Effects of Dexmedetomidine Versus Ketorolac as Local Anesthetic Adjuvants on the Onset and Duration of Infraclavicular Brachial Plexus Block

BACKGROUND: Infraclavicular brachial plexus block is an appropriate approach for distal arm and forearm surgeries. Local anesthetic adjuvant agents are used to improve the quality of nerve blocks. Dexmedetomidine and ketorolac are two different types of adjuvants, which have been used in some studies. OBJECTIVES: The purpose of this study was to examine the effects of dexmedetomidine and ketorolac as local anesthetic adjuvants on the onset and duration of infraclavicular brachial plexus block under ultrasound guide technique. PATIENTS AND METHODS: In a clinical trial study, 111 ASA class I and II patients who were candidates for elective distal arm and forearm surgeries under ultrasound guided infraclavicular brachial plexus block divided into three 37 patient groups. In dexmedetomidine group, 25 mL of lidocaine 1.5% plus 4 ml of normal saline and 100 mcg of dexmedetomidine was injected. Ketorolac group received 25 mL of Lidocaine 1.5% plus 5 mL of ketorolac, and placebo group received 25 mL of lidocaine 1.5% plus 5 mL of normal saline as local anesthetic solution. Sensory and motor onset blocks, duration of sensory and motor blocks and first time to analgesic request and hemodynamic parameters were all recorded. RESULTS: There were no significant differences in sensory block onset between three groups (P = 0.177). Motor block onset was statistically less in dexmedetomidine compared to ketorolac and placebo groups (both Ps < 0.001). Sensory block duration in dexmedetomidine group was significantly longer than ketorolac and placebo groups (both Ps < 0.001). Motor block duration in dexmedetomidine group was significantly longer than ketorolac and placebo groups (both Ps < 0.001). Time to first analgesic request after the procedures was longer in ketorolac compared to dexmedetomidine and placebo groups (P = 0.016, P < 0.001 respectively), but it was longer in dexmedetomidine compared to placebo group (P = 0.003). The differences of diastolic blood pressure in-between the 5th to 140th minutes after local anesthetic injection among the 3 groups were statistically significant and dexmedetomidine group shows the most reduction in diastolic blood pressure (P < 0.001). Dexmedetomidine showed the lowest mean arterial pressure (P = 0.016) and heart rate in dexmedetomidine group was significantly lower than ketorolac and placebo groups (P = 0.043). CONCLUSIONS: Our study showed that dexmedetomidine had better effects on sensory and motor block duration and motor block onset in comparison with ketorolac, as lidocaine adjuvants in infraclavicular brachial plexus block were present in both protocols. However, the first time to analgesic request by ketorolac was longer than dexmedetomidine.