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 doseresponse 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 mg). 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, 224.2 mg [95% confidence interval (CI) 229.5 to 219.0]}, compared with cardiac -thoracic surgery [29.7 mg (95% CI 217.6 to 21.80)]. 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 ]. 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. 2009; 102: 156-67 Br J Anaesth

Persistent hypothermia after intrathecal morphine: case report and literature review

“…The advantages of intrathecal morphine include its opioid sparing effect in the postoperative period, 1 targeted site of action in the central nervous system, and extended duration of action mediated by its effect on opioid receptors in the spinal cord. 2 Intrathecal doses of morphine can also be associated with pruritis, urinary retention, nausea, and delayed respiratory depression. 2,3 While hypothermia can be a common consequence of spinal anesthesia due to vasodilatation and the loss of the shivering reflex, 4 several anecdotal reports describe persistent hypothermia in the obstetrical population after spinal anesthesia using intrathecal morphine.…”

“…2 Intrathecal doses of morphine can also be associated with pruritis, urinary retention, nausea, and delayed respiratory depression. 2,3 While hypothermia can be a common consequence of spinal anesthesia due to vasodilatation and the loss of the shivering reflex, 4 several anecdotal reports describe persistent hypothermia in the obstetrical population after spinal anesthesia using intrathecal morphine. [5][6][7][8][9] This case report describes persistent hypothermia following spinal anesthesia using intrathecal morphine for total knee arthroplasty and the return to normothermia after sublingual lorazepam.…”

Opioids added to local anesthetics for single-shot intrathecal anesthesia in patients undergoing minor surgery: A meta-analysis of randomized trials

“…For instance, there is now strong evidence that in patients undergoing major abdominal surgery, intrathecal morphine alone significantly decreases pain intensity and opioid requirements postoperatively [57]. However, dose responsiveness of intrathecal morphine remains obscure and potentially serious adverse effects such as respiratory depression may limit the usefulness of this analgesic technique [57].…”

Recent Advances in Postoperative Pain Therapy for Thoracic Surgery

“…The effectiveness of a single injection of an opioid into the subarachnoid space is a long-established but infrequently used analgesic technique in thoracic surgery [92][93][94]. Predominantly, subarachnoidal formulated morphine (100-1,000 lg) and sufentanil (\25 lg) have been used for this purpose [94].…”

“…Predominantly, subarachnoidal formulated morphine (100-1,000 lg) and sufentanil (\25 lg) have been used for this purpose [94]. To date, a low number of studies published an effective pain relief during thoracic surgery but often lacked an evidence-based design [92,95].…”