Lack of recruitment

Blockade of the brachial plexus using a supraclavicular approach provides excellent anesthesia for upper extremity surgery. The most serious complication specific to this block is pneumothorax. Subsequent modifications of this block including the use of ultrasound have lowered the risk from 6% to <1%. Case reports remain and authors have described certain factors and strategies to reduce this risk. Most texts and journals describe the patient in a supine or semi-sitting position during the block. At the investigators institution the investigators perform the block in a semi-sitting position to facilitate needle tip visibility with ultrasound. The investigators plan to obtain ultrasound anatomic measurements in three different positions (supine, semi-sitting, sitting) using patients consented for supraclavicular nerve blocks.

Inclusion Criteria:

• all patients, 18 y/o to 65 y/o, who are scheduled to receive an ultrasound- guided supraclavicular nerve block

Exclusion Criteria:

• patient refusal to be included in the study,
• the presence of language barrier that inhibits proper communication with the patient, contraindications to regional anesthesia (local infection, severe pulmonary disease, or preexisting neuropathy)
• history of allergy to amide local anesthetics or narcotics
• the presence of a progressive neurological deficit
• history of hepatorenal insufficiency
• the presence of a coagulopathy or infection
• pregnancy
• a history of psychiatric disorder
• inability to follow study protocol

Patients 18 y/o to 65 y/o, who are scheduled to receive a ultrasound-guided supraclavicular nerve block as part of their postoperative pain management.