Is the effect of inguinal field block with 0.5% bupivacaine on postoperative pain after hernia repair enhanced by addition of ketorolac or S(+) ketamine?

OBJECTIVE: The aim of the study was to assess whether coadministration of S(+) ketamine or ketorolac would enhance or prolong local analgesic effect of bupivacaine after inguinal hernia repair.

DESIGN: Prospective double-blind randomized study evaluating pain intensity after surgery under general anesthesia.

SETTING: Outpatient facilities of the University Hospital of Lausanne.

PATIENT: Thirty-six ASA I-II outpatients scheduled for elective day-case inguinal herniorraphy.

INTERVENTION: Analgesia strategy consisted of a wound infiltration and an inguinal field block either with 30 mL bupivacaine (0.5%) or with the same volume of a mixture of 27 mL bupivacaine (0.5%) + 3 mL S(+) ketamine (75 mg) or a 28 mL bupivacaine (0.5%) + 2 mL ketorolac (60 mg). Postoperative analgesic regimen was standardized.

OUTCOME MEASURES: Pain intensity was assessed with a Visual Analog Scale, a verbal rating score, and by pressure algometry 2, 4, 6, 24, and 48 hours after surgery.

RESULTS: The 3 groups of patients experienced the highest Visual Analog Scale pain score at 24 hours, which was different from those at 6 and 48 hours (P < 0.05). Apart from a significantly lower pain sensation (verbal rating score) in the ketorolac group at 24 and 48 hours and only at 48 hours with ketamine, there were no other differences in pain scores, pain pressure thresholds, or rescue analgesic consumption between groups throughout the 48-hour study period.

CONCLUSION: The addition of S(+)-ketamine or ketorolac only minimally improves the analgesic effect of bupivacaine. This may be related to the tension-free hernia repair technique associated with low postoperative pain.