Coiling of echogenic perineural catheters with integral stylet: A proof-of-concept randomized control trial in a sciatic nerve block simulator_Data.xlsx

We conducted a randomized study of two methods of perineural catheter advancement, investigating a technique that facilitates the coiling of a regular straight catheter (with integral stylet) behind the sciatic nerve in an ultrasound (US) regional anaesthesia simulator.Two groups of twenty catheters each (method A and method B) were evaluated under real-time ultrasound imaging.In method A the catheter was advanced beyond the needle tip with the integral stylet extending along its entire length;in method B the catheter was advanced after its integral stylet was retracted by 6 cm, thus providing flexibility to the catheter’s distal end.Procedural time was limited to15 seconds (total allowed performance time for each coiling maneuver). Each attempt was stored digitally and analyzed off-line (frame by frame)by two co-investigators who were blinded to group allocation. The two investigators decided independently whether the catheter coiled or not. The result was considered positive (coiled catheter) only after unanimous agreement between the two investigators. If the catheter distal end was not coiled or if the catheter bypassed the nerve and then coiled, the catheter was withdrawn,the needle tip reoriented (rotation of needle shaft/tip at 90 degrees), and the catheter was readvanced. In total, three attempts were allowed (overall procedural time: 45 seconds).The number of attempts to coil a catheter, as well as the proportion of cases where a catheter was successfully looped on first attempt, were measured.The patency of coiled catheters was tested after normal saline (3 ml) infusion through the catheter. Contact of saline spread with the nerve was also recorded.