Obesity Does Not Worsen Outcomes in Pediatric ECMO

Introduction: Body mass index (BMI) has been recommended as a relative contraindication to ECMO support despite no study showing that obesity is associated with increased risk of mortality or complications. Adult studies have described an obesity survival paradox, in which obese patients requiring VV ECMO have improved outcomes compared to non-obese adults. No study to date has been performed to investigate obesity and ECMO outcomes in pediatric patients. We hypothesize that obesity does not affect survival in pediatric patients supported with ECMO.


Methods: A retrospective review of the Extracorporeal Life Support Organization (ELSO) registry database from 2016 to 2022 was performed to evaluate hospital mortality and incidence of complications as related to BMI. Patients were stratified according to the WHO definitions for overweight and obese for age. Multivariate analyses were performed to adjust for age, primary diagnosis, and comorbidities. Secondary analyses were performed to analyze mortality by BMI based on COVID status and mode of ECMO support.


Results: Of the 1509 individual runs retrieved from the database query, 1184 unique runs were included in the analysis. 588 (49.7%) patients were normal weight, 252 (21.3%) were overweight, and 344 (29%) were obese. The hospital mortality rates were not significantly different between normal weight (32.1%), overweight (24.2%), and obese (30.2%) patients (p=0.07). Fewer complications were seen in overweight patients as compared to normal weight (30.2% vs 41.2%, p=0.003) and to obese (30.2% vs 39%, p=0.027) patients, with no significant difference in between normal weight and obese patients (41.2% vs 39%, p=0.508). Significantly more patients on ECMO with COVID-19 were obese, but there was no significant difference in mortality between these patients (p=0.751). On subgroup analyses by mode of support, mortality rates did not differ in VA (p=0.583), VV (p=0.082), or VVA (p=0.856).


Conclusions: We found no significant difference in mortality rate or complications in obese patients compared to patients with a normal weight. Additionally, there was no significant difference in mortality when analyzed by COVID status or mode of support. This study supports the existing adult literature that BMI should not be used as exclusionary criteria for ECMO candidacy.