The physician performing the block will use standard aseptic technique and local anesthetic infiltration of the skin. Then, using ultrasound guidance and a 22g Touhy needle, a supraclavicular brachial plexus block will be placed using 25 mls of the study drug. The time of beginning of injection will be recorded. Starting at 10 minutes after injection, motor and sensory exam in the distribution of the ulnar, median, radial and musculocutaneous nerves using pinprick every 3 minutes until motor block and sensory block is complete. As has been used in prior studies, motor scores of 0, 1, and 2 will be used for no motor blockade (0), partial motor blockade (1), and complete motor blockade (2). Similarly, sensory scores will reflect no change in pinprick sensitivity (0), diminished pinprick sensitivity (1), and complete loss of sensitivity to pinprick (2). Being ready for surgical anesthesia will be defined as a score of 2 for sensory testing. Any patient not achieving a score of 2 on the sensory scale by 40 minutes will be considered a failed block. These scores will be recorded every 3 minutes until the block achieves scores of 2 and 2 or until the patient goes to the operating room (OR).