Decision support system to evaluate ventilation in the acute respiratory distress syndrome (DeVENT study)-trial protocol.

BACKGROUND: The acute respiratory distress syndrome (ARDS) occurs in response to a variety of insults, and mechanical ventilation is life-saving in this setting, but ventilator-induced lung injury can also contribute to the morbidity and mortality in the condition. The Beacon Caresystem is a model-based bedside decision support system using mathematical models tuned to the individual patient's physiology to advise on appropriate ventilator settings. Personalised approaches using individual patient description may be particularly advantageous in complex patients, including those who are difficult to mechanically ventilate and wean, in particular ARDS. METHODS: We will conduct a multi-centre international randomised, controlled, allocation concealed, open, pragmatic clinical trial to compare mechanical ventilation in ARDS patients following application of the Beacon Caresystem to that of standard routine care to investigate whether use of the system results in a reduction in driving pressure across all severities and phases of ARDS. DISCUSSION: Despite 20 years of clinical trial data showing significant improvements in ARDS mortality through mitigation of ventilator-induced lung injury, there remains a gap in its personalised application at the bedside. Importantly, the protective effects of higher positive end-expiratory pressure (PEEP) were noted only when there were associated decreases in driving pressure. Hence, the pressures set on the ventilator should be determined by the diseased lungs' pressure-volume relationship which is often unknown or difficult to determine. Knowledge of extent of recruitable lung could improve the ventilator driving pressure. Hence, personalised management demands the application of mechanical ventilation according to the physiological state of the diseased lung at that time. Hence, there is significant rationale for the development of point-of-care clinical decision support systems which help personalise ventilatory strategy according to the current physiology. Furthermore, the potential for the application of the Beacon Caresystem to facilitate local and remote management of large numbers of ventilated patients (as seen during this COVID-19 pandemic) could change the outcome of mechanically ventilated patients during the course of this and future pandemics. TRIAL REGISTRATION: ClinicalTrials.gov identifier NCT04115709. Registered on 4 October 2019, version 4.0.

Secreted Extracellular Cyclophilin A Is a Novel Mediator of Ventilator-induced Lung Injury.

Rationale: Mechanical ventilation is a mainstay of intensive care but contributes to the mortality of patients through ventilator-induced lung injury. eCypA (extracellular CypA [cyclophilin A]) is an emerging inflammatory mediator and metalloproteinase inducer, and the gene responsible for its expression has recently been linked to coronavirus disease (COVID-19). Objectives: To explore the involvement of eCypA in the pathophysiology of ventilator-induced lung injury. Methods: Mice were ventilated with a low or high Vt for up to 3 hours, with or without blockade of eCypA signaling, and lung injury and inflammation were evaluated. Human primary alveolar epithelial cells were exposed to in vitro stretching to explore the cellular source of eCypA, and CypA concentrations were measured in BAL fluid from patients with acute respiratory distress syndrome to evaluate the clinical relevance. Measurements and Main Results: High-Vt ventilation in mice provoked a rapid increase in soluble CypA concentration in the alveolar space but not in plasma. In vivo ventilation and in vitro stretching experiments indicated the alveolar epithelium as the likely major source. In vivo blockade of eCypA signaling substantially attenuated physiological dysfunction, macrophage activation, and MMPs (matrix metalloproteinases). Finally, we found that patients with acute respiratory distress syndrome showed markedly elevated concentrations of eCypA within BAL fluid. Conclusions: CypA is upregulated within the lungs of injuriously ventilated mice (and critically ill patients), where it plays a significant role in lung injury. eCypA represents an exciting novel target for pharmacological intervention.