Department of Critical Care, Percy Military Teaching Hospital, Clamart, France
| | - Pierre-Yves Cordier
- Department of Critical Care, Laveran Military Teaching Hospital, Marseille, France
| | - Pierre Renaudin
- Department of Public Health, Timone University Hospital, Marseille, France
| | - Eric Meaudre
- Department of Critical Care, Sainte Anne Military Teaching Hospital, Toulon, France
| | - Pierre Michelet
- UMR MD2, Aix-Marseille University, School of Medicine, Marseille, France.,Department of Critical Care, Timone University Hospital, Marseille, France
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Sperber J, Nyberg A, Lipcsey M, Melhus Å, Larsson A, Sjölin J, Castegren M. Protective ventilation reduces Pseudomonas aeruginosa growth in lung tissue in a porcine pneumonia model. Intensive Care Med Exp 2017; 5:40. [PMID: 28861863 PMCID: PMC5578946 DOI: 10.1186/s40635-017-0152-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Accepted: 08/21/2017] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND Mechanical ventilation with positive end expiratory pressure and low tidal volume, i.e. protective ventilation, is recommended in patients with acute respiratory distress syndrome. However, the effect of protective ventilation on bacterial growth during early pneumonia in non-injured lungs is not extensively studied. The main objectives were to compare two different ventilator settings on Pseudomonas aeruginosa growth in lung tissue and the development of lung injury. METHODS A porcine model of severe pneumonia was used. The protective group (n = 10) had an end expiratory pressure of 10 cm H2O and a tidal volume of 6 ml x kg-1. The control group (n = 10) had an end expiratory pressure of 5 cm H2O and a tidal volume of 10 ml x kg-1. 1011 colony forming units of Pseudomonas aeruginosa were inoculated intra-tracheally at baseline, after which the experiment continued for 6 h. Two animals from each group received only saline, and served as sham animals. Lung tissue samples from each animal were used for bacterial cultures and wet-to-dry weight ratio measurements. RESULTS The protective group displayed lower numbers of Pseudomonas aeruginosa (p < 0.05) in the lung tissue, and a lower wet-to-dry ratio (p < 0.01) than the control group. The control group deteriorated in arterial oxygen tension/inspired oxygen fraction, whereas the protective group was unchanged (p < 0.01). CONCLUSIONS In early phase pneumonia, protective ventilation with lower tidal volume and higher end expiratory pressure has the potential to reduce the pulmonary bacterial burden and the development of lung injury.
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Affiliation(s)
- Jesper Sperber
- Centre for Clinical Research Sörmland, Uppsala University, Uppsala, Sweden. .,Centre for Clinical Research Sörmland, Department of Anesthesiology & Intensive Care Mälarsjukhuset, SE-631 88, Eskilstuna, Sweden.
| | - Axel Nyberg
- Centre for Clinical Research Sörmland, Uppsala University, Uppsala, Sweden.,Centre for Clinical Research Sörmland, Department of Anesthesiology & Intensive Care Mälarsjukhuset, SE-631 88, Eskilstuna, Sweden
| | - Miklos Lipcsey
- Hedenstierna laboratory, Department of Surgical Sciences, Anesthesiology and Intensive Care, Uppsala University, Uppsala, Sweden
| | - Åsa Melhus
- Department of Medical Sciences, Section of Clinical Microbiology, Uppsala University, Uppsala, Sweden
| | - Anders Larsson
- Department of Medical Sciences, Biochemical structure and function, Uppsala University, Uppsala, Sweden
| | - Jan Sjölin
- Department of Medical Sciences, Infectious Diseases, Uppsala University, Uppsala, Sweden
| | - Markus Castegren
- Centre for Clinical Research Sörmland, Uppsala University, Uppsala, Sweden.,Hedenstierna laboratory, Department of Surgical Sciences, Anesthesiology and Intensive Care, Uppsala University, Uppsala, Sweden.,Perioperative Medicine and Intensive Care, Karolinska University Hospital and CLINTEC, Karolinska Institute, Stockholm, Sweden
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6
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Beitler JR, Owens RL, Malhotra A. Unmasking a Role for Noninvasive Ventilation in Early Acute Respiratory Distress Syndrome. JAMA 2016; 315:2401-3. [PMID: 27179463 PMCID: PMC5385101 DOI: 10.1001/jama.2016.5987] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Affiliation(s)
- Jeremy R Beitler
- Division of Pulmonary and Critical Care Medicine, University of California, San Diego
| | - Robert L Owens
- Division of Pulmonary and Critical Care Medicine, University of California, San Diego
| | - Atul Malhotra
- Division of Pulmonary and Critical Care Medicine, University of California, San Diego
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7
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Abstract
BACKGROUND Mechanical ventilation worsens acute respiratory distress syndrome, but this secondary "ventilator-associated" injury is variable and difficult to predict. The authors aimed to visualize the propagation of such ventilator-induced injury, in the presence (and absence) of a primary underlying lung injury, and to determine the predictors of propagation. METHODS Anesthetized rats (n = 20) received acid aspiration (hydrochloric acid) followed by ventilation with moderate tidal volume (V(T)). In animals surviving ventilation for at least 2 h, propagation of injury was quantified by using serial computed tomography. Baseline lung status was assessed by oxygenation, lung weight, and lung strain (V(T)/expiratory lung volume). Separate groups of rats without hydrochloric acid aspiration were ventilated with large (n = 10) or moderate (n = 6) V(T). RESULTS In 15 rats surviving longer than 2 h, computed tomography opacities spread outward from the initial site of injury. Propagation was associated with higher baseline strain (propagation vs. no propagation [mean ± SD]: 1.52 ± 0.13 vs. 1.16 ± 0.20, P < 0.01) but similar oxygenation and lung weight. Propagation did not occur where baseline strain was less than 1.29. In healthy animals, large V(T) caused injury that was propagated inward from the lung periphery; in the absence of preexisting injury, propagation did not occur where strain was less than 2.0. CONCLUSIONS Compared with healthy lungs, underlying injury causes propagation to occur at a lower strain threshold and it originates at the site of injury; this suggests that tissue around the primary lesion is more sensitive. Understanding how injury is propagated may ultimately facilitate a more individualized monitoring or management.
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8
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Nieman GF, Gatto LA, Habashi NM. Impact of mechanical ventilation on the pathophysiology of progressive acute lung injury. J Appl Physiol (1985) 2015; 119:1245-61. [PMID: 26472873 DOI: 10.1152/japplphysiol.00659.2015] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Accepted: 10/01/2015] [Indexed: 02/08/2023] Open
Abstract
The earliest description of what is now known as the acute respiratory distress syndrome (ARDS) was a highly lethal double pneumonia. Ashbaugh and colleagues (Ashbaugh DG, Bigelow DB, Petty TL, Levine BE Lancet 2: 319-323, 1967) correctly identified the disease as ARDS in 1967. Their initial study showing the positive effect of mechanical ventilation with positive end-expiratory pressure (PEEP) on ARDS mortality was dampened when it was discovered that improperly used mechanical ventilation can cause a secondary ventilator-induced lung injury (VILI), thereby greatly exacerbating ARDS mortality. This Synthesis Report will review the pathophysiology of ARDS and VILI from a mechanical stress-strain perspective. Although inflammation is also an important component of VILI pathology, it is secondary to the mechanical damage caused by excessive strain. The mechanical breath will be deconstructed to show that multiple parameters that comprise the breath-airway pressure, flows, volumes, and the duration during which they are applied to each breath-are critical to lung injury and protection. Specifically, the mechanisms by which a properly set mechanical breath can reduce the development of excessive fluid flux and pulmonary edema, which are a hallmark of ARDS pathology, are reviewed. Using our knowledge of how multiple parameters in the mechanical breath affect lung physiology, the optimal combination of pressures, volumes, flows, and durations that should offer maximum lung protection are postulated.
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Affiliation(s)
- Gary F Nieman
- Department of Surgery, Upstate Medical University, Syracuse, New York;
| | - Louis A Gatto
- Biological Sciences Department, State University of New York, Cortland, New York; and
| | - Nader M Habashi
- R Adams Cowley Shock/Trauma Center, University of Maryland Medical Center, Baltimore, Maryland
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9
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Gattinoni L, Taccone P, Carlesso E, Marini JJ. Prone position in acute respiratory distress syndrome. Rationale, indications, and limits. Am J Respir Crit Care Med 2014; 188:1286-93. [PMID: 24134414 DOI: 10.1164/rccm.201308-1532ci] [Citation(s) in RCA: 268] [Impact Index Per Article: 26.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
In the prone position, computed tomography scan densities redistribute from dorsal to ventral as the dorsal region tends to reexpand while the ventral zone tends to collapse. Although gravitational influence is similar in both positions, dorsal recruitment usually prevails over ventral derecruitment, because of the need for the lung and its confining chest wall to conform to the same volume. The final result of proning is that the overall lung inflation is more homogeneous from dorsal to ventral than in the supine position, with more homogeneously distributed stress and strain. As the distribution of perfusion remains nearly constant in both postures, proning usually improves oxygenation. Animal experiments clearly show that prone positioning delays or prevents ventilation-induced lung injury, likely due in large part to more homogeneously distributed stress and strain. Over the last 15 years, five major trials have been conducted to compare the prone and supine positions in acute respiratory distress syndrome, regarding survival advantage. The sequence of trials enrolled patients who were progressively more hypoxemic; exposure to the prone position was extended from 8 to 17 hours/day, and lung-protective ventilation was more rigorously applied. Single-patient and meta-analyses drawing from the four major trials showed significant survival benefit in patients with PaO2/FiO2 lower than 100. The latest PROSEVA (Proning Severe ARDS Patients) trial confirmed these benefits in a formal randomized study. The bulk of data indicates that in severe acute respiratory distress syndrome, carefully performed prone positioning offers an absolute survival advantage of 10-17%, making this intervention highly recommended in this specific population subset.
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Affiliation(s)
- Luciano Gattinoni
- 1 Dipartimento di Fisiopatologia Medico-Chirurgica e dei Trapianti, Fondazione IRCCS Ca' Granda-Ospedale Maggiore Policlinico, Università degli Studi di Milano, Milan, Italy
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10
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Early airway pressure release ventilation prevents ARDS-a novel preventive approach to lung injury. Shock 2013; 39:28-38. [PMID: 23247119 DOI: 10.1097/shk.0b013e31827b47bb] [Citation(s) in RCA: 90] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Acute respiratory distress syndrome (ARDS) afflicts 200,000 patients annually with a mortality rate of 30% to 60% despite wide use of low tidal volume (LTV) ventilation, the present standard of care. High-permeability alveolar edema and instability occur early in the development of ARDS, before clinical signs of lung injury, and represent potential targets for therapy. We hypothesize that early application of a protective ventilation strategy (airway pressure release ventilation [APRV]) will stabilize alveoli and reduce alveolar edema, preventing the development of ARDS. Yorkshire pigs (30-40 kg) were anesthetized and subjected to two-hit injury: (a) intestinal ischemia-reperfusion, (b) peritoneal sepsis, or sham surgery. Following surgery, pigs were randomized into APRV (n = 4), according to current published guidelines for APRV; LTV ventilation (n = 3), using the current published ARDS Network guidelines (6 mL/kg); or sham (n = 5). The clinical care of all pigs was administered per the Surviving Sepsis Campaign guidelines. Animals were killed, and necropsy performed at 48 h. Arterial blood gases were measured to assess for the development of clinical lung injury. Lung tissue epithelial cadherin (E-cadherin) was measured to assess alveolar permeability. Bronchoalveolar lavage fluid (BALF) surfactant protein A was measured to assess alveolar stability. Lung edema content and histopathology were analyzed at 48 h. Airway pressure release ventilation pigs did not develop ARDS. In contrast, pigs in the LTV ventilation met ARDS criteria (PaO2/FIO2 ratio) (APRV: baseline = 471 ± 16; 48 h = 392 ± 8; vs. LTV ventilation: baseline = 551 ± 28; 48 h = 138 ± 88; P < 0.001). Airway pressure release ventilation preserved alveolar epithelial integrity demonstrated by higher levels of E-cadherin in lung tissue as compared with LTV ventilation (P < 0.05). Surfactant protein A levels were higher in BALF from the APRV group, suggesting APRV preserved alveolar stability. Quantitative histologic scoring showed improvements in all stigmata of ARDS in the APRV group versus the LTV ventilation (P < 0.05). Airway pressure release ventilation had significantly lower lung edema (wet-dry weight) than LTV ventilation (P < 0.05). Protective ventilation with APRV immediately following injury prevents development of ARDS. Reduction in lung edema, preservation of lung E-cadherin, and surfactant protein A abundance in BALF suggest that APRV attenuates lung permeability, edema, and surfactant degradation. Protective ventilation could change the clinical paradigm from supportive care for ARDS with LTV ventilation to preventing development of ARDS with APRV.
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Abstract
The ability to compensate for life-threatening failure of respiratory function is perhaps the signature technology of intensive care medicine. Unchanging needs for providing effective life-support with minimized risk and optimized comfort have been, are now, and will be the principal objectives of providing mechanical ventilation. Important lessons acquired over nearly half-a-century of ICU care have brought us closer to meeting them, as technological advances in instrumentation now effectively put this hard-won knowledge into action. Rising demand in the face of economic constraints is likely to drive future innovations focused on reducing the need for user input, automating multi-element protocols, and carefully monitoring the patient for progress and complications.
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Affiliation(s)
- John J Marini
- University of Minnesota, Regions Hospital MS11203B, 640 Jackson Street, St Paul, MN 55101, USA.
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12
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Ferreira HC, Mazzoli-Rocha F, Momesso DP, Garcia CSNB, Carvalho GMC, Lassance-Soares RM, Prota LFM, Morales MM, Faffe DS, Carvalho AR, Rocco PRM, Zin WA. On the crucial ventilatory setting adjustment from two- to one-lung ventilation. Respir Physiol Neurobiol 2011; 179:198-204. [PMID: 21871975 DOI: 10.1016/j.resp.2011.08.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2011] [Revised: 08/10/2011] [Accepted: 08/12/2011] [Indexed: 11/28/2022]
Abstract
Lung mechanics, histology, oxygenation and type-III procollagen (PCIII) mRNA were studied aiming to evaluate the need to readjust ventilatory pattern when going from two- to one-lung ventilation (OLV). Wistar rats were assigned to three groups: the left lung was not ventilated while the right lung received: (1) tidal volume (V(T))=5 ml/kg and positive end-expiratory pressure (PEEP)=2 cm H(2)O (V5P2), (2) V(T)=10 ml/kg and PEEP=2 cm H(2)O (V10P2), and (3) V(T)=5 ml/kg and PEEP=5 cm H(2)O (V5P5). At 1-h ventilation, V5P2 showed hypoxemia, alveolar collapse and impaired lung function. Higher PEEP minimized these changes and prevented hypoxemia. Although high V(T) prevented hypoxemia and maintained a higher specific compliance than V5P2, a morphologically inhomogeneous parenchyma and higher PCIII expression resulted. In conclusion, the association of low V(T) and an adequate PEEP level could be useful to maintain arterial oxygenation without inducing a possible inflammatory/remodeling response.
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Affiliation(s)
- Halina C Ferreira
- Laboratory of Respiration Physiology, Carlos Chagas Filho Institute of Biophysics, Federal University of Rio de Janeiro, RJ, Brazil.
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13
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de Prost N, Ricard JD, Saumon G, Dreyfuss D. Ventilator-induced lung injury: historical perspectives and clinical implications. Ann Intensive Care 2011; 1:28. [PMID: 21906379 PMCID: PMC3224506 DOI: 10.1186/2110-5820-1-28] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2011] [Accepted: 07/23/2011] [Indexed: 01/17/2023] Open
Abstract
Mechanical ventilation can produce lung physiological and morphological alterations termed ventilator-induced lung injury (VILI). Early experimental studies demonstrated that the main determinant of VILI is lung end-inspiratory volume. The clinical relevance of these experimental findings received resounding confirmation with the results of the acute respiratory distress syndrome (ARDS) Network study, which showed a 22% reduction in mortality in patients with the acute respiratory distress syndrome through a simple reduction in tidal volume. In contrast, the clinical relevance of low lung volume injury remains debated and the application of high positive end-expiratory pressure levels can contribute to lung overdistension and thus be deleterious. The significance of inflammatory alterations observed during VILI is debated and has not translated into clinical application. This review examines seminal experimental studies that led to our current understanding of VILI and contributed to the current recommendations in the respiratory support of ARDS patients.
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Affiliation(s)
- Nicolas de Prost
- Assistance Publique - Hôpitaux de Paris, Hôpital Henri Mondor, Service de Réanimation Médicale, 51, Avenue de Tassigny, 94010, Créteil, France
| | - Jean-Damien Ricard
- Université Paris-Diderot and PRES Sorbonne Paris Cité, Site Xavier Bichat, 75018 Paris, France
- Assistance Publique - Hôpitaux de Paris, Hôpital Louis Mourier, Service de Réanimation Médicale, F-92700, 178, rue des Renouillers - 92701 Colombes Cedex, France
- INSERM U722, F-75018 Paris, France
| | - Georges Saumon
- Université Paris-Diderot and PRES Sorbonne Paris Cité, Site Xavier Bichat, 75018 Paris, France
| | - Didier Dreyfuss
- Université Paris-Diderot and PRES Sorbonne Paris Cité, Site Xavier Bichat, 75018 Paris, France
- Assistance Publique - Hôpitaux de Paris, Hôpital Louis Mourier, Service de Réanimation Médicale, F-92700, 178, rue des Renouillers - 92701 Colombes Cedex, France
- INSERM U722, F-75018 Paris, France
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14
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Matute-Bello G, Downey G, Moore BB, Groshong SD, Matthay MA, Slutsky AS, Kuebler WM. An official American Thoracic Society workshop report: features and measurements of experimental acute lung injury in animals. Am J Respir Cell Mol Biol 2011; 44:725-38. [PMID: 21531958 PMCID: PMC7328339 DOI: 10.1165/rcmb.2009-0210st] [Citation(s) in RCA: 1294] [Impact Index Per Article: 99.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Acute lung injury (ALI) is well defined in humans, but there is no agreement as to the main features of acute lung injury in animal models. A Committee was organized to determine the main features that characterize ALI in animal models and to identify the most relevant methods to assess these features. We used a Delphi approach in which a series of questionnaires were distributed to a panel of experts in experimental lung injury. The Committee concluded that the main features of experimental ALI include histological evidence of tissue injury, alteration of the alveolar capillary barrier, presence of an inflammatory response, and evidence of physiological dysfunction; they recommended that, to determine if ALI has occurred, at least three of these four main features of ALI should be present. The Committee also identified key "very relevant" and "somewhat relevant" measurements for each of the main features of ALI and recommended the use of least one "very relevant" measurement and preferably one or two additional separate measurements to determine if a main feature of ALI is present. Finally, the Committee emphasized that not all of the measurements listed can or should be performed in every study, and that measurements not included in the list are by no means "irrelevant." Our list of features and measurements of ALI is intended as a guide for investigators, and ultimately investigators should choose the particular measurements that best suit the experimental questions being addressed as well as take into consideration any unique aspects of the experimental design.
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Titration of mean airway pressure and FiO2 during high frequency oscillatory ventilation in a porcine model of acute lung injury. J Surg Res 2010; 164:e147-53. [PMID: 20851418 DOI: 10.1016/j.jss.2010.07.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2010] [Revised: 06/08/2010] [Accepted: 07/01/2010] [Indexed: 11/21/2022]
Abstract
BACKGROUND High frequency oscillatory ventilation (HFOV) is frequently utilized for patients with acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). However, precise criteria to titrate mean airway pressure (mPaw) and FiO(2) as the patient's condition improves are lacking. We hypothesized that reducing mPaw and FiO(2) too quickly after reaching target arterial oxygen saturation levels would promote ventilator induced lung injury (VILI). MATERIALS AND METHODS ALI was induced by instilling 3% Tween 20. Pigs were placed supine and received 30 min of nonprotective ventilation. Pigs were separated into two groups: HFOV constant (HFOVC, n = 3) = constant mPaw and FiO(2) for the duration; HFOV titrated (HFOVT, n = 4) = FiO(2) and/or mPaw were reduced every 30 min if the oxygen saturation remained between 88%-95%. Hemodynamic and pulmonary measurements were made at baseline, after lung injury, and every 30 min during the 6-h study. Lung histopathology was determined by quantifying alveolar hyperdistension, fibrin, congestion, atelectasis, and polymorphonuclear leukocyte (PMN) infiltration. RESULTS Oxygenation was significantly lower in the HFOVT group compared to the HFOVC group after 6 h. Lung histopathology was significantly increased in the HFOVT group in the following categories: PMN infiltration, alveolar hyperdistension, congestion, and fibrin deposition. CONCLUSIONS Rapid reduction of mPaw and FiO(2) in our ALI model significantly reduced oxygenation, but, more importantly, caused VILI as evidenced by increased lung inflammation and alveolar hyperdistension. Specific criteria for titration of mPaw and inspired oxygen are needed to maximize the lung protective effects of HFOV while maintaining adequate gas exchange.
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Pulmonary-derived phosphoinositide 3-kinase gamma (PI3Kγ) contributes to ventilator-induced lung injury and edema. Intensive Care Med 2010; 36:1935-45. [PMID: 20721532 DOI: 10.1007/s00134-010-2018-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2009] [Accepted: 07/13/2010] [Indexed: 01/14/2023]
Abstract
BACKGROUND Ventilator-induced lung injury (VILI) occurs in part by increased vascular permeability and impaired alveolar fluid clearance. Phosphoinositide 3-kinase gamma (PI3Kγ) is activated by mechanical stress, induces nitric oxide (NO) production, and participates in cyclic adenosine monophosphate (cAMP) hydrolysis, each of which contributes to alveolar edema. We hypothesized that lungs lacking PI3Kγ or treated with PI3Kγ inhibitors would be protected from ventilation-induced alveolar edema and lung injury. METHODS Using an isolated and perfused lung model, wild-type (WT) and PI3Kγ-knockout (KO) mice underwent negative-pressure cycled ventilation at either -25 cmH₂O and 0 cmH₂O positive end-expiratory pressure (PEEP) (HIGH STRESS) or -10 cmH₂O and -3 cmH₂O PEEP (LOW STRESS). RESULTS Compared with WT, PI3Kγ-knockout mice lungs were partially protected from VILI-induced derangement of respiratory mechanics (lung elastance) and edema formation [bronchoalveolar lavage (BAL) protein concentration, wet/dry ratio, and lung histology]. In PI3Kγ-knockout mice, VILI induced significantly less phosphorylation of protein kinase B (Akt), endothelial nitric oxide synthase (eNOS), production of nitrate and nitrotyrosine, as well as hydrolysis of cAMP, compared with wild-type animals. PI3Kγ wild-type lungs treated with AS605240, an inhibitor of PI3Kγ kinase activity, in combination with enoximone, an inhibitor of phosphodiesterase-3 (PDE3)-induced cAMP hydrolysis, were protected from VILI at levels comparable to knockout lungs. CONCLUSIONS Phosphoinositide 3-kinase gamma in resident lung cells mediates part of the alveolar edema induced by high-stress ventilation. This injury is mediated via altered Akt, eNOS, NO, and/or cAMP signaling. Anti-PI3Kγ therapy aimed at resident lung cells represents a potential pharmacologic target to mitigate VILI.
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Graf J, Mentzelopoulos SD, Adams AB, Zhang J, Tashjian JH, Marini JJ. Semi-quantitative tracking of intra-airway fluids by computed tomography. Clin Physiol Funct Imaging 2009; 29:406-13. [PMID: 19622102 DOI: 10.1111/j.1475-097x.2009.00885.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND Airway secretions are a source of complications for patients with acute and chronic lung diseases, yet lack of techniques to quantitatively track secretions hampers research into clinical measures to reduce their pathologic consequences. METHODS In a preserved swine lung model, we tracked a contrasted mucus simulant (CMS) using sequential computed tomography (CT). Known drivers of secretion movement - gravity and ventilation - were tested. Ten millilitres of CMS were unilaterally introduced (1 ml min(-1)) into the airways of 12 lung sets. After instillation, six lung sets were maintained prone and six were rotated 180 degrees . Subsequently, all were mechanically ventilated for 10 min. CTs were obtained before infusion, after infusion and after ventilation +/- rotation. For CT analysis, the lungs were partitioned into eight sub-cuboids using anatomic landmarks. The volumes of two CT number ranges representing CMS and poor aeration/collapse were computed in every sub-cuboid for each CT acquisition. Volume differences between study time points were used to quantify changes. RESULTS CMS and poor aeration/collapse volume change distributed gravitationally after infusion. After ventilation without rotation, the CMS and poor aeration/collapse volumes remained within the originally injected sub-cuboid, although the poor aeration/collapse volume expanded (27.3 +/- 6.1-->50.5 +/- 7.4 ml, P<0.05). After ventilation + rotation, there was a reduction in the CMS and poor/aeration collapse volumes in the originally injected sub-cuboid (14.4 +/- 1.7-->4.4 +/- 0.6 ml, P<0.05 and 18.3 +/- 3.8-->11.9 +/- 2.7 ml, P<0.05, respectively) accompanied by increases in the gravitationally opposite sub-cuboid (1.7 +/- 0.2-->11.1 +/- 1.1 ml, P<0.05 and 0.8 +/- 0.5-->40.6 +/- 3.5 ml, P<0.05, respectively). CONCLUSION Movement of fluids within the bronchial tree can be semi-quantitatively tracked with analysis of sequential CT acquisitions. In this isolated swine lung model, gravity had an important and brisk effect on movement of a viscous fluid, whereas ventilation tended to embed it peripherally.
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Affiliation(s)
- Jerónimo Graf
- Pulmonary and Critical Care Research, Regions Hospital, St Paul, MN 55101, USA.
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Loss of airway pressure during HFOV results in an extended loss of oxygenation: a retrospective animal study. J Surg Res 2009; 162:250-7. [PMID: 19560160 DOI: 10.1016/j.jss.2009.04.026] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2008] [Revised: 04/03/2009] [Accepted: 04/13/2009] [Indexed: 01/11/2023]
Abstract
BACKGROUND Patients with acute respiratory distress syndrome (ARDS) are often ventilated with high airway pressure. Brief loss of airway pressure may lead to an extended loss of oxygenation. While using high frequency oscillatory ventilation (HFOV) in a porcine acute lung injury model, two animals became disconnected from the ventilator with subsequent loss of airway pressure. We compared the two disconnected animals to the two animals that remained connected to determine causes for the extended reduction in oxygenation. METHODS ARDS was induced using 5% Tween. Thirty min of nonprotective ventilation (NPV) followed before placing the pigs on HFOV. Measurements were made at baseline, after lung injury, and every 30min during the 6-h study. Disconnections were treated by hand-ventilation and a recruitment maneuver before being placed back on HFOV. The lungs were histologically analyzed and wet/dry weights were measured to determine lung edema. RESULTS Hemodynamics and lung function were similar in all pigs at baseline, after injury, and following NPV. The animals that remained connected to the oscillator showed a continued improvement in PaO(2)/FiO(2) (P/F) ratio throughout the study. The animals that experienced the disconnection had a significant loss of lung function that never recovered. The disconnect animals had more diffuse alveolar disease on histologic analysis. CONCLUSIONS A significant fall in lung function results following disconnection from HFOV, which remains depressed for a substantial period of time despite efforts to reopen the lung. Dispersion of edema fluid is a possible mechanism for the protracted loss of lung function.
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Propagation prevention: a complementary mechanism for "lung protective" ventilation in acute respiratory distress syndrome. Crit Care Med 2008; 36:3252-8. [PMID: 18936705 DOI: 10.1097/ccm.0b013e31818f0e68] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
OBJECTIVE To describe the clinical implications of an often neglected mechanism through which localized acute lung injury may be propagated and intensified. DATA EXTRACTION AND SYNTHESIS Experimental and clinical evidence from the medical literature relevant to the airway propagation hypothesis and its consequences. CONCLUSIONS The diffuse injury that characterizes acute respiratory distress syndrome is often considered a process that begins synchronously throughout the lung, mediated by inhaled or blood-borne noxious agents. Relatively little attention has been paid to possibility that inflammatory lung injury may also begin focally and propagate sequentially via the airway network, proceeding mouth-ward from distal to proximal. Were this true, modifications of ventilatory pattern and position aimed at geographic containment of the injury process could help prevent its generalization and limit disease severity. The purposes of this communication are to call attention to this seldom considered mechanism for extending lung injury that might further justify implementation of low tidal volume/high positive end-expiratory pressure ventilatory strategies for lung protection and to suggest additional therapeutic measures implied by this broadened conceptual paradigm.
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Do airway secretions play an underappreciated role in acute respiratory distress syndrome? Curr Opin Crit Care 2008; 14:44-9. [PMID: 18195625 DOI: 10.1097/mcc.0b013e3282f2f4cb] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE OF REVIEW We review the evidence that airway secretions may have an underappreciated role in acute respiratory distress syndrome, contributing to physiologic disarrangements, ventilator dependence and perhaps to injury generation. As common manipulations of ventilator settings, position and fluid status have the potential to influence these problems, explorations into the secretion dynamics of acute lung injury may be fertile ground for developing therapeutic advances. RECENT FINDINGS Principles that govern the interaction of airflow and airway fluids suggest that mobile fluids and secretions are pumped by well-selected ventilatory patterns toward the airway opening. Conversely, other selections may inhibit these fluids from clearance or encourage their translocation between lung regions. Recent laboratory work demonstrates that choices for tidal volume and positive end-expiratory pressure may localize or disperse proteinaceous lung edema or bacteria. Gravitational factors may interact with ventilatory pattern for benefit or harm. SUMMARY Capability of ventilation and positioning to mobilize secretions implies the potential for clearance or containment of inflammatory mediators and infection. Ventilatory and positional prescriptions could be designed to meet one of either conflicting targets. Additional experimental and clinical investigations are required before adopting these proposed therapeutic principles into practice.
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Antonelli M, Azoulay E, Bonten M, Chastre J, Citerio G, Conti G, De Backer D, Lemaire F, Gerlach H, Groeneveld J, Hedenstierna G, Macrae D, Mancebo J, Maggiore SM, Mebazaa A, Metnitz P, Pugin J, Wernerman J, Zhang H. Year in review in Intensive Care Medicine, 2007. II. Haemodynamics, pneumonia, infections and sepsis, invasive and non-invasive mechanical ventilation, acute respiratory distress syndrome. Intensive Care Med 2008; 34:405-22. [PMID: 18236026 DOI: 10.1007/s00134-008-1009-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2008] [Accepted: 01/07/2008] [Indexed: 01/14/2023]
Affiliation(s)
- Massimo Antonelli
- Department of Intensive Care and Anaesthesiology, Policlinico Universitario A. Gemelli, Università Cattolica del Sacro Cuore, Largo A. Gemelli 8, 00168 Rome, Italy.
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Terbutaline lessens protein fluxes across the alveolo-capillary barrier during high-volume ventilation. Intensive Care Med 2007; 34:763-70. [DOI: 10.1007/s00134-007-0954-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2007] [Accepted: 10/25/2007] [Indexed: 01/11/2023]
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