BACKGROUND: New catheter-over-needle (CON) technology for continuous peripheral nerve blockade has emerged, but its effect on the risk of perineural catheter tip dislocation is unknown. Less flexible catheters may be more likely to migrate away from the nerve with simulated patient movement. In the present study, we evaluated catheter tip migration between CON catheters and traditional catheter-through-needle (CTN) catheters during ultrasound-guided short-axis in-plane (SAX-IP) insertion. METHODS: We evaluated the migration of popliteal-sciatic catheters in a prone, unembalmed male cadaver. Thirty catheter placement trials were divided randomly into two groups based on the catheter type: CON or CTN. A single anesthesiology resident placed the catheters by SAX-IP insertion, and the catheters were then examined by ultrasound before and after ipsilateral knee range of motion (ROM) exercises (0°–130° flexion). A blinded expert regional anesthesiologist performed caliper measurements on the ultrasound images before and after the ROM exercises. The primary outcome was the change in distance from the catheter tip to the center of the nerve (cm) between before and after the ROM exercises. RESULTS: The change in the tip-to-nerve distance (median [10th–90th percentile]) was 0.06 (−0.16 to 0.23) cm for the CTN catheter and 0.00 (−0.12 to 0.69) for the CON catheter (P = 0.663). However, there was a statistically significant increase in dislocation out of the nerve compartment for the CON catheter (4/15; 0/15 for CTN) (P = 0.043). CONCLUSIONS: Although the use of different catheter designs had no effect on the change in the measured migration distance of popliteal-sciatic catheters, 27% of the CON catheters were dislocated out of the nerve compartment. These results may influence the choice of catheter design when using SAX-IP perineural catheter insertion.
Anesthesia, Conduction ; Anesthesiology ; Cadaver* ; Catheters* ; Dislocations* ; Exercise ; Humans ; Knee ; Male ; Nerve Block ; Peripheral Nerves ; Range of Motion, Articular ; Sciatic Nerve ; Ultrasonography

BACKGROUND: Despite the benefits of continuous peripheral nerve blocks, catheter dislodgment remains a major problem, especially in the ambulatory setting. However, catheter dressing techniques to prevent such dislodgment have not been studied rigorously. We designed this simulation study to test the strength of two commercially available catheter dressings. METHODS: Using a cadaver model, we randomly assigned 20 trials to one of two dressing techniques applied to the lateral thigh: 1) clear adhesive dressing alone, or 2) clear adhesive dressing with an anchoring device. Using a digital luggage scale attached to a loop secured by the dressing, the same investigator applied steadily increasing force with a downward trajectory towards the floor until the dressing was removed or otherwise disrupted. RESULTS: The weight, measured (median [10th–90th percentile]) at the time of dressing disruption or removal, was 1.5 kg (1.3–1.8 kg) with no anchoring device versus 4.9 kg (3.7–6.5 kg) when the dressing included an anchoring device (P < 0.001). CONCLUSIONS: Based on this simulation study, using an anchoring device may help prevent perineural catheter dislodgement and therefore premature disruption of continuous nerve block analgesia.
Adhesives ; Analgesia ; Anesthesia, Conduction ; Bandages* ; Cadaver ; Catheters* ; Humans ; Nerve Block ; Peripheral Nerves* ; Research Personnel ; Thigh