 INCLUSIONEXCLUSION CRITERIA To be included the subject must be admitted to the ICU; have an arterial line as standard of care; have at least 2 hours of a temperature greater than 38.3C; within 24 hours of fever onset or ICU admission; be hemodynamically stable, and not received any drugs with known antipyretic effects at least 6 hours prior to initiating the study. Patients are excluded if they have an acute brain injury, liver dysfunction, cardiac dysfunction, requiring greater than 50 fraction of inspired oxygen FiO; mechanical ventilation is permitted, any extracorporeal blood treatments dialysis, plasmapheresis, etc., injury to more than 20 of the skin i.e. burn patient, or the responsible physician is opposed to enrolment. 