SPARK Study - Sympathetic Periarterial Radial Block in Healthy Volunteers (SPARK)

June 16, 2026 updated by: Duke University

SPARK Study - Sympathetic PeriArterial Radial blocK Study

The SPARK Study evaluates changes in peripheral sympathetic vasomotor activity following a targeted, ultrasound-guided periarterial sympathetic block of the distal radial artery in healthy volunteers. Autonomic reactivity will be assessed before and after the block using digit-specific pulse-amplitude index and infrared thermography during standardized cold pressor testing.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Not yet recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
20

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Phase 4

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • United States
    • North Carolina
      • Durham, North Carolina, United States, 27710
        • Duke University Medical Center

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Adult

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • Age 18-50 years
  • ASA physical status I-II
  • Able to understand and provide informed consent
  • Able to comply with study procedures and follow-up
  • Two hands with 5 intact digits and no significant upper extremity injury

Exclusion Criteria:

  • Allergy to lidocaine or similar anesthetics
  • Allergy to adhesives or ultrasound gel
  • Neuromuscular, autonomic, or major vascular disorders affecting upper extremities
  • Peripheral neuropathy
  • Raynaud's phenomenon or digital ischemia
  • Coagulopathy or anticoagulation
  • Active skin infection near block site
  • Pregnancy
  • BMI > 35 kg/m²
  • Inability to tolerate cold exposure
  • Any condition interfering with study conduct

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Basic Science
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Single

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: Left Wrist Block
Ultrasound-guided periarterial block with 2% lidocaine at left wrist.
Drug: Lidocaine 2%
Small-volume injection (5 mL) of 2% lidocaine around radial artery under ultrasound guidance.
Experimental: Right Wrist Block
Ultrasound-guided periarterial block with 2% lidocaine at right wrist.
Drug: Lidocaine 2%
Small-volume injection (5 mL) of 2% lidocaine around radial artery under ultrasound guidance.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Pulse amplitude index (PAI)
Time Frame: PAI will be measured at: 1) Baseline; 2) after the first cold pressor test at 0, 5, 10, and 15 minutes; 3) after the sympathetic block at 5 and 10 minutes; 4) after the second cold pressor test at 0, 5, 10, and 15 minutes.
Pulse Amplitude Index (PAI) is a noninvasive measure of digital perfusion derived from photoplethysmography (PPG) signals recorded from the fingers. PAI reflects changes in pulse waveform amplitude and serves as an indirect marker of peripheral blood flow and sympathetic vasomotor tone. In this study, PAI will be continuously recorded using digital sensors placed on the index and fifth fingers of the hand undergoing periarterial radial block, as well as the contralateral index finger. Measurements will be obtained at baseline, following cold pressor testing, after the periarterial radial block, and following repeat cold pressor testing. Changes in PAI across time points will be used to assess alterations in peripheral perfusion associated with sympathetic modulation.
PAI will be measured at: 1) Baseline; 2) after the first cold pressor test at 0, 5, 10, and 15 minutes; 3) after the sympathetic block at 5 and 10 minutes; 4) after the second cold pressor test at 0, 5, 10, and 15 minutes.
Hand temperature
Time Frame: Thermal images will be obtained at: 1) Baseline; 2) after the first cold pressor test at 0, 5, 10, and 15 minutes; 3) after the sympathetic block at 5 and 10 minutes; 4) after the second cold pressor test at 0, 5, 10, and 15 minutes.
Hand temperature is a noninvasive measure of peripheral skin temperature used as an indicator of changes in local blood flow and sympathetic vasomotor activity. In this study, hand temperature will be assessed using infrared thermographic imaging of both hands. Thermal images will be acquired under standardized environmental conditions at baseline, following cold pressor testing, after the periarterial radial block, and following repeat cold pressor testing. Temperature values will be derived from predefined regions of interest on the hands based on arterial territories, and compared across time points to evaluate changes in peripheral perfusion associated with sympathetic modulation.
Thermal images will be obtained at: 1) Baseline; 2) after the first cold pressor test at 0, 5, 10, and 15 minutes; 3) after the sympathetic block at 5 and 10 minutes; 4) after the second cold pressor test at 0, 5, 10, and 15 minutes.

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Temporal Changes in Cold Pressor Test-Induced Vasomotor Responses Pre- and Post-Block
Time Frame: Data will be obtained at: 1) Baseline; 2) after the first cold pressor test at 0, 5, 10, and 15 minutes; 3) after the sympathetic block at 5 and 10 minutes; 4) after the second cold pressor test at 0, 5, 10, and 15 minutes.
Temporal changes in cold pressor test (CPT)-induced vasomotor responses pre- and post-block refer to time-dependent alterations in peripheral vascular tone before and after periarterial radial block-induced sympathetic modulation. In this study, CPT-induced vasomotor responses will be assessed by evaluating changes in pulse amplitude index (PAI) and hand skin temperature across predefined time points. Measurements will be obtained immediately following CPT, and at serial intervals. CPT will be performed before and after the periarterial radial block. Comparisons of these temporal response patterns before and after the block will be used to characterize the effects of sympathetic modulation on peripheral vasoconstriction and vasodilation.
Data will be obtained at: 1) Baseline; 2) after the first cold pressor test at 0, 5, 10, and 15 minutes; 3) after the sympathetic block at 5 and 10 minutes; 4) after the second cold pressor test at 0, 5, 10, and 15 minutes.
Change in Vasomotor Measures in the Fifth Finger
Time Frame: PAI and thermal images will be measured at: 1) Baseline; 2) after the first cold pressor test at 0, 5, 10, and 15 minutes; 3) after the sympathetic block at 5 and 10 minutes; 4) after the second cold pressor test at 0, 5, 10, and 15 minutes.
Change in vasomotor measures in the fifth finger refers to alterations in peripheral perfusion and skin temperature measured in the fifth digit ipsilateral to the periarterial radial block, an area predominantly innervated by the ulnar nerve. In this study, the fifth finger will serve as an internal control for comparison with the radial-innervated index finger. Changes will be assessed using pulse amplitude index (PAI) and infrared thermographic imaging. Measurements will be obtained at baseline, following cold pressor testing, after periarterial radial block, and following repeat cold pressor testing. Responses in the ulnar-innervated fifth finger will be used to evaluate regional vasomotor changes and to track potential extension of radial sympathetic modulation to adjacent, non-radial territories.
PAI and thermal images will be measured at: 1) Baseline; 2) after the first cold pressor test at 0, 5, 10, and 15 minutes; 3) after the sympathetic block at 5 and 10 minutes; 4) after the second cold pressor test at 0, 5, 10, and 15 minutes.
Change in Vasomotor Measures in the Contralateral Index Finger
Time Frame: PAI and thermal images will be measured at: 1) Baseline; 2) after the first cold pressor test at 0, 5, 10, and 15 minutes; 3) after the sympathetic block at 5 and 10 minutes; 4) after the second cold pressor test at 0, 5, 10, and 15 minutes.
Change in vasomotor measures in the contralateral index finger refers to alterations in peripheral perfusion and skin temperature measured in the index finger of the hand opposite to the periarterial radial block. This contralateral finger serves as an internal control to account for systemic sympathetic responses to cold pressor testing that are independent of the local effects of the block and to compare sympathetic reactivity between hands. Vasomotor measures will be assessed using pulse amplitude index (PAI) derived from photoplethysmography and infrared thermographic imaging. Measurements will be obtained at baseline, following cold pressor testing, after periarterial radial block, and following repeat cold pressor testing. Changes across time points will be used to distinguish local from systemic vasomotor effects.
PAI and thermal images will be measured at: 1) Baseline; 2) after the first cold pressor test at 0, 5, 10, and 15 minutes; 3) after the sympathetic block at 5 and 10 minutes; 4) after the second cold pressor test at 0, 5, 10, and 15 minutes.

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Duke University

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: David MacLeod, Duke University

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
September 1, 2026

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
December 1, 2026

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
April 1, 2027

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
February 18, 2026

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
February 18, 2026

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
February 24, 2026

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
June 17, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
June 16, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
March 1, 2026

More Information

Terms related to this study

Keywords

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • Pro00119632

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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