Comparison of Perineural Catheter Depth for the Continuous Popliteal Nerve Block Using Ultrasound Guidance and Dermabond

Study Overview
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Brief Summary
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The study will investigate the difference in success rate between popliteal peripheral nerve catheters placed at 1 centimeter compared to 5 centimeters past the tip of a Tuohy needle.

Detailed Description
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Traditionally for the lower extremity, peripheral nerve catheters have been threaded greater than or equal to 5 centimeters past the tip of the Tuohy needle. The major rational for this practice is to reduce dislodgement. However, the greater the distance that a catheter is advanced, the greater the risk of contacting undesired structures, kinking, looping and knotting. For the continuous popliteal nerve block, the catheter is threaded perpendicular to the course of the nerve. This could result in the tip of the catheter being a significant distance from the targeted nerve which may lead to a decrease in the success rate or efficacy of the block. Greater efficacy may be seen if the needle is closer to its target. This may be quantified by documenting a faster onset of motor and sensory changes and/or a lower catheter infusion rate required to maintain pain control. The study will investigate the difference in success rate between popliteal peripheral nerve catheters placed at 1 centimeter compared to 5 centimeters past the tip of a Tuohy needle.

Official Title
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Comparison of Perineural Catheter Depth for the Continuous Popliteal Nerve Block Using Ultrasound Guidance and Dermabond

Conditions
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Neuromuscular Inhibition

Intervention / Treatment
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* Procedure: 1 cm
* Procedure: 5 cm


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Will be having a popliteal nerve blocks Do not meet any of the exclusion criteria listed below. Exclusion Criteria: < 18 years old BMI > 35 Pregnant patients Diabetes mellitus or patients with known neuropathy Amputations & polytrauma patients Patients allergic to local anesthetics Chronic Pain patients Patients in whom communication is a problem

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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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Group 1<br> | Procedure: 1 cm<br>* A Tuohy needle will be advanced in-plane with the bevel cephalad to a point that lies between the tibial and common peroneal branches of the sciatic nerve. The catheter will be advanced 1 cm past the tip of the Tuohy<br>* Other names: 20-gauge non-stimulating catheter;|
| Experimental: Group 2<br> | Procedure: 5 cm<br>* A Tuohy needle will be advanced in-plane with the bevel cephalad to a point that lies between the tibial and common peroneal branches of the sciatic nerve. The catheter will be advanced 5 cm past the tip of the Tuohy<br>* Other names: 20-gauge non-stimulating catheter;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in Peripheral block score (PBS). | The extent of popliteal nerve blockade will be captured with four sensory groups (sural, superficial peroneal, tibial, and deep peroneal) and three motor groups (superficial peroneal, tibial, and deep peroneal). For each group, a score of 0, 1, or 2 will be assigned based on complete, partial, or no blockade, respectively. The peripheral block score (PBS) outcome variable will be based on the sum of these values and will range from 0 to 14. | 10, 20, and 30 minutes after intervention | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Pain score | The investigators will examine the difference in the pain scores (0-10 numeric rating scale) between the two groups. | Arrival to PACU (Immediately after surgery, approximately 3-5 hours after intervention) | 
| Analgesia failure rate | The investigators will examine the difference in analgesia failure rates in the PACU. Analgesia failure is defined as the failure of a rescue bolus (to treat patient pain). | Arrival to PACU (Immediately after surgery, approximately 3-5 hours after intervention) | 
| Catheter dislodgement rates | The investigators will examine the difference in the catheter dislodgement rates. | Arrival to PACU (Immediately after surgery, approximately 3-5 hours after intervention) | 
| Difference in total opioid usage | The investigators will examine the difference in the total opioid usage. We will compare medications separately and in total equivalent units (using an opioid conversion table). | Length of Stay In PACU (Approximately 5-7 hours after intervention) | 
| Degree of Doppler color agitation | The investigators will examine the relationship between the degree of Doppler color agitation (evaluated at the time the catheter is placed) and block success (i.e., the outcome in the primary analysis). Degree of agitation color will be defined as the percentage of nerve covered during the color agitation. | Immediately after intervention |