Ultrasound-guided infragluteal sciatic nerve block: a comparison between four different techniques

Ultrasound guided sciatic block can be performed by different techniques. We compared namely short or long axis views of the sciatic nerve with in-plane or out-of-plane needle insertion techniques for the infragluteal sciatic nerve block (ISNB).

One hundred twenty patients with American Society of Anesthesiologists physical status I-III, scheduled for foot surgery were assigned into four groups. Group SI: patients received ultrasound-guided SNB using short axis (S) view of the SN and in-plane (I) insertion of needle. Group LI: patients received SNB using long axis (L) view of SN and (I) insertion of the needle. Group SO: patients received SNB using (S) view of SN and out-of-plane (O) insertion of the needle. Group LO: patients received SNB using (L) view of SN and (O) insertion of the needle. Primary outcomes included the time to perform the block (recognition and performance time) and the level of patient discomfort during block placement.

The recognition time and performance time were shortest in LI group (51 ± 16.4 and 87.7 ± 14.8 s), while they were longest in LO group (138.7 ± 21.4 and 160.3 ± 17.5 s). There were no significant differences between the groups as regards the number of attempts and needle redirections to elicit sciatic motor response. The level of patient discomfort was significantly less in the LI group in comparison with the SI and LO groups.

The LI approach required less time to complete the infragluteal sciatic nerve block procedure and it was more comfortable for the patients in comparison to the SO, SI and LO approaches.