Objectives: 

To evaluate the relationship between the duration of pre-extracorporeal membrane oxygenation (ECMO) mechanical ventilation and mortality in acute respiratory distress syndrome (ARDS) patients undergoing venovenous ECMO.

Design: 

Retrospective cross-sectional study using the National Inpatient Sample database.

Setting: 

National Inpatient Sample database from January 2019 to December 2022.

Patients: 

Inclusion criteria were: 1) adults (age ≥ 18 yr old) who received venovenous ECMO and 2) ARDS diagnosis. Exclusion criteria were: 1) receipt of venovenous ECMO before intubation, 2) receipt of lung transplant, and 3) missing data for regression analysis variables.

Interventions: 

None.

Measurements and Main Results: 

Survey-weighted multivariable logistic regression to assess the association between in-hospital mortality and time from mechanical ventilation to venovenous ECMO initiation was performed. A national estimate of 9090 patients were identified. The duration of pre-ECMO mechanical ventilation was not significantly associated with in-hospital mortality (odds ratio [OR], 1.02; 95% CI, 0.98–1.06; p = 0.367). Late initiation of venovenous ECMO (pre-ECMO mechanical ventilation > 7 d) was not associated with an increased risk of in-hospital mortality (OR, 1.18; 95% CI, 0.91–1.54; p = 0.216).

Conclusions: 

Our study suggests that pre-ECMO mechanical ventilation duration does not independently predict mortality in patients with ARDS. This challenges the conventional belief that ECMO must be initiated within 7 days and supports a more individualized approach to ECMO candidacy.