Intraoperative phenylephrine infusion to reduce perioperative shivering in lower segment caesarean section: A randomised controlled study.

Background: Shivering is described as an involuntary, repetitive activity of the skeletal muscles that can have deleterious effects on anaesthetized patients. This study aimed to evaluate the effectiveness of phenylephrine infusion in preventing perioperative shivering in patients undergoing lower segment cesarean section under spinal anesthesia and to observe the change in the patient's core temperature between the study and control groups.

Methods: A total of 118 patients scheduled for elective lower segment cesarean section under spinal anesthesia were recruited for this prospective, double-blind, randomized controlled study. The patients were randomized into 2 groups with 59 patients per group. The phenylephrine Group received phenylephrine infusion at a rate of 0.5 mcg/kg/minutes, while the Control Group received normal saline at an equivalent rate. Systolic and diastolic blood pressure, heart rate, core temperature, and the presence and intensity of shivering were recorded before induction and every 15 minutes intraoperatively and postoperatively.

Results: The incidence of intraoperative shivering was significantly lower in the Phenylephrine Group compared to control group (29.1% vs 47.5% respectively; P = .044). Postoperatively, the Phenylephrine Group also had a lower incidence of shivering (34.5% vs 42.4%), but the difference was not statistically significant (P value = 0.391). There were no significant differences in the intensity of shivering between the 2 groups perioperatively, as well as in the systolic and diastolic blood pressure and core temperature. The phenylephrine Group showed a significantly lower heart rate at 15, 30, and 45 minutes after spinal block (P value = .005, .000, and .008, respectively), and at 0 and 30 minutes (P value = .004 and .020 respectively) in the recovery room. There were no significant differences in perioperative adverse events such as hypotension, hypertension, and bradycardia.

Conclusion: Phenylephrine infusion reduces the incidence of perioperative shivering in lower segment cesarean sections under spinal anesthesia.