title: Benefit and risk of intrathecal morphine without local anaesthetic in patients undergoing major surgery: meta-analysis of randomized trials.
abstract: Intrathecal morphine without local anaesthetic is often added to a general anaesthetic to prevent pain after major surgery. Quantification of benefit and harm and assessment of dose-response are needed. We performed a meta-analysis of randomized trials testing intrathecal morphine alone (without local anaesthetic) in adults undergoing major surgery under general anaesthesia. Twenty-seven studies (15 cardiac-thoracic, nine abdominal, and three spine surgery) were included; 645 patients received intrathecal morphine (dose-range, 100-4000 microg). Pain intensity at rest was decreased by 2 cm on the 10 cm visual analogue scale up to 4 h after operation and by about 1 cm at 12 and 24 h. Pain intensity on movement was decreased by 2 cm at 12 and 24 h. Opioid requirement was decreased intraoperatively, and up to 48 h after operation. Morphine-sparing at 24 h was significantly greater after abdominal surgery {weighted mean difference, -24.2 mg [95% confidence interval (CI) -29.5 to -19.0]}, compared with cardiac-thoracic surgery [-9.7 mg (95% CI -17.6 to -1.80)]. The incidence of respiratory depression was increased with intrathecal morphine [odds ratio (OR) 7.86 (95% CI 1.54-40.3)], as was the incidence of pruritus [OR 3.85 (95% CI 2.40-6.15)]. There was no evidence of linear dose-responsiveness for any of the beneficial or harmful outcomes. In conclusion, intrathecal morphine decreases pain intensity at rest and on movement up to 24 h after major surgery. Morphine-sparing is more pronounced after abdominal than after cardiac-thoracic surgery. Respiratory depression remains a major safety concern.
authors.affiliation: Division of Anaesthesiology, University Hospitals of Geneva, 24, rue Micheli-du-Crest, CH-1211 Geneva 14, Switzerland.
authors.forename: N
authors.initials: N
authors.lastname: Meylan
authors.forename: N
authors.initials: N
authors.lastname: Elia
authors.forename: C
authors.initials: C
authors.lastname: Lysakowski
authors.forename: M R
authors.initials: MR
authors.lastname: Tramèr
mesh_terms: D000701:Analgesics, Opioid / Q000008:administration & dosage* / Q000009:adverse effects; D000768:Anesthesia, General; D000779:Anesthetics, Local; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D006801:Humans; D007278:Injections, Spinal; D009020:Morphine / Q000008:administration & dosage* / Q000009:adverse effects; D010147:Pain Measurement / Q000379:methods; D010149:Postoperative Pain / Q000517:prevention & control*; D016032:Randomized Controlled Trials as Topic; D012131:Respiratory Insufficiency / Q000139:chemically induced
chemical_list: D000701:Analgesics, Opioid; D000779:Anesthetics, Local; D009020:Morphine