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Effects of Heating on Exercise Pressor Reflex in Peripheral Artery Disease: Exercise Ability (EPR)

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details.
 
ClinicalTrials.gov Identifier: NCT03900832
Recruitment Status : Suspended (Temporarily suspended due to Pandemic.)
First Posted : April 3, 2019
Last Update Posted : April 17, 2020
Sponsor:
Information provided by (Responsible Party):
Jian Cui, Milton S. Hershey Medical Center

Brief Summary:
The study objectives of this projects are to examine the hypothesis that the sympathetic and blood pressure responses to exercise will be attenuated during and after heat exposure in patients with peripheral artery disease, via altering the sensitivity of the muscle afferent receptors.

Condition or disease Intervention/treatment Phase
PAD Other: Without Heating Other: Warm Bath Other: Neutral Bath Other: Heating Suit Other: Lower limb warm water immersion Other: Gardner walking protocol Early Phase 1

Detailed Description:

Peripheral arterial disease (PAD) affects 8-12 million Americans and its cardinal symptom is leg pain during exercise, termed "intermittent claudication". The diagnosis of PAD involves measuring the ankle-brachial index (ABI, i.e. the systolic pressure in the ankle divided by the systolic pressure in the arm); values below 0.9 are indicative of large vessel obstruction. Intermittent claudication is the most common symptom of this disease and it regularly occurs during exercise/physical activity but is relieved promptly by rest. Previous studies suggest that as the exercise pressor reflex is activated in patients with PAD, BP and heart rate (HR) are exaggerated. The BP rises during walking in the PAD patients were significantly greater than that seen in healthy control subjects. A recent human study from our group further indicates that an early BP response occurred during plantar flexion exercise before claudication was noted by the subjects, which may suggest that the accentuated BP response was due to an augmented muscle mechanoreflex in PAD. Moreover, another recent study from our group also showed that PAD patients have augmented renal vasoconstriction during plantar flexion exercise.

It has been shown that exercise has benefits for patients with PAD. However, exercise becomes limited due to the pain and fatigue associated with the disease. Moreover, the augmented pressor response to exercise in PAD may increase the risk for the end organ damage (e.g. brain and/or heart). Thus, finding alternate/complimentary interventions that modulate the cardiovascular system and autonomic nervous system, and can be tolerated by the patients, would be beneficial.

One possible intervention is heat exposure, since acute bouts of exercise and acute heat exposure have similar acute effects on both the autonomic and cardiovascular systems. For example, both exercise and heat exposure increase body temperature, increase HR, increase cardiac output (CO), increase left ventricular ejection fraction (EF), and enhance myocardial function. In the peripheral circulation, both exercise and heat exposure increase limb blood flow , muscle blood flow, and skin blood flow. Moreover, recent studies suggest that whole body exposure improves the endothelium function in PAD patients (e.g. activates endothelial progenitor cells CD34+).

However, the effect of heat treatment on the ability of walking of PAD patients has not been examined. Moreover, it is unknown if heating can normalize/decrease the accentuated the pressor responses to exercise in PAD patients.

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Study Type : Interventional  (Clinical Trial)
Estimated Enrollment : 32 participants
Allocation: Randomized
Intervention Model: Crossover Assignment
Intervention Model Description: The investigators will examine (using a prospective observational design) if heating will affect walking ability, blood pressure and heart rate responses in PAD patients. Each subject will serve as their own control. Additionally, we will compare these responses between PAD patients and healthy controls subjects.
Masking: Single (Outcomes Assessor)
Masking Description: Subjects will be aware if they are being heated or not, but data analysis process is blinded.
Primary Purpose: Basic Science
Official Title: Effects of Heating on Exercise Pressor Reflex in Peripheral Artery Disease: Exercise Ability
Actual Study Start Date : February 15, 2017
Estimated Primary Completion Date : July 2024
Estimated Study Completion Date : July 2024

Resource links provided by the National Library of Medicine


Arm Intervention/treatment
Placebo Comparator: PAD without heating
Subjects will walk on a treadmill using the Gardner protocol until the patient says they want to stop. BP, HR and NIRS will be continuously measured during Gardner protocol. Skin blood flow, skin temperature and BP will be measured in the supine position before and after the Gardner protocol.
Other: Without Heating
Subject will complete walking protocol without any heating procedure

Other: Gardner walking protocol
The Gardner protocol begins at 2 mph and 0% grade for 2 minutes. The grade increases by 2% every 2 minutes (the speed remains 2 mph) until the subject says they want to stop or 22 minutes maximum. BP and HR will also be measured throughout the protocol.

Experimental: PAD warm bath
Subjects will take a warm bath. Then, subjects will walk on a treadmill using the Gardner protocol until the patient says they want to stop. BP, HR and NIRS will be continuously measured during Gardner protocol. Skin blood flow, skin temperature and BP will be measured in the supine position before and after the Gardner protocol.
Other: Warm Bath

Subjects will sit in a warm bathtub with water up to their shoulders, while one arm will be out of water for BP and HR measurement. The water temperature and internal temperature (Tcore), BP and HR will be measured throughout the bath.

The water temperature will be controlled between 38-41°C. Subjects will remain in the tub for ≤ 30 minutes. If the HR increases more than 15 -20 bpm, or a significant BP drop occurs (e.g. BP >20 mmHg), the subject will be removed from the bath even if the time is <30 min.


Other: Gardner walking protocol
The Gardner protocol begins at 2 mph and 0% grade for 2 minutes. The grade increases by 2% every 2 minutes (the speed remains 2 mph) until the subject says they want to stop or 22 minutes maximum. BP and HR will also be measured throughout the protocol.

Placebo Comparator: PAD neutral bath
Subjects will take a neutral bath. Then, subjects will walk on a treadmill using the Gardner protocol until the patient says they want to stop. BP, HR and NIRS will be continuously measured during Gardner protocol. Skin blood flow, skin temperature and BP will be measured in the supine position before and after the Gardner protocol.
Other: Neutral Bath

Subjects will sit in a warm bathtub with water up to their shoulders, while one arm will be out of water for BP and HR measurement. The water temperature and internal temperature (Tcore), BP and HR will be measured throughout the bath.

The water temperature will be controlled between 35 - 37°C. Subjects will remain in the tub for ≤ 30 minutes.


Other: Gardner walking protocol
The Gardner protocol begins at 2 mph and 0% grade for 2 minutes. The grade increases by 2% every 2 minutes (the speed remains 2 mph) until the subject says they want to stop or 22 minutes maximum. BP and HR will also be measured throughout the protocol.

Experimental: PAD heating suit
Whole body heating with the suit will be performed. Then, subjects will walk on a treadmill using the Gardner protocol until the patient says they want to stop. BP, HR and NIRS will be continuously measured during Gardner protocol. Skin blood flow, skin temperature and BP will be measured in the supine position before and after the Gardner protocol.
Other: Heating Suit
The mean skin temperature Tsk will be controlled with a water-perfused suit worn by subjects. Whole-body heating will be accomplished by perfusing warm water (~ 45 - 50 °C) through the suit to elevate the Tsk to ≤ 38 °C (100 oF). Warm water is through plastic tubes, and subjects' skin will not directly touch warm water. The heating will be continued until the ∆Tcore reaches ~ 0. 6 - 1.0 °C. This may take approximately 60 - 90 min.

Other: Gardner walking protocol
The Gardner protocol begins at 2 mph and 0% grade for 2 minutes. The grade increases by 2% every 2 minutes (the speed remains 2 mph) until the subject says they want to stop or 22 minutes maximum. BP and HR will also be measured throughout the protocol.

Experimental: PAD lower limb warm water immersion
Subjects will place their lower legs in warm water. Then, subjects will walk on a treadmill using the Gardner protocol until the patient says they want to stop. BP, HR and NIRS will be continuously measured during Gardner protocol. Skin blood flow, skin temperature and BP will be measured in the supine position before and after the Gardner protocol.
Other: Lower limb warm water immersion
Subjects will sit on a chair and put their lower legs and feet in a bucket with warm water. The water level will be just below the knees (depth of approximately 40 cm). The water temperature will be monitored and controlled at ~38 - 42 °C throughout the 30 minutes. BP, HR, Tcore, the skin temperature and skin blood flow (e.g. on a thigh and/or forearm) will be measured before, during and after the lower limbs warm water immersion.

Other: Gardner walking protocol
The Gardner protocol begins at 2 mph and 0% grade for 2 minutes. The grade increases by 2% every 2 minutes (the speed remains 2 mph) until the subject says they want to stop or 22 minutes maximum. BP and HR will also be measured throughout the protocol.

Placebo Comparator: Healthy subjects without heating
Subjects will walk on a treadmill using the Gardner protocol until the patient says they want to stop. BP, HR and NIRS will be continuously measured during Gardner protocol. Skin blood flow, skin temperature and BP will be measured in the supine position before and after the Gardner protocol.
Other: Without Heating
Subject will complete walking protocol without any heating procedure

Other: Gardner walking protocol
The Gardner protocol begins at 2 mph and 0% grade for 2 minutes. The grade increases by 2% every 2 minutes (the speed remains 2 mph) until the subject says they want to stop or 22 minutes maximum. BP and HR will also be measured throughout the protocol.

Experimental: Healthy subjects warm bath
Subjects will take a warm bath. Then, subjects will walk on a treadmill using the Gardner protocol until the patient says they want to stop. BP, HR and NIRS will be continuously measured during Gardner protocol. Skin blood flow, skin temperature and BP will be measured in the supine position before and after the Gardner protocol.
Other: Warm Bath

Subjects will sit in a warm bathtub with water up to their shoulders, while one arm will be out of water for BP and HR measurement. The water temperature and internal temperature (Tcore), BP and HR will be measured throughout the bath.

The water temperature will be controlled between 38-41°C. Subjects will remain in the tub for ≤ 30 minutes. If the HR increases more than 15 -20 bpm, or a significant BP drop occurs (e.g. BP >20 mmHg), the subject will be removed from the bath even if the time is <30 min.


Other: Gardner walking protocol
The Gardner protocol begins at 2 mph and 0% grade for 2 minutes. The grade increases by 2% every 2 minutes (the speed remains 2 mph) until the subject says they want to stop or 22 minutes maximum. BP and HR will also be measured throughout the protocol.

Placebo Comparator: Healthy subjects neutral bath
Subjects will take a neutral bath. Then, subjects will walk on a treadmill using the Gardner protocol until the patient says they want to stop. BP, HR and NIRS will be continuously measured during Gardner protocol. Skin blood flow, skin temperature and BP will be measured in the supine position before and after the Gardner protocol.
Other: Neutral Bath

Subjects will sit in a warm bathtub with water up to their shoulders, while one arm will be out of water for BP and HR measurement. The water temperature and internal temperature (Tcore), BP and HR will be measured throughout the bath.

The water temperature will be controlled between 35 - 37°C. Subjects will remain in the tub for ≤ 30 minutes.


Other: Gardner walking protocol
The Gardner protocol begins at 2 mph and 0% grade for 2 minutes. The grade increases by 2% every 2 minutes (the speed remains 2 mph) until the subject says they want to stop or 22 minutes maximum. BP and HR will also be measured throughout the protocol.

Experimental: Healthy subjects heat suit
Whole body heating with the suit will be performed. Then, subjects will walk on a treadmill using the Gardner protocol until the patient says they want to stop. BP, HR and NIRS will be continuously measured during Gardner protocol. Skin blood flow, skin temperature and BP will be measured in the supine position before and after the Gardner protocol.
Other: Heating Suit
The mean skin temperature Tsk will be controlled with a water-perfused suit worn by subjects. Whole-body heating will be accomplished by perfusing warm water (~ 45 - 50 °C) through the suit to elevate the Tsk to ≤ 38 °C (100 oF). Warm water is through plastic tubes, and subjects' skin will not directly touch warm water. The heating will be continued until the ∆Tcore reaches ~ 0. 6 - 1.0 °C. This may take approximately 60 - 90 min.

Other: Gardner walking protocol
The Gardner protocol begins at 2 mph and 0% grade for 2 minutes. The grade increases by 2% every 2 minutes (the speed remains 2 mph) until the subject says they want to stop or 22 minutes maximum. BP and HR will also be measured throughout the protocol.

Experimental: Healthy subjects lower limb immersion
Subjects will place their lower legs in warm water. Then, subjects will walk on a treadmill using the Gardner protocol until the patient says they want to stop. BP, HR and NIRS will be continuously measured during Gardner protocol. Skin blood flow, skin temperature and BP will be measured in the supine position before and after the Gardner protocol.
Other: Lower limb warm water immersion
Subjects will sit on a chair and put their lower legs and feet in a bucket with warm water. The water level will be just below the knees (depth of approximately 40 cm). The water temperature will be monitored and controlled at ~38 - 42 °C throughout the 30 minutes. BP, HR, Tcore, the skin temperature and skin blood flow (e.g. on a thigh and/or forearm) will be measured before, during and after the lower limbs warm water immersion.

Other: Gardner walking protocol
The Gardner protocol begins at 2 mph and 0% grade for 2 minutes. The grade increases by 2% every 2 minutes (the speed remains 2 mph) until the subject says they want to stop or 22 minutes maximum. BP and HR will also be measured throughout the protocol.




Primary Outcome Measures :
  1. Walking time in minutes [ Time Frame: Recording walking time to fatigue (up to 22 minutes maximum) during of every 3-4 hour study visit. ]
    Walking time on treadmill using Gardner protocol

  2. Blood pressure in mmHg [ Time Frame: Recorded continuously during the 3-4 hour study visit ]
    Cuffs placed on a finger and arm will monitor blood pressure.

  3. Heart Rate in beats per minute [ Time Frame: Recorded continuously during the 3-4 hour study visit ]
    Electrocardiogram (ECG) patches attached to a Cardiocap will monitor heart rat


Secondary Outcome Measures :
  1. Internal Temperature in degrees C [ Time Frame: Recorded continuously during the 3-4 hour study visit ]
    The internal temperature (Tcore) will be measured from the stomach/intestines via a telemetry pill swallowed by subjects.

  2. Near infrared spectroscopy (NIRS) in arbitrary units [ Time Frame: Recorded continuously during the 3-4 hour study visit ]
    This system is designed specifically for non-invasive measurements of muscle tissue. The system measures the tissue saturation of the investigated muscle, called the 'tissue saturation index' (TSI).



Information from the National Library of Medicine

Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the contacts provided below. For general information, Learn About Clinical Studies.


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Ages Eligible for Study:   21 Years to 85 Years   (Adult, Older Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes
Criteria

Inclusion Criteria:

All subjects

  • Capable of giving informed consent
  • Any race or ethnicity
  • Men and women age 21- 85 years (inclusive)
  • Fluent in written and spoken English

Patients with peripheral arterial disease (PAD)

  • Diagnosed with PAD (i.e., ankle-brachial index below 0.9)
  • Fontaine stage II or less - no pain while resting
  • Satisfactory history and physical exam

Healthy subjects

  • Satisfactory history and physical examination
  • Free of acute medical conditions

Exclusion Criteria:

For patients with PAD and Healthy subjects

  • Age < 21 years
  • Pregnant or nursing women
  • Decisional impairment
  • Prisoners

For patients with PAD

  • History of CAD with symptoms of unstable angina or myocardial infarction (<6 months)
  • History of epilepsy or seizure disorders

For healthy subjects

• Any other chronic diseases (heart, lung, neuromuscular disease or diabetes)


Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT03900832


Locations
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United States, Pennsylvania
Penn State Milton S. Hershey Medical Center
Hershey, Pennsylvania, United States, 17033
Sponsors and Collaborators
Milton S. Hershey Medical Center
Investigators
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Principal Investigator: Jian Cui Penn State College of Medicine
Publications:
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Responsible Party: Jian Cui, Associate Professor of Medicine, Milton S. Hershey Medical Center
ClinicalTrials.gov Identifier: NCT03900832    
Other Study ID Numbers: STUDY00005798
First Posted: April 3, 2019    Key Record Dates
Last Update Posted: April 17, 2020
Last Verified: April 2020
Individual Participant Data (IPD) Sharing Statement:
Plan to Share IPD: No

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Studies a U.S. FDA-regulated Drug Product: No
Studies a U.S. FDA-regulated Device Product: No
Keywords provided by Jian Cui, Milton S. Hershey Medical Center:
exercise
blood pressure response
heating
Additional relevant MeSH terms:
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Peripheral Arterial Disease
Atherosclerosis
Arteriosclerosis
Arterial Occlusive Diseases
Vascular Diseases
Cardiovascular Diseases
Peripheral Vascular Diseases