Ultrasound Guided Repositioning of a New Suture-Method Catheter for Adductor Canal Block

Study Overview
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Brief Summary
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This is a randomized clinical trial in healthy volunteers. 12 volunteers will have suture-method catheters placed in the adductor canal of each leg using the long-axis plane and short-axis plane technique. The investigators will inject LA in both catheters to confirm correct position. Following return of cold sensation the catheter is then displaced intentionally. The orifice is identified by injection of isotonic saline to ensure a proper displacement (spread outside of the adductor canal) and the distance from the delivery orifice of the catheter to the adductor canal is noted. A second investigator will assess distance from the LA delivery orifice of the catheter to the adductor canal using hydrodissection with isotonic saline to pinpoint the delivery orifice and subsequently reposition the catheter to obtain LA spread within the adductor canal. Successful repositioning is defined as a combination of LA spread within the adductor canal and loss of cold sensation on the medial part of the lower leg.

Detailed Description
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The study objective is to investigate whether it is possible to reposition a displaced suture-method catheter using ultrasound. A peripheral nerve catheter will be inserted on each side under US guidance. An investigator will insert one catheter in the short-axis plane of the adductor canal using an in plane technique: The needle is inserted through the vastus medialis into the adductor canal and exits superficial to the femoral artery through the sartorius muscle. The second catheter is inserted from proximal to distal direction in the long-axis plane using a combination of in-plane and out-of-plane techniques. 10mL of isotonic saline is used for hydro-dissection for both catheter insertions to facilitate placement. Both catheters are injected with 15 mL LA with an immediate assessment of the spread being within or outside the adductor canal. Loss of cold sensation in the cutaneous saphenous nerve innervation area will be evaluated 15 minutes after injection by another investigator, who is blinded to allocation and randomization. Following return of normal sensory function the catheter is then intentionally displaced at least 2 cm outside the adductor canal in the direction of the entry or exit site according to randomization. The distance from the LA delivery orifice of the catheter to the adductor canal is noted. Adequate displacement requires that injection of isotonic saline does not result in spread within the adductor canal. A third investigator will assess distance from the LA delivery orifice of the catheter to the adductor canal and subsequently reposition the catheter using saline to pinpoint location of the delivery orifice. Once the catheter is repositioned LA is injected. The US scan during LA injection is performed with a fourth investigator present to evaluate for satisfactory spread within the adductor canal. The 2 investigators will not communicate regarding the assessment of spread within the adductor canal. Evaluation of cold sensation on the medial part of the lower leg is performed 15 minutes after 15mL LA (lidocaine 10 mg/mL) injection by investigator 2. The catheters are then removed and the study is completed. Distance from catheter delivery orifices to the adductor canal is defined as following: Distance from the LA delivery orifice to the fascia surrounding the adductor canal is noted in the short axis group. The distance from the LA delivery orifice to the penetration of the aponeurosis lying just below the sartorius muscle is noted in the long axis group. Both represent anatomical reference points for the adductor canal. Satisfactory spread within the adductor canal is defined as following: The LA injection spreads deeper along the lateral side of the femoral artery, observed in the two-dimensional plane while producing minimal displacement of the roof and the overlying sartorius muscle. The injection may spread occasionally superficially over the femoral artery within the canal and will then force the artery deeper. If the injection spreads more medially and superficially over the saphenous nerve and femoral artery in an anterolateral to posteromedial direction, initially resembling the injections within the adductor canal but separates the sartorius muscle from the femoral artery by lifting the sartorius muscle medially off the hyperechoic roof of the adductor canal it is considered not to spread within the adductor canal.13 Successful primary placement and subsequent repositioning is defined as the combination of satisfactory spread within the adductor canal (assessed using SAX visualization of the adductor canal for both catheters) and loss of cold sensation.

Official Title
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Ultrasound Guided Repositioning of a New Suture-method Catheter for Adductor Canal Block - a Randomized Study in Healthy Volunteers

Conditions
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Anesthesia, Pain, Postoperative, Pain, Pain, Joint

Intervention / Treatment
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* Procedure: SAX catheter insertion
* Procedure: LAX catheter insertion


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Male or female ≥18 years of age. ASA classification ≤ II. Written informed consent obtained from subject and ability for subject to comply with the requirements of the study. Exclusion Criteria: Previous surgery or ongoing pain or other disability of investigated region resulting in sensory or neurologic deficits in the investigated region. Allergy to LA. Pregnancy (all female participants will be tested for urine hCG), breastfeeding, or unwilling to practice birth control during participation in the study.

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Device Feasibility
Allocation: Randomized
Intervention Model: Parallel Assignment
Interventional Model Description: This is a randomized clinical trial in healthy volunteers. 12 volunteers will have suture-method catheters placed in the adductor canal of each leg using the long-axis plane and short-axis plane technique
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: SAX catheter insertion<br>Ultrasound guided cather insertion in the short axis (SAX) of the adductor canal. Injection of lidocaine through the catheter | Procedure: SAX catheter insertion<br>* Suture-method catheter inserted in the short axis of the adductor canal<br>|
| Active Comparator: LAX catheter insertion<br>Ultrasound guided cather insertion in the long axis (LAX) of the adductor canal. Injection of lidocaine through the catheter | Procedure: LAX catheter insertion<br>* Suture-method catheter inserted in the long axis of the adductor canal<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Successful repositioning | Defined as a combination of spread within the adductor canal and loss of cold sensation on the medial part of the lower leg after repositioning and second LA injection. - investigator 3 will evaluate spread and investigator 2 will evaluate cold sensation | 15 min after second injection | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Successful primary placement | Defined as a combination of spread within the adductor canal and loss of cold sensation after initial LA injection - investigator 1 will evaluate spread and investigator 2 will evaluate cold sensation | 15 min after first injection | 
| Estimation of Limits of Agreement | in evaluation of displacement distance of the catheter between investigator 1 and 3 | within 15 minutes, after displacement/repositioning.(recorded by after displacement and repeated just before attempted repositioning) | 
| Interrater agreement for satisfactory spread within the adductor Canal, (Cohen's Kappa) | Investigator 3 and 4 will independently evaluate spread within the adductor canal. | recorded immediately after second LA injection |