Effect of prewarming on body temperature in short-term bladder or prostatic transurethral resection under general anesthesia: A randomized, double-blind, controlled trial

Abstract

Perioperative hypothermia causes postoperative complications. Prewarming reduces body temperature decrease in long-term surgeries. We aimed to assess the effect of different time-periods of prewarming on perioperative temperature in short-term transurethral resection under general anesthesia. Randomized, double-blind, controlled trial in patients scheduled for bladder or prostatic transurethral resection under general anesthesia. Eligible patients were randomly assigned to receive no-prewarming or prewarming during 15, 30, or 45 min using a forced-air blanket in the pre-anesthesia period. Tympanic temperature was used prior to induction of anesthesia and esophageal temperature intraoperatively. Primary outcome was the difference in core temperature among groups from the induction of general anesthesia until the end of surgery. Repeated measures multivariate analysis of covariance modeled the temperature response at each observation time according to prewarming. We examined modeled contrasts between temperature variables in subjects according to prophylaxis. We enrolled 297 patients and randomly assigned 76 patients to control group, 74 patients to 15-min group, 73 patients to 30-min group, and 74 patients to the 45-min group. Temperature in the control group before induction was 36.5 ± 0.5 °C. After prewarming, core temperature was significantly higher in 15- and 30-min groups (36.8 ± 0.5 °C, p = 0.004; 36.7 ± 0.5 °C, p = 0.041, respectively). Body temperature at the end of surgery was significantly lower in the control group (35.8 ± 0.6 °C) than in the three prewarmed groups (36.3 ± 0.6 °C in 15-min, 36.3 ± 0.5 °C in 30-min, and 36.3 ± 0.6 °C in 45-min group) (p < 0.001). Prewarming prior to short-term transurethral resection under general anesthesia reduced the body temperature drop during the perioperative period. These time-periods of prewarming also reduced the rate of postoperative complications.Study Registration Registered at ClinicalTrials.gov (Identifier: NCT03630887).

Figure 1

Flow chart diagram.

Figure 2

Repeated measures model for perioperative temperatures according to the prewarming duration: estimated marginal means (°C). 15-min: prewarmed for 15 min; 30-min: prewarmed for 30 min; 45-min: prewarmed for 45 min. The effects on temperature of the prewarming for 15 min did not show a statistically significant difference with the control group (p = 0.099). However, the effects showed statistically significant differences with the groups prewarmed for 30 min (p = 0.010) and for 45 min (p = 0.003).

Figure 3

Survival function for the length of stay in PACU according to the prewarming duration. The median length of stay obtained in each group were as follows: in the control group, 135 min; in the group prewarmed for 15 min, 120 min; in the group prewarmed for 30 min, 100 min; and in the group prewarmed for 45 min, 108 min.