Ultrasound-guided sciatic nerve block: a comparison between four different infragluteal probe and needle alignment approaches.

PURPOSE

Our aim was compare onset time of sciatic nerve blockade (SNB) performed distal to the subgluteal fold using four different ultrasound (US)-guided approaches in patients undergoing foot or ankle surgery.

METHODS

Patients were assigned to one of four groups: SI patients received SNB using short-axis (SA) view of the SN and in-plane (IP) placement of block needle (SA-IP approach); LI patients received SNB using long-axis (LA) view of the SN and IP needle placement (LA-IP approach); SO patients received the block using SA view of the SN and out-of-plane (OP) needle placement (SA-OP approach); LO patients received SNB using LA view of the SN and OP needle placement (LA-OP). Primary outcome included onset time of sensory and motor SNB. Patient satisfaction concerning the postoperative analgesia was noted.

RESULTS

The LI group had significantly faster onset of sensory blockade on the distribution of tibial nerve (16.0 ± 5.6 vs. 23.5 ± 3.6) and common peroneal nerve (12.5 ± 4.3 vs. 19.1 ± 5.4 min) in comparison with the LO group. The LI group had significantly faster onset of motor blockade on the distribution of tibial nerve (21.1 ± 6.2 vs. 26 ± 3.1) and common peroneal nerve (17.7 ± 4.8 vs. 23.7 ± 5.8 min.) in comparison with the LO group. The LI group had the highest rate of patient satisfaction for postoperative analgesia and the LO group had the lowest.

CONCLUSION

The LA-IP approach resulted in a rapid onset of SNB and was associated with the best satisfaction for postoperative analgesia in comparison with LA-OP, SA-IP, and SA-OP approaches for patients undergoing foot and ankle surgery.