A randomised double‐blind controlled study evaluating the hypothermic effect of 150 μg morphine during spinal anaesthesia for Caesarean section

Abstract

SummaryWe studied the hypothermic effect of adding 150 lg morphine during spinal anaesthesia in 60 parturients scheduled for elective caesarean section. All the parturients received intrathecal injection of a solution containing 150 lg morphine or normal saline in addition to 10-12 mg hyperbaric bupivacaine 0.5%. In both groups, a significant decrease in body temperature was noted. There was no difference in the area under the curve for temperature against time for the two groups; however, the maximum decrease in temperature from baseline was significantly larger after morphine than after saline injection (mean (SD) 1.11 (0.61)°C vs 0.76 (0.39)°C, respectively; p = 0.01) and the time to nadir temperature was significantly longer (59.5 (17.6) min vs 50.4 (15.9) min, respectively; p = 0.047). The lowest temperature observed in the morphine group was 34.3°C. We conclude that intrathecal injection of 150 lg morphine intensified the intra-operative hypothermic effect of bupivacaine spinal anaesthesia for caesarean section. Intra-operative hypothermia has been reported in parturients receiving spinal anaesthesia [1]. For parturients undergoing caesarean section, bupivacaine is a commonly used agent for providing spinal anaesthesia. When morphine is used in addition to local anaesthetics, it prolongs the duration of analgesia and provides postoperative pain relief [2]. Severe hypothermia has been reported when a large dose of morphine was used in spinal anaesthesia [3]. Although hypothermia associated with smaller doses of morphine has been reported sporadically [4,5], it is not known whether a very small dose of morphine (150 lg) would also intensify spinal anaesthesia-induced hypothermia. This randomised double-blind controlled study was performed to evaluate the effect of adding 150 lg of morphine to bupivacaine on body temperature in parturients during elective caesarean section under spinal anaesthesia. MethodsWe included 60 term pregnant women (ASA physical status 1-2) scheduled for elective caesarean section after informed consent. This study was approved by the institutional reviewing board. The individuals were assigned to receive either morphine or saline by a computer-generated randomisation table. The assignments were blinded to both the parturients and the anaesthetists who performed the spinal injection and measured the body temperature. After the parturients were transferred to the operating room, regular noninvasive blood pressure was recorded every 3 min. Lead-II configuration of the ECG and pulse oximetry were continuously displayed. Body temperatures were recorded from the same ear with an infrared tympanic thermometer (Welch Allyn 9000, accuracy ± 0.2°F). The room temperature was kept constant at 24°C. The parturients were prehydrated with 1000 ml Hartmann's solution, which was prewarmed to 37°C. After hydration, the baseline body temperature was obtained. A 27-G Quincke spinal needle was introduced into the subarachnoid space at the L2-3 or L3-4 interspace in the lateral decubitus position, and 10-...

Persistent hypothermia after intrathecal morphine: case report and literature review

“…12 Decreases in tympanic temperature occurred in both groups, but the morphine group experienced a larger decrease than the placebo group, i.e., 1.11 (0.61)°C vs 0.76 (0.39)°C, respectively; P = 0.01. 12 The lowest tympanic temperatures were 34.3°C and 35.2°C in the morphine and placebo groups, respectively.…”

A reply

“…B. Theaker N. Soni Chelsea & Westminster Hospital London SW10 9NH, UK E-mail: cbtheaker@hotmail.com I read Bell's editorial 'Routine preoxygenation -a new minimum standard of care' with interest [1]. Pre-oxygenation before induction of general anaesthesia has been recommended to increase the body oxygen reserves and, thereby, delay the onset of oxyhaemoglobin desaturation during subsequent apnoea.…”

“…We wish to comment on two papers recently published in Anaesthesia [1,2]. Both articles reported the incidence of hypothermia associated with the administration of intrathecal opioids for Caesarean section.…”

“…The paucity of data regarding pressure ulcer development in intensive care was highlighted by the authors of the recent randomised trial of pressure-relieving devices [1]. This is a subject that is not normally taught or considered to be a main stream topic in the medical management of the critically ill patient [2].…”

“…It is somewhat surprising to learn that whilst the Department of Health has issued guidance on issues as diverse as West Nile fever [1] and botulism [2], it has yet to issue formal guidance on the use of specialist beds and pressure sores. However, on the 22nd September 2005 the National Institute for Clinical Excellence in conjunction with the Royal College of Nursing published a document entitled 'The Management of Pressure Ulcers in Primary and Secondary Care: A clinical practice guideline care' [3].…”