Coiling of Echogenic Sciatic Nerve Perineurial Catheters with Integral Stylet

To assess procedural effectiveness of the preferred coiling technique (method B), a pilot study was performed. Straight perineural catheters with coiled distal ends behind the sciatic nerve were examined in 25 patients who had sustained tibia fractures. Patients were placed in the lateral position (with the injured leg uppermost) and a US-guided sciatic nerve block was performed under aseptic conditions. The sciatic nerve was visualized at the upper third of the posterior thigh (short axis view) and a Tuohy needle (21 G × 10 mm, SonoLong/NanoLine, PAJUNK, Germany) was inserted in a lateral to medial direction. The needle was placed underneath the sciatic nerve and 10 ml of ropivacaine (0.1%) were injected. A perineural catheter (with retracted integral stylet by 6 cm) (SonoLong Sono, PAJUNK, Germany) was then threaded through the needle tip and coiled behind the sciatic nerve. Confirmation of correct catheter tip placement was defined as adequate spread and contact of ropivacaine injectate (3 ml, 0.1%) with the sciatic nerve (Figure 2C). If the distribution of the local anaesthetic (LA) could not be visualized on the first infusion, 2 additional injections were performed until the distribution was clearly seen. If LA spread could not be visually confirmed, or if, when confirmed, LA did not come in contact with the sciatic nerve, the case was excluded. Subcutaneous tunneling (4 cm long) and placement of a transparent adhesive dressing were used to secure the catheter. All sciatic nerve blocks were followed by an adductor canal block (10 ml of ropivacaine 0.5%) and general anaesthesia. A continuous infusion of ropivacaine (8-12 ml, 0.1%) was commenced and a combination of oxycodone 5 mg with paracetamol 325 mg was provided on an as-needed basis after surgery. All nerve blocks were assessed and data were collected in the post-anaesthetic care unit, and every 12 hours thereafter until 36 hours postoperatively from members of acute pain service (APS) team not participating in the study.