Efficacy and Safety Study of Dexmedetomidine as an Additive to Local Anesthetics in Shoulder Surgery

Study Overview
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Brief Summary
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The purpose of this study is to test the efficacy and safety of dexmedetomidine added to ropivacaine in patients undergoing shoulder surgery.

Detailed Description
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Peripheral nerve blocks are used throughout the world in lieu of general anesthesia and, more commonly, to provide analgesia and opioid sparing in the postoperative course. Long acting local anesthetics, such as ropivacaine, can provide analgesia for 11.5 ± 5 hours. This leads to many patients reporting their first pain in the evening and nighttime hours when access to healthcare providers and support is most limited. A number of additives to local anesthetics have been studied in humans with limited success. Recent work by a group in Michigan found a dose dependent increase in the duration of analgesia to a thermal stimulus when dexmedetomidine was added to ropivacaine for sciatic nerve blocks in rat. The goal of the study is to investigate the safety and efficacy of dexmedetomidine added to ropivacaine for interscalene brachial plexus nerve block for shoulder surgery in humans. Provided the initial safety can be established, the trial will continue to evaluate secondary goals including the duration of analgesia, onset of sensory and motor blockade, and opioid-induced side effects. Tertiary outcomes will include subject satisfaction.

Official Title
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The Efficacy and Safety of Dexmedetomidine as an Additive to Ropivacaine for Interscalene Brachial Plexus Blocks for Shoulder Surgery

Conditions
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Drug Safety, Self Efficacy

Intervention / Treatment
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* Drug: dexmedetomidine
* Drug: saline


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: ASA I-III adult subjects Age 18-75 Elective shoulder surgery Plan for interscalene brachial plexus block combined with general anesthesia Interscalene block Willingness to be contacted postoperatively for brief (5-10min) phone call questionnaires Written informed consent Exclusion Criteria: Age < 18 Age > 75 Inability to understand protocol due to language barrier; difficulty with German language Chronic pain requiring daily opioids > 15 mg oral morphine equivalents (equals oral usage of > 10 mg oxycodone/daily; > 5 mg methadone/day; > 4 mg hydromorphone/day) Moderate (NRS pain score > 5) daily average pain Daily use of gabapentin, pregabalin, tricyclic antidepressant, serotonin- norepinephrine reuptake inhibitor, tramadol Hypersensitivity to amide local anesthetics History of hypersensitivity or allergic reaction to clonidine or dexmedetomidine Uncontrolled anxiety Schizophrenia or bipolar disorder Preexisting nerve damage (sensory or motor) in the extremity to be blocked Peripheral neuropathy Significant cardiovascular disease (second (Mobitz II type) or third degree heart block, congestive heart failure, chronic heart failure NYHA III-IV, symptomatic coronary artery disease CSS III-IV) BMI > 35 Uncontrolled diabetes (blood sugar > 250 recorded in last 30 days or HbA1c > 7.5%) Chronic clonidine therapy (clonidine patch - Catapres or clonidine tablets) Hepatic Impairment (CHILD B or higher) Renal Impairment (creatinin > 2.0 mg/dl) Ongoing drug or alcohol abuse Pregnancy Prisoners

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 75 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: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: ropivacaine + dexmedetomidine<br>This group represents the standard of care drug (ropivacaine) plus the new additive to be studied (dexmedetomidine) | Drug: dexmedetomidine<br>* ropivacaine 100 mg + 150 mcg dexmedetomidine, single shot perineural application<br>|
| Active Comparator: ropivacaine + saline<br>This group represents the current standard of care in peripheral nerve blockade | Drug: saline<br>* ropivacaine + saline placebo, single shot perineural application<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Efficacy of dexmedetomidine in perineural application | The time until the patient describes the blockade as completely gone will be analysed and compared between the groups. | 24 hrs | 
| Safety of dexmedetomidine in perineural application | Any serious and/or unexpected adverse (AE) events will be assessed on an individual basis by the Principal Investigator and the DSMB. After the first twenty subjects (10 controls and 10 receiving study agent) have completed the study, the data will be reviewed. Provided the DSMB determines the initial safety is established, enrollment will proceed until a total of 62 subjects (31 subjects/group) have been accrued. | 30 days | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Analgesia | Analgesia will be assessed based on postoperative pain scores | first 24-48 hrs | 
| Onset of sensory blockade | The subject's sensory function will be measured every 2 minutes for the first 20 minutes, until the loss of sensory function in the dermal distribution of the shoulder. | every 3 minutes for the first 21 minutes | 
| Duration of motor blockade | The time to return of motor strength will be recorded in the subject's postoperative course. | first 24-48 hrs | 
| Opioid-induced side effects | Opioid-induced side effects will be recorded in the subject's postoperative course. | first 24-48 hrs |