Outcomes in Obese Adult Venoarterial Extracorporeal Membrane Oxygenation: A Systematic Review

Historically, extracorporeal membrane oxygenation (ECMO) in critical illness and respiratory failure has been used cautiously in patients with morbid obesity. However, recent data show favorable mortality outcomes for higher body mass index (BMI) groups, termed the "obesity paradox." This study examines whether this phenomenon extends to obese patients undergoing venoarterial ECMO (VA-ECMO). A systematic literature review of articles from 2000 to 2022 evaluated mortality and complications in adult patients undergoing VA-ECMO, stratified by body mass index (BMI). Results were synthesized qualitatively and with a χ² analysis comparing mortality for patients with BMI <30 and BMI ≥30. Five studies with 1,196 patients were included. The most common complications included acute renal failure (15.0%-53.3%) and major bleeding (7.5%-42.0%). One study reported more complications in obese than nonobese patients (51% in BMI ≥35 v 25% in BMI 17.5-24.9, p = 0.002). Four of 5 cohort studies found no association between BMI and mortality. The χ² analysis demonstrated no difference in mortality for BMI <30 (60.3%) and BMI ≥30 (58.6%), p = 0.6. Overall, current evidence does not demonstrate a consistent association between BMI and mortality in patients undergoing VA-ECMO. Although these findings suggest that obesity alone should not preclude consideration of VA-ECMO, the available data are limited and heterogeneous, warranting caution in interpreting these results.