Cardiovascular Responses to Heat Waves in the Elderly
Study Details
Study Description
Brief Summary
The purpose of this study is to assess the cardiovascular responses of the elderly to heat wave conditions
| Condition or Disease | Intervention/Treatment | Phase |
|---|---|---|
|
Detailed Description
Heat waves are lethal and cause a disproportionate number of deaths in the elderly relative to any other age group. It is important to note that such deaths are primarily cardiovascular, not hyperthermia itself, in origin. Nevertheless, we know relatively little about the effects of aging on cardiovascular function during actual heat wave-like conditions. The central hypothesis of this work is that the elderly exhibit greater cardiovascular stress during heat wave conditions. Aim 1 will test the hypothesis that recognized impairments in thermoregulatory capacity in the elderly will culminate in heightened cardiovascular stress during prolonged exposure to heat wave conditions. Comprehensive cardiovascular and thermal responses in the elderly, relative to younger adults, 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). The expected outcome from this body of work will re-shape our understanding of the consequences of aging on cardiovascular function during heat waves
Study Design
Arms and Interventions
| Arm | Intervention/Treatment |
|---|---|
| Younger participants Individuals aged 18-39 years |
Other: Simulated heat wave
Individuals will be exposed to thermoneutral climate conditions and two simulated heat wave conditions.
|
| Older participants Individuals aged 65 years or older |
Other: Simulated heat wave
Individuals will be exposed to thermoneutral climate conditions and two simulated heat wave conditions.
|
Outcome Measures
Primary Outcome Measures
- Core body temperature [Prior to and throughout each simulated heat wave exposure; an average of 480 minutes.]
Core body temperature will be measured from gastrointestinal temperature via an ingestible telemetric pill.
- Measures of left ventricular function [Prior to, during, and after each simulated heat wave exposure; approximately 20 min each]
Measures of left ventricular function, such as ventricular wall motion and ventricular filling, will be obtained from echocardiography images.
Secondary Outcome Measures
- Skin temperature [Prior to and throughout each simulated heat wave exposure; an average of 480 minutes.]
Skin temperature will be measured from small temperature sensitive electrodes attached to the participant's skin
- Heart rate [Prior to and throughout each simulated heat wave exposure; an average of 480 minutes.]
Heart rate will be measured from ECG electrodes attached to the participant
- Arterial blood pressure [Prior to and throughout each simulated heat wave exposure; an average of 480 minutes.]
Arterial blood pressure will be measured using a standard arm blood pressure cuff
- Cardiac output [Prior to, during, and after each simulated heat wave exposure; approximately 20 min each]
Cardiac output (how much blood is ejected from the heart) will be measured using echocardiography and nitrous oxide rebreathing approaches.
- Cerebral perfusion [Prior to, during, and after each simulated heat wave exposure; approximately 20 min each]
Cerebral perfusion will be measured by doppler ultrasound of the internal carotid and vertebral arteries
Eligibility Criteria
Criteria
Inclusion Criteria:
-
Healthy male and female individuals
-
18-35 years or 65+ years of age
-
Free of any underlying moderate to serious medical conditions
Exclusion Criteria:
-
Known heart disease; other chronic medical conditions requiring regular medical therapy including cancer, diabetes, neurological diseases, uncontrolled hypertension, and uncontrolled hypercholesterolemia.
-
Taking of any medications (such as beta blockers and non-dihydropyridine calcium channel blockers) that have known influences on either cardiac function or sweating responses.
-
Abnormalities detected on routine screening.
-
Individuals who participate in a structured aerobic exercise training program at moderate to high intensities.
-
Current smokers, as well as individuals who regularly smoked within the past 3 years.
-
Body mass index of greater than 30 kg/m^2
-
Pregnant individuals
Contacts and Locations
Locations
| Site | City | State | Country | Postal Code | |
|---|---|---|---|---|---|
| 1 | Texas Health Presbyterian Hospital Dallas | Dallas | Texas | United States | 75231 |
Sponsors and Collaborators
- University of Texas Southwestern Medical Center
Investigators
None specified.Study Documents (Full-Text)
None provided.More Information
Publications
None provided.- STU_2019_1759