A prospective, randomised, single-blinded controlled trial comparing ultrasound versus nerve stimulator guidance for...

Interscalene block is usually performed using either ultrasound (US) or nerve stimulator (NS) guidance. This single-blinded, prospective, randomised study was performed to find out whether US was able to offer distinct advantages over conventional NS guidance.

100 patients in the American Society of Anaesthesiology (ASA) physical status I to III, aged 18-70 years were randomised into US guided or NS guided group for interscalene block with 15 ml 0.5% bupivacaine and 5 ml 2% lignocaine. Patients were premedicated with midazolam 0.03 mg/kg (maximum 2 mg) and fentanyl 2 mcg/kg (max 100 mcg) was used as rescue analgesia.

Mean time of onset of sensory block in the NS group was 6.2 min (3.1), the US group 4.7 min (1.1), p value (<0.001). Mean duration of post-operative analgesia in NS group 323.6 min (98.6), US group 558.6 min (144.3), (p < 0.001). Mean time for performance of block NS Group 7.3 min (2.0), and in the US group 4.9 min (1.3), (p < 0.001). Number of needle passes NS group 1.7(0.9), US group 1.3 (1.0), (p < 0.005). Total cost per surgery with NS was Rs 363.10 less than in the US-guided block. Incremental cost effectiveness ratio for ultrasound group for onset of block was Rs -242.07, Rs 92.0 for duration of block and Rs -151.29 for time for performance of block. No incident of post-operative neurological complications seen in either group.

Ultrasound use offers faster onset, longer duration of block, reduces time for performance of blocks with comparable complication rates. For most of the measured parameters it was superior but more costly than nerve stimulator for directly measured costs.