A Comparative Study of Three Warming Interventions to Determine the Most Effective in Maintaining Perioperative Normothermia

Perioperative hypothermia poses a challenge because of its deleterious effects on patient recovery. The current practice of applying two cotton blankets on patients during surgery is thought to be less ideal than using reflective insulation or forced-air warming. We studied 300 patients who underwent unilateral total knee replacement and were randomized equally to three groups: (a) the two-cotton-blanket group, (b) the one-reflective-blanket with one-cotton-blanket group, and (c) the forced-air-warming with one-cotton-blanket group. Tympanic temperature readings were taken before surgery in the induction room, on arrival at the recovery room, and at 10-min intervals until discharge from the recovery room. On arrival at the recovery room, the forced-air-warming group had significantly higher temperatures (adjusted for sex, age, and patient’s induction room temperature) of 0.577°C ± 0.079°C (95% confidence interval [CI], 0.427–0.726;P < 0.001) and 0.510°C ± 0.08°C (95% CI, 0.349–0.672;P < 0.001) more than the reflective-blanket and two-cot-ton-blanket groups, respectively. The forced-air-warming group took a significantly (P < 0.001) shorter time of 18.75 min (95% CI, 13.88–23.62) to achieve a temperature of 36.5°C in the recovery room as compared with 41.78 min (95% CI, 36.86–46.58) and 36.43 min (95% CI, 31.23–41.62) for the reflective-blanket and two-cotton-blanket groups, respectively. The reflective technology was less effective than using two cotton blankets, and the forced-air warming was most efficient in maintaining perioperative normothermia.