Background and objectives: Ultrasound (US) imaging facilitates catheter placement adjacent to the most appropriate elements of the brachial plexus, which for shoulder surgery are the C5YC6 roots or superior trunk. Therefore, it was investigated whether such placement would improve catheter effectiveness compared to placement with traditional techniques.
Methods: Needles introduced for catheter insertion were prospectively randomized to either US guidance immediately lateral to the C5-C6 roots/superior middle trunks (n = 43) or neurostimulation (NS) guidance to an appropriate motor response at less than 0.5 mA (n = 40). Ropivacaine 0.5% 30 mL was administered via the catheter before surgery under general anesthesia. After surgery, ropivacaine 0.2% infusion at 2 mL/hr with on-demand 5-mL boluses via an elastomeric pump was continued at home for 2 to 5 days. Patients were questioned regarding the need for ropivacaine boluses, tramadol, and numerical rating pain score (NRPS) on postoperative days 1 and 2.
Results: Catheter interventions for an NRPS of greater than 2 (0-10) in recovery were lower in the US group (US = 2/43, NS = 10/39; P = 0.007). Day 1 median ropivacaine bolus consumption (US = 1, NS = 2; P = 0.03) and the proportion of subjects requiring 2 or more tramadol tablets (US = 2/43, NS = 7/39; P = 0.04) were lower in the US group. These differences were not present on day 2. Postoperative pain was similar in both groups. Median (quartiles) needle time under the skin was lower in the US group (49 secs [41-55 secs]) than the NS group (97 secs [80-137 secs]) (P G 0.001) and was associated with a 1-point reduction in procedural NRPS (median [quartiles]: US = 2 [1-4], NS = 3 [2-6]; P = 0.002).
Conclusions: After shoulder surgery, interscalene catheters placed with US demonstrated improved effectiveness during the first 24 hrs compared with those placed with NS. These catheters were also placed with less needling and a very small reduction in procedure-related pain.