Effect of ultra-low-dose naloxone with ultrasound-guided transversus abdominis plane block on postoperative pain relief in patients undergoing laparoscopic cholecystectomy

Introduction
Transversus abdominis plane (TAP) blocks have been described as an effective component of multimodal postoperative analgesia for a wide variety of abdominal procedures such as bowel resection, open/laparoscopic appendectomy, cesarean delivery, hysterectomy, laparoscopic cholecystectomy, open prostatectomy, renal transplant surgery, and abdominoplasty. Various adjuvants have been added to augment the effect and prolong the duration of action of analgesia in TAP block. The mechanism of action of ultra-low-dose naloxone includes selective inhibition of the impulses from excitatory opioid receptors and release of encephalin.
Aim
This study investigated the effect of ultra-low-dose naloxone on intensity and duration of analgesia of transversus abdominis plane block (TAP block). The primary outcome of the work is to assess the quality of TAB block with addition of ultra-low-dose naloxone in terms of time to first analgesic request (rescue analgesia) and visual analogue score (VAS) score. The secondary outcome is to assess opioid consumption and occurrence of complications (nausea and vomiting).
Patients and methods
A total of 100 elective laparoscopic cholecystectomy patients were included in our study who were divided randomly into two groups: in the naloxone group (N) (50 patients), bilateral ultrasound-guided subcostal TAP block was done with injection of bupivacaine 0.25% in the plane +100 ng naloxone with total volume of 20 ml in each side, and in the control group (C) (50 patients), bilateral ultrasound-guided subcostal TAP block was done with injection of bupivacaine 0.25% in the plane with total volume 20 ml in each side. Then, the patients were assessed for postoperative pain after full recovery as baseline and then every 4 h for 24 h by VAS. Time to first analgesic request (rescue analgesia), postoperative opioid consumption for the first 24 h, and any adverse effects (nausea and vomiting) were noted.
Results
We found, a highly significant decrease in VAS scores at 12, 16, 20, and 24 h in naloxone group compared with the control group (<0.01). There was a nonsignificant difference regarding VAS scores at PACU, 4, and 8 h (>0.05). Moreover, there was a highly significant increase in time to first analgesic request in naloxone group compared with the control group (<0.01). Regarding secondary outcomes, there was a highly significant decrease in postoperative opioid consumption in naloxone group compared with the control group (<0.01), and nonsignificant difference regarding nausea and vomiting (>0.05).
Conclusion
Ultra-low-dose naloxone usage in TAP block helps in reducing postoperative pain scores and postoperative opioid consumption in patients who underwent laparoscopic cholecystectomy.