Starting with ultrasonography decreases popliteal block performance time in inexperienced hands: a prospective randomized study

Abstract

BackgroundThe widespread of hallux valgus surgery in a day care setting enhanced the role of regional anaesthesia in the last few years. Sciatic nerve block at popliteal fossa has been shown to provide safe and effective analgesia. Our purpose was to compare the success rate and performance time of popliteal block during resident’s training for regional anaesthesia by using nerve stimulation (NS) or combined nerve stimulation and ultrasound (NS + US).Methods70 adult patients undergoing hallux valgus surgery were randomly assigned to receive sciatic nerve block at popliteal fossa with US+NS or NS alone with a double injection technique for peroneal and tibial branches, respectively. Two residents experienced with nerve stimulator performed the procedures after a learning phase concerning ultrasonography. A local anaesthetic solution, containing 10 mL of 0.75% ropivacaine and 10 mL of 2% lidocaine was used: 12 mL were infiltrated close the tibial nerve, and 8mL were infiltrated close the common peroneal nerve. Block success rate, sensory block onset time, block performance time were evaluated. Recourse to general anaesthesia was considered as failure.ResultsNo differences were detected in success rate and onset time of sensory block between the two groups (P > 0.05). The time to block tibial nerve and the overall block time were significantly faster in US+NS group (P < 0.05).ConclusionsUltrasound guidance for popliteal nerve block resulted in similar success rate with a faster procedure time when compared with nerve stimulator, thus providing a possible effect on resident education and operating room efficiency.

Evidence Basis for Ultrasound Guidance for Lower-Extremity Peripheral Nerve Block

“…In the clinical studies that directly compared USG with PNS, USG significantly decreased BPT, 10,11,46 decreased cumulative 48-hour local anesthetic requirements, 12 and increased the rate of complete sensory and motor block. 45,48 Ultrasound guidance was equivalent to PNS in only 1 RCT in terms of surgical block success for single-injection popliteal sciatic nerve block, 46 and this was a secondary outcome.…”

“…45,48 Ultrasound guidance was equivalent to PNS in only 1 RCT in terms of surgical block success for single-injection popliteal sciatic nerve block, 46 and this was a secondary outcome. In a single RCT, USG provided no significant analgesic benefit in cumulative 48-hour opioid consumption as the primary outcome but did provide significant local anesthetic sparing (75% less) during the 48-hour sciatic perineural infusion as a secondary outcome.…”

“…46 These 3 studies demonstrated that USG consistently decreased BPT and increased the rate of complete sensory block within the predefined time frames. In addition, USG also demonstrated significant benefits in secondary outcomes of decreased number of needle passes 44,46 and decreased block-related discomfort, 44 as well as higher rates of complete motor block. 45,46 In contrast, there was no difference between USG compared with PNS in terms of surgical block success or sensory block duration.…”

“…43 Since the initial systematic review, there have been 18 additional high-quality RCTs (Jadad scores ≥3) investigating the utility of USG for sciatic nerve block in 1186 patients. Five RCTs directly compared USG with PNS (Table 2) for popliteal sciatic nerve block; 3 for single-injection techniques [44][45][46] and 2 for continuous popliteal sciatic nerve catheter placement. 47,48 Ten studies (Table 3) compared clinically relevant block-related outcomes based on different local anesthetic distribution patterns within these defined fascial compartments [49][50][51][52][53][54][55][56][57][58] : (1) circumferential local anesthetic distribution proximal versus distal with the sciatic nerve bifurcation (SNBF) and (2) subparaneural versus extraparaneural local anesthetic distribution proximal or distal with the SNBF.…”

“…In addition, USG also demonstrated significant benefits in secondary outcomes of decreased number of needle passes 44,46 and decreased block-related discomfort, 44 as well as higher rates of complete motor block. 45,46 In contrast, there was no difference between USG compared with PNS in terms of surgical block success or sensory block duration. 44,45 One study comparing an ultrasound-guided SAX-IP technique with a PNS technique for placement of continuous popliteal sciatic catheters found no significant difference in the primary outcome of 48-hour cumulative postoperative opioid consumption 47 and no significant differences in the secondary outcomes of postoperative resting or dynamic analgesia.…”