Indoor Overheating and Physiological Strain in Older Adults With COPD
Trial statusNot yet recruiting
Trial phaseNot applicable
Trial typeInterventional
Biological sexAll
Age60-80
SponsorUniversity of Ottawa
About this trial
During warm weather, homes without air conditioning can stay hot for long periods, and most heat-related health problems in Canada happen indoors rather than outdoors. Health Canada recommends that indoor temperatures not exceed 26 °C in homes occupied by people who are more susceptible to heat. That recommendation is based largely on population-level evidence, and very little is known about how susceptible individuals actually respond, physiologically, when indoor temperatures rise above it.
Older adults living with chronic obstructive pulmonary disease (COPD) are among the groups identified as more susceptible to heat. COPD involves persistent airflow limitation, reduced lung and cardiovascular reserve, and altered cellular stress responses. Despite this, no laboratory study has directly measured how adults with COPD respond to a full day spent indoors in warm conditions.
This randomized crossover trial will measure how older adults with COPD respond to two different indoor environments, each experienced for eight hours on separate days at least one week apart. One day is spent at the recommended indoor temperature limit and the other at a warmer temperature representative of conditions recorded inside Canadian homes during hot weather. Participants remain seated and rest throughout; no exercise or work is performed.
Throughout each day, the research team continuously measures core body temperature, skin temperature, heart rate, and measures blood pressure, lung function, breathlessness, thermal comfort, cognitive performance, and balance at set time points. Blood and urine samples are collected at the start and end of each day. Participants are monitored continuously by trained staff.
The results are intended to strengthen the evidence base behind Canadian indoor temperature guidance and to inform recommendations for protecting people living with chronic lung disease during hot weather.
Eligibility criteria
This trial does not accept healthy volunteersQualifiers
Aged 60 to 80 years
Physician diagnosis of chronic obstructive pulmonary disease made at least 5 years previously
Clinically stable, with no acute exacerbation or active respiratory infection in the preceding 6 weeks
Current non-smoker
Disqualifiers
Physical restriction preventing safe participation, including unstable cardiac or pulmonary disease, uncontrolled hypertension (resting blood pressure exceeding 150/95 mmHg), severe arthritis, renal impairment, active proliferative retinopathy, history of disabling stroke, or intermittent claudication
Recent change in medications judged by the investigators to make participation inadvisable
Cardiac abnormalities identified on electrocardiogram during the screening exercise test
Regular work or exercise in hot environments (heat acclimatized)
Trial design
Design model
Crossover
Treatments tested in this trial
Simulated indoor thermal environment
Other interventionDay-long (8 h) passive exposure in a climate-controlled environmental chamber at a set air temperature and relative humidity. Participants remain seated or resting.
Treatment groups
18 Participants
are divided into 2 treatment groupsGroup A: Recommended indoor temperature limit (26 °C)Active comparator 1 intervention
Group B: Indoor overheating (36 °C)Experimental treatment 1 intervention
Trial outcomes
Primary outcomes
1
Core temperature (Peak)
Peak rectal temperature (15 min average) during exposure. Rectal temperature is measured continuously throughout the simulated indoor overheating exposure.
Time frame
End of 8-hour exposureSecondary outcomes
1
Profiles of Mood States (POMS)
Potential changes in mood (7 subscales of mood: tension, anger, depression, fatigue, confusion, vigor and esteem-related affect). The POMS-40 is a validated, self-administered questionnaire that examines seven distinct aspects of mood state across two positive subscales (Esteem-Related Affect, and Vigor) and five negative subscales (Fatigue, Tension, Confusion, Anger, and Depression), which are described across 40 distinct adjectives. For each individual item, participants were asked to describe "how you feel right now" by responding using a 5-point Likert scale (0 = "Not at all", 1 = "A little", 2 = "Moderately", 3 = "Quite a lot", or 4 = "Extremely"). The values of items associated with a specific subscale (e.g., Fatigue) were summed to calculate its score.
Time frame
At the start (hour 0) and end of exposure (hour 8)2
Environmental Symptoms Questionnaire (ESQ)
Self-reported environmental reactions and medical symptomatology associated with prolonged heat exposure. The ESQ-IV is a validated 68-item, self-administered questionnaire that has been used successfully in identifying symptomatology during exposure to a wide variety of environmental conditions, including heat exposure \[24, 25\]. Participants are asked to assess and described "how you have been feeling today" by responding to each item using a 6-point Likert scale (0 = "Not at all", 1 = "Slight", 2 = "Somewhat", 3 = "Moderate", 4 = "Quite a bit", or 5 = "Extreme"). Total Symptom Score was calculated from this data by taking the sum of the intensity ratings from all 68 individual items using reverse scores for the three positive items from the list ("I Felt Good", "I Felt Alert", and "I Felt Wide Awake").
Time frame
At the start (hour 0) and end of exposure (hour 8)3
Orthostatic intolerance symptoms assessment
Cumulative sum of scores on 6 questions asking participant to rank symptoms associated with orthostatic intolerance during the lying to standing tests. All symptoms scored on a scale from 0 (none) to 10 (worst possible) and include feelings of: (1) "dizziness, lightheadedness, feeling faint, or feeling like you might black out"; (2) "Problems with vision (blurring, seeing spots, tunnel vision, etc.)"; (3) "Weakness"; (4) "Fatigue"; (5) "Trouble concentrating"; and (6) "Head and neck discomfort".
Time frame
At the start (hour 0) and end of exposure (hour 8)4
Perceived arousal (Felt Arousal Scale)
Perceived arousal assessed using the Felt Arousal Scale, a single-item 6-point numerical rating scale on which participants respond to the question "How worked up are you?" Scores range from a minimum of 1 (low arousal) to a maximum of 6 (high arousal).
Time frame
End of 8-hour exposureSponsors and contacts
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Source ClinicalTrials.gov
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