Table 1 Inclusion and exclusion criteria

• Aged 18 or older

• Capacity to provide informed written consent

• Upper limb fracture and/dislocation requiring ED closed reduction and immobilisation

• Refusal to consent

• Local anaesthetic allergy

• Open fractures, unstable fracture and/or dislocations that require urgent surgical fixation

• Pregnancy

• Anticoagulation

• Chronic lung disease (e.g., chronic obstructive pulmonary disease or unstable asthma)

• Skin infection over the supraclavicular site of injection

• Previous surgery or radiation therapy to the supraclavicular region

• Severe hypertension (> 160 mmHg)

• Compartment syndrome

• Congenital or idiopathic methaemoglobinaemia

• Sickle cell disease

• Peripheral vascular disease

• Peripheral neuropathy

• Cardiac conduction abnormality