RecruitingACTRN12622000367741

Cool water foot immersion, skin wetting and fan use as low-cost, at home cooling strategies for older adults during heat waves

The efficacy of foot immersion alone or combined with fan use and skin wetting as a low-cost cooling strategy for older adults during hot humid and hot dry heatwaves

Sponsor

The University of Sydney

Enrollment

41 participants

Start Date

May 12, 2022

Study Type

Interventional

Conditions

Summary

Our laboratory has been conducting research in collaboration with the Montreal Heart Institute, Montreal, CA. examining the effect of fan use with and without skin wetting on thermal and cardiovascular strain in older adults with and without CAD during a 3-hour simulated heatwave. These data demonstrate that fan use during a hot and humid heatwave (38°C, 60% humidity) mitigates the rise in core temperature and heart rate compared to no fan use. During a hot and dry heatwave (45°C, 10% humidity), wetting the skin with 18°C water mitigates the rise in core temperature and heart rate compared to no cooling intervention. This study is is the second phase of identifying low-cost cooling strategies for older adults who are healthy and have heart disease to use in home during heat waves. In this study we aim to investigate whether there is an additional benefit of cold-water foot immersion when combined with fan use during a simulated hot and humid (38°C, 60% humidity) heat wave. A secondary aim of this study is to investigate whether there is an additional benefit of cold-water foot immersion when combined with skin wetting during a simulated hot and dry (45°C, 10% humidity) heatwave.

Eligibility

Sex: Both males and femalesMin Age: 60 Yearss

Plain Language Summary

Simplified for easier understanding

Heatwaves are becoming more frequent and severe due to climate change, and older adults — especially those with heart disease — are at significantly higher risk of heat-related illness and death. Air conditioning is the most effective protection but is not available to everyone. This study explores practical, low-cost alternatives that people can use at home. Building on earlier research, this study tests whether soaking your feet in cool water provides additional protection when combined with fan use (during hot, humid conditions) or skin wetting (during hot, dry conditions). Participants will undergo carefully monitored simulated heatwave sessions in a climate-controlled laboratory, and researchers will measure body temperature, heart rate, and cardiovascular strain. You may be eligible for the healthy cohort if you are 60 years or older, a non-smoker (or quit more than 2 years ago), and otherwise in good health. For the heart disease cohort (based in Montreal), you must be aged 50–80 with a confirmed diagnosis of coronary artery disease. People with uncontrolled diabetes, high blood pressure, serious organ disease, or very high BMI are not eligible.

This summary was AI-generated to explain the trial in plain language. It is not medical advice. Always discuss eligibility with your doctor before enrolling in a clinical trial.

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Interventions

Each participant will take part in 6 experimental trials consisting of 3 hour of simulated heatwave exposure randomised within each heat wave condition: Hot and dry heat wave: 1. No cooling (com

Each participant will take part in 6 experimental trials consisting of 3 hour of simulated heatwave exposure randomised within each heat wave condition: Hot and dry heat wave: 1. No cooling (comparator) 2. Foot immersion 3. Foot immersion + skin wetting Hot and humid heat wave: 1. No cooling (comparator) 2. Foot immersion 3. Foot immersion + electric fan In each exposure, they will be asked to sit in a regulated environmental chamber at a temperature of either 45ºC, 10% RH (hot and dry heat wave) or 38ºC, 60% RH (hot and humid heat wave). Participants will be provided water to replenish fluid (i.e., sweat) losses equivalent to 1ml/kg of body weight every 20 min throughout the trial. Each trial will be separated by at least 72 h. Foot immersion: in all foot immersion trials, participants will place their feet in cool 18ºC water inside a 40L bucket up to their calf for 20 min, followed by 10 min out of the water, and repeated throughout the trial. In our previous study, we identified that skin wetting is the best cooling intervention in hot and dry heat waves, while electric fan is the best cooling intervention for hot and humid heatwaves. Therefore, the following combination interventions will also be studied: Foot immersion + skin wetting: in the foot immersion + skin wetting trials, foot immersion will be combined with wetting the skin using a spray bottle every 5 min intervals. Each 5 min throughout the protocol the researcher will spray the skin on the face, neck, upper and lower arms and upper and lower legs (except when inside the bucket) with tap water (~18ºC). A total of 18 sprays (1.2g water per spray) will be applied (1 x forehead; 1 x posterior neck; 1 x upper and 1 x lower of both arms; 3 x upper and 3 x lower of both legs) when feet are out of the water; and a total of 12 sprays will be applied (excluding lower sites of both legs) when feet are immersed in the water. Foot immersion + electric fan: in the foot immersion + electric fan trials, foot immersion will be combined with an 18" electric fan placed in 1.0m in front of the participant and directly blowing on them at a speed of 4.0m/s.

Locations(1)

Montreal, Canada

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