Introduction: Intravenous regional anesthesia (IVRA) of the upper limb is a simple and effective technique that can be used at all age groups, and its cost is low. One of its limitations is lack of postoperative pain relief after tourniquet deflation. Several pharmacological adjuvants (drugs) have been added to lidocaine to improve postoperative analgesia after IVRA, such as opioids, tramadol, nonsteriodal anti-inflammatory drugs, clonidine, dexmedetomidine and other drugs.
Methods: We used nitroglycerine (NTG) as an adjuvant to lidocaine to evaluate its effect on the quality on IVRA and postoperative pain relief. After informed written consent and ethical committee approval, forty patients undergoing short hand and forearm surgery under IVRA were randomly assigned into two equal groups. Group I (control group) received 3 mg/kg of lidocaine 2% diluted with saline to a total volume of 40 ml for IVRA. Group II (NTG group) received the same dose of lidocaine to which we added 100 µg nitroglycerine diluted to the same volume of solution. Tourniquet pain as well as hemodynamic parameters were measured and recorded 2, 5, 10,15,20,30 and 40 minutes after tourniquet inflation. Onset of sensory and motor block was recorded in each patient. At the end of surgery and after tourniquet deflation, sensory and motor recovery times were tested at 5, 10, 15, 20 and 30 minutes then every 1 hour till full recovery. Visual analogue scale (VAS) was used for assessment of postoperative pain at 15; 30 minutes, 1 hour, and then every 2 hour for 24 hours. Time for the first analgesic requirement was observed and recorded. Postoperative analgesia was achieved by using diclofenac 75mg. i.m, oral diclofenac 50mg. was given if needed in the first 24 hours (if VAS>3). Side effects were noted and recorded.
Results: There was significant shortening in VAS score of tourniquet pain in NTG group compared to control group (P<0.05). Sensory and motor block onset times were less in NTG in comparison with control group (3.95 ± .82 vs 5.60 ± 1.0 min ) for sensory,( 6.35 ± .98 vs 7.65 ± 1.20 min) for motor block. Sensory and motor recovery times were prolonged in NTG group compared to control group ( 7.75 ± 2.7 vs 3.8 ± 1.2 min ) for sensory, (12.60 ± 3.76 vs 5.95 ± 1.7min ) for motor recovery. Postoperative analgesia after tourniquet deflation was prolonged with statistically significant difference in VAS scores in all reading of first four hours postoperatively. Time (in minutes) to the first analgesic requirement time was prolonged in NTG group compared to control group (206 ± 33 vs 62 ± 20 min). Diclofenac consumption was much less in NTG group than in control group (127 ± 27 vs 165± 27 mg). No side effects were observed in any patients of either group.
Conclusion: addition of nitroglycerine to lidocaine in intravenous regional anesthesia improves sensory and motor block and decreases tourniquet pain and prolongs postoperative analgesia with no side effects.
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