Clinical trial NCT06618352: Physiological Strain in Young Adults During a Simulated Heat Wave
Official title: The Effects of Indoor Overheating on Physiological Strain in Young Adults During a Simulated Multi-day Heat Event
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: NA
Conditions: Heat Stress
Physiological Stress
Keywords: Heat wave
Indoor temperatures
Thermoregulation
Heat strain
Young adults
Cardiovascular strain
Sleep
Fatigue
Lead sponsor: University of Ottawa
Sponsor class: OTHER
First posted: 2024-10-01
Enrollment: 20
Sex: ALL
Minimum age (years): 18
Maximum age (years): 35
Standard ages: ADULT
Accepts healthy volunteers: yes
Allocation: NA
Intervention model: SINGLE_GROUP
Primary purpose: BASIC_SCIENCE

Brief summary: The likelihood of exposure to overheated indoor environments is increasing as climate change is exacerbating the frequency and severity of hot weather and extreme heat events. Prolonged exposure to excessive heat stress can result in a deterioration in physiological function leading to a myriad of pathophysiological conditions (e.g., heat exhaustion, acute kidney injury, adverse cardiovascular events, heat stroke) that if left untreated can lead to death. While the relationship between extreme heat events and human health has been assessed in relation to outdoor exposure to high heat conditions, relatively little is known about the effects of daylong exposures to indoor overheating on the body's physiology.

In this study, investigators will examine the change in physiological responses (i.e., thermal, cardiovascular) in young (18-35 years) adults exposed to successive days and nights of high indoor temperatures typical of conditions recording in dwellings without air conditioning during the 2021 Western Heat Dome. Specifically, study participants will be housed in a large environmental chamber (outfitted with bed, work space, sitting area, kitchen and bathroom) for three successive days (three days and two nights) while exposed to indoor overheating where daytime temperatures will be maintained at 36°C (45% relative humidity; note: 36°C, temperatures experienced in homes without air-conditioning) for a 10-hour daytime exposure period (DAYTIME: defined as the time period from 9:00 to 19:00). For the nighttime exposure period (NIGHTTIME: defined as the time period from 19:00 to 9:00), participants will be exposed to nighttime temperatures fixed at 31°C (45% relative humidity; note: reductions in indoor temperatures during the nighttime in large urban centers range between 4-6°C). Participants will be permitted to move freely throughout the day in the chamber, but will be restricted from performing any physical activity except for the completion of a battery of tests (cardiovascular, cognitive and posture assessments performed prior to (as performed between 7:00 and 9:00) and the end (as performed between 17:00 and 19:00) of the daytime exposure). During the nighttime period, participants will be permitted to move freely until they decide to go to bed.


Eligibility criteria: Inclusion Criteria:

* Non-smoking.
* English or French speaking.
* Ability to provide informed consent.

Exclusion Criteria:

* Chronic health conditions.
* Endurance trained
* Regular exposure to heat (e.g., hot baths, sauna, regular exercise in the heat, recent vacation to area with high temperature).

Primary outcomes:
measure: Core temperature (Peak) during daytime
timeFrame: End of daytime exposure (hour 10 for Day 1, 2 and 3 of the three day exposure) (daytime defined as period between 9:00 to 19:00)
measure: Core temperature (AUC) during daytime
timeFrame: End of daytime exposure (hour 10 for Day 1, 2 and 3 of the three day exposure) (daytime defined as period between 9:00 to 19:00)
measure: Core temperature end of daytime exposure
timeFrame: End of daytime exposure (hour 10 for Day 1, 2 and 3 of the three day exposure) (daytime defined as period between 9:00 to 19:00)
measure: Heat rate peak during daytime
timeFrame: End of daytime exposure (hour 10 for Day 1, 2 and 3 of the three day exposure) (daytime defined as period between 9:00 to 19:00)
measure: Heat rate AUC during daytime
timeFrame: End of daytime exposure (hour 10 for Day 1, 2 and 3 of the three day exposure) (daytime defined as period between 9:00 to 19:00)
measure: Cardiac response to standing from supine (30:15 Ratio) during daytime
timeFrame: At the start (hour 0) and end of daytime exposure (hour 10 for Day 1, 2 and 3 of the three day exposure) (daytime defined as period between 9:00 to 19:00)
measure: Cognitive function during daytime
timeFrame: At the start (hour 0) and end of daytime exposure (hour 10 for Day 1, 2 and 3 of the three day exposure) (daytime defined as period between 9:00 to 19:00)
measure: Postural stability during daytime
timeFrame: At the start (hour 0) and end of daytime exposure (hour 10 for Day 1, 2 and 3 of the three day exposure) (daytime defined as period between 9:00 to 19:00)
measure: Systolic Response to Standing From Supine during daytime
timeFrame: At the start (hour 0) and end of daytime exposure (hour 10 for Day 1, 2 and 3 of the three day exposure) (daytime defined as period between 9:00 to 19:00)
measure: Systolic blood pressure during daytime
timeFrame: End of daytime exposure (hour 10 for Day 1, 2 and 3 of the three day exposure) (daytime defined as period between 9:00 to 19:00)
measure: Diastolic blood pressure during daytime
timeFrame: End of daytime exposure (hour 10 for Day 1, 2 and 3 of the three day exposure) (daytime defined as period between 9:00 to 19:00)
measure: Rate pressure product during daytime
timeFrame: End of daytime exposure (hour 10 for Day 1, 2 and 3 of the three day exposure) (daytime defined as period between 9:00 to 19:00)
measure: Heart rate variability: SDNN during daytime
timeFrame: End of daytime exposure (hour 10 for Day 1, 2 and 3 of the three day exposure) (daytime defined as period between 9:00 to 19:00)
measure: Heart rate variability: RMSSD during daytime
timeFrame: End of daytime exposure (hour 10 for Day 1, 2 and 3 of the three day exposure) (daytime defined as period between 9:00 to 19:00)
measure: Fluid consumption during daytime
timeFrame: End of daytime exposure (hour 10 for Day 1, 2 and 3 of the three day exposure) (daytime defined as period between 9:00 to 19:00)
measure: Fluid loss during daytime
timeFrame: End of daytime exposure (hour 10 for Day 1, 2 and 3 of the three day exposure) (daytime defined as period between 9:00 to 19:00)
measure: Change in plasma volume during daytime
timeFrame: End of daytime exposure (hour 10 for Day 1, 2 and 3 of the three day exposure) (daytime defined as period between 9:00 to 19:00)
measure: Thermal comfort scale during daytime
timeFrame: End of daytime exposure (hour 10 for Day 1, 2 and 3 of the three day exposure) (daytime defined as period between 9:00 to 19:00)
measure: Thermal sensation scale during daytime
timeFrame: End of daytime exposure (hour 10 for Day 1, 2 and 3 of the three day exposure) (daytime defined as period between 9:00 to 19:00)
measure: Thirst sensation scale during daytime
timeFrame: End of daytime exposure (hour 10 for Day 1, 2 and 3 of the three day exposure) (daytime defined as period between 9:00 to 19:00)
measure: Arousal scale during daytime
timeFrame: End of daytime exposure (hour 10 for Day 1, 2 and 3 of the three day exposure) (daytime defined as period between 9:00 to 19:00)
measure: Orthostatic intolerance symptoms assessment during daytime
timeFrame: End of daytime exposure (hour 10 for Day 1, 2 and 3 of the three day exposure) (daytime defined as period between 9:00 to 19:00)
measure: Core temperature (Peak) during nighttime
timeFrame: End of nighttime exposure (hour 24 for Day 1 and Day 2 of the three day exposure; no nighttime exposure for Day 3) (daytime defined as period between 19:00 to 9:00)
measure: Core temperature (AUC) during nighttime
timeFrame: End of nighttime exposure (hour 24 for Day 1 and Day 2 of the three day exposure; no nighttime exposure for Day 3) (daytime defined as period between 19:00 to 9:00)
measure: Core temperature end of nighttime
timeFrame: End of nighttime exposure (hour 24 for Day 1 and Day 2 of the three day exposure; no nighttime exposure for Day 3) (daytime defined as period between 19:00 to 9:00)
measure: Heat rate peak during nighttime
timeFrame: End of nighttime exposure (hour 24 for Day 1 and Day 2 of the three day exposure; no nighttime exposure for Day 3) (daytime defined as period between 19:00 to 9:00)
measure: Heat rate AUC during nighttime
timeFrame: End of nighttime exposure (hour 24 for Day 1 and Day 2 of the three day exposure; no nighttime exposure for Day 3) (daytime defined as period between 19:00 to 9:00)
measure: Heart rate variability: SDNN during nighttime
timeFrame: End of nighttime exposure (hour 24 for Day 1 and Day 2 of the three day exposure; no nighttime exposure for Day 3) (daytime defined as period between 19:00 to 9:00)
measure: Heart rate variability: RMSSD during nighttime
timeFrame: End of nighttime exposure (hour 24 for Day 1 and Day 2 of the three day exposure; no nighttime exposure for Day 3) (daytime defined as period between 19:00 to 9:00)
Secondary outcomes:
measure: Muscle oxygen during battery of cardiovascular, postural and cognitive tests during daytime
timeFrame: End of daytime exposure (hour 10 for Day 1, 2 and 3 of the three day exposure) (daytime defined as period between 9:00 to 19:00)
measure: Profiles of Mood States (POMS) during daytime
timeFrame: End of daytime exposure (hour 10 for Day 1, 2 and 3 of the three day exposure) (daytime defined as period between 9:00 to 19:00)
measure: Environmental Symptoms Questionnaire (ESQ)
timeFrame: End of daytime exposure (hour 10 for Day 1, 2 and 3 of the three day exposure) (daytime defined as period between 9:00 to 19:00)
measure: Sleep quality and quantify assessment
timeFrame: End of daytime exposure (hour 10 for Day 1, 2 and 3 of the three day exposure) (daytime defined as period between 9:00 to 19:00)
measure: Sleepiness during daytime
timeFrame: End of daytime exposure (hour 10 for Day 1, 2 and 3 of the three day exposure) (daytime defined as period between 9:00 to 19:00)
Other outcomes:
Locations:
city: Ottawa
country: Canada
facility: University of Ottawa
state: Ontario
Study officials:
affiliation: University of Ottawa
name: Glen P Kenny, PhD
role: PRINCIPAL_INVESTIGATOR
References: