Continuous Adductor Canal Nerve Blocks: Relative Effects of a Basal Infusion v. Hourly Bolus Doses
Condition: Healthy Human Volunteers
Intervention: Bolus; Basal
Intervention description: An adductor canal catheter was inserted and ropivacaine 0.2% administered as hourly bolus doses of 8 mL each: one at time point zero and then on the hour for 7 additional doses.; An adductor canal catheter was inserted and ropivacaine 0.2% administered as a continuous basal infusion (8 mL/h) from time point zero for a total of 8 hours.
Phase: Phase 4
Study type: Interventional
Primary purpose: Treatment
Allocation: Randomized
Intervention model: Parallel Assignment
Intervention model description: This is a split-body study in which each study subject receives both treatments: one on each side of the body. Which treatment is applied to which side of the body is randomized (and masked).
Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Masking description: The only individual aware of the treatment group assignments is the investigational pharmacist who has no interaction with the study subjects. Treatment group assignments were released by the investigational pharmacy only after completion of data collection.
Enrollment: 24.0
Sex: All
Minimum age: 18 Years
Healthy volunteers: Accepts Healthy Volunteers

Summary:

      Patients usually experience moderate-to-severe pain following the knee replacement that is
      often treated with a femoral nerve block (injection of numbing medicine placed around the
      main nerve of the knee joint). To make the nerve block last longer, a tiny tube is often
      placed next to the nerve and numbing medicine is infused for multiple days. However, while
      the numbing medicine takes away pain, it also decreases sensations, muscle strength, and
      proprioception (knowing where the leg is in space without looking at it) which greatly
      increases the risk of falling. Since falling can be catastrophic following major surgery, a
      femoral nerve blocks are being phased out by surgeons and anesthesiologists. The
      most-promising replacement is called an adductor canal nerve block. For this new type of
      block, a perineural catheter is inserted into a small canal in the middle of the upper leg.
      This canal contains the sensory nerve fibers leading to the knee, and only a single nerve
      that serves a relatively small muscle. Multiple studies have demonstrated a dramatic increase
      in muscle strength using the new adductor canal block compared with the traditional femoral
      block. However, practitioners perceptions of the new block is that it provides insufficient
      pain control following knee arthroplasty, even though all of the sensory nerves affected with
      the femoral block are also-theoretically-affected with the adductor canal block. One reason
      for this difference may be the small canal of the latter which is a relatively tight area in
      which the numbing medicine might not spread particularly well (due to pressure from
      surrounding tissues). One way to possibly counter this issue is by providing repeated boluses
      of the numbing medicine that will improve the medicine's spread relative to a
      more-traditional slow, continuous ("basal") infusion. This study seeks to compare these two
      techniques of medication administration through perineural adductor canal catheters:

      Our primary aim is to test the hypothesis that, for continuous adductor canal blocks,
      providing local anesthetic as repeated, hourly bolus doses results in an increased sensory
      block compared with providing local anesthetic as a continuous basal infusion at an
      equivalent hourly dose.

      As a secondary aim, we hypothesize that, for continuous adductor canal blocks, providing
      local anesthetic as repeated, hourly bolus doses results in either equivalent or less motor
      block compared with providing local anesthetic as a continuous basal infusion at an
      equivalent hourly dose.
    

Eligibility criteria:

        Inclusion Criteria:

          -  (1) age ≥ 18 years; and (2) willing to have bilateral adductor canal perineural
             catheters placed with subsequent ropivacaine administration and motor/sensory testing
             for 14 hours, requiring an overnight stay in the UCSD CTRI-CCR to allow dissipation of
             local anesthetic infusion effects by the following morning.

        Exclusion Criteria:

          -  (1) current daily analgesic use; (2) opioid use within the previous 4 weeks; (3) any
             neuro-muscular deficit of either femoral nerves and/or quadriceps muscles; (4) morbid
             obesity [weight > 35 kg/m2]; (5) pregnancy (as determined by a urine pregnancy test
             prior to any study interventions); and (6) incarceration. We expect to recruit a
             maximum of 30 healthy volunteers; with a target goal of 24 for the analysis. Selection
             for inclusion will not be based on gender, race, or socioeconomic status. The study
             population of interest includes men and women of all races and socioeconomic status.
             There will be no participants from vulnerable populations, such as pregnant women,
             children, or prisoners.