Prevalence, Risk Factors, and Mortality of Venovenous Extracorporeal Membrane Oxygenation Escalation in Acute Respiratory Distress Syndrome: A Multicenter Cohort Study From the Chinese Society of Extracorporeal Life Support Registry

OBJECTIVES: Patients with acute respiratory distress syndrome (ARDS) undergoing venovenous extracorporeal membrane oxygenation (ECMO) may experience severe cardiogenic shock, necessitating ECMO mode "escalation" for cardiopulmonary co-support. There is a paucity of data regarding the prevalence, risk factors, and mortality of venovenous ECMO escalation. We aimed to conduct a large study to address this issue. DESIGN: A multicenter cohort study. SETTING: The analysis was conducted based on data from the Chinese Society of Extracorporeal Life Support registry, a nationwide voluntary platform capturing clinical information of patients receiving ECMO support. Data were collected from 112 centers across China between January 2017 and December 2023. PATIENTS: Eligible participants included adult patients with ARDS receiving venovenous ECMO, excluding pregnant patients and those with missing data on escalation. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The primary outcome was in-hospital mortality. Of the 3333 patients on venovenous ECMO, 157 (4.7%) underwent escalation to venoarterial ECMO (n = 41), veno-arterial-venous (VAV) ECMO (n = 68), and veno-veno-arterial (VVA) ECMO (n = 48). Several characteristics, including hospital's annual venovenous ECMO volume (hospitals > 15 cases per year vs. those < 6 cases per year; odds ratio [OR], 0.596; 95% CI, 0.382-0.930), were associated with the occurrence of escalation. The overall in-hospital mortality was 47.9%. Both escalation and lower hospital's venovenous ECMO volume were independently associated with an increased mortality. Compared with patients escalated to VVA ECMO, those escalated to venoarterial ECMO had a significantly higher survival rate (OR, 3.444; 95% CI, 1.046-11.342), whereas those escalated to VAV ECMO did not. CONCLUSIONS: In this study, 4.7% of ARDS patients with venovenous ECMO underwent a mode escalation. Escalation was independently associated with higher in-hospital mortality, an association that may be partially confounded by low hospital's venovenous ECMO volume. Among the modes after escalation, venoarterial ECMO was associated with a significantly higher survival rate. These findings require validation by further prospective multicenter studies to guide decision-making for ARDS patients requiring ECMO support.