The use of prone position ventilation in Danish patients with COVID-19-induced severe acute respiratory distress syndrome treated with veno-venous extracorporeal membrane oxygenation: A nationwide cohort study with focus on pulmonary effects.

Background: Prone position ventilation (PPV) is recommended for patients with COVID-19 induced severe Adult Respiratory Distress Syndrome (ARDS) and is used for patients supported with V-V ECMO as well. The purpose of this study was to describe the use of PPV in these patients focusing on physiological effects with the hypothesis that PPV could reduce oxygen need and improve dynamic compliance.

Methods: This study was a nationwide retrospective analysis of all COVID-19 patients in Denmark from March 2020 - December 2021 with severe ARDS and need of V-V ECMO support. Data on the number of patients treated with PPV, number of PPV sessions, timing, the time spent in prone position, pulmonary physiological response types with analysis of variables affecting the response are reported.

Results: Out of 68 patients 44 were treated with 220 PPV sessions and a positive clinical response was observed in 80% of patients but only in 45% of sessions. On a single session level, increased compliance was observed in 38% and increased oxygenation in only 15% of 220 sessions, with within-patient heterogeneity. Higher dynamic compliance at the beginning of a PPV session was associated with a lower delta change in dynamic compliance during PPV. The response to a PPV session could not be predicted by the response in the prior session. Dynamic compliance did not change during the ECMO course.

Conclusion: Eighty percent of patients responded positively during a PPV session, but this was not associated with overall pulmonary improvement. On a single patient level, responses were heterogenous and only 45% of sessions resulted in clinical improvement. Response in dynamic compliance was associated with starting values of compliance.