Local Heat Stress in Autonomic Failure Patients With Supine Hypertension

December 25, 2021 updated by: Italo Biaggioni, Vanderbilt University
Patients with autonomic failure are characterized by disabling orthostatic hypotension (low blood pressure on standing), and at least half of them also have high blood pressure while lying down (supine hypertension). Exposure to heat, such as in hot environments, often worsens their orthostatic hypotension. The causes of this are not fully understood. The purpose of this study is to evaluate whether applying local heat over the abdomen of patients with autonomic failure and supine hypertension would decrease their high blood pressure while lying down. This will help us better understand the mechanisms underlying this phenomenon, and may be of use in the treatment of supine hypertension.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

Primary autonomic failure is a neurodegenerative condition characterized by severe impairment of the autonomic nervous system. The clinical hallmark of autonomic failure is disabling orthostatic hypotension, but at least half of patients are also hypertensive while lying down. This supine hypertension can be severe and associated with end-organ damage and worsening of orthostatic hypotension due to increased pressure natriuresis. It also complicates the management of these patients by limiting the use of daytime pressor agents for the treatment of orthostatic hypotension.

It is well known that heat exposure (e.g. hot weather or a hot bath or shower) produces an acute and temporary worsening of orthostatic hypotension in autonomic failure patients. However, the mechanisms underlying this phenomenon are completely unexplored. Factors that may predispose autonomic failure patients to the acute lowering blood pressure effects of heat stress include 1) impaired heat dissipation due to inability to sweat, 2) preserved heat-mediated skin vasodilation, and 3) blunted sympathetic hemodynamic responses to maintain blood pressure. In this study, we test the hypothesis that moderate levels of local (abdominal) passive heat stress will lower blood pressure in autonomic failure patients with supine hypertension.

To test this hypothesis, we propose this pilot study with the following specific aims:

  1. To evaluate the acute blood pressure effects of local passive heat stress in autonomic failure patients with supine hypertension, we will compare changes in BP between controlled local heat stress (~44ºC) using a commercial heating pad that covers the abdomen and part of the torso, and a control (non-heating) study day using the same heating pad but turned off.
  2. To evaluate the mechanisms underlying BP changes during local heat stress, we will compare changes in hemodynamic parameters (cardiac output, stroke volume and peripheral vascular resistance), segmental fluid shifts (measured by segmental bioimpedance), skin blood flow and skin temperature between the heat and non-heating study days.

Study Type

Interventional

Enrollment (Actual)

22

Phase

  • Not Applicable

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
    • Tennessee
      • Nashville, Tennessee, United States, 37232
        • Vanderbilt University

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

Ages Eligible for Study

18 years to 80 years (Adult, Older Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Description

Inclusion Criteria:

  • Male and female patients, between 18-80 yrs., with primary autonomic failure (Parkinson Disease, Multiple System Atrophy, and Pure Autonomic Failure) and supine hypertension. Supine hypertension will be defined as SBP≥150 mmHg.
  • Patients able and willing to provide informed consent.

Exclusion Criteria:

  • Pregnancy
  • Significant cardiac, renal or hepatic illness, or with contraindications to administration of pressor agents or with other factors, which in the investigator's opinion would prevent the subject from completing the protocol including clinically significant abnormalities in clinical, mental or laboratory testing.

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: Other
  • Allocation: Randomized
  • Interventional Model: Crossover Assignment
  • Masking: Single

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Local Heat Stress
Passive heat-stress using a commercial heating pad applied over the abdomen and part of the torso
Other: Passive heat stress
Passive heat stress will be applied with a commercial heating pad that covers all the abdomen and part of the torso to provide local heating at ~44ºC continuously for 2 hr.
Other Names:
  • Heating pad
Sham Comparator: Control (Non-heating)
Commercial heating pad applied over the abdomen and part of the torso but turned off
Other: Control (non-heating)
Heating pad will be applied over the abdomen and part of the torso but it will be turned off.
Other Names:
  • sham

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Change in Systolic Blood Pressure
Time Frame: 2 hours of heat stress or sham
Change from baseline in systolic blood pressure at 2 hr post-intervention
2 hours of heat stress or sham

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Percent Change in Hemodynamic Parameters (Cardiac Output, Stroke Volume and Systemic Vascular Resistance)
Time Frame: 2 hours of heat stress or sham
Percent change from baseline ([post-intervention - baseline]/baseline X 100) in cardiac output, stroke volume and systemic vascular resistance at 2 hours post-intervention
2 hours of heat stress or sham

Collaborators and Investigators

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

Sponsor

Vanderbilt University

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

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 (Actual)

April 1, 2015

Primary Completion (Actual)

February 1, 2021

Study Completion (Actual)

February 1, 2021

Study Registration Dates

First Submitted

April 10, 2015

First Submitted That Met QC Criteria

April 14, 2015

First Posted (Estimate)

April 15, 2015

Study Record Updates

Last Update Posted (Actual)

March 10, 2022

Last Update Submitted That Met QC Criteria

December 25, 2021

Last Verified

December 1, 2021

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 141523 (Other Identifier: Vanderbilt IRB)

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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