Background and Aims This prospective double-blind randomized study aimed at evaluating the analgesic efficacy of ultrasonography-guided transversus abdominis plane (TAP) block when adding dexmedetomidine to the local anesthetic solution in patients undergoing unilateral elective inguinal hernia repair under general anesthesia.

Methods Fifty-eight patients were allocated to TAP block with either a solution of 25ml ropivacaine 0.5% and 2ml N/S 0.9% (group R) or a solution of 25ml ropivacaine 0.5% and 2ml dexmedetomidine 0.5 mcg/kg (group RD). The primary end point was pain score during movement 24 hours postoperatively as assessed with the numeric rating scale (NRS). Secondary endpoints included pain scores during rest and during movement at several time points postoperatively, intraoperative remifentanil consumption, morphine administration in the Post Anesthesia Care Unit (PACU) and 24-hour postoperative morphine consumption administered via a patient-controlled analgesia device (PCA). Six and twelve months postoperatively, the occurrence of chronic pain was assessed by phone interview.

Results There was not significant difference demonstrated between the two groups as to the primary endpoint. However, the RD group demonstrated lower intraoperative remifentanil consumption (p<0.001), lower PACU morphine requirement (p=0.04), lower PCA morphine requirement (p=0.01) and lower NRS scores 3 hours postoperatively both at rest and during movement (p=0.02 and p=0.034) as compared to the R group. Additionally, the incidence of chronic pain at 6 months was significantly lower in the RD group compared to the R group (p=0.025).

Conclusions Dexmedetomidine added to the local anesthetic mixture during TAP block performance seems to affect aspects of acute and chronic postoperative pain after inguinal hernia repair.

Ethics Committee Approval