Background

Extracorporeal membrane oxygenation (ECMO) is a critical life-support intervention for patients with severe respiratory and circulatory failure. Nevertheless, identifying the optimal timing of ECMO initiation and its correlation with survival, mortality, and complication rates continues to pose significant clinical challenges.

Purpose

This study intends to conduct a systematic review of the existing medical literature to clarify ECMO initiation timing and its association with patient outcomes, aiming to furnish evidence-based recommendations for clinical decision-making.

Methods

We performed systematic searches across PubMed, Embase, Scopus, The Cochrane Library, and Web of Science for eligible cohort and case–control studies. Studies combining ECMO with other extracorporeal life-support modalities were excluded to eliminate survival confounding. Inclusion criteria encompassed adult ECMO recipients with reported initiation timing and at least one outcome measure. Study quality was evaluated using the Newcastle–Ottawa Scale (NOS).

Results

From 1583 identified records, 30 studies were finally included, comprising 2 prospective cohorts, 1 case–control, and 27 retrospective cohorts. ECMO initiation timing was heterogeneously defined across multiple time intervals and clinical scenarios. Of the full set of 30 included studies, 23 performed statistical analyses examining the link between ECMO initiation delay and mortality; 18 of these 23 studies (60% of all 30 included studies) reported that prolonged ECMO initiation time was significantly associated with higher in-hospital or long-term mortality. Five of the 23 mortality-analyzing studies detected no statistically significant timing-mortality correlation, while the remaining 7 studies only reported organ complication outcomes and did not conduct any statistical testing of mortality as an endpoint. Quality appraisal demonstrated only one low-quality study, with all others graded as medium to high quality.

Conclusion

For patients with severe ARDS, cardiogenic shock, drug-induced shock, cardiac arrest, or post-cardiotomy shock, early ECMO initiation—such as within 7 days of mechanical ventilation—can effectively decrease mortality and reduce the incidence of neurological, hepatic, and renal complications.