Analgesic Effect of Intrathecal Morphine Combined With Low Dose Local Anesthetics on Postoperative Analgesia After Liver Resection

All patients enrolled in the current study will receive intrathecal injections immediately prior to general anesthesia. The patient will be on his or her side in the fetal position and after palpating the back to secure the space between the 3rd and 4th lumbar spine, the area will be properly disinfected and draped with a sterile towel. Using a 25G needle, a small volume of 1% lidocaine will be injected at the proposed puncture site. For the control group, 2ml of 1% lidocaine will be injected subcutaneously with the 25G needle used during local anesthetic injection. For the morphine group and the morphine + bupivacaine group, a 25G pencil point spinal needle will be used to advance into the intrathecal space. After confirming intrathecal position of the needle by CSF regurgitation, morphine 400mg or morphine 400mcg+ bupivacaine 5mg each to a total volume of 2ml will be injected. Afterwards, all patients will undergo general anesthesia by the same method.