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Trial registered on ANZCTR


Registration number
ACTRN12619000663156
Ethics application status
Approved
Date submitted
24/04/2019
Date registered
3/05/2019
Date last updated
3/05/2019
Date data sharing statement initially provided
3/05/2019
Date results information initially provided
3/05/2019
Type of registration
Retrospectively registered

Titles & IDs
Public title
Are electric fans effective for keeping people cool in both very-hot-and-dry and hot-and-humid heatwaves?
Scientific title
Efficacy of electric fan use in simulated very-hot-and-dry and hot-and-humid heatwaves in young healthy male adults at rest
Secondary ID [1] 298040 0
None
Universal Trial Number (UTN)
U1111-1232-1710
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Heat-related illness 312509 0
Hyperthermia 312510 0
Heat-related cardiovascular strain 312511 0
Thermal discomfort 312512 0
Dehydration 312513 0
Condition category
Condition code
Injuries and Accidents 311050 311050 0 0
Other injuries and accidents
Public Health 311051 311051 0 0
Other public health
Metabolic and Endocrine 311052 311052 0 0
Normal metabolism and endocrine development and function
Cardiovascular 311118 311118 0 0
Other cardiovascular diseases

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
Two target heatwave conditions will be tested: ~46degC with 10% relative humidity and ~40degC with 50% relative humidity. All participants will be exposed to both conditions two times: once with an electric fan for cooling and once without (control trial). All participants will complete four experimental trials in total.
For each of the four experimental trials, participants will arrive at the laboratory, be instrumented in temperate (~22degC) conditions outside of the climatic chamber, have their pre-exposure body weight measured, then will enter the climatic chamber set to one of the two environmental conditions, where they will sit passively for 2 hours before re-measuring their body mass, then exiting the climatic chamber to be de-instrumented. In all four trials, participants will be given 250 ml of cool (~22degC) tap water, at 30, 60 and 90 min of exposure (750 ml total water consumption throughout the entire two-hour exposure). In the conditions using an electric fan, a common 44.5 cm diameter standing floor fan will be placed 1.25 meters in front of the participants and placed on the “high” setting, eliciting an air speed of approximately 2.0 meters per second. The fan will be turned on immediately following the participants assuming their seated position within the climatic chamber and will remain on throughout the 2-hour exposure. For safety purposes, as well as to ensure the participant remains seated throughout the 2 hour exposure and the exact experimental protocol is followed, one member of the research team will remain inside the climatic chamber with the participant at all times, while a second research team member will remain outside of the climate chamber, in order to provide assistance, in case it is needed.
At least 24 hours will separate all experimental trials and all four experimental trials will be completed within a one-month period, in order to minimize seasonal variations in physiological responses.
Only data from participants who have completed all four experimental trials will be included. In the event of a participant starting data collection but being unable or unwilling to complete data collection, their de-identified data will be kept with the rest of the study data, but not included in the analysis, and another participant will be recruited to replace them in order to ensure an adequate sample size. In order to minimize participant dropout, all participants will have the experimental procedures and measurement equipment explained to them thoroughly prior to testing in order to minimize participants being caught off-guard/ unprepared for the discomforts and inconveniences associated with this type of research.
Intervention code [1] 314272 0
Prevention
Intervention code [2] 314273 0
Treatment: Devices
Comparator / control treatment
In order to assess the effectiveness of electric fan use in each heatwave condition, there will be one control trial with no fan use for each condition. Therefore there will be one interventional trial (i.e. with fan use) and one control trial (i.e. without fan use) for each of the two environmental conditions (i.e. there will be four experimental trials in total). In the two control trials, the participants to sit in the heatwave conditions while drinking cool (22 degree celsius) tap water at 30, 60 and 90 min of exposure (i.e. 750 ml total water consumption throughout the trial).

To ensure physiological responses return to normal between trials, a wash-out period of at least 24 hours will separate all experimental trials. In order to minimize seasonal variations in physiological responses, all four experimental trials will be completed within a one-month period.
Control group
Active

Outcomes
Primary outcome [1] 319839 0
Rectal temperature - will be measured using a paediatric thermistor probe (Mon-a-therm General Purpose Temperature Probe 400TM, Covidien, Mansfield, USA) inserted to a minimum of 12 cm past the anal sphincter. Data will be recorded every five seconds and displayed in real-time on a personal computer.

Potential risks: Elevations in core temperature are much smaller with passive heating (i.e. sitting in a hot environment) compared to active heating (i.e. exercise) as core temperature will not increase until the body’s heat loss mechanisms can no longer offset the heat gain from the environment. Indeed in a similar study in hot and humid conditions, the highest core temperature observed in any participant was 37.62°C and the largest change in core temperature was 1.08°C. As such, risks of hyperthermia related injuries in the present investigation are minimal. Nevertheless, there is always some risk that accompanies an elevation in core temperature and dehydration due to sweat loss. Worst-case scenario risks include: headache, weakness, dizziness, nausea, hyperventilation, hypotension, confusion, diarrhoea, vomiting and loss of consciousness. These symptoms however, are unlikely under the present experimental conditions. In order to minimize these risks, the participant will be under close examination by the investigators during all protocols, additionally core body temperatures will be monitored continuously during the experimental trials, and the trials will be ended if a rectal temperature of 39.0°C is reached. If the participant becomes light-headed or dizzy, the protocol will be stopped. A bathtub filled with cool water will be present in the climate chamber throughout testing and if at any time a participant becomes hyperthermic and/or display symptoms of hyperthermic illness, they will be quickly de-instrumented and helped into the bathtub to be cooled down. After initial cooling, the participant will be moved to an examination bed in an adjacent room maintained at a comfortable ambient temperature where the participant will be laid in the supine position, cooled with cold towels, and given a commercially available sports drink in order to rehydrate and maintain blood sugar.
Timepoint [1] 319839 0
Change from baseline following two hours of passive heat exposure.
Primary outcome [2] 319848 0
Rate pressure product - will be calculated by multiplying systolic blood pressure (measured using an automatic blood pressure cuff; Tango M2, SunTech Medical, Morrisville, USA) by heart rate (measured using 3-lead electrocardiography; Vrije Universiteit Ambulatory Monitoring System, Amsterdam, Netherlands) in order to best characterise cardiovascular strain.
Timepoint [2] 319848 0
Change from baseline following two hours of passive heat exposure.
Primary outcome [3] 319849 0
Whole-body sweat losses - will be calculated from the difference in pre and post exposure body mass measurements taken on a platform scale (Id1 multirange, Mettler-Toledo; accurate to 2 grams), corrected for weight gain through fluid ingestion and sweat trapped in clothing.
Timepoint [3] 319849 0
Total sweat loss following two hours of heat exposure.
Secondary outcome [1] 369695 0
Whole-body thermal discomfort - will be recorded on a hand-scored 120 mm visual analogue scale with anchor points every 30 mm which consisted of: not uncomfortable, slightly uncomfortable and very uncomfortable.
Timepoint [1] 369695 0
Changes from baseline following two hours of passive heat exposure.
Secondary outcome [2] 369696 0
Heart rate - will be measured using 3-lead electrocardiography (Vrije Universiteit Ambulatory Monitoring System, Amsterdam, Netherlands).
Timepoint [2] 369696 0
Changes from baseline following two hours of passive heat exposure.
Secondary outcome [3] 369697 0
Systolic blood pressure - will be measured using an automatic blood pressure cuff (Tango M2, SunTech Medical, Morrisville, USA).
Timepoint [3] 369697 0
Changes from baseline following two hours of passive heat exposure.

Eligibility
Key inclusion criteria
Healthy young adult males who are healthy (no self-reported history of respiratory, metabolic, cardiovascular, blood pressure disease, or of diabetes and not currently on any medication related to these conditions). Non-smokers.
Minimum age
18 Years
Maximum age
40 Years
Gender
Males
Can healthy volunteers participate?
Yes
Key exclusion criteria
Females (due to differences in thermoregulatory responses owing to hormonal variations across the menstrual cycle), those older than 40 or younger than 18, anyone with metabolic, cardiovascular or autonomic disorders. Anyone currently taking prescription medication.

Study design
Purpose of the study
Prevention
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Central randomisation was used wherein an allocation list was maintained on a central computer and as participants were recruited to the experiment, they were assigned their treatment order by order of entrance into the study.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Permuted block randomisation was used by employing a Latin Square design which was downloaded from the internet.
Masking / blinding
Open (masking not used)
Who is / are masked / blinded?



Intervention assignment
Crossover
Other design features
Participants were blinded to the primary hypotheses governing the experiment. All participants will complete two trials (one with a fan and one without) within each of the two different target ambient conditions (~46degC with 10% relative humidity and ~40degC with 50% relative humidity) for a total of four completed trials each.
Phase
Not Applicable
Type of endpoint(s)
Efficacy
Statistical methods / analysis
All data will be expressed as a mean with standard deviation whereas differences between groups were reported as absolute differences with 95% confidence intervals. The change in thermometric rectal temperature, cardiovascular (heart rate, rate pressure product and systolic blood pressure), thermal discomfort and hydration status (whole-body sweat losses) values from baseline to the end of the 2 h exposure will be evaluated using a two-way repeated measures Analyses of Variance (ANOVA) with the repeated measures of heatwave (two levels: very-hot-and-dry and hot-and-humid) and cooling intervention (two levels: control and electric fan use). In the event of a significant interaction, individual differences will be assessed using a Holm-Sidak post-hoc test with the probability of making a type I error maintained throughout at 5%. All statistical analyses will be performed with GraphPad Prism (version 7.0, GraphPad Software, La Jolla, CA).

Recruitment
Recruitment status
Completed
Date of first participant enrolment
Anticipated
Actual
Date of last participant enrolment
Anticipated
Actual
Date of last data collection
Anticipated
Actual
Sample size
Target
Accrual to date
Final
Recruitment in Australia
Recruitment state(s)
NSW

Funding & Sponsors
Funding source category [1] 302567 0
University
Name [1] 302567 0
University of Sydney Bridging Support Grant
Address [1] 302567 0
University of Sydney
Level 6, Jane Foss Russell Building
University of Sydney NSW 2006
Country [1] 302567 0
Australia
Funding source category [2] 302585 0
University
Name [2] 302585 0
University of Sydney - Sydney Research Excellence Initiative 2020 (SREI)
Address [2] 302585 0
University of Sydney
Level 6, Jane Foss Russell Building
University of Sydney NSW 2006
Country [2] 302585 0
Australia
Primary sponsor type
Individual
Name
Associate Professor Ollie Jay
Address
75 East Street
C43A - Jeffrey Miller Admin Building
The University of Sydney, Cumberland Campus
Lidcombe, NSW 2141
Country
Australia
Secondary sponsor category [1] 302476 0
None
Name [1] 302476 0
Address [1] 302476 0
Country [1] 302476 0

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 303212 0
University of Sydney Human Research Ethics Committee
Ethics committee address [1] 303212 0
Margaret Telfer Building (K07)
University of Sydney
NSW 2006
Ethics committee country [1] 303212 0
Australia
Date submitted for ethics approval [1] 303212 0
14/04/2015
Approval date [1] 303212 0
17/07/2015
Ethics approval number [1] 303212 0
2015/223
Ethics committee name [2] 303225 0
University of Sydney Human Research Ethics Committee
Ethics committee address [2] 303225 0
Margaret Telfer Building (K07)
University of Sydney
NSW 2006
Ethics committee country [2] 303225 0
Australia
Date submitted for ethics approval [2] 303225 0
18/05/2017
Approval date [2] 303225 0
26/06/2017
Ethics approval number [2] 303225 0
2017/477

Summary
Brief summary
In Australia and globally, mean yearly temperatures and heatwaves are on the rise, causing elevated morbidity and mortality rates. It is typically the elderly, poor, and socially isolated who suffer most. Often, these groups lack access to air conditioning, whereas less privileged groups have started using air conditioning more regularly, causing the electricity demand during hot weather periods to increase faster than what existing infrastructure can supply. This mismatch causes regular power failures during heatwaves, which deprive life-saving electricity to those who truly need it. Clearly, alternatives to air conditioning are required.

While many cooling alternatives exist, most have never been objectively tested under heatwave conditions. This lack of evidence is detrimental and leads to the spread of misinformation. For example, many major health organizations, including the World Health Organization (WHO), currently advise against the use of electric fans in hot conditions. On the contrary, a recent (2012) Cochrane review concluded that no evidence whatsoever currently exists in the literature supporting or refuting the use of electric fans during heat waves. Following-on, we recently (2015) published a study in the Journal of the American Medical Association demonstrating fan use was better than no fan use for young healthy adults in humid environments at 36°C and 42°C; both conditions at which fan use is commonly discouraged.

From a theoretical standpoint, electric fans should be effective in hot and humid conditions because they help increase sweating efficiency, i.e. the amount of sweat that we produce which actually contributes to heat loss. Unlike hot humid conditions, in very-hot and dry conditions, sweating efficiency may be at 100% and therefore fan use may not be beneficial as the increased air speed (when air temperature is above skin temperature) would increase heat gain from the environment through convection without any supplying any additional evaporative heat loss.

Therefore, the purpose of this study will be to objectively test the effectiveness of electric fan use for cooling healthy adults during heatwaves in two heatwave conditions (very-hot-and-dry and hot-and-humid).

We hypothesize that in very-hot-and-dry conditions, electric fan use will make people hotter, more uncomfortable, increase their cardiovascular strain and increase their rate of dehydration, whereas in the hot-and-humid conditions, fan use will cool people, make them more comfortable and lower their cardiovascular strain at the cost of a slightly elevated sweat rate.
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 92870 0
A/Prof Ollie Jay
Address 92870 0
75 East Street
C43A - Jeffrey Miller Admin Building
The University of Sydney
Cumberland Campus
Lidcombe, NSW, 2141
Country 92870 0
Australia
Phone 92870 0
+61,2,93519328
Fax 92870 0
+61,2,93519204
Email 92870 0
ollie.jay@sydney.edu.au
Contact person for public queries
Name 92871 0
A/Prof Ollie Jay
Address 92871 0
75 East Street
C43A - Jeffrey Miller Admin Building
The University of Sydney
Cumberland Campus
Lidcombe, NSW, 2141
Country 92871 0
Australia
Phone 92871 0
+61,2,93519328
Fax 92871 0
+61,2,93519204
Email 92871 0
ollie.jay@sydney.edu.au
Contact person for scientific queries
Name 92872 0
A/Prof Ollie Jay
Address 92872 0
75 East Street
C43A - Jeffrey Miller Admin Building
The University of Sydney
Cumberland Campus
Lidcombe, NSW, 2141
Country 92872 0
Australia
Phone 92872 0
+61,2,93519328
Fax 92872 0
+61,2,93519204
Email 92872 0
ollie.jay@sydney.edu.au

Data sharing statement
Will individual participant data (IPD) for this trial be available (including data dictionaries)?
Yes
What data in particular will be shared?
Data for the primary and secondary outcome variables at rest, and the change from baseline following the 2-h exposure for all participants will be made available.
When will data be available (start and end dates)?
The data will be made available immediately upon publication of the data in a suitable scientific journal. The data will be available in perpetuity and in the event the data is for some reason no longer available on the journal website, a copy of the data set will be kept by the authors in order to provide it upon request.
Available to whom?
Data will be available to anyone with access to the journal that publishes the associated manuscript.
Available for what types of analyses?
Data will be available for this wishing to use them in meta-analyses.
How or where can data be obtained?
Either by a link to the file containing the data or else hosted on the publishing journal's website.
What supporting documents are/will be available?
Ethical approval
How or where can supporting documents be obtained?
Type [1] 1939 0
Ethical approval
Citation [1] 1939 0
Link [1] 1939 0
Email [1] 1939 0
Other [1] 1939 0
Summary results
Have study results been published in a peer-reviewed journal?
No
Other publications
Have study results been made publicly available in another format?
No
Results – basic reporting
Results – plain English summary