Onset and Duration of a Digital Nerve Block
Conditions
Brief summary
The duration of the autonomic (sympathetic) block will last longer than the sensory block. The duration of the increased perfusion index will last longer than either the sympathetic or sensory block.
Detailed description
The Masimo SpHb™ (SpHb) is a device used to monitor the blood hemoglobin level via a sticky sensor connected to a finger. Our results from 2 recent studies undertaken with this device concluded: 1) that it is not always accurate when the finger is cold such as during surgical blood loss, and 2) a local nerve block to the finger improved the finger temperature and the accuracy of the device. Our purpose is to investigate the duration of effect of two local nerve blocking drugs (lidocaine and bupivacaine - both FDA approved drugs in routine use) in a finger on each hand. Having a better understanding of how long the nerve block lasts could help determine when an additional block might be necessary to maintain the accuracy of the device during surgical blood loss. We previously listed the primary outcome for this study as the time until return to baseline finger temperature. However, in blinded looks at the data it became clear that defining time until return to baseline from the serial temperature measurements in an objective fashion would be extremely difficult and potentially controversial. We have modified the primary outcome to be the change in the average temperature from baseline to post-intervention.
Interventions
DRUGLidocaine Digital Nerve Block
Lidocaine 1% Digital Nerve Block (2 cc
DRUGBupivacaine Digital Block
Bupivacaine 0.25% Digital Block (2 cc)
Sponsors
University of California, San Francisco
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
OTHER
Masking
DOUBLE (Subject, Outcomes Assessor)
Eligibility
Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
Yes
Inclusion criteria
* Non-smokers
Exclusion criteria
* History of allergic response to local anesthetics * BMI \>25 * Pregnant of nursing * Current smokers or past smokers of \> 1 pack year history * Neurological deficit and/or injury in the upper extremities * Current respiratory infection * Per investigator judgement, would not be suitable for study
Design outcomes
Primary
| Measure | Time frame |
|---|---|
| The Change in the Average Finger Temperature From Baseline to Post-intervention. | 30 minutes prior and 240 minutes post intervention. |
Countries
United States
Participant flow
Recruitment details
Volunteers recruited through local media source. Protocol consisted of a single study day in anesthesia research study space at the University of California San Francisco Parnassus campus.
Participants by arm
| Arm | Count |
|---|---|
| Lidocaine Block, Right Finger; Bupivacaine Block, Left Finger Lidocaine 1% Digital Nerve Block (2 cc) , right finger. Bupivacaine 0.25% Digital Nerve Block (2 cc), left finger | 6 |
| Lidocaine Block, Left Finger; Bupivacaine Block, Right Finger Lidocaine 1% Digital Block (2cc), left finger; Bupivacaine 0.25% Digital Block (2 cc), right finger. | 6 |
| Total | 12 |
Baseline characteristics
| Characteristic | Lidocaine Block, Right Finger; Bupivacaine Block, Left Finger | Lidocaine Block, Left Finger; Bupivacaine Block, Right Finger | 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 | 6 Participants | 6 Participants | 12 Participants |
| Region of Enrollment United States | 6 participants | 6 participants | 12 participants |
| Sex: Female, Male Female | 3 Participants | 3 Participants | 6 Participants |
| Sex: Female, Male Male | 3 Participants | 3 Participants | 6 Participants |
Adverse events
| Event type | EG000 affected / at risk | EG001 affected / at risk |
|---|---|---|
| deaths Total, all-cause mortality | — / — | — / — |
| other Total, other adverse events | 1 / 12 | 1 / 12 |
| serious Total, serious adverse events | 0 / 12 | 0 / 12 |
Outcome results
Primary
The Change in the Average Finger Temperature From Baseline to Post-intervention.
Time frame: 30 minutes prior and 240 minutes post intervention.
Population: The correspondingly-treated(lidocaine, bupivacaine) finger of all 12 study participants included in analysis for each arm/group
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Lidocaine | The Change in the Average Finger Temperature From Baseline to Post-intervention. | -1.35 degrees centigrade | Standard Error 0.71 |
| Bupivacaine | The Change in the Average Finger Temperature From Baseline to Post-intervention. | 0.93 degrees centigrade | Standard Error 0.71 |