Extracorporeal life support (ECLS) combined with tidal volumes and airway pressures lower than the current standard of care may help improve outcomes in patients with the most severe forms of acute respiratory distress syndrome (ARDS), according to study results published in the American Journal of Respiratory and Critical Care Medicine.
Ventilator-induced lung injury is a major contributor to morbidity and mortality in patients with ARDS. Given that the overarching goal of invasive mechanical ventilation during ECLS in ARDS is to decrease the intensity and, therefore, reduce the possibility of ventilator-induced lung injury while maximizing the benefits of ECLS, the precise way in which ventilator variables should be adjusted remains to be determined.
Researchers derived data from a recent randomized controlled trial, a post hoc analysis of that trial, a meta-analysis, and a large, international, multicenter observational study. They sought to summarize the current understanding of the role ECLS may play in minimizing ventilator-induced lung injury; suggest best practice mechanical ventilation strategies during ECLS, while taking into consideration the existing data; describe the interplay among ECLS, gas exchange, and ventilator parameters; and identify the areas of research that are needed to better inform the optimal management of mechanical ventilation and spontaneous breathing efforts during ECLS.
The researchers’ suggestions reflect the consensus opinions of clinicians and researchers with expertise in mechanical ventilation, ARDS, and ECLS, which originated from a roundtable discussion that took place at the Fourth Annual International ECMO Network Scientific Meeting in Rome, Italy, in 2018.
Both preclinical and human data have suggested that ventilator-induced lung injury continues to occur during episodes of ARDS, despite adherence to best practices of conventional ventilator management. It appears reasonable to establish that tidal volumes and airway pressures need to be reduced below the current standard of care to minimize ventilator-induced lung injury and maximize patient outcomes. Respiratory rate has also been proposed as a potential target for ventilator-induced lung injury reduction. The use of extracorporeal gas exchange has been shown to offer an opportunity for attaining ultra-lung protective ventilation, including decreases in respiratory rate, while alleviating the resultant respiratory acidosis.
Because no large, prospective clinical trials are available that compare different ventilator strategies during ECLS for ARDS, no definitive standard of care exists. Before the consideration of ECLS, however, use of standard-of-care lung protective ventilation, prone positioning, positive end expiratory pressure titration, conservative fluid balance, and neuromuscular blockade all need to be optimized.
The investigators concluded that use of the EOLIA (Extracorporeal Membrane Oxygenation for ARDS) protocol during ECMO is a reasonable new minimum standard to be applied in patients with ARDS. They do recommend targeting respiratory rates of ≤10 (the lower range in EOLIA). Moreover, the excess work involved in breathing might promote lung injury in patients with ARDS and should be avoided regardless of whether ECLS is being used. Future studies are warranted, focusing on more precisely delineating the ideal strategies for optimizing invasive ventilation during ECLS for ARDS.
Disclosures: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.
Abrams D, Schmidt M, Pham T, et al; for the International ECMO Network (ECMONet). Mechanical ventilation for ARDS during extracorporeal life support: research and practice [published online November 14, 2019]. Am J Respir Crit Care Med. doi:10.1164/rccm.201907-1283CI