Efficacy of Multimodal Opioid Therapy During Hepatic Resection Surgery

Choice of analgesia in hepatic resection surgery can be severely limited. This can depend upon on the pre-operative hepatic pathophysiology or the extent of parenchymal resection, both of which will affect peri-operative hepatic function, capacity for drug handling and risk of coagulopathy. Use of IV morphine during hepatic resection can result in high plasma levels post-operatively due to a reduced rate of morphine metabolism, risking a higher rate of morbidity. However, this remains a mainstay of peri-operative analgesia in combination with controversial non-opioid supplementation (paracetamol, non-steroidal anti-inflammatory drugs). This study compares the efficacy of IV morphine only versus a combination of pre-incisional intrathecal morphine and intra-operative IV remifentanil. Intrathecal morphine provides the mainstay of post-operative analgesia for 12-24 hours and remifentanil provides profound, titratable intra-operative analgesia until the delayed onset of the intrathecal morphine. We hypothesise that this combination might provide desirable intra-operative haemodynamic conditions and eliminate the post-operative additive effects of long-acting, intra-operative IV opioid and intrathecal morphine. Further, if the dose of intrathecal morphine is adequate, this would result in a low rate of post-operative analgesic supplementation and fewer side effects. The titratable dose range of remifentanil is limited to the lower range found to risk post-operative hyperalgesia.