Thermal management of the patient: where does the patient lose and/or gain temperature?

PURPOSE OF REVIEW: Anesthesia inhibits normal thermoregulatory control, leading to perioperative hypothermia or allowing therapeutic hypothermia. During the last decade many studies have shown the effects of anesthesia on thermoregulation. As a consequence many active warming and cooling devices are available to manipulate patients' core temperature. This review focuses on new findings in the field of temperature management. RECENT FINDINGS: Thermal management of patients has improved tremendously in recent years. Many outcome studies have shown adverse effects of perioperative hypothermia, as well as beneficial effects of therapeutic hypothermia after out-of-hospital cardiac arrest and brain trauma. However, inducing hypothermia is limited by physiologic thermoregulatory responses. Small reductions in core temperature lead to vasoconstriction and shivering, effectively hindering hypothermia. Thus prevention of vasoconstriction and shivering have become major goals during induction of therapeutic hypothermia. All anesthetics, opioids and sedatives lower the vasoconstriction and shivering threshold, thus allowing hypothermia. However, these drugs have side effects, such as respiratory depression, sedation and nausea. Several drugs, alone or in combination, lower the shivering threshold while causing minimal or no side effects. SUMMARY: Anesthesia affects thermoregulatory control and leads to perioperative hypothermia. The prevention of perioperative hypothermia improves patient's outcome. Therapeutic hypothermia can be induced and also improves outcome in certain conditions.