Application Site Discomfort, Medical Device Discomfort
Conditions
Keywords
Tourniquet pain, Subcutaneous axillary local anesthetic, ability to tolerate tourniquet discomfort.
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.
Interventions
10-15 mL 0.25% Bupivicaine with epinephrine 1:200,000 subcutaneous axillary ring
DRUGNormal Saline
Sponsors
University of North Carolina, Chapel Hill
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
PREVENTION
Masking
QUADRUPLE (Subject, Caregiver, Investigator, Outcomes Assessor)
Eligibility
Sex/Gender
ALL
Age
18 Years to 70 Years
Healthy volunteers
Yes
Inclusion criteria
Volunteers will be eligible for the study if they meet all of the below criteria; * American Society of Anesthesiologists (ASA) classification I or II * 18 years of age to a maximum of 70 years of age
Exclusion criteria
* Pre-existing parasthesia or neuropathy of any kind * History of excessive alcohol consumption (\> three drinks per night) * Take analgesics on a regular basis * History of any drug abuse * Baseline systolic blood pressure ≥ 150 * Baseline diastolic blood pressure ≥ 85 * BMI ≥ 30 Pregnancy Allergic reaction to local anesthetic
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Time in Minutes That Tq Remained Inflated | Tq was inflated 15 minutes after injection of Bupivacaine or placebo and remained inflated until subject could no longer tolerate it. Maximum allowable inflation time per session was 60 minutes. | 15 minutes after either Bupivacaine or placebo injection, Tq was inflated to 100 mm Hg over subjects systolic blood pressure. When the subject found the Tq too uncomfortable, the Tq was deflated and the time documented. Approximately one month later, each subject had the opposite injection of either placebo or Bupivacaine on the same arm, and the duration of Tq inflation was again measured. Due to a strong crossover effect, only the data assessed from the first intervention was analyzed. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Pain Score at Time of Tq Deflation | Tq will be deflated upon subject's request. VAS is assessed at time of deflation for degree of discomfort prompting deflation request, up to 60 minutes post intervention. | A visual analog pain score (VAS) from 0 to 10 was assessed at the time of Tq deflation. 0 indicating no pain, and 10 indicating the worst possible pain. All participants requested deflation prior to the maximum allowable 60 minutes, Subjects were instructed to request deflation at the same degree of discomfort for each visit. Due to a strong crossover effect, only the data assessed from the first intervention was analyzed. |
Countries
United States
Participant flow
Participants by arm
| Arm | Count |
|---|---|
| Bupivacaine Ring 1st Visit, Saline Ring 2nd Visit On the first visit, subcutaneous axillary ring of 10 to 15 ml of 0.25% Bupivacaine with epinephrine 1:200,000 was injected 15 minutes prior to tourniquet inflation. On the second visit, a subcutaneous axillary ring of 10 to 15 ml of saline was injected 15 minutes prior to tourniquet inflation. | 12 |
| Saline Ring 1st Visit, Bupivacaine Ring 2nd Visit On the first visit, a subcutaneous axillary ring of 10 to 15 mL of normal saline was injected 15 minutes prior to tourniquet inflation. On the second visit, a subcutaneous axillary ring of 10 to 15 ml of 0.25% Bupivacaine with epinephrine 1:200,000 was injected 15 minutes prior to tourniquet inflation. | 12 |
| Total | 24 |
Baseline characteristics
| Characteristic | Bupivacaine Ring 1st Visit, Saline Ring 2nd Visit | Saline Ring 1st Visit, Bupivacaine Ring 2nd Visit | Total |
|---|---|---|---|
| Age, Categorical <=18 years | 0 Participants | 0 Participants | 0 Participants |
| Age, Categorical >=65 years | 0 Participants | 0 Participants | 0 Participants |
| Age, Categorical Between 18 and 65 years | 12 Participants | 12 Participants | 24 Participants |
| Age, Continuous | 31.7 years STANDARD_DEVIATION 10 | 32.3 years STANDARD_DEVIATION 10.5 | 32.0 years STANDARD_DEVIATION 10.3 |
| Arm Dominance Dominant Arm | 6 participants | 6 participants | 12 participants |
| Arm Dominance Non-Dominant Arm | 6 participants | 6 participants | 12 participants |
| Region of Enrollment United States | 12 participants | 12 participants | 24 participants |
| Sex: Female, Male Female | 6 Participants | 6 Participants | 12 Participants |
| Sex: Female, Male Male | 6 Participants | 6 Participants | 12 Participants |
Adverse events
| Event type | EG000 affected / at risk | EG001 affected / at risk |
|---|---|---|
| deaths Total, all-cause mortality | — / — | — / — |
| other Total, other adverse events | 0 / 12 | 0 / 12 |
| serious Total, serious adverse events | 0 / 12 | 0 / 12 |
Outcome results
Primary
Time in Minutes That Tq Remained Inflated
15 minutes after either Bupivacaine or placebo injection, Tq was inflated to 100 mm Hg over subjects systolic blood pressure. When the subject found the Tq too uncomfortable, the Tq was deflated and the time documented. Approximately one month later, each subject had the opposite injection of either placebo or Bupivacaine on the same arm, and the duration of Tq inflation was again measured. Due to a strong crossover effect, only the data assessed from the first intervention was analyzed.
Time frame: Tq was inflated 15 minutes after injection of Bupivacaine or placebo and remained inflated until subject could no longer tolerate it. Maximum allowable inflation time per session was 60 minutes.
| Arm | Measure | Value (MEAN) |
|---|---|---|
| Bupivacaine Axillary Ring on 1st Visit | Time in Minutes That Tq Remained Inflated | 30.5 Minutes |
| Saline Axillary Ring on 1st Visit (Control Group) | Time in Minutes That Tq Remained Inflated | 22.4 Minutes |
Secondary
Pain Score at Time of Tq Deflation
A visual analog pain score (VAS) from 0 to 10 was assessed at the time of Tq deflation. 0 indicating no pain, and 10 indicating the worst possible pain. All participants requested deflation prior to the maximum allowable 60 minutes, Subjects were instructed to request deflation at the same degree of discomfort for each visit. Due to a strong crossover effect, only the data assessed from the first intervention was analyzed.
Time frame: Tq will be deflated upon subject's request. VAS is assessed at time of deflation for degree of discomfort prompting deflation request, up to 60 minutes post intervention.
| Arm | Measure | Value (MEAN) |
|---|---|---|
| Bupivacaine Axillary Ring on 1st Visit | Pain Score at Time of Tq Deflation | 6.1 scores on a scale |
| Saline Axillary Ring on 1st Visit (Control Group) | Pain Score at Time of Tq Deflation | 5.0 scores on a scale |