Protective Cooling Measures to Safeguard Elderly People From Dangerous Summer Heat

October 19, 2022 updated by: Glen P. Kenny, University of Ottawa

Evaluating the Efficacy of Cooling Centres for Limiting Heat Strain in Elderly Adults During Extreme Heat Events

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).

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Not yet recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Anticipated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
60

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Contact Backup

Study Locations

  • Canada
    • Ontario
      • Ottawa, Ontario, Canada, K1N6N5
        • University of Ottawa
        • Contact:
        • Contact:

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

60 years to 85 years (Adult, Older Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Description

Inclusion Criteria:

  • 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

Exclusion Criteria:

  • 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)

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Basic Science
  • Allocation: Randomized
  • Interventional Model: Crossover Assignment
  • Masking: Double

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: Extreme heat event simulation + no cooling (control)
Adults aged 60-85 years with or without type 2 diabetes and/or hypertension
Other: No cooling (control)
Participants are exposed to 35°C, 60% relative humidity for 8 hours.
Experimental: Extreme heat event simulation + recommended cooling
Adults aged 60-85 years with or without type 2 diabetes and/or hypertension
Other: Recommended cooling
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.
Experimental: Extreme heat event simulation + hybrid cooling
Adults aged 60-85 years with or without type 2 diabetes and/or hypertension
Other: Hybrid cooling
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

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Core temperature (peak)
Time Frame: 8-hour heat exposure
Peak rectal temperature measured during the 8-hour heat exposure.
8-hour heat exposure
Core temperature (AUC)
Time Frame: 8-hour heat exposure
Rectal temperature will be measured continuously throughout each exposure and the area under the curve will be calculated.
8-hour heat exposure

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Heart rate temperature (peak)
Time Frame: 8-hour heat exposure
Peak rectal temperature measured during the 8-hour heat exposure.
8-hour heat exposure
Heart rate (AUC)
Time Frame: 8-hour heat exposure
Heart rate will be measured continuously throughout each exposure and the area under the curve will be calculated.
8-hour heat exposure
Mean skin temperature
Time Frame: Before and continuously throughout each 8 hour exposure
Mean skin temperature calculated as a weighted average of skin temperatures at 8 body regions.
Before and continuously throughout each 8 hour exposure
Arterial blood pressures
Time Frame: Every hour during the 8-hour heat exposure
Systolic and diastolic pressures measured in triplicate.
Every hour during the 8-hour heat exposure
SDNN
Time Frame: Every hour during the 8-hour heat exposure
Standard deviation of normal-to-normal R-R intervals measured via 3-lead ECG.
Every hour during the 8-hour heat exposure
RMSSD
Time Frame: Every hour during the 8-hour heat exposure
Root mean squared standard deviation of normal-to-normal R-R intervals measured via 3-lead ECG.
Every hour during the 8-hour heat exposure
Rate pressure product
Time Frame: Every hour during the 8-hour heat exposure
Rate pressure product calculated as systolic blood pressure x heart rate.
Every hour during the 8-hour heat exposure
Body fluid loss
Time Frame: Every hour during the 8-hour heat exposure
Body fluid loss calculated as a change in body weight from pre-exposure values (corrected for food intake and deification).
Every hour during the 8-hour heat exposure
Stand test: 30:15 ratio
Time Frame: Prior to and following the 8-hour heat exposure
30:15 ratio calculated as the ratio of the RR interval measured after 30 heart beats following standing from a supine position to that measured after 15 heart beats.
Prior to and following the 8-hour heat exposure
Stand test: Systolic response to standing
Time Frame: Prior to and following the 8-hour heat exposure
Fall in systolic blood pressure after standing from a supine position.
Prior to and following the 8-hour heat exposure
Baroreflex sensitivity
Time Frame: Prior to and following the 8-hour heat exposure
Baroreflex sensitivity determined during cyclic stand-squat manoeuvres.
Prior to and following the 8-hour heat exposure
Change in plasma volume
Time Frame: Prior to and following the 8-hour heat exposure
Change in plasma volume calculated from venous blood samples (Dill and Costill technique)
Prior to and following the 8-hour heat exposure

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
University of Ottawa

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: 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

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Anticipated)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
May 1, 2023

Primary Completion (Anticipated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
May 1, 2024

Study Completion (Anticipated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
May 1, 2024

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
February 25, 2022

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
March 1, 2022

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
March 10, 2022

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
October 21, 2022

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
October 19, 2022

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
October 1, 2022

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • H-11-21-7566

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

Yes

IPD Plan Description

Deidentified participant data will be available from Dr. Kenny upon reasonable request and signed access agreement.

IPD Sharing Time Frame

After study completion

IPD Sharing Access Criteria

Reasonable request and signed access agreement

IPD Sharing Supporting Information Type

  • Study Protocol
  • Statistical Analysis Plan (SAP)
  • Informed Consent Form (ICF)
  • Analytic Code

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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