Ultrasound-guided popliteal sciatic nerve block using a pocket-sized ultrasound machine: preliminary evidence

Abstract

Editor'Real-time ultrasound guidance is a recent development in the area of peripheral nerve blocks and perioperative pain management.1Nowakowski P Bieryło A Duniec L Kosson D Łazowski T The substantial impact of ultrasound-guided regional anaesthesia on the clinical practice of peripheral nerve blocks.Anaesthesiol Intensive Ther. 2013; 45: 223-229Crossref PubMed Scopus (11) Google Scholar Recently, the development of digital technology and miniaturization of ultrasound scanners have moved these scanners from the echo laboratories into the white coat pocket. This makes them an excellent clinical tool, available for any physician in different clinical settings as a point-of-care ultrasonography tool.2Mjølstad OC Andersen GN Dalen H et al.Feasibility and reliability of point-of-care pocket-size echocardiography performed by medical residents.Eur Heart J Cardiovasc Imaging. 2013; 14: 1195-1202Crossref PubMed Scopus (75) Google Scholar In the present study, we tested the utility of a pocket-sized ultrasound machine equipped with a linear transducer for popliteal sciatic nerve block in patients with lower limb trauma. After institutional ethics committee approval and written informed consent, 15 patients with major foot, ankle, and tibia/fibula fractures were enrolled. Exclusion criteria were significant peripheral neuropathies, pregnancy, and psychiatric illness or altered level of consciousness. Staff anaesthetists with significant experience in the performance of ultrasound-guided blocks carried out all the procedures. Patients were positioned prone or in lateral recumbency with the affected limb uppermost. The skin was sterilized, and infiltration with lidocaine 1.5% (2–3 ml) was performed prior to needle insertion. A standardized local anaesthetic mixture of lidocane 2% (10 ml) and ropivacaine 0.5% (15 ml) were administered. The popliteal area was scanned and examined with a pocket-sized ultrasound machine armed with a linear probe (V-SCAN with dual probe; GE Healthcare, Waukesha, Wisconsin, USA; Fig. 1a). The sciatic nerve was identified in the popliteal fossa at the level of its bifurcation in both longitudinal and cross-sectional views (Fig. 1b and c). Nerve block was performed distal to its bifurcation by using a 21 or 19 gauge needle (Pajunk GmbH, Geisingen, Germany) if a peripheral nerve block catheter was to be placed. In eight of 15 patients, a continuous peripheral nerve block catheter was inserted. After local anaesthetic injection (Fig. 1d), the progress of the sensory block was assessed at 5 min intervals for the first 20 min. Sensory function was assessed as sensation to pinprick with a 23 gauge needle in the tibial (plantar area of the foot) and common peroneal (dorsal area of the foot) anatomical territories. Sensory function was graded as follows: zero, normal; one, moderate sensory loss; or two, complete sensory loss. Additionally, static and dynamic visual analogue scale scores were measured. A total score of three out of four was considered as successful sensory block. According to our results, the block success rate was 100%, and the static and dynamic visual analogue scale scores were zero at 20 min. No complications, including vascular puncture and local anaesthetic toxicity, were observed. A paraesthesia response was elicited in five of 15 patients. Postoperative neurological examination after recovery of sensory and motor function of the lower limb revealed no neurological deficit. A pocket-sized ultrasound linear probe seems to facilitate popliteal sciatic nerve block, providing a feasible and safe technique for perioperative pain management in patients with lower limb injuries. Further studies are required in order to validate our observations. None declared.