Low Dose Dexamethasone in Supraclavicular Blocks

Study Overview
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Brief Summary
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Brachial plexus nerve blocks provide superior analgesia over opioids while avoiding unwanted side effects. Single shot blocks with local anesthetic alone usually do not last the duration of the acute post-surgical pain period. This has led to the exploration of multiple adjuvants to increase the duration of single shot blocks, the most promising adjuvant being dexamethasone. Peri-neural administration is an off-label use of dexamethasone. While no adverse events have been reported in human clinical studies, logic would dictate that we minimize the dose needed to produce the desired effect. Most studies thus far have used peri-neural dexamethasone doses ranging from 4-10 mg. However, Albrecht et al. found no difference in block duration comparing 4 mg and 8 mg doses while Liu et al. reported equivalent block duration using doses of 1, 2 and 4 mg. Recent studies have evaluated whether systemic and peri-neural administrations of dexamethasone are equivalent, which would in turn imply a site of action. Results have been mixed. Four studies concluded peri-neural and intravenous administration are equivalent at prolonging analgesia, though one study had methodological errors, including the administration of intravenous dexamethasone to all patients. All of these studies used dexamethasone doses of 8 to 10 mg. One study where a lower dose (4 mg) was used found that peri-neural administration prolonged block duration whereas intravenous did not. With that, the rationale of our study is to determine if equivalent block-prolonging analgesia can be achieved using low dose (1 mg) dexamethasone given peri-neural or intravenous. Clinical experience at our centre has been that 1 mg dexamethasone added to 20 mL produces similar block duration to that reported in published studies using higher doses.

Detailed Description
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The investigators will evaluate the block-prolonging efficacy of dexamethasone 1 mg in supraclavicular blocks. The investigators will be answering essentially two questions. First, how long do supraclavicular blocks last when low dose dexamethasone is used as an adjunct. Only one study has looked at doses this low (Liu et al. 2015). Some methodological problems with this study include evaluation of shoulder surgery using supraclavicular blocks, which may or may not cover the posterior port site; use of the endpoint of time to first analgesic, which may or may not indicate actual block duration; and low numbers powered to 80%, which may yield spurious results. To avoid these issues the investigators chose upper limb surgery, a type of block which will definitely cover the entire surgical site, and an endpoint of time to first pain at surgical site, regardless of whether analgesic is needed. The investigators are also powering to 95% and recruiting higher numbers of patients. The second question evaluates the efficacy of 1 mg of intravenous dexamethasone. The study is powered to address this question, but in doing so is also powered adequately to address the first question. Studies to date have mixed results and methodological errors. No other studies have evaluated this dose of intravenous dexamethasone.

Official Title
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Low Dose Dexamethasone as an Adjuvant to Supraclavicular Brachial Plexus Blocks: A Prospective Randomized, Double Blinded, Control Study

Conditions
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Nerve Entrapment, Rheumatoid Arthritis, Osteoarthritis, Ligament Injury

Intervention / Treatment
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* Drug: Control intervention (no dexamethasone)
* Drug: Peri-neural Dexamethasone 1 mg
* Drug: Intravenous Dexamethasone 1 mg


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Adult 18 - 80 years BMI equal to or less than 35 Upper limb surgery Normal pre-operative sensation in the operative limb Exclusion Criteria: Pre-operative opioid greater than 4 Tylenol #3 per day (or equivalent) Pre-existing, fluctuating neurologic injury involving operative upper limb Patient refusal or patient inability to provide consent Suspected inability to comply with study procedures, including language difficulties or medical history and/or concomitant disease (skin infection at site of needle insertion) as judged by the investigator or attending anesthesiologist, reason for exclusion will be recorded. Patient pregnancy Patient BMI > 35 Patient allergy to any of the drugs used in the protocol Surgical concern of postoperative neurological injury from surgical manipulation. Brittle diabetics Other contraindication to receiving a block (coagulopathy, significant respiratory risk, etc.) Surgeon refusal (e.g. concerns about compartment syndrome); reason for exclusion will be recorded

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 |
| --- | --- |
| Placebo Comparator: Control (C)<br>Control intervention (no dexamethasone) | Drug: Control intervention (no dexamethasone)<br>* Patients receive a supraclavicular brachial plexus block with 30 mL of solution containing 0.5% bupivacaine, 1:400,000 epinephrine, 0.1 mL normal saline, and an intravenous solution of 50 mL normal saline.<br>* Other names: Control;|
| Experimental: Peri-neural (N)<br>Peri-neural Dexamethasone 1 mg | Drug: Peri-neural Dexamethasone 1 mg<br>* Patients receive a supraclavicular brachial plexus block with 30 mL of solution containing 0.5% bupivacaine, 1:400,000 epinephrine, 0.1 mL dexamethasone 1% (1 mg dexamethasone), and an intravenous solution of 50 mL normal saline.<br>* Other names: Peri-neural;|
| Experimental: Intravenous<br>Intravenous Dexamethasone 1 mg | Drug: Intravenous Dexamethasone 1 mg<br>* Patients receive a supraclavicular brachial plexus block with 30 mL of solution containing 0.5% bupivacaine, 1:400,000 epinephrine, 0.1 mL normal saline, and an intravenous solution of 49.9 mL normal saline with 0.1mL dexamethasone 1%<br>* Other names: IV;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Time to first sensation of pain at the surgical site. |  | 72 hours | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| duration of motor blockade | time (in hours) to return of full pre-operative strength in the operative limb | 72 hours | 
| morphine or morphine equivalent usage in the first 48 h postoperatively |  | 48 hours | 
| incidence of nausea and vomiting and pruritus in the first 48 h |  | 48 hours | 
| numerical rating scale (NRS) pain scores at 8 h, 24 h, 48 h, and post-operative day 7 |  | 7 days | 
| residual paraesthesias or motor blockade at 7 days. |  | 7 days | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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brachial plexus, supraclavicular, duration, dexamethasone, block