No abstract

A substantial proportion of patients with coronavirus disease 2019 (COVID-19) admitted to intensive care units (ICU) requires invasive mechanical ventilation for acute respiratory distress syndrome (ARDS), which is still associated with a high mortality rate (1). Applying the optimal positive end-expiratory pressure (PEEP) to ensure lung recruitment while limiting lung hyperinflation, remains challenging in ARDS (2, 3). Yet, there are few simple tools that might help personalize the level of PEEP in those patients at the bedside. Among them, lung ultrasound (LUS) aeration score and recruitment-to-inflation ratio (R/I) have the potential to identify patients who are more likely to benefit from PEEP (2). Previous studies indeed suggested that LUS could assess spatial distribution of PEEP-induced lung recruitment but does not reliably detect hyperinflation (4, 5). The R/I ratio is a recent tool that has been developed to evaluate both the potential for lung recruitment and the risk for hyperinflation, but does not provide regional information about lung recruitment (6-8). Therefore, these two tools, readily available at bedside in most ICUs, could provide additive and complementary information on lung recruitment. In the present study, we aimed to assess lung recruitability simultaneously by the R/I ratio and the LUS in patients with COVID-19-related ARDS. Methods We conducted a prospective observational study between March 31 and October 29, 2020 in a 26-bed university-affiliated ICU in Lyon, France, which was approved by our institutional ethics committee.