Protective Cooling Measures to Safeguard Elderly People From Dangerous Summer Heat

NCT05274009 | Unknown

• 1 other identifier: H-11-21-7566
• Study Type: interventional
• Target: 60
• Locations: 1 country
• Sites: 1

Brief Summary

With the increasing incidence and severity of extreme heat events accompanying climate change, there is an urgent need for sustainable cooling strategies to protect heat-vulnerable older adults, who are at increased risk of adverse health events during heat stress. Health agencies including the World Health Organization, the United States Centers for Disease Control and Prevention, and Health Canada currently recommend visiting a cooling centre or other air-conditioned location for 1-3 hours per day during extreme heat events to mitigate hyperthermia and strain on the cardiovascular system and therefore the risk adverse health events. However, our recent trial shows that while brief air-conditioning exposure is effective for reducing body temperature and cardiovascular burden in healthy older adults, the physiological impacts of cooling abate quickly following return to the heat. The purpose of this project is therefore to assess whether shorter but more frequent air-conditioning exposure provides more effective cooling than current recommendations (a single 1-3-hour cooling bout) in older adults with or without common chronic health conditions associated with increased vulnerability to extreme heat. This will be accomplished by evaluating physiological strain in older adults with and without diabetes and/or hypertension exposed for 8 hours to conditions reflective of extreme heat events in temperate, continental climates (35°C, 60% relative humidity). Participants will complete 3 separate simulated heat event exposures: i) a control trial (no cooling throughout the 8-hour heat event); ii) a recommended cooling trial (3 hours of heat exposure followed by 2 hours cooling); and iii) a hybrid cooling trial (2 hours of heat exposure followed by 1 hour cooling, another 2 hours heat exposure followed by 1 hour cooling, and a final 2-hour heat exposure).

Conditions

Hyperthermia; Heat; Weather; Aging; Type2 Diabetes; Hypertension; Heat Stress

Keywords

Heat wave; Cooling center; Heat strain; Cardiovascular strain; Heat and health protection; Extreme heat events; Thermal comfort

Outcome Measures

Primary Outcomes (2)

• Core temperature (peak)

  Peak rectal temperature measured during the 8-hour heat exposure.

  8-hour heat exposure

• Core temperature (AUC)

  Rectal temperature will be measured continuously throughout each exposure and the area under the curve will be calculated.

  8-hour heat exposure

Secondary Outcomes (12)

• Heart rate temperature (peak)

  8-hour heat exposure

• Heart rate (AUC)

  8-hour heat exposure

• Mean skin temperature

  Before and continuously throughout each 8 hour exposure

• Arterial blood pressures

  Every hour during the 8-hour heat exposure

• SDNN

  Every hour during the 8-hour heat exposure

Study Arms (3)

Extreme heat event simulation + no cooling (control)

EXPERIMENTAL

Adults aged 60-85 years with or without type 2 diabetes and/or hypertension

Other: No cooling (control)

Extreme heat event simulation + recommended cooling

EXPERIMENTAL

Adults aged 60-85 years with or without type 2 diabetes and/or hypertension

Other: Recommended cooling

Extreme heat event simulation + hybrid cooling

EXPERIMENTAL

Adults aged 60-85 years with or without type 2 diabetes and/or hypertension

Other: Hybrid cooling

Interventions

No cooling (control) OTHER

Participants are exposed to 35°C, 60% relative humidity for 8 hours.

Extreme heat event simulation + no cooling (control)

Recommended cooling OTHER

Participants are exposed to 35°C, 60% relative humidity for 3 hours, are then moved to an air-conditioned room for 2 hours (\~23°C, \~50% relative humidity), and then return to the heat for a final 3 hours.

Extreme heat event simulation + recommended cooling

Hybrid cooling OTHER

Participants are exposed to 35°C, 60% relative humidity for 2 hours, are moved to an air-conditioned room for 1 hour (\~23°C, \~50% relative humidity), return to the heat for 2 hours, move back to the air-conditioned room for 1 hour, and then return to the heat for a final 2 hours

Extreme heat event simulation + hybrid cooling

Eligibility Criteria

• Age: 60 Years - 85 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Adult aged 60-85 years
• Male or female
• Body mass index \< 35 kg/m2
• For participants with type 2 diabetes: at least one year lapsed since diagnosis and hemoglobin A1c 6.0-10.5%.
• For participants with hypertension: at least one year lapsed since diagnosis or average resting blood pressure \>140 systolic or \>90 diastolic

You may not qualify if:

• Currently smoking or quit \<5 years ago
• Moderate or serious medical conditions (other than Type 2 diabetes or high blood pressure), particularly those known to influence physiological responses to heat exposure (e.g., diagnosed heart disease, neurological disorders)
• Heat adapted due to repeated exposure to hot environments (use sauna, recent travel to hot climates, other)
• For participants with type 2 diabetes: "Brittle" diabetes: unpredictable hypo- \& hyperglycemia. Severe cardiovascular autonomic or peripheral neuropathy (guidelines.diabetes.ca/cpg)

Sponsors & Collaborators

• University of Ottawa: lead

Study Sites (1)

University of Ottawa

Ottawa, Ontario, K1N6N5, Canada

Location

MeSH Terms

Conditions

Hyperthermia; Hypertension; Heat Stress Disorders

Condition Hierarchy (Ancestors)

Body Temperature Changes; Signs and Symptoms; Pathological Conditions, Signs and Symptoms; Wounds and Injuries; Vascular Diseases; Cardiovascular Diseases

Study Officials

• Glen P Kenny, PhD

  University of Ottawa

  PRINCIPAL INVESTIGATOR

• Ronald J Sigal, MD, MPH

  University of Calgary

  PRINCIPAL INVESTIGATOR

• Robert D Meade, PhD

  University of Ottawa

  PRINCIPAL INVESTIGATOR

Central Study Contacts

Glen P Kenny, PhD

CONTACT

6135625800; gkenny@uottawa.ca

Robert D Meade, PhD

CONTACT

6136986071; rmead015@uottawa.ca

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: DOUBLE
• Who Masked: PARTICIPANT, OUTCOMES ASSESSOR
• Masking Details: Participants will be informed of the study interventions before providing informed consent but will be blinded to the specific trial condition at each of the 3 laboratory visits (control, recommended cooling, hybrid cooling). Data will be blinded prior to analysis.
• Purpose: BASIC SCIENCE
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Full Professor, University Research Chair

Model Details: Participant will complete 3 simulated extreme heat event exposures in random order: i) no cooling center intervention (control); ii) recommended cooling center intervention (1 x 2-hours of brief air-conditioning); and iii) hybrid cooling center intervention (2 x 1-hour interspersed brief air-conditioning)

Study Record Dates

• First Submitted: February 25, 2022
• First Posted: March 10, 2022
• Study Start: May 1, 2023
• Primary Completion: May 1, 2024
• Study Completion: May 1, 2024
• Last Updated: October 21, 2022

Record last verified: 2022-10

Data Sharing

• IPD Sharing: Will share
• Shared Documents: STUDY PROTOCOL, SAP, ICF, ANALYTIC CODE
• Time Frame: After study completion
• Access Criteria: Reasonable request and signed access agreement

Locations

CA (1)