The impact of body mass index on patient survival after therapeutic hypothermia after resuscitation

Objectives Therapeutic hypothermia improves survival in patients after cardiac arrest, yet the impact of body mass index (BMI) on survival is lesser known. We hypothesized that nonobese patients would have greater survival post-therapeutic hypothermia than obese patients. Methods We retrospectively evaluated 164 patients who underwent therapeutic hypothermia after resuscitation for cardiac arrest from January 2012 to September 2014. Logistic regression analysis was used to assess for survival based upon BMI and comorbidities (odds ratio, 95% confidence interval). Results Forty-one percent of patients were obese. Obese patients presented less frequently with ventricular fibrillation (P =.046) but had similar rates of pulseless electrical activity (P =.479) and ventricular tachycardia (P =.262) to nonobese patients. In multivariable analysis, BMI less than 30 kg/m², hypertension, presence of pacemaker/implantable cardioverter-defibrillator, high glomerular filtration rate, and low neuron-specific enolase were all associated with increased survival post-therapeutic hypothermia, respectively: 0.36 (0.16-0.78), 0.28 (0.12-0.66), 0.23 (0.08-0.62), 0.25 (0.11-0.56), and 0.37 (0.14-0.96). Other comorbidities demonstrated no association with survival. Conclusions Body mass index at least 30 kg/m² compared with BMI less than 30 kg/m² was a significant risk factor for mortality post-therapeutic hypothermia protocol. Absence of history of hypertension, lack of pacemaker/implantable cardioverter-defibrillator, high neuron-specific enolase, and renal disease had greater associations with death. Larger studies will be needed to validate these findings.