Propofol and postanaesthetic shivering

Abstract

SummarySixty A S A grade 1 unpremedicated patients scheduled for minor elective surgery were randomly allocated to receive general anaesthesia consisting of either propofol-nitrous oxide in oxygen or a conventional technique of thiopentone-isojlurane-nitrous oxide-oxygen. Baseline axillary temperature readings, duration of operation and intra-operative decrease in axillary temperature were similar in both groups. The patients who received propofol-nitrous oxide-oxygen anaesthesia had a significantly lower incidence of postanaesthetic shivering than the control group. A propofol-nitrous oxide-oxygen technique may be preferable when postanaesthetic shivering is deemed undesirable. Key wordsComplications, shivering. Anaesthetics, intravenous, propofol.Shivering is common during recovery from anaesthesia. The incidence ranges from 5% to more than 60% [l] and varies with the age and sex of patients, anaesthetic technique and the duration of operation [2-51. Whilst there is little difference in the incidence of postanaesthetic shivering amongst the commonly used volatile agents, the influence of a total intravenous technique with propofol remains undetermined. Therefore, we compared the incidence of postoperative shivering following propofol-nitrous oxide anaesthesia with a conventional isoflurane-nitrous oxide technique. MethodsAfter institutional ethics committee approval and informed patient consent were obtained, we prospectively studied 60 ASA grade 1 unpremedicated adult patients aged 18-55 years who were scheduled for elective noncavity surgery (knee arthroscopy, herniorrhaphy, removal of simpleorthopaedic implants and excision of breast lump). Patients who had a recent episode of infection or blood transfusion or were receiving regular medication were not studied.The patients were randomly divided into two groups: the first received thiopentone 5 mg.kg-' and fentanyl2 pg.kg-' on induction and were maintained with 70% nitrous oxide and 1.5% isoflurane in oxygen (thio/iso/N20 group) and the second received propofol 2 mg.kg-' and fentanyl 2 pg.kg-' on induction and then 70% nitrous oxide in oxygen and a propofol infusion for maintenance (propofol group). The continuous propofol infusion was delivered by a Terumo syringe pump with an initial rate of 10 mg.kg-'.h-', reduced by 2 mg.kg-'.h-' every 10 min until a rate of 6 mg.kg-'.h-' was reached. If the patient's pulse rate or systolic blood pressure exceeded by 30% the pre-operative baseline readings, an additional bolus of propofol 0.5 mg.kg-' was given and the infusion rate increased by 2 mg.kg-'.h-l. Continuous patient monitoring included ECG, pulse oximetry, noninvasive blood pressure and end-tidal carbon dioxide.Axillary temperature was recorded using an electronic thermometer (Terumo CIIS) prior to induction and at 15min intervals thereafter until the end of surgery. No warming mattress was used and the operating theatre temperature was maintained at 22(SD 0.5)"C and a relative humidity of 55-58%. Unwarmed intravenous fluid was infused at a rate of lOml.kg-'...

THIS ARTICLE HAS BEEN RETRACTED Physostigmine for the prevention of postanaesthetic shivering following general anaesthesia – a placebo‐controlled comparison with nefopam

“…During anaesthesia, patients are protected against thermoregulatory responses by a lowering of the threshold for shivering and vasoconstriction. During recovery from anaesthesia, thermoregulation is no longer inhibited and shivering is triggered and becomes apparent when temperature is below the thermoregulatory threshold [25].…”

“…threshold, resulting in the cessation of shivering [25]. Analgesic agents, such as meperidine and sufentanil, have been shown to prevent postanaesthetic shivering via the l-or b-receptors [26].…”

Treatment of postanesthetic shivering in children: A randomized control study comparing tramadol to pethidine

“…In this study, anaesthesia with intravenous propofol were induced and maintained with isoflurane. The use of volatile general anaesthetic agents is associated with a higher incidence of shivering than observed with intravenous agent (Cheong and Low, 1995). This may explain our higher incidence of 10%.…”

Tremores intra e pós-operatório: prevenção e tratamento farmacológico

“…Durante a anestesia o paciente não apresenta respostas de regulação térmica porque o reflexo está inibido. Durante a recuperação da anestesia a inibição desaparece e os tremores se iniciam quando a temperatura está abaixo do limiar de regulação térmica 47 .…”

“…During anesthesia, the patient has no thermal regulation responses, because the reflex is inhibited. During recovery, the inhibition disappears and tremors appear when the temperature is below the thermal regulation threshold 47 .…”