THE YEAR IN REVIEW: MECHANICAL VENTILATION DURING THE FIRST YEAR OF THE COVID-19 PANDEMIC

Abstract

Corona virus disease 2019 (COVID-19) represents the greatest medical crisis encountered in the young history of critical care and respiratory care. During the early months of the pandemic, when little was known about the virus, the acute hypoxemic respiratory failure it caused did not appear to fit conveniently or consistently into our classification of acute respiratory distress syndrome (ARDS). This not only re-ignited a half-century's long simmering debate over taxonomy, but also fueled similar debates over how PEEP and lung-protective ventilation should be titrated, as well as the appropriate role of non-invasive ventilation in ARDS. Furthermore, COVID-19 ignited other debates on emerging concepts such as ARDS phenotypes and patient self-inflicted lung injury from vigorous spontaneous breathing. Over a year later these early perplexities have receded into the background without having been reviewed or resolved. With a full year of evidence having been published this narrative review systematically analyzes whether or not COVID-19 associated respiratory failure is essentially ARDS, with perhaps a somewhat different course of presentation. This includes a review of the severity of hypoxemia and derangements in pulmonary mechanics, PEEP requirements, recruitment potential, the ability to achieve lung-protective ventilation goals, duration of mechanical ventilation, associated mortality, and response to non-invasive ventilation. It also reviews the concepts of ARDS phenotypes and patient self-inflicted lung injury as these are crucial to understanding the contentious debate over the nature and management of COVID-19.