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Trial registered on ANZCTR


Registration number
ACTRN12619000722190
Ethics application status
Approved
Date submitted
26/04/2019
Date registered
14/05/2019
Date last updated
9/01/2023
Date data sharing statement initially provided
14/05/2019
Type of registration
Prospectively registered

Titles & IDs
Public title
What is the impact of dousing water on the skin on the rate of dehydration during a simulated heatwave?
Scientific title
Water dousing on the skin surface during a very-hot-and-dry heatwave: impacts on fluid balance, and thermal and cardiovascular strain in young, middle aged and older adults
Secondary ID [1] 298025 0
None
Universal Trial Number (UTN)
U1111-1232-2565
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Dehydration 312523 0
Heat related illness 312524 0
Heat related cardiovascular strain 312525 0
Thermal discomfort 312526 0
Age related sweating decrements 312529 0
Condition category
Condition code
Public Health 311061 311061 0 0
Other public health
Injuries and Accidents 311145 311145 0 0
Other injuries and accidents
Cardiovascular 311146 311146 0 0
Normal development and function of the cardiovascular system

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
Each participant will undergo one four-hour simulated heatwave exposure in a climate chamber, undertaking one of three possible interventions:
1. Full fluid replacement, sham dousing (FFR-S) (comparator)
2. Quarter fluid replacement, sham dousing (QFR-S)
3. Quarter fluid replacement, frequent dousing (QFR-F)

They will be asked to sit in a thermally regulated environmental chamber at a temperature of 45°C and 15% relative humidity, with an electric fan stack on a low setting simulating a light breeze (~0.6 m/s).

Prior to exposure, predicted water loss due to sweat and respiration across the four hours will be calculated and used to determine the amount of fluid given to the participant to consume throughout. Briefly, this will be achieved using known thermoregulatory constants, the environmental conditions, and an assumed resting metabolic rate equal to one MET. The sweat loss required to achieve heat balance will be subsequently calculated, as will the respiratory water loss, and this will inform fluid consumption. In the FFR-S trial, participants will be given 100% of their predicted fluid losses, broken into four water drinks (~20°C). In the QFR-S and QFR-F trials the participant will receive only 25% of their predicted water losses, also broken into four drinks. These drinks will be of equal volume and delivered at the 35, 95, 155 and 215 minute time points.

In the two sham dousing trials (FFR-S and QFR-S) participants forearms will be doused with water once every five minutes using a spray bottle. This will be administered by the researcher. Each spray dispense 1.2ml of ~20 degrees Celsius water, for a total dousing in these two trials of 2.4ml per five minutes. In the optimal dousing trial (QFRO) participants will spray themselves a pre-determined number of times every two minutes. This number will also be based upon calculated fluid losses; 75% of the expected fluid losses across four hours will be calculated prior to exposure, and then broken down into two minute increments, then an allotted number of 1.2ml sprays will be determined. For a typical participant (75kg, 175cm) this will be equal to ~6 sprays (7.2ml) every two minutes. The participant will spray their forearms, legs, chest, abdomen and face. Adherence to the spraying routine throughout the QFR-F trial will be monitored by the researcher, who will offer reminders at each two minute time point.
Intervention code [1] 314295 0
Prevention
Intervention code [2] 314343 0
Treatment: Other
Comparator / control treatment
Full fluid replacement, sham dousing (FFR-S)
Control group
Placebo

Outcomes
Primary outcome [1] 319858 0
Resultant dehydration

Nude body mass will be measured on a platform scale and changes in body mass will be considered losses in body water. Total body mass loss and baseline body mass will be used to determine the level of dehydration (% total body mass) and indicate the effectiveness of dousing in mitigating dehydration rates, and reducing the amount of fluid that need be consumed to maintain hydration status.
Timepoint [1] 319858 0
The primary time point for this measure will be at the end of exposure. Additionally, measurements will be taken intermittently during exposure (30,90,150,210 minutes).
Primary outcome [2] 319859 0
Core temperature via ingestible telemetric pill

Participants will ingest a small telemetric pill ~6h prior to exposure. Throughout the exposure this will give an indication of intestinal temperature, an index of core temperature. Change in core temperature from baseline will indicate thermal strain caused by the exposure.
Timepoint [2] 319859 0
The primary time point for this measure will be at the end of exposure. Additionally, measurements will be taken intermittently during exposure (30, 60, 90, 120, 150, 180, 210 minutes).
Primary outcome [3] 319860 0
Rate pressure product

An automated blood pressure cuff will be employed to determine blood pressure, and a chest strap/ ECG heart rate monitor to measure heart rate. The product of systolic blood pressure and heart rate will be calculated as the rate pressure product and taken as an index of cardiovascular strain throughout the exposure.
Timepoint [3] 319860 0
The primary time point for this measure will be at the end of exposure. Additionally, measurements will be taken intermittently during exposure (30, 60, 90, 120, 150, 180, 210 minutes).
Secondary outcome [1] 369730 0
Thirst

Participants will be asked to rate their thirst, mouth dryness and how pleasant a drink of water would be on three separate visual analogue scales. These scales are each 100mm long and the participant may mark anywhere on the line, with a score between 0-100 being determined for each. These three scores will be taken as an indication of the participants level of thirst throughout the exposure.
Timepoint [1] 369730 0
Baseline measurements will be taken at the beginning of the exposure (minute 0), and further measures taken every half an hour throughout the exposure (30, 60, 90,120, 150, 180, 210 minutes) as well as at the end of exposure (240 minutes)
Secondary outcome [2] 369731 0
Thermal sensation

Using a visual analogue scale participants will rate their thermal sensation (very cold - very hot). This scores will indicate the thermal acceptability of the environment coupled with whatever exposure they are undertaking.
Timepoint [2] 369731 0
Baseline measurements will be taken at the beginning of the exposure (minute 0), and further measures taken every half an hour throughout the exposure (30, 60, 90,120, 150, 180, 210 minutes) as well as at the end of exposure (240 minutes)
Secondary outcome [3] 369732 0
Skin temperature

Four temperature sensors will be taped to the participant's skin surface (chest, shoulder, thigh, and calf) and be used to estimate mean skin temperature. This will be used to estimate dry heat exchange for each participant throughout the exposure.
Timepoint [3] 369732 0
These temperature sensors will record continuously throughout the whole exposure.
Secondary outcome [4] 369734 0
Orthostatic hypotension

Participants will be asked to stand immediately after a seated blood pressure reading, and a further blood pressure reading will be taken via an automated cuff after one minute of standing. This test is carried out to see if there is evidence of postural hypotension (a drop in BP following standing from a seated position).
Timepoint [4] 369734 0
Baseline measurements will be taken at the beginning of the exposure (minute 0), and further measure taken at the mid-point (120 minutes) and end (240 minutes) of the trial.
Secondary outcome [5] 369735 0
Heart rate

Heart rate will be monitored via a chest strap/ ECG.
Timepoint [5] 369735 0
This will be monitored and logged continuously throughout the whole exposure.
Secondary outcome [6] 369736 0
Blood pressure

Seated blood pressure will be taken in duplicate throughout the exposure via an automated blood pressure cuff.
Timepoint [6] 369736 0
Baseline measurements will be taken in duplicate at the beginning of the exposure (minute 0), and further measures taken every half an hour throughout the exposure (30, 60, 90,120, 150, 180, 210 minutes) as well as at the end of exposure (240 minutes)
Secondary outcome [7] 369886 0
Thermal Comfort

Using a visual analogue scale participants will rate their level of thermal comfort (not uncomfortable, slightly uncomfortable, uncomfortable, very uncomfortable). These scores will indicate the thermal acceptability of the environment coupled with whatever exposure they are undertaking.
Timepoint [7] 369886 0
Baseline measurements will be taken at the beginning of the exposure (minute 0), and further measures taken every half an hour throughout the exposure (30, 60, 90,120, 150, 180, 210 minutes) as well as at the end of exposure (240 minutes)

Eligibility
Key inclusion criteria
Participants must fall into one of our three potential age categories; 18-40, 45-55 or 65+ years old.
Minimum age
18 Years
Maximum age
No limit
Sex
Both males and females
Can healthy volunteers participate?
Yes
Key exclusion criteria
1. Not within a specified age bracket
2. Currently taking medication that may impact thermoregulatory outcomes
3. Current respiratory, renal or metabolic disease/ disorder(s)
4. Current smoker
5. Recent (<12 months) stomach surgery
6. Pregnant

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 via a computer
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Participants will be randomly assigned one of the three potential conditions via random number sequence, in a balanced fashion (i.e. same number of participants for each intervention). This randomisation will occur separately for each of the three age brackets.
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?
The people receiving the treatment/s


The people analysing the results/data
Intervention assignment
Parallel
Other design features
This experiment is double-blinded (participant and analysis), as it is impossible to blind the researcher to the QFR-F trial, as the dousing regularity changes from every five minutes, to every two minutes in this exposure. The researcher will be blinded to the treatment during the other two trials (FFR-S and QRF-S).

Data analysis will be blinded, with the key to unscramble the data only employed once a minimum of 6 participants from each age group have completed each condition (at least 54 participants completed). All further analysis beyond this point will remain blinded until all data collection has been completed.
Phase
Not Applicable
Type of endpoint/s
Efficacy
Statistical methods / analysis
The number of participants was selected by performing a power calculation for the difference between independent groups using an alpha of 0.05, a beta of 0.05, an effect size of 0.8 calculated from the difference in rate pressure product between a mildly dehydrated group and a fully hydrated group in previously published research. This calculation revealed each independent group will require 36 participants, giving us a total of 108 for three groups.

Additionally, as we will stratify data by age into three sub groups a further power calculation was performed to ensure adequate power to detect differences between age groups, using an alpha of 0.05, a beta of 0.05, an effect size of 1.8 based on the differences in whole body sweat rate observed between young and old individuals during passive heat exposure in previously published research. This determined that at least 8 participants from each age group must complete each independent trial.

Data for resultant dehydration core temperature, rate pressure product, thirst, orthostatic intolerance, skin temperature, thermal comfort, thermal sensation, heart rate and blood pressure will be analysed with a 3-way ANOVA with the repeated factor of time (5 levels: 0, 60, 120, 180 and 240 minutes), independent factor of condition (3 levels: FFR-S, QFR-S, QFR-F) and independent factor of age (3 levels: 18-40 years, 45-55 years, 65+ years).

If significant main effects or interactions are found, independent differences will be assessed using a two-tailed paired Student’s t-tests while maintaining a fixed probability (5%) of making a type I error using a Sidak correction.

Recruitment
Recruitment status
Recruiting
Date of first participant enrolment
Anticipated
17/05/2019
Actual
20/05/2019
Date of last participant enrolment
Anticipated
31/12/2023
Actual
Date of last data collection
Anticipated
31/03/2024
Actual
Sample size
Target
108
Accrual to date
53
Final
Recruitment in Australia
Recruitment state(s)
NSW

Funding & Sponsors
Funding source category [1] 302554 0
University
Name [1] 302554 0
Discretionary Research Account held at The University of Sydney by Dr. Ollie Jay
Country [1] 302554 0
Australia
Primary sponsor type
University
Name
The University of Sydney
Address
The University of Sydney
Camperdown
NSW
2006
Country
Australia
Secondary sponsor category [1] 302461 0
None
Name [1] 302461 0
NA
Address [1] 302461 0
NA
Country [1] 302461 0

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 303197 0
The University of Sydney Human Research Ethics Committee
Ethics committee address [1] 303197 0
Research Integrity & Ethics Administration
Research Portfolio
Level 3, F23 Administration Building
The University of Sydney, NSW, 2006
Ethics committee country [1] 303197 0
Australia
Date submitted for ethics approval [1] 303197 0
24/09/2018
Approval date [1] 303197 0
30/10/2018
Ethics approval number [1] 303197 0
2018/815

Summary
Brief summary
In an extreme heat context, dehydration has been demonstrated to increase cardiovascular strain and exacerbate core temperature rises. Naturally then, when heatwaves strike in areas where access to clean drinking water is limited, human health suffers. Although clean drinking water is often in short supply in these areas, there may be plentiful access to water that is not safe to consume, but can be doused on the skin, taking the place of sweat. We therefore wish to investigate whether dousing of water on the skin may slow an individual’s rate of dehydration, thereby reducing the amount of fluid they must consume to offset any hydration related exacerbations of physiological strain. To achieve this, we will compare resultant dehydration, as well as thermal and cardiovascular outcomes during a four hour passive heatwave exposure (45°C/ 15% relative humidity) during three different interventions:
1. Full fluid replacement, sham dousing (FFR-S) (comparator)
2. Quarter fluid replacement, sham dousing (QFR-S)
3. Quarter fluid replacement, optimal dousing (QFR-F)

Participants will complete only one exposure each, and will fit into one of three age brackets:
1. 18-40 years
2. 45-55 years
3. 65 + years

The research hypotheses going into this study are:
1. Resultant dehydration will be less in QFR-F than in QFR-S.
2. Heat related thermal and cardiovascular strain will be least inn FFR-S, followed by QFR-F and greatest in QFR-S.
3. During FFR-S and QFR-S the 65+ years age group will have a greater change in core temperature than the 45-55 years age group who will have a greater change in core temperature than the 18-40 years age group. During QFR-F all age groups will have similar changes in core temperature.
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 92822 0
A/Prof Ollie Jay
Address 92822 0
Room K216
The University of Sydney Cumberland Campus
75 East St Lidcombe
NSW 2141
Country 92822 0
Australia
Phone 92822 0
+61 449116760
Fax 92822 0
Email 92822 0
[email protected]
Contact person for public queries
Name 92823 0
Ollie Jay
Address 92823 0
Room K216
The University of Sydney Cumberland Campus
75 East St Lidcombe
NSW 2141
Country 92823 0
Australia
Phone 92823 0
+61 449116760
Fax 92823 0
Email 92823 0
[email protected]
Contact person for scientific queries
Name 92824 0
Ollie Jay
Address 92824 0
Room K216
The University of Sydney Cumberland Campus
75 East St Lidcombe
NSW 2141
Country 92824 0
Australia
Phone 92824 0
+61 449116760
Fax 92824 0
Email 92824 0
[email protected]

Data sharing statement
Will individual participant data (IPD) for this trial be available (including data dictionaries)?
Yes
What data in particular will be shared?
De-identified individual participant data underlying published results only.
When will data be available (start and end dates)?
Immediately following publication, no end date.
Available to whom?
Case-by-case basis at the discretion of the primary investigator.
Available for what types of analyses?
Meta-analysis.
How or where can data be obtained?
Access subject to approvals by the primary investigator with a requirement to sign a data access agreement.


What supporting documents are/will be available?

Doc. No.TypeCitationLinkEmailOther DetailsAttachment
1945Informed consent form    377441-(Uploaded-26-04-2019-10-52-18)-Study-related document.pdf
1946Ethical approval    377441-(Uploaded-26-04-2019-10-53-07)-Study-related document.pdf
1947Study protocol    377441-(Uploaded-07-05-2019-19-23-48)-Study-related document.pdf



Results publications and other study-related documents

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