Heat Waves and the Elderly - Cooling Modalities

Heat Waves in the Elderly: Reducing Thermal and Cardiovascular Consequences

The purpose of this study is to assess how well cooling modalities work in reducing cardiovascular stress of the elderly to heat wave conditions

Study Overview

• Status: Recruiting
• Conditions: Hyperthermia; Aging
• Intervention / Treatment: Other: Water Spray; Other: Fan; Other: Water Spray and Fan; Other: Control

Detailed Description

Heat waves are lethal and cause a disproportionate number of deaths in the elderly relative to any other age group. Such deaths are primarily cardiovascular, not hyperthermia itself, in origin. The central hypothesis of this work is that cardiovascular stress during heat wave conditions in the elderly can be reduced by applying low-energy cooling modalities. Comprehensive cardiovascular and thermal responses in the elderly will be evaluated during exposure to two prolonged heat wave conditions: hot and humid (replicating the 1995 Chicago heat wave), very hot and dry (replicating the 2018 Los Angeles heat wave). With each of these heat wave conditions individuals will be exposed to the following cooling modalities: no cooling (control), water spray, fan use, and fan use plus water spray.

• Study Type: Interventional
• Enrollment (Estimated): 50
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Zachary McKenna, PhD; Phone Number: 214-345-6557; Email: ZacharyMckenna@texashealth.org
• Study Contact Backup: Name: Taysom Wallace, MS; Phone Number: 214-345-5022; Email: TaysomWallace@texashealth.org

Study Locations

• United States
  • Texas
    • Dallas, Texas, United States, 75231
      • Recruiting
      • Texas Health Presbyterian Hospital Dallas
      • Contact: Zachary McKenna, PhD; Phone Number: 214-345-6557; Email: ZacharyMckenna@texashealth.org
      • Principal Investigator: Craig Crandall, PhD
      • Contact: Taysom Wallace, MS; Phone Number: 214.345.5022; Email: TaysomWallace@texashealth.org

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 65 years and older (Older Adult)
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• 65 years of age or older
• Free of any significant underlying medical problems based upon a detailed medical history and physical exam

Exclusion Criteria:

• Known heart disease
• Other chronic medical conditions requiring regular medical therapy including cancer, diabetes, uncontrolled hypertension, and uncontrolled hypercholesterolemia etc;
• Abnormality detected on routine screening suggestive of provokable ischemia or previously undetected cardiac disease or resting left bundle branch block on screening electrocardiogram.
• Current smokers, as well as individuals who regularly smoked within the past 3 years
• Subject with a body mass index ≥31 kg/m2
• Pregnant individuals

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Very hot and dry; Subjects will be exposed to 3 hours in a climate chamber set to approximately 47 deg C and 15% relative humidity, which reflects a very hot and dry heat wave condition similar to the 2018 Los Angeles heat wave. Four visits will be required to complete this arm, with each visit a different cooling modality applied.	Other: Water Spray; Participants will receive water spraying on their body throughout the climate chamber exposure.; Other: Fan; Participants will be exposed to a fan throughout the climate chamber exposure.; Other: Water Spray and Fan; Participants will receive both water spraying and a fan throughout the climate chamber exposure.; Other: Control; Participants will NOT receive either water spray or a fan exposure.
Experimental: Hot and humid; Subjects will be exposed to 3 hours in a climate chamber set to approximately 41 deg C and 40% relative humidity, which reflects hot and humid heat wave similar to the 1995 Chicago heat wave. Four visits will be required to complete this arm, with each visit a different cooling modality applied.	Other: Water Spray; Participants will receive water spraying on their body throughout the climate chamber exposure.; Other: Fan; Participants will be exposed to a fan throughout the climate chamber exposure.; Other: Water Spray and Fan; Participants will receive both water spraying and a fan throughout the climate chamber exposure.; Other: Control; Participants will NOT receive either water spray or a fan exposure.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in core body temperature	Change in core body temperature will be measured either from a temperature sensor pill or from a rectal thermometer	Body core temperature will be obtained within 60 min before the heat wave exposure after the 3 hour heat wave exposure.
Change in left ventricular function	Measures of left ventricular function, such as ventricular wall motion and ventricular filling, will be obtained from echocardiography images.	Within 60 minutes before each simulated heat wave exposure, around minute 90 of the heat wave exposure, and at the end of the 3 hour heat wave exposure

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Heart rate	Heart rate will be measured from ECG electrodes attached to the participant	Prior to and throughout each simulated heat wave exposure; approximately 420 minutes
Cardiac output	Cardiac output (how much blood is ejected from the heart) will be measured using 3D echocardiography.	Within 60 minutes before each simulated heat wave exposure and during each simulated heat wave exposure (up to 3 hours)
Arterial blood pressure	Arterial blood pressure will be measured using a standard arm blood pressure cuff.	Prior to and throughout each simulated heat wave exposure; an average of 480 minutes
Whole body sweat rate	Whole body sweat rate will be measured by through nude weight of the participant.	Within 60 minutes before each simulated heat wave exposure and within 30 minutes after each heat wave exposure.
Markers of renal function and injury - Cystatin C	Markers of renal function and injury (e.g., cystatin C) will be evaluated from blood sampling collection.	Within 60 minutes before each simulated heat wave exposure, during each simulated heat wave exposure (up to 3 hours), and within 2 hours after the simulated heat wave exposure
Markers of renal function and injury - Creatinine Clearance	Markers of renal function and injury (e.g., creatinine clearance) will be evaluated from blood sampling and urine collection.	Within 60 minutes before each simulated heat wave exposure, during each simulated heat wave exposure (up to 3 hours), and within 2 hours after the simulated heat wave exposure
Markers of renal function and injury - Insulin-like growth factor-binding protein 7	Markers of renal function and injury (e.g., Insulin-like growth factor-binding protein 7) will be evaluated from urine sampling.	Within 60 minutes before each simulated heat wave exposure, during each simulated heat wave exposure (up to 3 hours), and within 2 hours after the simulated heat wave exposure
Markers of renal function and injury - Tissue inhibitor of metalloproteinases 2	Markers of renal function and injury (e.g., Tissue inhibitor of metalloproteinases 2) will be evaluated from urine sampling.	Within 60 minutes before each simulated heat wave exposure, during each simulated heat wave exposure (up to 3 hours), and within 2 hours after the simulated heat wave exposure
Cerebral perfusion	Cerebral perfusion will be measured by Doppler ultrasound of the internal carotid and vertebral arteries.	Within 60 minutes before each simulated heat wave exposure and during each simulated heat wave exposure (up to 3 hours)
High sensitive cardiac troponin	A plasma-based marker of cardiac stress (high sensitive cardiac troponin) be evaluated from blood sampling.	Within 60 minutes before each simulated heat wave exposure, during each simulated heat wave exposure (up to 3 hours), and within 2 hours after the simulated heat wave exposure
Skin temperature	Skin temperature will be measured from small temperature sensitive electrodes attached to the participant's skin	Within 60 minutes before each simulated heat wave exposure and during each simulated heat wave exposure (up to 3 hours)
Forced vital capacity (FVC)	Forced vital capacity will be obtained from spirometry	Within 60 minutes before each simulated heat wave exposure and during each simulated heat wave exposure (up to 3 hours)

Collaborators and Investigators

• Sponsor: University of Texas Southwestern Medical Center

Study record dates

Study Major Dates

• Study Start (Actual): February 21, 2023
• Primary Completion (Estimated): October 1, 2025
• Study Completion (Estimated): August 31, 2026

Study Registration Dates

• First Submitted: July 27, 2022
• First Submitted That Met QC Criteria: July 29, 2022
• First Posted (Actual): August 2, 2022

Study Record Updates

• Last Update Posted (Actual): April 19, 2024
• Last Update Submitted That Met QC Criteria: April 17, 2024
• Last Verified: April 1, 2024

More Information

Terms related to this study

• Keywords: aging; cardiovascular; heat wave; low-energy cooling
• Additional Relevant MeSH Terms: Wounds and Injuries; Body Temperature Changes; Heat Stress Disorders; Hyperthermia
• Other Study ID Numbers: STU-2022-0625

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No