The effect of combining prewarming with intraoperative phenylephrine infusion on the prevention of hypothermia in patients undergoing urological surgery: a prospective, randomized, and controlled trial

Background: Hypothermia is common in patients undergoing urological surgery; however, no single preventative modality is completely effective. This study evaluated the effects of combining prewarming with intraoperative phenylephrine infusion for the prevention of hypothermia in patients undergoing urological surgery. Methods: This prospective study enrolled 58 patients scheduled for urological surgery under general anesthesia. The patients were randomized into two groups (n = 29). Patients in the experimental (prewarming and phenylephrine infusion) group (PP group) received prewarming for 20 min and intraoperative phenylephrine infusion, whereas those in the control group (C group) received no active prewarming with only intermittent administration of vasoactive agents. The patient's sublingual temperatures before and after anesthesia and nasopharyngeal temperature during anesthesia were recorded as core temperatures.Results: The incidence of intraoperative hypothermia was higher in the C group than in the PP group (57.7% [15/26] vs. 23.1% [6/26], P = 0.01). The severity of intraoperative hypothermia was higher in the C group than in the PP group (P = 0.004). The nasopharyngeal temperature at the end of surgery was lower in the C group than in the PP group (35.8 +/- 0.6 degrees C vs. 36.3 +/- 0.4 degrees C, P = 0.002). The trend of core temperature decline during the first hour after anesthesia induction differed between the two groups (P = 0.003; its decline was more gradual in the PP group).Conclusions: The combination of prewarming for 20 min and intraoperative phenylephrine infusion reduced the incidence and severity of intraoperative hypothermia and modified the trend of decreasing core temperatures in patients undergoing urological surgery.