Health Canada - Establishing Evidence-based Indoor Temperature Thresholds to Protect Health
试验速览
- 阶段
- 不适用
- 状态
- 已完成
- 入组人数
- 16
- 试验地点
- 1
- 主要终点
- Rectal temperature
研究概览
简要总结
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.
详细描述
OBJECTIVES
The objective of this project is to evaluate the effect of a range of environments experienced during heatwaves on body temperature and autonomic cardiovascular function in older adults. This will be accomplished by comparing thermal and cardiovascular responses in a group of older adults resting for 8-hours in a range of conditions representative of those experienced indoors during heatwaves. To assess how the strain experienced in these conditions affects haemodynamic regulation in turn, this study will also include validated tests of cardiovascular autonomic function.
Hypotheses
Indices of thermal and cardiovascular strain will not be appreciably modified in older adults resting in simulated indoor environments below the currently recommended thresholds set by Toronto Public Health (22°C and 26°C). However, at higher indoor temperatures (31°C and 36°C) thermal and cardiovascular responses will be elevated. The increased physiological strain in these conditions will be reflected in attenuated responses to validated cardiovascular autonomic functional tests.
METHODS
研究设计
- 研究类型
- Interventional
- 分配方式
- Randomized
- 干预模型
- Crossover
- 主要目的
- Basic Science
- 盲法
- Single (Outcomes Assessor)
盲法说明
Participant identifier and experimental arm will be blinded from investigator responsible for analyzing outcomes in the cardiovascular battery (see detailed description).
入排标准
- 年龄范围
- 65 Years 至 80 Years（Older Adult）
- 性别
- All
- 接受健康志愿者
- 是
入选标准
- •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.
排除标准
- •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).
研究组 & 干预措施
HOT condition
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.
干预措施: Simulated heatwave exposure (Other)
WARM Condition
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.
干预措施: Simulated heatwave exposure (Other)
TEMPERATE Condition
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.
干预措施: Simulated heatwave exposure (Other)
COOL Condition
Participants are exposed to 22°C and 45% relative humidity for 8 hours. These conditions are consistent with actively cooled (air-conditioned) domicile.
干预措施: Simulated heatwave exposure (Other)
结局指标
主要结局
Rectal temperature
时间窗: Final 15 min of exposures
Index of core body temperature
Mean skin temperature
时间窗: Final 15 min of exposures
Calculated based on skin temperature measured over 8 body regions
次要结局
- Serum osmolality(Hour 8 of exposure)
- Rate pressure product(Final 15 min of exposures)
- Arterial blood pressures(Final 15 min of exposures)
- Resting cardiac baroreflex sensitivity(Hour 6 of exposure)
- Integrated baroreflex sensitivity(Hour 6 of exposure)
- Change in body weight(Hour 8 of exposure)
- Change in plasma volume(Hour 8 of exposure)
- Heart rate(Final 15 min of exposures)
- Ewings battery tests(Hour 6 of exposure)
- Resting heart rate variability(Hour 6 of exposure)
研究者
Glen P. Kenny
Full Professor, University Research Chair
University of Ottawa