The Effects of Dexamethasone on Low Dose Interscalene Brachial Plexus Block

Phase 4

Completed

Conditions: Nerve Block
Shoulder Surgery

Interventions: Drug: Perineural dexamethasone
Drug: Systemic Dexamethasone

Registration Number: NCT02322242

Lead Sponsor: Dr. Stephen Choi

Brief Summary: 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: 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.

Recruitment & Eligibility

Status: COMPLETED

Sex: All

Target Recruitment: 182

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

Study & Design

Study Type: INTERVENTIONAL

Study Design: PARALLEL

Arm && Interventions

Group	Intervention	Description
Perineural Dexamethasone	Perineural dexamethasone	ISB performed with local anesthetic (ropivacaine 0.5%) and perinerual dexamethasone (4mg)
Systemic Dexamethasone	Systemic Dexamethasone	ISB with local anesthetic alone (ropivacaine 0.5%) alone and intravenous dexamethasone (4mg)

Primary Outcome Measures

Name	Time	Method
Duration of Sensory Block	1 day postoperative	Defined as time from completion of block procedure to NRS for pain \> 0 (in hours)

Secondary Outcome Measures

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