The dose-response relationship of ketorolac as a component of intravenous regional anesthesia with lidocaine

Ketorolac (K) is a useful addition to lidocaine for IV regional anesthesia (IVRA). However, the minimal dose of K that is effective for this purpose has not been established. We added 0, 5, 10, 15, 20, 30, and 60 mg of K to 0.5% lidocaine IVRA for either carpal tunnel release or tenolysis. Pain was assessed in the postanesthesia care unit by using a visual analog scale. The duration of analgesia (time to first request for pain relief) and the use of Tylenol No. 3 tablets (T3) were measured. A linear dose-response relationship was observed between the dose of K and the duration of analgesia (r = 0.988) up to 20 mg of K. Similarly, the number of T3 tablets used was inversely related to the dose of K (r = 0.960) over the same range. There were no significant differences among the groups who received 20, 30, or 60 mg of K. We conclude that 20 mg of K is the optimal dose for inclusion with 0.5% lidocaine for IVRA under the conditions of our study. Implications: The antiinflammatory drug ketorolac is a useful addition to lidocaine for TV regional anesthesia. This study showed that 20 mg of ketorolac is equally effective as 60 mg in this context. However, smaller doses provided less effective pain relief, and a linear dose-response relationship was demonstrated.