Positive fluid balance and mortality in adult patients treated with extracorporeal membrane oxygenation: A retrospective study

Background Intravenous fluid is important for resuscitation and maintenance of circuit flow in patients with extracorporeal membrane oxygenation, but fluid overload is widely recognized as detrimental in critically ill patients. This study aimed to evaluate the association between positive fluid balance and outcomes in adult patients treated with extracorporeal membrane oxygenation. Methods This was a retrospective observational study of a tertiary hospital from October 2010 to January 2018. Patients aged ≥18 years who received extracorporeal membrane oxygenation for ≥48 h were included. The fluid balance was determined as the difference between fluid intake and fluid output, and the cumulative fluid balance was calculated as the sum of these values on the preceding days. The primary outcome was hospital mortality. Results Of the 123 included extracorporeal membrane oxygenation episodes, 79 were venovenous extracorporeal membrane oxygenation. The hospital mortality rate was 31.7%. Seventy-eight patients underwent continuous renal replacement therapy during their extracorporeal membrane oxygenation course. Non-survivors had a greater cumulative fluid balance (p≤0.001) and a lower cumulative fluid output (p = 0.006) than survivors on day 7. Fluid intake was not significantly different between survivors and non-survivors (p = 0.583). In the multivariate analysis, the cumulative fluid balance (per litre) on day 7, but not on day 3, was associated with increased hospital mortality (adjusted OR: 1.17, 95% CI: 1.06–1.29, p = 0.001). Conclusions In adult patients treated with extracorporeal membrane oxygenation, a higher positive cumulative fluid balance on day 7 was associated with increased hospital mortality. The association between positive fluid balance and mortality was mainly influenced by lower fluid output rather than an increase in fluid intake.