Abstract 104: Metabolic Effect of Temperature Manipulation in Healthy Individuals

Abstract

Introduction: Temperature manipulation to decrease metabolism is commonly after acute brain injury. Preclinical data suggest metabolism decreases 7-8% for each degree C drop in core temperature. We hypothesized similar results would be found in healthy individuals. Methods: Following informed consent and physical screening, we administered a 1mcg/kg bolus of dexmedetomidine followed by 20cc/kg of cold (4C) saline bolus. We cooled subjects using surface pads (emcools (Austria)). Dexmedetomidine infusion was titrated to effect (max dose <1.5mcg/kg/hr). We recorded vital signs, Richmond Agitation Sedation Scale, Bedside Shivering Assessment Scale and sensation of cold every 15 minutes. We measured resting metabolism at baseline and after each 1 C decrease in temperature thereafter using indirect calorimetry and a ventilated canopy system. We analyzed data using analysis of variance. Results: Median age in the 9 enrolled subjects was 30 (SD 10) years and most (78%) were male. Median height was 173 (IQR 168, 180) cm and median weight was 77 (IQR 72, 83) kg. Baseline VO2 was 3.4 (IQR 3.0, 3.8) ml/kg/min and baseline energy expenditure was 1692 (IQR 1579, 1845) kcal/day. Both VO2 and energy expenditure decreased with core temperature (p=0.017 and p=0.027) (Table). Conclusion: Metabolic rate decreases with core temperature manipulation. The largest change occurs between 37C and 36C with smaller changes thereafter.