The catheter-over-needle assembly facilitates delivery of a second local anesthetic bolus to prolong supraclavicular brachial plexus block without time-consuming catheterization steps: a randomized controlled study

Single-shot delivery of a supraclavicular brachial plexus block is effective for providing outpatient surgical anesthesia; however, patients generally must use oral analgesics to control pain shortly after discharge from the hospital. Catheterized delivery of supraclavicular blocks can be challenging to perform. We aimed to show that administering a second postoperative bolus of local anesthetic through a catheter placed by a catheter-over-needle assembly not only avoids time-consuming steps but also provides an extended analgesic effect compared with the traditional single-shot approach.

Patients were randomized into two groups: one group received a single-shot supraclavicular block with 25-30 mL of local anesthetic (1.5% lidocaine and 0.125% bupivacaine mixture), while the other group received a supraclavicular block via a catheter-over-needle assembly with the same volume and concentration of local anesthetic as for the single-shot block, which was followed by a second bolus of analgesic solution (0.2 % ropivacaine 20 mL) administered postoperatively through the catheter before its removal. The duration between the initial bolus and onset of pain was measured as well as the duration of pain relief from the last bolus.

Thirty patients were enrolled and randomized into the single-shot supraclavicular block group (n = 15) and the catheter-over-needle group (n = 15). One patient withdrew from the study, and five patients were lost to follow-up. We observed no significant difference between the two groups in time to perform the blocks. The mean (standard deviation [SD]) times were 3.1 (1.9) min and 4.4 (2.7) min for the top-up group and single-shot group, respectively (single-shot took 1.3 min longer than the catheter-over-needle group; 95% confidence interval [CI]: −0.65 to 3.25; P = 0.17). The mean (SD) duration of analgesia, measured from the beginning of the local anesthetic bolus to the onset of pain requiring rescue analgesia was 617.5 (288) min in the catheter-over-needle group and 377.2 (161.3) min in the single-shot control group (difference = 240.3 min; 95% CI: 46.8 to 433.8; P = 0.03).

Using the catheter-over-needle assembly for supraclavicular brachial plexus block facilitated effective delivery of a supplementary bolus of local anesthetic without extending the time to perform the block or increasing the number of steps. It also prolonged analgesia significantly compared with the single-shot approach. This trial was registered at: ClinicalTrials.gov, ID: NCT01522066.