Heat loss occurs in a number of different ways including heat passing directly from the patient to the environment, cold air moving over the patient’s body, transfer of heat to the cold OR table, and evaporation of moisture from the body’s surface.

The Effects of Hypothermia A relatively small drop in core temperature can result in major complications and death. These effects are well documented and include:

Increases in surgical site infections (SSIs). The incidence of culture positive wound infections was 3
times higher according to one study.2 Increased bleeding. Blood loss is significantly greater in hypothermic
patients at the end of surgery and 3, 12, & 24 hours after surgery.3 Increased cardiac events. Hypothermic
patients were 2 - 3 times more likely to have ECG events, myocardial ischemia and ventricular tachycardia.4 Increased mortality rates. Hypothermia occurring during surgery is associated with significantly increased mortality rates.5

Prolonged and altered effect of drugs used during anesthesia. In hypothermic patients, the average duration of neuromuscular blocking agents and the onset of action of neuromuscular reversal agents is more than doubled.6 Extra time in recovery. Patients with a temperature of 4°C need an average of 90 minutes longer in the PACU than normothermic patients.7

End of Surgery
End of surgery blood loss is higher in hypothermic patients at the end of surgery. Schneid, Lancet 1996

Induction of Anesthesia
Core temperature can drop as much as
1.6°C in the first hour after induction of general and regional anesthesia
Sessler, Anesthesiology

Increased Infection Rate
Infection rates for hypothermic patients are significantly higher than for normalthermic patients. Kurz, New Eng J Med 1996

Prolonged Recovery
Hypothermic patients stay in the post anesthesia care unit an average of 90
minutes longer. Lenhardt, Anesth 1997