Active versus Passive Warming In The Prevention of Inadvertent Intraoperative Hypothermia

Abstract

Objective: To compare the efficacy of active warming with passive warming in prevention of inadvertent intraoperative hypothermia (IPH) in patients undergoing surgery under general anesthesia lasting longer than 30 minutes.

Methodology: Sixty patients planned for low to moderate risk surgery under general anesthesia lasting at least 30 minutes were randomly divided into 2 groups. After the measurement of preoperative baseline core temperature on patient’s arrival in the OR. In the Active Warming group, forced air warming was initiated before induction of anesthesia and was continued throughout the surgery. In the Control Group, patients were only covered with cotton blankets and surgical drapes. Intraoperatively core body temperature was measured using nasopharyngeal probe at 15 minute intervals. At the end of surgery, patient was shifted to PACU where body temperature was again recorded at 10 minute intervals using an infrared tympanic membrane thermometer.

Results: The Mean ± SD of age in the study was 36.95 ± 9.659. The male gender was 38.3%, and the female gender was 61.7% of the study population. A 40% and 16% decrease in the incidence of intraoperative and postoperative hypothermia respectively, is observed in the active warming group. As for the severity of intraoperative hypothermia, a significant reduction in mild hypothermia is observed (p-value <0.015) but the results for moderate hypothermia are not statistically significant (p-value 0.09). The incidence of postoperative shivering was 20% in the active warming group and 16.9% in the control group (p-value 0.399), which was not statistically significant.

Conclusion: This study demonstrated the benefits of active warming using forced air warmer in preventing inadvertent intraoperative hypothermia in patients undergoing procedures longer than 30 minutes under general anesthesia. It effectively reduces the incidence and severity of intraoperative and postoperative hypothermia.