An Observational Study to Evaluate Anterior Approach Sciatic Nerve Block in Combination with Femoral Nerve or Saphenous Block for Below Knee Surgeries

Introduction: Sciatic nerve block is useful technique for unilateral lower limb surgeries particularly in patients who are not suitable for Central neuraxial blocks. Methodology: Forty patients from 20-70 years of either sex scheduled for below knee lower limb surgeries on elective or emergency basis, under sciatic nerve block by anterior approach in combination with femoral or saphenous nerve block were included under this trial. All blocks were given by landmark and PNS guided technique. Nerve block characteristics, success rate, patient comfort, complication etc. were observed. Results: Majorities of the patients (77.5%) required singe attempt. Only in 87.5 % patients’ plantar flexion was observed with nerve locator. In 5% patients, drug was injected when only paresthesia was found. Onset of sensory block was relatively fast 7.95 ±0.9 mins but motor blocks took time to establish 15.23 ± 0.9 mins. Primary block achieved in 21.5 ± 1.34 mins. Total procedure time with supplemental block were 5.76 ± 0.56 mins. Readiness time for surgery was 31.4 ±1.1 mins. Duration of motor block (3.86 ± 0.28 hrs) was less than the sensory block (8.27 ± 0.5 hrs). Duration of analgesia was quite larger (9.46 ± 0.52 hrs). Incidence of discomfort associated with performance of block was less. About block technique 78.9% patients said it hardly hurt. Only in 2.6 % patients required supplementation in form of IV sedation. 5% failed block patients were given spinal anaesthesia 35 minutes after block. Conclusion: Sciatic nerve block by anterior approach, lessen total procedure time for combination blocks. Foot twitches should be considered as end point and hamstring contractions should not accepted as motor response. In difficult block, try internal rotation of leg to expose nerve under the femur. Sciatic bock takes longer time (fairly 25-30 minutes) for full motor and sensory block achievement and provide long lasting postoperative analgesia, better tourniquet tolerance with stable hemodynamics. Anterior sciatic nerve block is therefore safe and effective technique and deserve to be used more widely for unilateral lower limb surgeries and postoperative analgesia.