This clinical trial is being conducted to study lung function and movement of the major muscle involved in breathing (the diaphragm) after a brachial plexus nerve block (nerve "freezing"). The purpose of this study is to find out what effects (good and bad) ultrasound guided nerve freezing has on the movement of the patient's diaphragm and their lung function.

The potential advantage of ultrasound guidance will be a lesser chance of freezing the nerves that innervate the diaphragm and thus having less of an effect on lung function.

The supraclavicular approach to brachial plexus blockade was first described by Kulenkampf in 1911. With classic "blind" techniques, an incidence of pneumothorax has been reported ranging from 0.5-6.0%, limiting its widespread use, despite the belief that the supraclavicular approach is the most consistent, effective technique for anesthetizing the brachial plexus. With the advent of ultrasound guidance and real time visualization this risk has been minimized and a resurgence in utilization of this approach has occurred. Increased block success, diminished performance times, and lower anesthetic volumes have been observed with this technique when compared to nerve stimulator techniques. Despite these advantages, brachial plexus anesthesia above the clavicle is associated with diaphragmatic dysfunction and caution must be demonstrated in patients with respiratory disease. Interscalene brachial plexus blockade has been widely documented to produce a 100% incidence of hemidiaphragmatic paresis and an associated 25% mean reduction in forced vital capacity (FVC) with local anesthetic volumes ranging from 20 - 45mL 8-10, these parameters for supraclavicular brachial plexus blockage are not as well defined. Previous investigations report an incidence of hemidiaphragmatic paresis of 1-75% with supraclavicular brachial plexus blockade. This study will address whether diaphragmatic function and respiratory mechanics can be preserved with lower anesthetic volumes in ultrasound guided supraclavicular brachial plexus blockade.

Inclusion Criteria:

• eligible patients undergoing Supraclavicular blockade

Exclusion Criteria:

• < 18 years of age,
• mental illness precluding informed consent,
• infection at the injection site,
• coagulopathy,
• allergy to local anesthetics,
• inability to comprehend English,
• pulmonary disease, and
• pregnancy

Pateints at the HSC Pain Management Centre