Hydromorphone is Noninferior to Dexamethasone as an Adjuvant to Ropivacaine for Transversus Abdominis Plane Block After Laparoscopic Colorectal Cancer Surgery: A Randomized, Double-Blind Trial

Purpose: The transversus abdominis plane (TAP) block provides analgesia for laparoscopic colorectal cancer surgery. To extend block duration and provide adequate analgesia, adjuvants such as dexamethasone and hydromorphone have been used. This study hypothesized that hydromorphone is an effective adjuvant for local anesthetics, and it is noninferior to dexamethasone for the TAP block duration. Patients and Methods: Eighty-one subjects undergoing laparoscopic colorectal cancer surgery were randomized to Group C (given TAP- block with 40 mL of 0.25% ropivacaine and saline), Group H (given TAP- block with 40 mL of 0.25% ropivacaine, 0.05mg/mL hydromorphone and saline), or Group D (given TAP- block with 40 mL of 0.25% ropivacaine, 0.25mg/mL dexamethasone and saline). The primary outcome was the first request time for patient-controlled intravenous analgesia (PCIA). Additional outcomes included visual analog scale (VAS) scores, total opioid use, side effects including nausea, vomiting, pruritus, and respiratory depression. Results: Eighty subjects completed the study. Compared with Group C (428.6 ± 175.3 min), both Group D (546.1 ± 190.5 min; P = 0.032) and Group H (620.2 ± 185.3 min; P = 0.001) showed significantly prolonged first request time for PCIA. Moreover, the difference between the mean first request time for PCIA in Group H and Group D was 74.0 (95% confidence interval [CI], -37.7 to 185.7, P = 0.020 for noninferiority). The VAS score on coughing in Group D showed a significant decrease compared with Group C at 12 h post-operatively (P = 0.006). No significant differences were observed in other outcomes. Conclusion: The addition of hydromorphone to ropivacaine in TAP block provided noninferior analgesia duration compared to dexamethasone for laparoscopic colorectal cancer surgery.