To evaluate the effect of addition of Bupivacaine to intrathecal Morphine on intra-operative and post-operative analgesia in patients undergoing hepatobiliary surgeries under general anaesthesia - a randomised controlled study

Hepatobiliary surgeries are being performed with increasing frequency due to a rising incidence of hepatobiliary diseases. Effectively administered analgesia not only enables greater patient satisfaction by minimising acute postoperative pain, but through alleviating the acute physiological stress response to surgery, it facilitates enhanced recovery outcomes including early mobilisation and return to normal activity, reduced length of hospital stay, and reduced cardiac, respiratory and gastrointestinal postoperative complications leading to improved long-term patient survival rates. Thoracic epidural analgesia is often considered the gold standard analgesic modality in most peri-operative care programmes for patients undergoing hepatobiliary surgeries as it provides required level of analgesia to support mobilization, significant reduction in pulmonary, cardiovascular and thromboembolic morbidity in early post-operative period and reduced requirement of additional opioid analgesia. Despite its popularity, there exists high rates of epidural failure and concerns on its complications especially since epidural is an invasive, high-cost, labour-intensive technique. Furthermore, there is increased risk of epidural hematoma formation - secondary to coagulation changes after hepatobiliary surgeries, even in patients with normal preoperative coagulation profile. Also it is critical to remove the epidural catheter in a timely manner to minimize complications due to post-operative coagulation disturbances. Given the concerns raised with epidural analgesia in the context of hepatobiliary surgeries, intrathecal anaesthesia has emerged as a promising best practice yielding better patient outcomes as it is a simpler and quicker alternative neuraxial anaesthesia technique, with a lower rate of technical failure. Intrathecal morphine has good analgesic effects with significantly lower failure rates, and other benefits such as decreased postoperative fluid requirements, and shorter postoperative stays. But administration of ITM alone does not adequately prevent the establishment of central sensitization caused by incisional injury—as part of a pre-emptive analgesic strategy, nor assist with low CVP fluid strategies often deployed in these cases. Our hypothesis is that hyperbaric bupivacaine has sufficient cephalad spread to T4, serving as an analgesic bridge prior to the onset of action of intrathecal morphine, thereby lowering opioid requirements intraoperatively and postoperatively. Hence this study aims at prospectively evaluating the potential benefits of the addition of hyperbaric 0.5% bupivacaine to IT morphine 0.25 mg as a spinal regimen for hepatobiliary surgeries done under general anaesthesia.