The effect of preemptive analgesia with bupivacaine on postoperative pain of inguinal hernia repair under spinal anesthesia: a randomized clinical trial.

PURPOSE: In the absence of any study on the use of bupivacaine as a long acting local anesthetic for the purpose of inducing preemptive analgesia in patients undergoing inguinal hernia repair under spinal anesthesia, this study was conducted to provide some evidence for possible benefits of such practice.

METHODS: In this randomized clinical trial, local infiltration of bupivacaine in patients undergoing inguinal hernia repair under spinal anesthesia was compared with placebo. The patients were randomly divided to two groups of 30 including the case group who received 10 cc of 0.5 % bupivacaine and the control group who received 10 cc of normal saline in the operation site before surgical incision. At the end of spinal block effect, patients were followed for symptoms of pain intensity according to numerical rating scale method, nausea, vomiting and opioid use for 24 h past the operation.

RESULTS: The pain scores, nausea, vomiting and postoperative opioid use were 69.6, 76.5, 83.2 and 80 % respectively lower in first 24 h among the case group (P < 0.001, P = 0.005, P = 0.001 and P < 0.001). The number of patients with at least one analgesic request in first 24 h after operation was 64.2 % lower in case group, while time of first analgesic request was 67 % longer in treatment group (P < 0.001 and P < 0.001).

CONCLUSION: The pre-operative local infiltration of bupivacaine reduces pain, nausea, vomiting and opioid use in the first 24 h after inguinal hernia surgery under spinal anesthesia. Therefore, further evaluation of the efficacy of this technique as a modality of preemptive analgesia is suggested.