title: A randomised controlled trial of hyperbaric bupivacaine with opioids, injected as either a mixture or sequentially, for spinal anaesthesia for caesarean section.
abstract: It is common practice to mix opioids with hyperbaric bupivacaine in a single syringe before intrathecal injection of the mixture. Mixing these drugs may alter the density of the hyperbaric solution, affecting the spread of local anaesthetic and opioid. Forty-eight women having elective caesarean section under spinal anaesthesia were recruited to this double-blind, randomised trial. Group M (n=24) received 2 ml of 0.5% hyperbaric bupivacaine plus morphine 100 microg plus fentanyl 15 microg, mixed in a syringe prior to administration. Group S (n=24) received 2 ml of 0.5% bupivacaine through one syringe, followed by morphine 100 microg plus fentanyl 15 microg through a separate syringe. All patients received patient-controlled intravenous morphine for 24 hours postoperatively. Block characteristics, postoperative pain scores and morphine use were noted. The patients in Group M had higher levels of sensory block to cold than those in Group S (median T2 vs. T3) (P = 0.003). Five patients in Group M and none in Group S had a block to cold > or = T1 (P = 0.02). There was no difference between groups in the incidence of hypotension, need for vasopressor or side-effects. Morphine consumption was significantly higher in group M (13.3 +/- 11.2 vs. 6.2 +/- 7.2 mg, P = 0.015). Mixing of fentanyl and morphine with hyperbaric bupivacaine results in a higher level of sensory block than sequential administration of bupivacaine then opioid and may be associated with higher postoperative opioid requirement.
authors.affiliation: Department of Women's Anaesthesia, KK Women's and Children's Hospital, Singapore.
authors.forename: S
authors.initials: S
authors.lastname: Desai
authors.forename: Y
authors.initials: Y
authors.lastname: Lim
authors.forename: C H
authors.initials: CH
authors.lastname: Tan
authors.forename: A T H
authors.initials: AT
authors.lastname: Sia
mesh_terms: D000328:Adult; D000701:Analgesics, Opioid / Q000008:administration & dosage*; D000773:Anesthesia, Obstetrical; D000775:Anesthesia, Spinal; D000779:Anesthetics, Local / Q000008:administration & dosage*; D002045:Bupivacaine / Q000008:administration & dosage*; D002585:Cesarean Section; D004311:Double-Blind Method; D005260:Female; D005283:Fentanyl / Q000008:administration & dosage; D006801:Humans; D007267:Injections; D009020:Morphine / Q000008:administration & dosage; D010149:Postoperative Pain / Q000517:prevention & control; D011247:Pregnancy
chemical_list: D000701:Analgesics, Opioid; D000779:Anesthetics, Local; D009020:Morphine; D005283:Fentanyl; D002045:Bupivacaine