ABSTRACT
INTRODUCTION: Fever after acute brain injury appears to be a detrimental factor, associated with impaired neurological outcomes. This study assessed physiological changes in systemic oxygen consumption (VO2) during cutaneous cooling after severe brain injury. METHODS: This prospective, observational, clinical study evaluated ten, critically ill, brain-injured patients requiring mechanical ventilation with a core body temperature of greater or equal to 38 degrees C. Febrile patients failing to defervesce after acetaminophen underwent indirect calorimetry for a 1-hour baseline period followed by a 4 h cooling period. The Arctic Sun(R) Temperature Management System (Medivance) directed core temperature to a goal of 36 degrees C. RESULTS: The patients had a mean age of 32 years (95% CI 23, 40), Glasgow Coma Scale of 6 (95% CI 5,7), and APACHE 2 score of 19 (95% CI 15, 22), with 8 of 10 patients suffering traumatic brain injuries. The baseline 1-h core temperature was significantly reduced from 38.6 degrees +/- 0.9 to 36.3 degrees +/- 1.2 degrees C (P < 0.0001) over 4 h. Two cohorts were identified based upon the presence or absence of shivering. Within the non-shivering cohort, systemic VO2 was significantly reduced from 415 +/- 123 to 308 +/- 115 ml/min (-27 +/- 18%) (P < 0.05). In contrast, those with shivering showed no significant reduction in VO2, despite significantly decreasing core temperature. The overall percentage change of VCO2 correlated with VO2 (r (2) = 0.91). CONCLUSION: Fever reduction in acute brain injury appears to significantly reduce systemic VO2, but is highly dependent on shivering control.
