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

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.

Conditions

• PAD

Interventions

OTHER

Without Heating

Subject will complete walking protocol without any heating procedure

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

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

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

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.

Sponsors & Collaborators

• Milton S. Hershey Medical Center

  lead OTHER

Principal Investigators

• Jian Cui · Penn State College of Medicine

Study Design

Allocation

RANDOMIZED

Purpose

BASIC_SCIENCE

Masking

SINGLE

Model

CROSSOVER

Eligibility

Min Age

21 Years

Max Age

85 Years

Sex

ALL

Healthy Volunteers

Yes

Timeline & Regulatory

Start

2019-05-15

Primary Completion

2025-07-31

Completion

2025-07-31

Countries

• United States

Study Locations