PHYSOSTIGMINE PREVENTS POSTANESTHETIC SHIVERING AS DOES MEPERIDINE ORCLONIDINE

Background: Postanesthetic shivering develops in as many as one half o f patients recovering from isoflurane anesthesia, Cholinergic stimulat ion of the hypothalamic-pituitary-adrenal axis and adrenal medulla by physostigmine enhances secretion of arginine vasopressin, epinephrine, and norepinephrine. Because the hypothalamus is the dominant thermore gulatory controller in mammals, and these neurotransmitters may be inv olved in body temperature control, physostigmine administration may in fluence the incidence of shivering, Accordingly, the authors tested th e hypothesis that physostigmine administration inhibits postanesthetic shivering, Its efficacy was compared with that of saline (negative co ntrol) and meperidine and clonidine (positive controls). Methods: Sixt y patients having surgery of the ear or nose were tested, General anes thesia was induced with 2 mg/kg propofol, 0.1 mg/kg vecuronium, and 1. 5 mu g/kg fentanyl and maintained with isoflurane (1.5 +/- 0.4%) in 70 % nitrous oxide, At the end of surgery, the patients were randomly ass igned to receive an intravenous bolus of 0.04 mg/kg physostigmine, iso tonic saline, 0.5 mg/kg meperidine, or 1.5 mu g/kg clonidine. Heart fa te, mean arterial blood pressure, oxygen saturation, visual analog pai n score, temperature, and postanesthetic shivering were measured durin g recovery. Results: Postanesthetic shivering occurred in 6 of 15 (40% ) patients given saline. In contrast, postanesthetic shivering was sig nificantly reduced in physostigmine-treated patients (1 of 15, or 7%) and was absent in patients given clonidine or meperidine. Conclusions: Physostigmine inhibited shivering as well as did two established trea tments, meperidine and clonidine. These data suggest that cholinergic systems contribute to the genesis and control of postanesthetic shiver ing.