Catheter-over Needle: Outpatient Study

Background: Local anesthetic (LA) may be delivered by a single injection or by continuous infusion through an indwelling catheter. A downside of the single-shot technique is that the LA has a limited duration of action, meaning that, after discharge, patients sometimes have to contend with post-surgical pain that limits their activities and reduces their quality of life. Occasionally, a supplementary dose of analgesic, such as morphine or a LA, will be administered, either intravenously or via single injection. We speculate that, rather than using a single injection, post-operative pain management may be better controlled by installing a perineural catheter pre- or intra-operatively, which would allow a flexible schedule of LA delivery post-operatively and enable clinicians to tailor an analgesia regimen to the patient's needs. Our aim is to compare the effectiveness of a double-shot anesthetic infusion - one to block the nerve and another to provide postoperative analgesia - to the conventional single-shot method in controlling pain following a regional nerve block.

Study objective: To assess the value of a catheter-delivered supplementary infusion of LA to control postoperative pain after a regional block.

Hypothesis: Patients who have received a regional nerve block will experience less post-surgical pain when a second shot of LA is delivered through a perineural indwelling catheter just prior to discharge.

Study procedures: We will recruit patients who are scheduled to undergo surgery that requires a regional block of the upper extremity. We anticipate recruiting thirty individuals; the control group will receive one dose of LA using the conventional single-shot method, and the study group will be fitted with a perineural catheter through which one dose of LA will be delivered prior to surgery and another just before discharge from the hospital.

On the day of surgery, participating patients will be taken to the regional block area. Control group patients will be given a single injection of LA, under ultrasound guidance, to block the appropriate target nerve(s). These patients will undergo surgery and post-anesthesia recovery as per standard procedures. For patients in the experimental group, the attending anesthesiologist will, under ultrasound guidance, insert a perineural catheter at an appropriate location to block the target nerve. Once the catheter is in place, a single dose of LA will be delivered to block the target nerve, and the catheter will remain in the patient throughout the procedure. In the post-anesthesia recovery area, patients with a catheter will receive a second bolus infusion of the same LA. When the patient is approved for discharge, the catheter will be removed, the insertion site cleaned, and the patient will be allowed to go home.

A research assistant ask patients to rate their pain using a 0-10 numerical rating scale: 1) prior to delivery of the first dose of LA, 2) immediately following surgery (just before the second anesthetic infusion for experimental group patients), and 3) immediately before discharge from the hospital (after the second anesthetic infusion for experimental group patients). On the day after surgery, the research assistant will contact patients in both groups and will ask them to rate their pain over the 24-hour post-operative period. Pain reporting at these four time points will provide us with a comprehensive assessment of patient comfort after their regional nerve block and whether the second infusion of LA was effective at alleviating post-operative pain.

Primary outcomes:

1. Postoperative pain levels
2. Patient comfort at home

Inclusion criteria: Adult; scheduled for surgery that requires peripheral nerve blockade.

Exclusion criteria: Failure to provide informed consent; allergy to LA; neurological pathology and/or deficit in the block region.