# Prognosis After Seven Days of Veno‐Venous Extracorporeal Membrane Oxygenation Support

## TL;DR

This study examines the prognosis of patients on veno-venous ECMO for seven days, finding that certain respiratory and ECMO parameters can predict hospital survival.

## Contribution

The study introduces a survival favorability margin to predict hospital survival based on day 7 ECMO and respiratory parameters.

## Key findings

- Hospital survival rate was 45.1% for patients still on V-V ECMO after seven days.
- Six parameters (three respiratory and three ECMO) significantly predicted survival when above the favorability margin.
- Patients with all predictors below the margin had very low survival rates (13.8%).

## Abstract

Prognostication in patients receiving veno‐venous extracorporeal membrane oxygenation (V‐V ECMO) remains challenging, particularly during prolonged support. Accurate prognostic indicators are essential for patients, caregivers, and clinicians. This study evaluates outcomes in patients supported with V‐V ECMO for at least seven days.

We conducted a single‐center retrospective cohort study of patients cannulated for V‐V ECMO due to respiratory failure. The primary endpoint was hospital survival. The subgroup of patients still on V‐V ECMO on day 7, stratified by respirator and ECMO parameters, was analyzed with respect to predictors of the primary outcome. A survival favorability margin was defined as the bound of the hospital survivors' 95% confidence interval closest to the non‐survivor median.

Among 299 patients treated with V‐V ECMO (median age 55 years, 66.9% male), hospital survival was 44.8%. Pneumonia was the primary cause of respiratory failure in 216 patients (72.2%). By day 7, 182/299 patients (60.9%) remained on V‐V ECMO, with a hospital survival rate of 45.1%. Three respiratory parameters (ventilator FiO2, tidal volume, compliance) and three V‐V ECMO parameters (blood flow, sweep gas flow, O2 fraction) significantly predicted hospital survival (all p ≤ 0.015). All six predictors separated survivors and non‐survivors through day 1 to 10 (all p < 0.001). Moreover, the clustering of several parameters above the favorability margin showed a clear discrimination of the overall survival (≥ 5 vs. zero parameters, survival 67.5% vs. 13.8%, OR 13.0, 95% CI 3.5–38.6, p < 0.001).

Among patients still on V‐V ECMO on day seven, respiratory and ECMO parameters above the favorability margin correlated strongly with hospital survival. Survival was rare in patients with all predictors below the favorability margin. Day seven could provide a useful, though not definitive, time point for prognostication based on respiratory and ECMO parameters.

The hospital survival rate of patients still on V‐V ECMO after seven days was 45.1%. Survival correlates with the respiratory situation on day seven defined as points scored above the favorability margin of survival. Day 7 may be too early to predict prognosis in V‐V ECMO.