A Randomized, Observer-Masked, Controlled, Parallel-Arm, Clinical Trial Comparing Through-the-Needle With Suture-Method Perineural Catheter Designs for Continuous Popliteal-Sciatic Nerve Blocks

This investigation will be a randomized, observer-masked, controlled, parallel-arm, human-subjects clinical trial. Of note, the investigators will be using standard-of-care perineural catheters and local anesthetic under their FDA-approved purpose and do not plan to research a possible change of indication or use of these drugs as part of this research project.

Consenting adults undergoing surgery with a planned popliteal-sciatic perineural catheter placement will be offered enrollment. Study inclusion will be proposed to eligible patients prior to surgery. If a patient desires study participation, written, informed consent will be obtained using a current UCSD IRB-approved ICF.

Following written, informed consent, the investigators will collect baseline anthropomorphic information (age, sex, height, and the investigatorsight). Subjects will be then be randomized using a computer-generated list and opaque, sealed envelopes to one of two treatment groups (blocks of 4, no stratification): perineural catheter insertion using (1) through-the-needle technique or (2) suture technique. All catheters will be placed by a regional anesthesia fellow or resident under the direct supervision and guidance of a regional anesthesia attending (or by the attending him/herself).

All subjects will have a peripheral intravenous (IV) catheter inserted, standard noninvasive monitors applied, supplemental oxygen administered via a nasal cannula or face mask, and positioned prone. Midazolam and fentanyl (IV) will be titrated for patient comfort, while ensuring that patients remain responsive to verbal cues. The area that will be subsequently covered by the catheter dressing will be clipped of hair, if necessary. The ultrasound will be placed to visualize the short axis (cross-section) of the sciatic nerve to identify the sciatic nerve bifurcation which will subsequently be marked, as well as the location 5 cm cephalad to the bifurcation. The area will be cleaned with chlorhexidine gluconate and isopropyl alcohol and a clear, sterile, fenestrated drape applied. The ultrasound probe will be placed to visualize the short-axis (cross-section) of the target nerve(s) and the target for the catheter to intercept the nerve may be anywhere between the bifurcation and 5 cm cephalad to the bifurcation. All catheters will be placed using standard UCSD ultrasound-guided perineural catheter techniques as previously described. Normal saline 5-20 mL will be administered via the needle and/or catheter to allow catheter insertion and/or testing of catheter location (viewed with ultrasound).

Local anesthetic (20 mL, lidocaine 2% with epinephrine 1:200,000-400,000) will be administered via the catheter. A "successful" catheter insertion will be defined as sensory-block onset in the tibial nerve distribution within 30 minutes following the local anesthetic injection. If the nerve block fails, the catheter will be replaced or the patient removed from further study.