The Effects of Dexamethasone on Low Dose Interscalene Brachial Plexus Block

Study Overview
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Brief Summary
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A standard interscalene nerve block is performed with long acting local anesthetic (bupivacaine or ropivacaine in concentrations varying from 0.25% to 0.75%). The purpose of this study is to investigate the effect of the addition of perineural dexamethasone (4mg) to a standard ropivacaine solution (0.5%) on analgesic duration of low dose interscalene block compared to ropivacaine alone for interscalene block with systemic dexamethasone. Ropivacaine is not an intervention as a local anesthetic is pre-requisite to performing a nerve block.

Detailed Description
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Interscalene brachial plexus block (ISB) is regarded as the standard of care for analgesia after shoulder surgery providing superior analgesia and reducing opioid consumption. Shoulder surgery, previously requiring inpatient admission for pain control, is now commonly performed on an ambulatory basis facilitated by ISB analgesia. The effects of single injection ISB dissipate after several hours unmasking the moderate to severe pain of the surgical insult and require strong opioid analgesia. Efforts to prolong ISB duration by increasing local anaesthetic (LA) dose are limited by their pharmacodynamics and narrow therapeutic window. To address some of these issues faced with prolonging ISB analgesia the addition of perineural adjuvants to local anesthetic (eg. clonidine, dexmedetomidine), have been investigated in an attempt to prolong peripheral nerve block duration with limited success. However, the corticosteroid dexamethasone, has been added to local anesthetic solutions for ISB and has demonstrated promise in preliminary studies. Perineural dexamethasone (8-10mg) in conjunction with local anesthetic prolongs the duration of ISB with an effect sizes ranging from 40% to 75% (absolute effect   6 to 10 hours). Dexamethasone, however, is only approved for intramuscular or intravenous administration and therefore perineural use is currently off-label. There are several reasons that warrant a new randomized trial. Chiefly, all of the previous trials do not reflect modern regional anesthetic practice. These trials utilized peripheral nerve stimulation (PNS) and local anesthetic volumes of 30 to 40 ml. Modern ultrasound guided ISB (US-ISB) allows for more accurate, targeted deposition of local anesthetic with volumes ranging from 5 to 10 ml with no difference in block efficacy or duration compared to larger volumes (≥20ml). An ideal solution would be a local anesthetic with adjuvant mixture that allowed administration of lower volumes but with prolonged analgesic duration. The use of low dose local anesthetic with dexamethasone could be one such solution. A trial that demonstrates enhanced block quality and duration associated with perineural dexamethasone added to low dose local anesthetic may allow us to achieve both prolonged duration of effect and reduced side effects due to unwanted local anesthetic spread. This would create further significant benefits for patients and further promote the use of low dose local anesthetic techniques to anesthesiologists who do not currently use this technique.

Official Title
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Comparison of the Effects of Perineural Versus Systemic Dexamethasone on Low Dose Interscalene Brachial Plexus Block: A Randomized Control Trial

Conditions
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Shoulder Surgery, Nerve Block

Intervention / Treatment
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* Drug: Systemic Dexamethasone
* Drug: Perineural dexamethasone


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patients undergoing arthroscopic shoulder surgery at Sunnybrook Health Sciences Centre, Toronto Western Hospital and Women's College Hospital. ASA functional status class I to III Age 18 to 80 years BMI ≤ 35 kg/m2 Exclusion Criteria: Lack of patient consent Allergy to dexamethasone or ropivacaine BMI > 35 kg/m2 Contraindications to low dose dexamethasone including peptic ulcer disease, systemic infection, glaucoma, active varicella/herpetic infections, diabetes mellitus Contraindications to ISB including severe Chronic Obstructive Pulmonary Disease (Forced expiratory volume < 40% predicted), coagulopathy, pre-existing neurologic deficit in ipsilateral upper extremity, localized infection Pregnant or nursing females Chronic opioid use defined as > 30mg oral morphine or equivalent per day Unable to take acetaminophen or celecoxib

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 80 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: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Quadruple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Perineural Dexamethasone<br>ISB performed with local anesthetic (ropivacaine 0.5%) and perinerual dexamethasone (4mg) | Drug: Perineural dexamethasone<br>* Perinerual administration of dexamethasone (4mg)<br>* Other names: Dexamethasone Sodium Phosphate Injection;|
| Other: Systemic Dexamethasone<br>ISB with local anesthetic alone (ropivacaine 0.5%) alone and intravenous dexamethasone (4mg) | Drug: Systemic Dexamethasone<br>* Intravenous infusion of dexamethasone (4mg)<br>* Other names: Dexamethasone Sodium Phosphate Injection;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Duration of Sensory Block | Defined as time from completion of block procedure to NRS for pain > 0 (in hours) | 1 day postoperative | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Time to First Opioid Consumption | Defined as time from completion of block procedure to first consumption of opioid analgesic (in hours) | 1 day postoperative | 
| Duration of Motor Block | Defined as time from completion of block procedure to return to baseline motor function (in hours) | 1 day postoperative | 
| Post-operative Oxygen Saturation on Room Air | Pulse oximetry (in %) measured 1 hour after arrival in post-operative recovery room, scale 0-100, higher number is better | 1 hour postoperative | 
| Opioid Consumption | Opioid consumption (in oral morphine equivalents) will be recorded at 12 hours, 24 hours, and 7 days | 7 days postoperative | 
| Numeric Rating Scale for Pain (NRS 0-10) | Recorded at 12 hours, 24 hours, and 7 days 0 is no pain, 10 is the worst pain imaginable. Lower number is better. | 7 days postoperative | 
| Postoperative Serum Blood Glucose | Measured 1 hour after arrival to the post-operative recovery room | 1 hour postoperative | 
| Number of Participants With Nerve Damage From Interscalene Block | Defined as persistent paresthesia, and sensory/motor block at 7 days | 7 Days postoperative | 
| Infection | Number of participants with localized infection at nerve block site | 7 Days postoperative | 
| Number of Participants With Postoperative Nausea and/or Vomiting | Number of participants with postoperative nausea and/or vomiting assessed at 12 hours, 24, hours, and 7 days postoperatively | 7 days postoperative |