Criteria for core hypothermia: temperature < 36°C
Risk factors increasing the risk of hypothermia:
(1) high ASA physical status (risk greatest if ASA >= III, risk for ASA II > ASA I)
(2) magnitude of the operation (risk greatest if major surgery; risk medium > minor)
(3) use of combined epidural and general anesthesia
(4) duration of surgery > 2 hours
(5) not monitoring temperature during the procedure
Protective factors reducing the risk of hypothermia:
(1) high body weight and greater body surface area
(2) higher preoperative temperature
(3) warmer operating room temperature
Mortality in the patients was increased if:
(1) ASA >= II
(2) emergency surgery
(3) > 2 days in the ICU
Hypothermia was not an independent risk factor, but was associated with these.
Of these variables the only ones which the physician has any control:
(1) duration of the surgery
(2) temperature of the operating room
(3) monitoring of temperature during surgery
(4) type of anesthesia selected
Other factors that could reduce hypothermia:
(1) use of fluid warmer, especially with blood transfusion
(2) use of a patient warming device
For the implementation:
(1) An ASA >= III or major operation were high risk for hypothermia.
(2) An ASA = II, medium surgery, use of combined anesthesia, > 2 hours, failure to monitor, low body weight, low preoperative temperature, and cooler operating room temperature were taken as moderate risk factors.
