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Trial registered on ANZCTR


Registration number
ACTRN12621001165875
Ethics application status
Approved
Date submitted
15/06/2021
Date registered
27/08/2021
Date last updated
27/08/2021
Date data sharing statement initially provided
27/08/2021
Type of registration
Prospectively registered

Titles & IDs
Public title
The influence of 7mm wetsuit thickness on respiratory function of healthy divers.

Scientific title
Investigating the influence of 7mm wetsuit thickness on respiratory function including forced vital capacity (FVC) of healthy adult divers.
Secondary ID [1] 304486 0
None
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Respiratory 322330 0
Condition category
Condition code
Respiratory 320003 320003 0 0
Normal development and function of the respiratory system

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
What is involved for participants:

Participants will be asked to complete a questionnaire which documents age, sex, ethnic origin (for spirometry inputs) , dive qualifications, number of dives experience (categorical data), wetsuit thickness, followed by height and weight measurement (for BMI calculations, and spirometry inputs).

Following their consent to participate, subjects will be briefed on spirometry technique.

Participants will be asked to complete a spirometry measurement dressed in loose clothes or when wearing their own personal wetsuit. The test involves exhaling into a piece of equipment for 20-30 seconds while wearing a nose clip.

The test will be performed up to 6 times over a 10 minute period until two consistent samples are achieved.

The order of sampling (wearing or not wearing a wetsuit, single or double layer) will be randomised to minimise practice effect for participants. Each set of samples measuring lung function will occur between 15 and 30 minutes after the previous measurements, to allow divers to change (their clothes or wetsuit), and to rest before the next test.

If divers own two wetsuits (for example a second winter double layer wetsuit), three sets of samples will be collected each separated by 15-30 minutes (in the order determined by randomisation).

The total period of sampling will be in a single observation session of no longer than 60-90 minutes duration. Participants will receive no further observation after finishing this session.

The session will be supervised by the research study doctors in the hyperbaric facility who designed the study.
Intervention code [1] 320848 0
Other interventions
Comparator / control treatment
Study participants will have lung function measured as a baseline (without wetsuit) and when wearing a wetsuit.- their baseline measurement will be a control sample for the wearing wetsuit measurement
Control group
Active

Outcomes
Primary outcome [1] 327871 0
FVC measured using spirometry when participants are wearing a wetsuit (minimum 7mm thickness), dry not immersed
Timepoint [1] 327871 0
Within one hour of baseline lung function measurement
Primary outcome [2] 328440 0
FEV1 measured using spirometry when participants are wearing a wetsuit (minimum 7mm thickness), dry not immersed
Timepoint [2] 328440 0
Within one hour of baseline lung function measurement
Secondary outcome [1] 396823 0
FVC measured using spirometry when participants are wearing a double layer wetsuit (minimum 7mm thickness each layer), dry not immersed
Timepoint [1] 396823 0
Within one hour of baseline lung function measurement
Secondary outcome [2] 399019 0
FEV1 measured using spirometry when participants are wearing a double layer wetsuit (minimum 7mm thickness each layer), dry not immersed
Timepoint [2] 399019 0
Within one hour of baseline lung function measurement

Eligibility
Key inclusion criteria
Adult (18 years or over) qualified healthy non-smoker active divers
Free of respiratory or cardiac illness, not pregnant
Dive regularly but have not dived in the last 24 hours.
Divers will have fasted for 2 hours before the assessment
Minimum age
18 Years
Maximum age
No limit
Gender
Both males and females
Can healthy volunteers participate?
Yes
Key exclusion criteria
Declared by qualified diving doctor as unfit to dive

Study design
Purpose of the study
Educational / counselling / training
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Sealed Opaque envelopes
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Simple randomisation using a randomisation table created by computer software (i.e. computerised sequence generation)
Masking / blinding
Open (masking not used)
Who is / are masked / blinded?



Intervention assignment
Other
Other design features
Study participants will not be randomised before entering the study. Once they agree to participate, the sampling order of their measurement of lung function (in or out of a wetsuit) will be randomised. Once the order of sampling is allocated, neither the subject nor the investigator will not be blinded to the lung function measurements

The randomisation of sampling order (in or out of a wetsuit) is to avoid a possible learning effect when performing the lung function. For example - if the learning effect produced an improvement in lung function, and the "in wetsuit" sample was always second sample, we may potentially miss a real decrement in lung function.

Study participants and investigators will not be blinded to whether or not the subject is wearing a wetsuit,
Phase
Not Applicable
Type of endpoint(s)
Safety
Statistical methods / analysis
Previous studies demonstrated a fall in FVC of 5% for divers wearing thin (3mm wetsuits). We expect a greater fall in FVC for 7mm wetsuits.
Two samples (of 24 males and 24 females) would have an 82% power to detect a significant difference at a = 0.05 based on expected minimum fall in FVC of 5% in a wetsuit in each sample. We plan to recruit 80 subjects (40 males and 40 females). This would also allow independent analysis of groups split according to sex.
FVC and FEV1 values will be tested against normality (KS testing) and then sample means compared using paired Student’s t-test and Pearson’s and Spearman’s correlation coefficient (r). Where more than two measurements are available (i.e.. two wetsuit measurements), ANOVA will be used to calculate statistical significance. A P value< 0.05 will be considered statistically significant.

Recruitment
Recruitment status
Not yet recruiting
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)
TAS
Recruitment hospital [1] 19742 0
Royal Hobart Hospital - Hobart
Recruitment postcode(s) [1] 34382 0
7000 - Hobart

Funding & Sponsors
Funding source category [1] 308847 0
Hospital
Name [1] 308847 0
Royal Hobart Hospital, Department of Diving and Hyperbaric Medicine
Address [1] 308847 0
26 Campbell Street
Hobart Tas 7000
Country [1] 308847 0
Australia
Funding source category [2] 309290 0
Other
Name [2] 309290 0
Royal Hobart Hospital Department of Diving and Hyperbaric Medicine Research Trust Fund
Address [2] 309290 0
26 Campbell Street
Hobart Tasmania 7000
Country [2] 309290 0
Australia
Primary sponsor type
Hospital
Name
Royal Hobart Hospital, Department of Diving and Hyperbaric Medicine
Address
26 Campbell Street
Hobart Tasmania 7000
Country
Australia
Secondary sponsor category [1] 310260 0
None
Name [1] 310260 0
Address [1] 310260 0
Country [1] 310260 0

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 308756 0
University of Tasmania Human Research Integrity and Ethics Committee
Ethics committee address [1] 308756 0
Office of Research Services
Churchill Avenue
Sandy Bay
TAS 7005
Ethics committee country [1] 308756 0
Australia
Date submitted for ethics approval [1] 308756 0
09/06/2021
Approval date [1] 308756 0
11/08/2021
Ethics approval number [1] 308756 0

Summary
Brief summary
The hypothesis to be tested is that wearing thicker wet suits (7mm or double 7mm on torso) impairs the ventilatory mechanics of healthy divers.

This has never been studied for colder water wetsuits that are often used in Tasmania. Divers wearing thinner wetsuits (median 3mm), have been studied in the past.

The aim is to measure the effect that wearing thicker (7mm or greater thickness) wetsuits has on the respiratory function of healthy divers measured by lung function testing..

A series of volunteer healthy divers will be enrolled. Spirometry (lung function) measurements will be be undertaken firstly without a wetsuit, and when wearing 7mm one- piece Summer suit and/or 7mm dual layer Winter suits, These wetsuits are standard for Tasmania’s climate.

Based on previous studies of divers in thinner wetsuits, we expect that there will be significant impairment in lung function when wearing a 7mm or greater thickness wetsuit. The information gained from the study could guide medical advice to older divers and also divers with pre-existing medical conditions. In addition it may provide some physiological information that helps to unlock why some older divers in colder water are prone to breathing problems associated with immersion.
Trial website
Not applicable
Trial related presentations / publications
Public notes
Advertisements to recruit both recreational and occupational divers have been sent to dive clubs and dive companies

Contacts
Principal investigator
Name 111778 0
Prof David Smart
Address 111778 0
Supervisor of Training
Department of Diving and Hyperbaric Medicine
Royal Hobart Hospital
26 Campbell Street
Hobart Tas 7000
Country 111778 0
Australia
Phone 111778 0
+61 3 61668849
Fax 111778 0
+61 3 61730410
Email 111778 0
david.smart@ths.tas.gov.au
Contact person for public queries
Name 111779 0
Prof David Smart
Address 111779 0
Supervisor of Training
Department of Diving and Hyperbaric Medicine
Royal Hobart Hospital
26 Campbell Street
Hobart Tas 7000
Country 111779 0
Australia
Phone 111779 0
+61 3 61668849
Fax 111779 0
+61 3 61730410
Email 111779 0
david.smart@ths.tas.gov.au
Contact person for scientific queries
Name 111780 0
Dr Graham Stevens
Address 111780 0
Senior Registrar
Department of Diving and Hyperbaric Medicine
Royal Hobart Hospital
26 Campbell St
Hobart Tas 7000
Country 111780 0
Australia
Phone 111780 0
+61 3 61668193
Fax 111780 0
+61 3 61730410
Email 111780 0
graham.stevens@ths.tas.gov.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?
Amalgamated participant data underlying published results only
When will data be available (start and end dates)?
Beginning from publication and ending 5 years following main results publication
Available to whom?
Other researchers with related project
Available for what types of analyses?
Any Purpose
How or where can data be obtained?
david.smart@ths.tas.gov.au
What supporting documents are/will be available?
No other documents available
Summary results
No Results