HyperthermiaNCT05601713
Mitigating Heat-induced Physiological Strain and Discomfort in Older Adults Via Lower Limb Immersion and Neck Cooling
A study testing Lower limb immersion and Lower limb immersion + neck cooling in people with Hyperthermia and Weather; Heat, run by University of Ottawa at 1 site in Canada.
Trial summary
The incidence and severity of hot weather and extreme heat events (heat waves) is increasing. As such, there is an urgent need to develop heat-alleviation strategies that can provide targeted protection for older adults who are at an elevated risk for heat-induced illnesses or death due to impaired body temperature… Read more about this study
- Who is it for?
- Ages 65 to 85 yearsHealthy volunteers can take part
- Conditions the study is for
- Hyperthermia, Weather; Heat, Heat Stress
- What is being tested?
- Lower limb immersion and Lower limb immersion + neck cooling
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 18 participants
- Where
- 1 siteCanada
- Study dates
- 28 Sep 2022to 4 May 2023
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 65 to 85 years
- All sexes
- Healthy volunteers accepted
- Older adult
Who may be able to join
- Male or female adults.
- Aged 65-85 years.
- Non-smoking.
- English or French speaking.
- Ability to provide informed consent.
Who cannot join
- Physical restriction (e.g., due to disease: 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 (e.g., medications increasing risk of heat-related illness; beta blockers, anticholinergics, etc.)
- Cardiac abnormalities identified via 12-lead ECG during an incremental exercise test to volitional fatigue (performed for all participants).
- Peak aerobic capacity (VO2peak), as measured during an incremental exercise test to volitional fatigue, exceeding the 50th percentile of age- and sex-specific normative values published by the American College of Sports Medicine (ACSM).
Trial locations and contacts
1 site in 1 country.
About this study
Official title: Evaluating the Efficacy of Lower Leg Immersion With and Without Neck Cooling for Limiting Heat Strain in Elderly Adults During Extreme Heat Events
The incidence and severity of hot weather and extreme heat events (heat waves) is increasing. As such, there is an urgent need to develop heat-alleviation strategies that can provide targeted protection for older adults who are at an elevated risk for heat-induced illnesses or death due to impaired body temperature and cardiovascular regulation. While air-conditioning provides the most effective protection from extreme heat, it is inaccessible for many individuals and cannot be used during power outages (e.g., heat-related rolling blackouts). Immersion of the lower limbs in cold water and/or the application of cold towels to the neck have been recommended as simple and sustainable alternatives to air-conditioning. However, empirical data to support the efficacy of these interventions for mitigating physiological strain and discomfort in older adults is lacking. To address this knowledge gap, this randomized crossover trial will evaluate the effect of lower limb immersion with and without application of cold towels to the neck on body core temperature, cardiovascular strain and autonomic function, dehydration, and thermal comfort in adults aged 65-85 years exposed to simulated heat wave conditions (38°C, 35% relative humidity) for 6 hours.
- Conditions
- Hyperthermia, Weather; Heat, Heat Stress, Heat Syncope, Aging
- Being tested
- No cooling (control), Lower limb immersion, Lower limb immersion + neck cooling
- Keywords
- Heat wave, Cooling intervention, Heat strain, Cardiovascular strain, Heat and health protection, Extreme heat events
- Medical subject headings
- Hyperthermia, Heat Stress Disorders
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
No cooling (control)Other
Participants are exposed to 38°C, 35% relative humidity for 6 hours without cooling interventions (control condition). Drinking water is available ad libitum.
Lower limb immersionOther
Participants are exposed to 38°C, 35% relative humidity for 6 hours. For the last 40 min of each hour, participants lower limbs are immersed in cool water (~20°C) up to the level of mid calf. Drinking water is available ad libitum.
Lower limb immersion + neck coolingOther
Participants are exposed to 38°C, 35% relative humidity for 6 hours. For the last 40 min of each hour, participants lower limbs are immersed in cool water (~20°C) up to the level of mid calf. During limb immersion, a towel soaked in cool water (~20°C) is placed around the participants neck. The towel is re-wet half way through the 40-min limb immersion. Drinking water is available ad libitum.
| Study group | Role | What they receive |
|---|---|---|
| No cooling intervention (control) | Active comparator | Adults aged 65-85 years with or without type 2 diabetes and/or hypertension. Receives: Other: No cooling (control) |
| Lower limb immersion | Experimental | Adults aged 65-85 years with or without type 2 diabetes and/or hypertension. Receives: Other: Lower limb immersion |
| Lower limb immersion + neck cooling | Experimental | Adults aged 65-85 years with or without type 2 diabetes and/or hypertension. Receives: Other: Lower limb immersion + neck cooling |
What is being measured
The primary outcome is the main question the study is designed to answer.
Core temperature
Rectal temperature measured as an index of core temperature (15 minute average)
Measured: End of heat exposure (hour 6)
Secondary outcomes (14)
Heart rate
Heart rate derived from 3-lead electrocardiogram (15 minute average)
Measured: End of heat exposure (hour 6)
Systolic blood pressure
Systolic blood pressure measured in triplicate via automated oscillometry (~60 seconds between measures)
Measured: End of heat exposure (hour 6)
Diastolic blood pressure
Diastolic blood pressure measured in triplicate via automated oscillometry (~60 seconds between measures)
Measured: End of heat exposure (hour 6)
Rate pressure product
Rate pressure product, an index of myocardial work and strain, calculated as systolic blood pressure x heart rate.
Measured: End of heat exposure (hour 6)
Heart rate variability: SDNN
Standard deviation of normal-to-normal RR intervals (SDNN) measured during 5 minutes of paced breathing (15 breaths/min) with participants in the seated position. SDNN will be evaluated twice, during two paced breathing periods (separated by 4 min of seated rest).
Measured: End of heat exposure (hour 6)
Heart rate variability: RMSSD
Root mean squared standard deviation of normal-to-normal RR intervals (RMSSD) measured during 5 minutes of paced breathing (15 breaths/min) with participants in the seated position. RMSSD will be evaluated twice, during two paced breathing periods (separated by 4 min of seated rest).
Measured: End of heat exposure (hour 6)
Cardiac response to standing from supine (30:15 ratio)
Cardiac response to standing evaluated as the ratio between the highest RR interval (lowest heart rate) measured at the 30th heart beat after standing from supine (+/- 5 beats) and the lowest RR interval (highest heart rate) measured at the 15th heart beat after standing (+/- 5 beats). Cardiac response to standing will be evaluated twice, during two lying-to-standing tests (separated by 10 min of supine rest).
Measured: End of heat exposure (hour 6)
Systolic response to standing from supine
Systolic blood pressure response to standing evaluated as the difference in blood pressure measured between the standing and supine. Standing systolic blood pressure will be taken as the lowest value of those measured after 60 and 120 seconds of standing. Systolic response to standing will be evaluated twice, during two lying-to-standing tests (separated by 10 min of supine rest).
Measured: End of heat exposure (hour 6)
Integrated baroreflex sensitivity (sit-to-stand maneuvers)
Determined from beat-to-beat arterial pressures and heart rate (volume-clamp technique) during 5 min of sit-to-stand maneuvers performed at 0.05 Hz (3 cycles per min; 15 total cycles).
Measured: End of heat exposure (hour 6)
Fluid consumption
Cumulative fluid consumption calculated by weighing participant water intake at the start and end of each hour of exposure.
Measured: End of heat exposure (hour 6)
Fluid loss
Fluid loss calculated as the change in body mass during each exposure presented as a percentage of baseline body mass (corrected for food consumption)
Measured: End of heat exposure (hour 6)
Change in plasma volume
Change in plasma volume from baseline values calculated from duplicate measurements of hemoglobin and hematocrit at the start and end of each exposure using the technique by Dill and Costill.
Measured: End of heat exposure (hour 6)
Thermal comfort
Thermal comfort assessed via a visual analog scale ("How comfortable does your body temperature feel?") ranging from extremely uncomfortable to extremely comfortable (midpoint: neutral).
Measured: End of heat exposure (hour 6)
Orthostatic intolerance symptoms assessment
Cumulative sum of scores on 6 questions asking participant to rank symptoms associated with orthostatic intolerance during the last 1-2 hours (including the lying-to-standing and sit-to-stand 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".
Measured: End of heat exposure (hour 6)
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted1 Nov 2022
- Study start28 Sep 2022
- Primary completion4 May 2023
- Study completion4 May 2023
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for HyperthermiaStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Crossover
- Model description
- Participant will complete 3 simulated extreme heat event exposures in random order: i) no cooling intervention (control); ii) lower limb water immersion; and iii) lower limb water immersion with application of cool wet towel to the neck.
- Masking
- Double blind
- Who is masked
- Participant, Outcomes assessor
- Enrolment
- 18 participants (actual)
Sponsor and investigators
- Lead sponsor
- University of Ottawa
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Glen P. Kenny, University of Ottawa
- Investigators
- Glen P Kenny, PhD, Principal investigator, University of OttawaRobert D Meade, PhD, Principal investigator, University of OttawaRonald J Sigal, MD, MPH, Principal investigator, University of Calgary
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05601713
- Sponsor's protocol ID
- H-11-20-6234
- Status last verified
- May 2023
- First submitted
- 19 Oct 2022
- Last updated
- 10 May 2023
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Yes: Deidentified participant data will be made available with approved analysis plan and signed access agreement
Study at a glance
From the registry record, last updated by the sponsor on 10 May 2023. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Evaluating the Efficacy of Lower Leg Immersion With and Without Neck Cooling for Limiting Heat Strain in Elderly Adults During Extreme Heat Events
- ClinicalTrials.gov ID
- NCT05601713
- Acronym / sponsor ID
- H-11-20-6234
- Conditions
- Hyperthermia, Weather; Heat, Heat Stress, Heat Syncope, Aging
- Keywords
- Heat wave, Cooling intervention, Heat strain, Cardiovascular strain, Heat and health protection, Extreme heat events
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 18 participants (actual)
- Lead sponsor
- University of OttawaUniversity, hospital or other
- Study start
- 28 Sep 2022 (actual)
- Primary completion
- 4 May 2023 (actual)
- Study completion
- 4 May 2023 (actual)
- First posted
- 1 Nov 2022 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The incidence and severity of hot weather and extreme heat events (heat waves) is increasing. As such, there is an urgent need to develop heat-alleviation strategies that can provide targeted protection for older adults who are at an elevated risk for heat-induced illnesses or death due to impaired body temperature and cardiovascular regulation. While air-conditioning provides the most effective protection from extreme heat, it is inaccessible for many individuals and cannot be used during power outages (e.g., heat-related rolling blackouts). Immersion of the lower limbs in cold water and/or the application of cold towels to the neck have been recommended as simple and sustainable alternatives to air-conditioning. However, empirical data to support the efficacy of these interventions for mitigating physiological strain and discomfort in older adults is lacking. To address this knowledge gap, this randomized crossover trial will evaluate the effect of lower limb immersion with and without application of cold towels to the neck on body core temperature, cardiovascular strain and autonomic function, dehydration, and thermal comfort in adults aged 65-85 years exposed to simulated heat wave conditions (38°C, 35% relative humidity) for 6 hours.
Study design
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Double blind (participant, outcomes assessor)
- Number of arms
- 3
- Model description
- Participant will complete 3 simulated extreme heat event exposures in random order: i) no cooling intervention (control); ii) lower limb water immersion; and iii) lower limb water immersion with application of cool wet towel to the neck.
| Arm | Type | Receives |
|---|---|---|
| No cooling intervention (control) | Active comparator | Other: No cooling (control)Adults aged 65-85 years with or without type 2 diabetes and/or hypertension. |
| Lower limb immersion | Experimental | Other: Lower limb immersionAdults aged 65-85 years with or without type 2 diabetes and/or hypertension. |
| Lower limb immersion + neck cooling | Experimental | Other: Lower limb immersion + neck coolingAdults aged 65-85 years with or without type 2 diabetes and/or hypertension. |
Who may qualify
- Ages
- 65 to 85 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Older adult
Key inclusion criteria (5 listed)
- Male or female adults.
- Aged 65-85 years.
- Non-smoking.
- English or French speaking.
- Ability to provide informed consent.
Key exclusion criteria (4 listed)
- Physical restriction (e.g., due to disease: 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 (e.g., medications increasing risk of heat-related illness; beta blockers, anticholinergics, etc.)
- Cardiac abnormalities identified via 12-lead ECG during an incremental exercise test to volitional fatigue (performed for all participants).
- Peak aerobic capacity (VO2peak), as measured during an incremental exercise test to volitional fatigue, exceeding the 50th percentile of age- and sex-specific normative values published by the American College of Sports Medicine (ACSM).
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| No cooling (control)Participants are exposed to 38°C, 35% relative humidity for 6 hours without cooling interventions (control condition). Drinking water is available ad libitum. | Other | No cooling intervention (control) |
| Lower limb immersionParticipants are exposed to 38°C, 35% relative humidity for 6 hours. For the last 40 min of each hour, participants lower limbs are immersed in cool water (~20°C) up to the level of mid calf. Drinking water is available ad libitum. | Other | Lower limb immersion |
| Lower limb immersion + neck coolingParticipants are exposed to 38°C, 35% relative humidity for 6 hours. For the last 40 min of each hour, participants lower limbs are immersed in cool water (~20°C) up to the level of mid calf. During limb immersion, a towel soaked in cool water (~20°C) is placed around the participants neck. The towel is re-wet half way through the 40-min limb immersion. Drinking water is available ad libitum. | Other | Lower limb immersion + neck cooling |
Primary outcome
Core temperature
Time frame: End of heat exposure (hour 6)
Rectal temperature measured as an index of core temperature (15 minute average)
14 secondary outcomes
Heart rate
Time frame: End of heat exposure (hour 6)
Systolic blood pressure
Time frame: End of heat exposure (hour 6)
Diastolic blood pressure
Time frame: End of heat exposure (hour 6)
Rate pressure product
Time frame: End of heat exposure (hour 6)
Heart rate variability: SDNN
Time frame: End of heat exposure (hour 6)
Heart rate variability: RMSSD
Time frame: End of heat exposure (hour 6)
Cardiac response to standing from supine (30:15 ratio)
Time frame: End of heat exposure (hour 6)
Systolic response to standing from supine
Time frame: End of heat exposure (hour 6)
Integrated baroreflex sensitivity (sit-to-stand maneuvers)
Time frame: End of heat exposure (hour 6)
Fluid consumption
Time frame: End of heat exposure (hour 6)
Fluid loss
Time frame: End of heat exposure (hour 6)
Change in plasma volume
Time frame: End of heat exposure (hour 6)
Thermal comfort
Time frame: End of heat exposure (hour 6)
Orthostatic intolerance symptoms assessment
Time frame: End of heat exposure (hour 6)
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 10 May 2023.
- Individual participant dataSharing planned: Yes. Deidentified participant data will be made available with approved analysis plan and signed access agreement
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Glen P Kenny, PhD principal investigator
University of Ottawa
Robert D Meade, PhD principal investigator
University of Ottawa
Ronald J Sigal, MD, MPH principal investigator
University of Calgary
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Lower limb immersion and Lower limb immersion + neck cooling in people with Hyperthermia and Weather; Heat, run by University of Ottawa at 1 site in Canada.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 5 inclusion and 4 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 10 May 2023. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Canada. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Core temperature (time frame: End of heat exposure (hour 6)). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 10 May 2023; AzTrials last refreshed its copy on 7 Nov 2026.