IV Dexamethasone for Prolongation of Peripheral Nerve Block

Phase 3

Completed

Brief Summary: This is a volunteer study examining the effect of different doses of IV dexamethasone on prolongation of median nerve block in the forearm.

Detailed Description: 18 healthy volunteers aged 18-50 will be recruited (6 patients in each dosing group). Each volunteer will receive two forearm median nerve blocks separated by a two week washout period. One block will be conducted alongside an infusion of normal saline (control). The other block will be conducted alongside a randomised dose of IV dexamethasone (2, 4 or 8mg). The order of these interventions will be random. Blocks will be assessed quantitatively with cold and sharp sensation, electrical stimulation, quantitative sensory testing (thermal tolerance) and grip strength dynamometry. Measures or sensory and motor block including onset, intensity and duration will be compared between dosing groups.

Recruitment & Eligibility

Inclusion Criteria

ASA 1 (normal healthy) volunteers.
18 - 50 years of age.
60 - 100kg weight.
English speaking.
Female volunteers of childbearing potential will be required to provide a negative pregnancy test before being allowed to participate.
Females of child bearing potential must be willing to use medically acceptable birth control methods between study interventions and for a minimum of 2 weeks following the second nerve block.

Exclusion Criteria

Medical disorders (including bleeding disorders).
Use of systemic steroids within 2 weeks of the study, prescription medications, live viral vaccines or any recreational drug use.
Hypersensitivity to bupivacaine, dexamethasone or any component of saline.
Contraindication to regional anesthetic block.
Inability to provide informed consent.
Baseline abnormality of hand sensation or motor function.
Pregnancy / breast feeding.
Individuals with mental health disorders (for example bipolar disorder or depression).
Individuals with cataracts or glaucoma.
Any known contraindication to IV dexamethasone as per the product monograph - bacteremia and systemic fungal infections, hypersensitivity to any of the products components, gastric and duodenal ulcers, certain viral infections i.e. varicella herpes genitalis.

Arm && Interventions

Group	Intervention	Description
Dexamethasone 2mg	IV dexamethasone	The experimental intervention in this arm will be an IV infusion of 2mg of dexamethasone. Volunteers will also have a cross-over placebo comparator (saline infusion).
Dexamethasone 4mg	IV dexamethasone	The experimental intervention in this arm will be an IV infusion of 4mg of dexamethasone. Volunteers will also have a cross-over placebo comparator (saline infusion).
Dexamethasone 8mg	IV dexamethasone	The experimental intervention in this arm will be an IV infusion of 8mg of dexamethasone. Volunteers will also have a cross-over placebo comparator (saline infusion).

Primary Outcome Measures

Name	Time	Method
The duration of sensory anesthesia and analgesia following median nerve block	This will be assessed for up to 12 hours following block

Secondary Outcome Measures

Name	Time	Method
Side effects related to nerve block or IV infusion of dexamethasone	Volunteers will be phoned at 24-36 hrs and then 7-10 days to ensure full resolution of the block
The duration of motor block following median nerve block	This will be assessed for up to 12 hours following block

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