Early Positive Fluid Balance is Associated with Mortality in Patients Treated with Veno-Arterial Extra Corporeal Membrane Oxygenation For Cardiogenic Shock: a Retrospective Cohort Study

Purpose: Veno-arterial Extracoporeal Membrane Oxygenation (VA-ECMO) provides circulatory assistance for patients in cardiogenic shock. Large quantities of fluids are often required, especially during the early stages, but can result in a potentially harmful fluid-overload. The objective was to determine the association of early fluid-balance and mortality.

Methods: Retrospective single-center study in 101 VA-ECMO patients between 2013 and 2016. Daily fluid-balance and weight changes over the 5 first days were observed. Analyses between survivors and non-survivors were conducted using Mann-Whitney tests and logistic regression multivariable and Cox hazard-proportional analyses to determine any association with 28-days mortality.

Results: Mortality was 47.5%. The fluid-balance was higher in non-survivors at day-1 (47.3[18.1-71.9] vs. 19.3[1.5-36.2] mL/kg, P < 0.0001) and day-2 (30.6[14.8-71.0] vs. 10.1[-9.8 to 34.7] mL/kg, P = 0.025), as was the cumulative fluid-balance over the first 5 days (107.3[40.5-146.2] vs. 53.0[7.5-74.3] mL/kg, P = 0.04). The administration of unintentional fluids (used for preparation and infusion of drugs) represented an important part of the administrated fluids (15 mL/kg/d-23 mL/kg/d). A significant but moderate correlation was observed between fluid-balance and weight variations over the 5 days (r values ranging from 0.36 to 0.54). Among other parameters, day-1 fluid-balance was independently associated with mortality (OR = 14.34 [1.58-129.79], P = 0.02) and day-1 and day-2 with time to death (HR = 8.26 [1.12-60.98], P = 0.04 and 2.89 [1.26-6.65], P = 0.01). A threshold of 38.8 mL/kg predicted mortality with a sensitivity of 60% and specificity of 83% (area under the curve: 0.749).

Conclusion: Early positive fluid-balance is associated with mortality in VA-ECMO patients.