Brachial plexus block as done by landmark technique use large volume of local anaesthetics (at least 30-40 ml), leading to higher incidence of phrenic nerve involvement and diaphragmatic dysfunction. With use of ultrasound dose of local anaesthetic can be reduced. Volume as low as 20 ml when use by ultrasound guidance has shown to provide successful block with no hemidiaphragmatic palsy when compared with nerve stimulation technique. But no study has compared the different volumes of drug on success rate and diaphragmatic motility.So in this study , the investigators want to compare the incidence of hemidiaphragm paralysis and success of block with different volumes of local anaesthetic , so that the lowest effective dose with higher safety profile can be determined.

Inclusion

• Age between 18 and 60 years undergoing distal arm surgery
• American Society of Anesthesiologists physical status 1 to 3
• Able to give informed consent
• Body weight greater than 50 kg

Exclusion

• Patient refusal for supraclavicular block.
• Inability to obtain informed consent.
• Contraindication to Brachial plexus block
• Pulmonary and cardiac disorders
• Pregnancy
• Allergy to local anesthetic
• Chest or shoulder deformities