Conditions: Application Site Discomfort Medical Device Discomfort
Keywords: Tourniquet pain Subcutaneous axillary local anesthetic ability to tolerate tourniquet discomfort.
Allocation: RANDOMIZED | Intervention model: CROSSOVER
Enrollment: 24
Healthy volunteers: yes

Brief summary:
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.

Detailed description:

Arms:
arm 1: A subcutaneous axillary ring of 10 to 15 mL of 0.25% Bupivacaine with epinephrine 1:200,000 will be injected in the arm 15 minutes prior to tourniquet inflation. arm 2: A subcutaneous axillary ring of 10 to 15 mL of normal saline will be injected in the arm 15 minutes prior to tourniquet inflation.

Interventions: intervention 1: Bupivacaine with Epinephrine intervention 2: Normal Saline
Intervention descriptions: intervention 1: 10-15 mL 0.25% Bupivicaine with epinephrine 1:200,000 subcutaneous axillary ring intervention 2: None

Protocol document: