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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

24/03/2024

Date data sharing statement initially provided

27/08/2021

Date results provided

24/03/2024

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]

None

Universal Trial Number (UTN)

Trial acronym

Linked study record

Health condition

Health condition(s) or problem(s) studied:

Respiratory

Condition category

Condition code

Respiratory

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]

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]

FVC measured using spirometry when participants are wearing a wetsuit (minimum 7mm thickness), dry not immersed

Timepoint [1]

Within one hour of baseline lung function measurement

Primary outcome [2]

FEV1 measured using spirometry when participants are wearing a wetsuit (minimum 7mm thickness), dry not immersed

Timepoint [2]

Within one hour of baseline lung function measurement

Secondary outcome [1]

FVC measured using spirometry when participants are wearing a double layer wetsuit (minimum 7mm thickness each layer), dry not immersed

Timepoint [1]

Within one hour of baseline lung function measurement

Secondary outcome [2]

FEV1 measured using spirometry when participants are wearing a double layer wetsuit (minimum 7mm thickness each layer), dry not immersed

Timepoint [2]

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

Sex

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

Completed

Date of first participant enrolment

Anticipated

1/09/2021

Actual

31/08/2021

Date of last participant enrolment

Anticipated

31/12/2022

Actual

31/10/2022

Date of last data collection

Anticipated

31/12/2022

Actual

31/10/2022

Sample size

Target

Accrual to date

Final

Recruitment in Australia

Recruitment state(s)

TAS

Recruitment hospital [1]

Royal Hobart Hospital - Hobart

Recruitment postcode(s) [1]

7000 - Hobart

Funding & Sponsors

Funding source category [1]

Hospital

Name [1]

Royal Hobart Hospital, Department of Diving and Hyperbaric Medicine

Address [1]

26 Campbell Street
Hobart Tas 7000

Country [1]

Australia

Funding source category [2]

Other

Name [2]

Royal Hobart Hospital Department of Diving and Hyperbaric Medicine Research Trust Fund

Address [2]

26 Campbell Street
Hobart Tasmania 7000

Country [2]

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]

None

Name [1]

Address [1]

Country [1]

Ethics approval

Ethics application status

Approved

Ethics committee name [1]

University of Tasmania Human Research Integrity and Ethics Committee

Ethics committee address [1]

Office of Research Services
Churchill Avenue
Sandy Bay
TAS 7005

Ethics committee country [1]

Australia

Date submitted for ethics approval [1]

09/06/2021

Approval date [1]

11/08/2021

Ethics approval number [1]

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

Prof David Smart

Address

iN2Deep Medical Consulting
25 Salacia Avenue
Howrah Tasmania 7018

Country

Australia

Phone

+61 437221422

Fax

+61 3 61730410

dsmart@iinet.net.au

Contact person for public queries

Name

David Smart

Address

iN2Deep Medical Consulting
25 Salacia Avenue
Howrah Tasmania 7018

Country

Australia

Phone

+61 437221422

Fax

+61 3 61730410

dsmart@iinet.net.au

Contact person for scientific queries

Name

Graham Stevens

Address

Senior Registrar
Department of Diving and Hyperbaric Medicine
Royal Hobart Hospital
26 Campbell St
Hobart Tas 7000

Country

Australia

Phone

+61 3 61668193

Fax

+61 3 61730410

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?

graham.stevens@ths.tas.gov.au

What supporting documents are/will be available?

No Supporting Document Provided

Results publications and other study-related documents

Documents added manually

No documents have been uploaded by study researchers.

Documents added automatically

No additional documents have been identified.

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