Healthy VolunteersPhase 4SPARKNCT07429292
SPARK Study - Sympathetic Periarterial Radial Block in Healthy Volunteers
A Phase 4 study testing Lidocaine 2% in people with Healthy Volunteers and Sympathetic Activity, run by Duke University at 1 site in United States.
Trial summary
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. Read more about this study
- Who is it for?
- Ages 18 to 50 yearsHealthy volunteers can take part
- Conditions the study is for
- Healthy Volunteers, Sympathetic Activity
- What is being tested?
- Lidocaine 2%
- Type of treatment
- Injection or infusion
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 20 participants
- Where
- 1 siteUnited States
- Study dates
- Jan 2027to Aug 2027
- Phase
- Phase 4
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 50 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- 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
Who cannot join
- 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
Show all 11Show fewer
- Active skin infection near block site
- Pregnancy
- BMI > 35 kg/m²
- Inability to tolerate cold exposure
- Any condition interfering with study conduct
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
United States1 site
Duke University Medical Center
Durham, North Carolina, 27710
About this study
Official title: 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.
- Conditions
- Healthy Volunteers, Sympathetic Activity
- Being tested
- Lidocaine 2%
- Keywords
- Sympathetic Block, Radial Artery, Cold Pressor Test, Periarterial block
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Lidocaine 2%Drug
Small-volume injection (5 mL) of 2% lidocaine around radial artery under ultrasound guidance.
| Study group | Role | What they receive |
|---|---|---|
| Left Wrist Block | Experimental | Ultrasound-guided periarterial block with 2% lidocaine at left wrist. Receives: Drug: Lidocaine 2% |
| Right Wrist Block | Experimental | Ultrasound-guided periarterial block with 2% lidocaine at right wrist. Receives: Drug: Lidocaine 2% |
What is being measured
The primary outcome is the main question the study is designed to answer.
Pulse amplitude index (PAI)
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.
Measured: 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
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.
Measured: 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 outcomes (3)
Temporal Changes in Cold Pressor Test-Induced Vasomotor Responses Pre- and Post-Block
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.
Measured: 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
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.
Measured: 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
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.
Measured: 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.
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted24 Feb 2026
- Study startJan 2027 (estimated)
- Primary completionMay 2027 (estimated)
- Study completionAug 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Healthy VolunteersStudies of the same condition, open and under way.
- More trials run by Duke UniversityThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 4
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Single blind
- Who is masked
- Outcomes assessor
- Enrolment
- 20 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Duke University
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
- Investigators
- David MacLeod, Principal investigator, Duke University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07429292
- Sponsor's protocol ID
- Pro00119632
- Acronym
- SPARK
- Status last verified
- Nov 2026
- First submitted
- 18 Feb 2026
- Last updated
- 6 Nov 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 6 Nov 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- SPARK Study - Sympathetic PeriArterial Radial blocK Study
- ClinicalTrials.gov ID
- NCT07429292
- Acronym / sponsor ID
- SPARK / Pro00119632
- Conditions
- Healthy Volunteers, Sympathetic Activity
- Keywords
- Sympathetic Block, Radial Artery, Cold Pressor Test, Periarterial block
- Phase
- Phase 4
- Study type
- Interventional
- Recruitment status
- Not yet recruiting
- Enrolment
- 20 participants (estimated)
- Lead sponsor
- Duke UniversityUniversity, hospital or other
- Study start
- Jan 2027 (estimated)
- Primary completion
- May 2027 (estimated)
- Study completion
- Aug 2027 (estimated)
- First posted
- 24 Feb 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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 design
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Single blind (outcomes assessor)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Left Wrist Block | Experimental | Drug: Lidocaine 2%Ultrasound-guided periarterial block with 2% lidocaine at left wrist. |
| Right Wrist Block | Experimental | Drug: Lidocaine 2%Ultrasound-guided periarterial block with 2% lidocaine at right wrist. |
Who may qualify
- Ages
- 18 to 50 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (5 listed)
- 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
Key exclusion criteria (11 listed)
- 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
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Lidocaine 2%Small-volume injection (5 mL) of 2% lidocaine around radial artery under ultrasound guidance. | Drug | Left Wrist Block, Right Wrist Block |
Primary outcome
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.
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.
3 secondary outcomes
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.
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 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.
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 6 Nov 2026.
- Individual participant dataSharing planned: No
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Screening Protocol
Pain
Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
David MacLeod principal investigator
Duke University
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 4 study testing Lidocaine 2% in people with Healthy Volunteers and Sympathetic Activity, run by Duke University at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 5 inclusion and 11 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: opening soon, as of the sponsor's last update on 6 Nov 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Phase 4 studies take place after a treatment is approved, to learn more about its long-term benefits and risks in everyday use.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
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.). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 6 Nov 2026.