Intrathecal Morphine for Cardiac Surgery: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Cardiac surgeries often result in significant postoperative pain, leading to considerable use of opioids for pain management. However, excessive opioid use can lead to undesirable side effects and chronic opioid use. This systematic review and meta-analysis aimed to evaluate whether preoperative intrathecal morphine could reduce postoperative opioid consumption in patients undergoing cardiac surgery requiring sternotomy. We conducted a systematic search of Cochrane, EMBASE, and MEDLINE databases from inception to May 2022 for randomized controlled trials that evaluated the use of intrathecal morphine in patients undergoing cardiac surgery. Studies that evaluated intrathecal administration of other opioids or combinations of medications were excluded. The primary outcome was postoperative morphine consumption at 24 h. Secondary outcomes included time to extubation and hospital length of stay. The final analysis included ten randomized controlled trials, with a total of 402 patients. The results showed that postoperative morphine consumption at 24 h was significantly lower in the intervention group (standardized mean difference -1.43 [-2.12, -0.74], 95% CI, P < 0.0001). There were no significant differences in time to extubation and hospital length of stay. Our meta-analysis concluded that preoperative intrathecal morphine is associated with lower postoperative morphine consumption at 24 h following cardiac surgeries, without prolonging the time to extubation. The use of preoperative intrathecal morphine can be considered part of a multimodal analgesic and opioid-sparing strategy in patients undergoing cardiac surgery.