Establishing Evidence-based Indoor Temperature Thresholds to Protect Health

NCT04348630 | Completed

• 1 other identifier: 2018-026H
• Study Type: interventional
• Target: 16
• Locations: 1 country
• Sites: 1

Brief Summary

An individual's ability to adequately cope with short- or long-term increases in ambient temperature is critical for maintaining health and wellbeing. Prolonged increases in temperature (heatwaves) pose a serious health risk for older adults, who have a reduced capacity to regulate body temperature. Currently, however, there is a lack of information regarding how different environmental conditions experienced during heatwaves impact body temperature regulation and physiological function. This is particularly important in the context of ambient conditions in the home, where older adults spend the majority of their time. This project will address this important issue by exposing healthy older adults to prolonged (8-hour) simulated heatwaves comprising a range of environmental conditions representative of an actively cooled domicile through to a worst-case scenario (i.e., no capacity for home cooling). The investigators will directly measure their ability to regulate their body temperature and the associated impact on the autonomic control of the heart. The investigators anticipate that physiological strain will be mild during prolonged exposure to conditions below the currently recommended thresholds set by Toronto Public Health (26°C). However, at higher indoor temperatures, impairments in body temperature and cardiovascular regulation will be seen.

Conditions

Aging; Heat Stress; Physiological Stress

Keywords

Heatwave,; heat-vulnerability; Indoor environments; Cardiovascular strain; thermoregulation; heat strain

Outcome Measures

Primary Outcomes (2)

• Rectal temperature

  Index of core body temperature

  Final 15 min of exposures

• Mean skin temperature

  Calculated based on skin temperature measured over 8 body regions

  Final 15 min of exposures

Secondary Outcomes (10)

• Heart rate

  Final 15 min of exposures

• Arterial blood pressures

  Final 15 min of exposures

• Rate pressure product

  Final 15 min of exposures

• Ewings battery tests

  Hour 6 of exposure

• Resting heart rate variability

  Hour 6 of exposure

Study Arms (4)

HOT condition

EXPERIMENTAL

Participants are exposed to 36°C and 45% relative humidity for 8 hours. These conditions were chosen to represent an extreme heat condition (i.e., heatwave) and are similar to peak domicile conditions measured in low-income high-rise apartment complexes during heatwaves.

Other: Simulated heatwave exposure

WARM Condition

EXPERIMENTAL

Participants are exposed to 31°C and 45% relative humidity for 8 hours. These conditions are similar to mean domicile conditions measured in a variety of domicile types during heat waves complexes during heatwaves and are consistent with the World Heath Organization recommendation for maximal indoor temperatures.

Other: Simulated heatwave exposure

TEMPERATE Condition

EXPERIMENTAL

Participants are exposed to 26°C and 45% relative humidity for 8 hours. These conditions are consistent with Toronto Public Health recommendation for maximal indoor temperatures, which are based on the increase in mortality associated with increases in outdoor temperature above these limits.

Other: Simulated heatwave exposure

COOL Condition

EXPERIMENTAL

Participants are exposed to 22°C and 45% relative humidity for 8 hours. These conditions are consistent with actively cooled (air-conditioned) domicile.

Other: Simulated heatwave exposure

Interventions

Simulated heatwave exposure OTHER

Older adults are exposed to a 8-hour simulated exposure

COOL Condition; HOT condition; TEMPERATE Condition; WARM Condition

Eligibility Criteria

• Age: 65 Years - 80 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Older Adult (65+)

You may qualify if:

• Male or female (non-pregnant) adults aged 18-80 with or without a) chronic hypertension (elevated resting blood pressure; as defined by Heart and Stroke Canada and Hypertension Canada), b) type 2 diabetes as defined by Diabetes Canada, with at least 5 years having elapsed since time of diagnosis and or c) obesity as defined by the World Health Organization (Body Mass Index \[BMI\] greater than or equal to 30)
• non-smoking.

You may not qualify if:

• \- Episode(s) of severe hypoglycemia (requiring the assistance of another person) within the previous year, or inability to sense hypoglycemia (hypoglycemia unawareness).
• Serious complications related to your diabetes (gastroparesis, renal disease, uncontrolled hypertension, severe autonomic neuropathy).
• Uncontrolled hypertension - BP \>150 mmHg systolic or \>95 mmHg diastolic in a sitting position.
• Restrictions in physical activity due to disease (e.g. intermittent claudication, renal impairment, active proliferative retinopathy, unstable cardiac or pulmonary disease, disabling stroke, severe arthritis, etc.).
• Use of or changes in medication judged by the patient or investigators to make participation in this study inadvisable.
• Cardiac abnormalities identified in your physical health screening form (adults \<65 years of age and older; adults \<60 years of age and older with diabetes and or hypertension) or during exercise stress testing as assessed by 12-lead (all adults ≥65 years of age and older).

Sponsors & Collaborators

• University of Ottawa: lead

Study Sites (1)

University of Ottawa

Ottawa, Ontario, K1N6N5, Canada

Location

MeSH Terms

Conditions

Heat Stress Disorders

Condition Hierarchy (Ancestors)

Wounds and Injuries

Study Officials

• Glen P Kenny, PhD

  University of Ottawa

  PRINCIPAL INVESTIGATOR

• Ronald J Sigal, MD, MPH

  University of Calgary

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: SINGLE
• Who Masked: OUTCOMES ASSESSOR
• Masking Details: Participant identifier and experimental arm will be blinded from investigator responsible for analyzing outcomes in the cardiovascular battery (see detailed description).
• Purpose: BASIC SCIENCE
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Full Professor, University Research Chair

Study Record Dates

• First Submitted: April 13, 2020
• First Posted: April 16, 2020
• Study Start: June 1, 2019
• Primary Completion: November 11, 2021
• Study Completion: November 11, 2021
• Last Updated: March 30, 2023

Record last verified: 2023-03

Locations

CA (1)