Intrathecal morphine versus modified thoracoabdominal nerve block through the perichondrial approach for postoperative analgesia after major open abdominal surgery: A randomized clinical study

Background and Aims: This study aimed to compare postoperative opioid consumption and analgesic profiles between the modified thoracoabdominal nerve block through the perichondrial approach (M-TAPA) and intrathecal morphine (ITM) in major open abdominal surgery. Material and Methods: This study prospectively evaluated two postoperative analgesic strategies—ITM (200 μg) or bilateral M-TAPA with 0.25% bupivacaine (20 mL per side)—in 56 American Society of Anesthesiologists I–III patients managed with major open abdominal surgery. Following exclusions, 25 patients per group were analyzed. All patients received standardized multimodal analgesia. Total 24-h opioid consumption in morphine milligram equivalents was defined as the primary outcome. Resting and first mobilization numeric rating scale (NRS) scores, patient satisfaction, and adverse events were evaluated as secondary outcomes. Results: Total opioid consumption over the initial 24 postoperative hours was 8 mg (interquartile range [IQR], 5–14) in the ITM group compared with 12 mg (IQR, 9–20.5) in the M-TAPA group ( P = 0.025; 95% confidence interval: −9.51 to −0.97). Opioid consumption was comparable between groups in the initial 6 h postoperatively; however, ITM demonstrated greater opioid-sparing effects during the 6–36 h interval. Resting NRS scores were maintained under 4 in both groups. The mean sensory block duration of M-TAPA was 7.68 ± 2.98 h. Adverse events were infrequent, with pruritus observed in one ITM patient. Conclusions: ITM provides a more prolonged opioid-sparing effect, while M-TAPA offers effective early postoperative analgesia. These findings support individualized selection of regional analgesic techniques, particularly when neuraxial opioids are contraindicated or undesirable.