Control of Tourniquet Pain With an Axillary Ring of Subcutaneous Local Anesthetic

Purpose: Even with excellent regional anesthesia of the upper extremity, tourniquet (Tq)
pain from an upper arm Tq can limit the ability to use regional anesthesia as the primary
anesthetic for surgical procedures on the upper extremity. The aim of this study is to
determine whether a subcutaneous ring of local anesthetic on the inner aspect of the upper
arm just distal to axillary crease will significantly diminish Tq pain. If it does,
peripheral nerve blocks distal to the Tq (i.e., nerve blocks at the elbow) could be used as
the primary anesthetic for surgery of the hand and forearm. These distal peripheral nerve
blocks have fewer complications than brachial plexus blocks performed at higher levels, and,
postoperatively, the patient has better control of his or her arm when distal nerve blocks
are used.

Procedures (methods): This is a prospective, cross-over study to examine the effectiveness
of an upper arm Subcutaneous ring of local anesthetic alone in relieving Tq pain. This
Subcutaneous ring of local anesthetic is often referred to as "Intercostobrachial nerve
block" or "Subcutaneous ring anesthesia (SRA)." Twenty volunteers will be randomized into
four groups of 5 participants each. During the initial experiment, the first group will be
given SRA with 10-15 mL of 0.25% Bupivacaine with Epinephrine 1:200,000 on their dominant
arm, the second group will be given SRA with 10-15 mL of 0.25% Bupivacaine with Epinephrine
1:200,000 on their non-dominant arm, the third group will be given "sham" SRA with saline on
their dominant arm, and the fourth group will be given "sham" SRA with saline on their
non-dominant arm. 15 minutes after SRA, a Tq will be applied to the arm with the
subcutaneous injection and it will be inflated to 100 mm Hg above the subject's baseline
systolic blood pressure. We will monitor heart rate, blood pressure (opposite arm) and pain
(0 to 10 VAS) every 5 minutes. Each Tq will be released when the subject requests deflation
or when 1 hour of Tq time has elapsed, whichever occurs first. The subject's discomfort
level (VAS) just prior to deflation will be recorded. Since Tq pressure alone can inhibit
nerve function, we will monitor motor and sensory function distal to the Tq every 10 minutes
during Tq inflation and for 30 minutes after Tq deflation. One to two weeks after this
initial study, the same 20 subjects will receive SRA on the same arm and the same parameters
will be measured. The 10 subjects who received 0.25% Bupivacaine the first time will receive
Normal Saline, and the 10 subjects who received Normal Saline the first time will receive
0.25% Bupivacaine. In this way, each subject will act as his or her own control.