The additional analgesic effects of transverse abdominis plane block in patients receiving low-dose intrathecal morphine for minimally invasive colorectal surgery: a randomized, single-blinded study

PURPOSE: Intrathecal analgesia (ITA) and transverse abdominis plane block (TAPB) are effective pain control methods in abdominal surgery. However, there is still no gold standard for postoperative pain control in minimally invasive colorectal surgery. This study aimed to investigate whether the analgesic effect could be increased when TAPB, which can further reduce wound somatic pain, was administered in low-dose morphine ITA patients. METHODS: Patients undergoing elective colorectal surgery were randomized into an ITA with TAPB group or an ITA group. Patients were evaluated for pain 0, 8, 16, 24, and 48 hours after surgery. The primary outcome was the total morphine milligram equivalents administered 24 hours after surgery. The secondary outcomes were pain scores, ambulatory variables, inflammation markers, hospital stay duration, and complications within 48 hours after surgery. RESULTS: A total of 64 patients were recruited, and 55 were compared. There was no significant difference in morphine use over the 24 hours after surgery in the 2 groups (ITA with TAPB, 15.3 mg vs. ITA, 10.2 mg; P = 0.270). Also, there was no significant difference in pain scores. In both groups, the average pain score at 24 and 48 hours was 2 points or less, showing effective pain control. CONCLUSION: ITA for pain control in patients with colorectal surgery is an effective pain method, and additional TAPB was not effective.