Interscalene Brachial Plexus Block Washout to Reverse Inadvertent Phrenic Nerve Blockade

Study Overview
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Brief Summary
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One of the most frequently performed peripheral nerve blocks (the injection of local anesthetic near nerves to block sensation/ movement to a specific part of the body) is the interscalene brachial plexus block for upper extremity surgeries. This type of block can unmask underlying respiratory issues such as shortness of breath due to a well-known and typically insignificant side effect of temporary diaphragmatic paralysis. The nerve block may be able to use saline solution to wash out the local anesthetic and potentially reverse this respiratory side effect. Specifically, the goal of this study is to determine if the injection of saline through the nerve block catheter reverses blockade of the phrenic nerve supplying the diaphragm, without affecting the ability of the nerve block to provide pain control after surgery.

Official Title
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Interscalene Brachial Plexus Block Washout to Reverse Inadvertent Phrenic Nerve Blockade

Conditions
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Anesthesia, Local, Phrenic Nerve Paralysis, Upper Extremity Injury, Phrenic Nerve Palsy on the Left, Phrenic Nerve Palsy on the Right

Intervention / Treatment
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* Procedure: Normal saline injected via interscalene nerve catheter
* Other: Placebo


Participation Criteria
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Eligibility Criteria
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Inclusion criteria: All adult patients (18 years and over) scheduled for surgery requiring a continuous interscalene brachial plexus nerve block catheter as part of their anesthetic care. Exclusion criteria: Concomitant life-threatening injuries and other concomitant injuries causing significant pain Pregnant Any condition impairing patient's ability to consent to participation in study, and an existing condition contraindicating a nerve block, i.e. nerve injury, existing bleeding disorder, infection in the vicinity of the block, and patient refusal.

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 |
| --- | --- |
| Placebo Comparator: Placebo group<br>After surgery, in the post-operative recovery room, patients randomized to both the intervention and control groups will have 10cc 0.5% ropivacaine bolused via their nerve catheters. After 30 minutes, the following will be measured/assessed: spirometry data, pain scores (using the Numeric Rating Scale), and, if time is sufficient, bilateral diaphragmatic excursion via ultrasonography and brachial plexus motor and sensory exams. This control group will have no normal saline injected into their nerve catheter (no intervention). Then, both the control and treatment groups will have the following measured/assessed after 5, 15 and 30 minutes: spirometry data, pain scores (using the Numeric Rating Scale), and, if time is sufficient, bilateral diaphragmatic excursion via ultrasonography and brachial plexus motor and sensory exams. Investigators will be blinded to whether the patient is in the intervention or treatment group. | Other: Placebo<br>* With the catheter covered, placebo group patients will go through the same steps as the treatment group, but no solution will be injected into the interscalene nerve block catheter.<br>|
| Active Comparator: Treatment group<br>After surgery, in the post-operative recovery room, patients randomized to both the intervention and control groups will have 10cc 0.5% ropivacaine bolused via their nerve catheters. After 30 minutes, the following will be measured/assessed: spirometry data, pain scores (using the Numeric Rating Scale), and, if time is sufficient, bilateral diaphragmatic excursion via ultrasonography and brachial plexus motor and sensory exams. This group will then have 30ml of normal saline injected into their nerve catheter. Then, both the control and treatment groups will have the following measured/assessed after 5, 15 and 30 minutes: spirometry data, pain scores (using the Numeric Rating Scale), and, if time is sufficient, bilateral diaphragmatic excursion via ultrasonography and brachial plexus motor and sensory exams. Investigators will be blinded to whether the patient is in the intervention or treatment group. | Procedure: Normal saline injected via interscalene nerve catheter<br>* With the catheter covered, treatment group patients will receive a normal saline (NS) bolus regimen (30cc 0.9% NS) via their interscalene nerve block catheter.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in forced vital capacity (FVC) | Spirometry data will be collected using a digital spirometer before nerve block is placed, after surgery, and after receiving either the placebo or treatment. | Before the nerve block placement, within 1 hour after the surgery, then in 5, 15, and 30 minutes after the saline injection/placebo (1 minute each for a total of 5 assessments) | 
| Change in peak expiratory flow (PEF) | Spirometry data will be collected using a digital spirometer before nerve block is placed, after surgery, and after receiving either the placebo or treatment. | Before the nerve block placement, within 1 hour after the surgery, then in 5, 15, and 30 minutes after the saline injection/placebo (1 minute each for a total of 5 assessments) | 
| Change in forced expiratory volume in 1 second (FEV1) | Spirometry data will be collected using a digital spirometer before nerve block is placed, after surgery, and after receiving either the placebo or treatment. | Before the nerve block placement, within 1 hour after the surgery, then in 5, 15, and 30 minutes after the saline injection/placebo (1 minute each for a total of 5 assessments) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Diaphragmatic excursion | Diaphragmatic excursion will be assessed via ultrasound before nerve block is placed, after surgery, and while receiving either the placebo or treatment. | Before nerve block is placed, within 1 hour after the surgery, and while receiving either the placebo or treatment (5 minutes each for a total of 3 assessments.) | 
| Brachial plexus sensory and motor exam | Brachial plexus sensory and motor exam changes will be assessed before nerve block is placed, after surgery, and while receiving either the placebo or treatment. | Before nerve block is placed, within 1 hour after the surgery, and while receiving either the placebo or treatment (2 minutes each for a total of 3 assessments). | 
| Pain scores | The Numerical Pain Rating Scale is a subjective measure in which individuals rate their pain on an eleven-point numerical scale. The scale is composed of 0 (no pain at all) to 10 (worst imaginable pain). Pain scores will be assessed before nerve block is placed, after surgery, while receiving either the placebo or treatment. | Pain scores will be assessed before nerve block is placed, within 1 hour after the surgery, while receiving either the placebo or treatment. (1 minute each for a total of 3 assessments) |