To characterize the impact of BMI (body mass index) on HIBI (hypoxic-ischemic brain injury) in patients receiving ECPR, with the hypothesis that elevated BMI is associated with increased risk of HIBI.

The Extracorporeal Life Support Organization (ELSO) registry was queried for patients who received ECPR during 2020-2024. Patients were categorized into 5 standard BMI groups. Normal Weight was used as the reference group. Generalized additive model (GAM) analysis was performed to identify the BMI range with greatest predicted HIBI risk. Multivariable logistic regression was used to compare odds of HIBI and post-HIBI mortality between standard BMI groups and Normal Weight.

Of 6413 included patients (median age = 57.4, 68.6% male, median BMI = 28.1), 10.5% of Class 1 Obesity patients experienced HIBI compared to 5.0% of Normal Weight patients, 9.6% of Class 2 Obesity patients, 6.3% of Overweight patients, and 3.6% of Underweight patients (p < 0.001). GAM analysis showed a non-linear relationship between BMI and HIBI with highest predicted HIBI risk for Class 1 Obesity patients, which was confirmed by multivariable regression (adjusted odds ratio (aOR) = 1.86, 95%CI = 1.09, 3.20, p = 0.02). HIBI led to >90% mortality in all BMI categories, with increased odds of post-HIBI mortality for Class 1 Obesity patients compared to Normal Weight (aOR = 1.97, 95%CI = 1.14, 3.47, p = 0.016). There was no significant difference in odds of HIBI or post-HIBI mortality for any other BMI category compared to Normal Weight.

ECPR patients with Class 1 Obesity had increased odds of HIBI and post-HIBI mortality compared to Normal Weight patients after adjusting for covariates.