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Trial registered on ANZCTR


Registration number
ACTRN12621001767897
Ethics application status
Approved
Date submitted
24/11/2021
Date registered
23/12/2021
Date last updated
23/12/2021
Date data sharing statement initially provided
23/12/2021
Type of registration
Prospectively registered

Titles & IDs
Public title
The effects of loaded breathing on brain blood flow and cognition
Scientific title
The effects of loaded breathing on cerebral blood flow and cognition in young and healthy volunteers
Secondary ID [1] 305864 0
None
Universal Trial Number (UTN)
U1111-1271-8659
Trial acronym
LoadBrain
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Respiratory Disease 324412 0
Condition category
Condition code
Respiratory 321893 321893 0 0
Chronic obstructive pulmonary disease
Neurological 321894 321894 0 0
Studies of the normal brain and nervous system

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
The study will be a randomised controlled design. Participants will attend the laboratory for two visits that will each last 2 hours. Visits will be separated by a minimum of 48 h and a maximum of 1 week. The first visit will be a screening and familiarisation session. During the visit, participants will have height, body mass and pulmonary function measured. Participants will then be familiarised with the following 4 experimental conditions:

Control (unloaded breathing)
Control (unloaded breathing) + cognitive testing
Inspiratory loaded breathing
Inspiratory loaded breathing + cognitive testing

During the second visit, participants will repeat the 4 experimental conditions. These will be undertaken in random order and there will be a 5 min washout period between conditions. Each condition will be preceded and followed by 3 min of rest and recover. Each condition will last 10 min.

During the experimental conditions, participants will breathe thorough a pressure-threshold loading device. Participants will be seated with their feet and back supported. The pressure-threshold loading device will be placed on a table and its height adjusted so the participant can reach the mouthpiece with their head and neck in a neutral alignment. Adjustable weights will be attached to the plunger with an inspiratory threshold load that has to be met in order for the participant to inspire. No weights will be added for the control conditions. Weights corresponding to a threshold pressure of 70% of the participants maximal inspiratory pressure will be added for the loaded breathing conditions. Breathing frequency will be set to 15 breaths/min and inspiratory duty cycle (ratio of inspiratory contraction time to total respiratory cycle duration) at 0.7. A metronome will be used to control breathing pattern. Target inspiratory mouth pressure will be displayed on a computer screen to provide continuous visual feedback. Before and after the experimental conditions, 3 min of rest and recovery data will be collected.

At minute 4 of the experimental conditions, participants will undertake the Trail Making Task Parts A and B which assesses central executive function delivered using an iPad (6th generation, Apple Inc, Cupertino, CA, USA). The duration of this cognitive test is approximately 1 min.

Transcranial Doppler ultrasonography (TCD; DopplerBox X; Compumedics DWL, Singen, Germany) will be used to measure cerebrovascular haemodynamics.

Heart rate and arterial blood pressure will be measured on a continuous beat-to-beat
basis using finger photoplethysmography (Human NIBP controller; AD Instruments, Bella Vista, NSW, Australia) placed on the middle finger of the nondominant hand and supported on a front table positioned at the heart level.

Testing will be undertaken by the primary investigator Dr Dean Mills who holds a PhD in respiratory physiology and has 10 years of experience in the area.

Testing will be delivered face to face at the University of Southern Queensland, Sport and Exercise Laboratory, Ipswich, QLD.
Intervention code [1] 322278 0
Behaviour
Intervention code [2] 322402 0
Prevention
Comparator / control treatment
Each partcipant will act as their own control.

The Control (unloaded breathing) and Control (unloaded breathing) + cognitive testing are considered a comparator/control condition,
Control group
Active

Outcomes
Primary outcome [1] 329669 0
Cognition will be assessed using the Trail Making Task Parts A and B which assesses central executive function delivered using an iPad (6th generation, Apple Inc, Cupertino, CA, USA). The duration of this cognitive test is approximately 1 min.
Timepoint [1] 329669 0
At minute 4 of each experimental condition particpants will commence the cognitive test.
Primary outcome [2] 329670 0
Cerebrovascular blood flow will be assessed using transcranial Doppler ultrasonography (TCD; DopplerBox X; Compumedics DWL, Singen, Germany). Participants will be seated and fitted with a headpiece that houses two 2-MHz TCD ultrasound probes that will be fixed and aligned bilaterally to the left and right cranial temporal bone windows to insonate the middle cerebral artery at a depth of approximately 40-65 mm. Beat-to-beat measurements of cerebral blood flow velocity will be recorded from the middle cerebral artery onto software (QL Reader; Compumedics DWL, Singen, Germany) sampling at 100 Hz and stored for subsequent offline analysis. If a bilateral signal is not obtained, then analysis will take place with only the side that was able to be obtained.
Timepoint [2] 329670 0
Cerebrovascular blood flow will be measured continuously during each condition.
Secondary outcome [1] 403388 0
Heart rate and arterial blood pressure will be measured on a continuous beat-to-beat
basis using finger photoplethysmography (Human NIBP controller; AD Instruments, Bella Vista, NSW, Australia) placed on the middle finger of the nondominant hand and supported on a front table positioned at the heart level.

This is a composite secondary outcome.
Timepoint [1] 403388 0
Heart rate and arterial blood pressure will be measured continuously during each condition.

Eligibility
Key inclusion criteria
Apparently healthy, and free of known disease and/or signs or symptoms of disease..
Minimum age
18 Years
Maximum age
40 Years
Sex
Both males and females
Can healthy volunteers participate?
Yes
Key exclusion criteria
Current tobacco or electronic cigarette smoker; history or current symptoms of cardiopulmonary disease; contraindications to respiratory testing; and body mass index <18.5 or >30 kg/m2.

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)
Allocation is not concealed
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Simple randomisation using a randomisation table from a statistic book.
Masking / blinding
Open (masking not used)
Who is / are masked / blinded?



Intervention assignment
Crossover
Other design features
Phase
Not Applicable
Type of endpoint/s
Efficacy
Statistical methods / analysis
Statistical analyses will be performed using SPSS for Windows (IBM, Chicago, USA). We will use a convenience sample size, as we do not have any published data to estimate the differences between the experimental conditions. A two-way analysis of variance (ANOVA) will be used to determine the effects of ‘experimental condition’ and ‘time’. Significant interaction effects will be followed by planned pairwise comparisons between conditions using the Bonferroni method. Statistical significance will be set at P < 0.05. Results will be presented as means ± SD.

Recruitment
Recruitment status
Not yet recruiting
Date of first participant enrolment
Anticipated
10/01/2022
Actual
Date of last participant enrolment
Anticipated
5/12/2022
Actual
Date of last data collection
Anticipated
12/12/2022
Actual
Sample size
Target
20
Accrual to date
Final
Recruitment in Australia
Recruitment state(s)
QLD
Recruitment postcode(s) [1] 36063 0
4305 - Raceview

Funding & Sponsors
Funding source category [1] 310215 0
University
Name [1] 310215 0
University of Southern Queensland
Country [1] 310215 0
Australia
Primary sponsor type
University
Name
University of Southern Queensland
Address
University of Southern Queensland, School of Health and Wellbeing, Ipswich Campus, Ipswich, 11 Salisbury Road, Ipswich, QLD, 4305
Country
Australia
Secondary sponsor category [1] 311326 0
None
Name [1] 311326 0
Address [1] 311326 0
Country [1] 311326 0

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 309897 0
University of Southern Queensland Human Research Ethics
Ethics committee address [1] 309897 0
Office of Research, University of Southern Queensland
West St, Darling Heights,
Toowoomba, Queensland, 4350, Australia
Ethics committee country [1] 309897 0
Australia
Date submitted for ethics approval [1] 309897 0
09/11/2021
Approval date [1] 309897 0
24/11/2021
Ethics approval number [1] 309897 0
H20REA068

Summary
Brief summary
Cognition is required so that individuals can make decisions, communicate, think, analyse and move on a daily basis. Patients with chronic obstructive pulmonary disease (COPD) have impaired cognition compared to age matched healthy controls and this is associated with increased mortality and disability (Wen et al. 2018). However, the mechanisms for this cognitive dysfunction remain poorly understood. Several studies have also reported that a reduced brain (cerebral) blood flow can lead to cognitive dysfunction and patients with COPD also have a reduced brain blood flow compared to age matched healthy controls (Beaudin et al. 2017). This finding suggests that the impaired cognition observed in patients with COPD may be due to a reduction in brain blood flow. However, this hypothesis has not been tested. Patients with COPD experience airway obstruction which loads the respiratory muscles and increases the work of breathing. Inspiratory loaded breathing required healthy individuals to breathe through a narrow tube and increases the work of breathing and replicates an exacerbation of COPD. This model of airway obstruction can be used to replicate COPD in healthy young individuals and investigate the effects of loaded breathing on cognition and brain blood flow.

The aim of the study is to investigate the effects of inspiratory loaded breathing on cerebrovascular blood flow and cognition in healthy young adults.

We will test the hypothesis that inspiratory loaded breathing reduces cerebrovascular blood flow and cognition.
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 115762 0
Dr Dean Mills
Address 115762 0
University of Southern Queensland
School of Health and Wellbeing
Room B202, 11 Salisbury Road, Ipswich Campus, Ipswich, 4305
Queensland, Australia
Country 115762 0
Australia
Phone 115762 0
+61 7 3812 6147
Fax 115762 0
Email 115762 0
dean.mills@usq.edu.au
Contact person for public queries
Name 115763 0
Dr Dean Mills
Address 115763 0
University of Southern Queensland
School of Health and Wellbeing
Room B202, 11 Salisbury Road, Ipswich Campus, Ipswich, 4305
Queensland, Australia
Country 115763 0
Australia
Phone 115763 0
+61 7 3812 6147
Fax 115763 0
Email 115763 0
dean.mills@usq.edu.au
Contact person for scientific queries
Name 115764 0
Dr Dean Mills
Address 115764 0
University of Southern Queensland
School of Health and Wellbeing
Room B202, 11 Salisbury Road, Ipswich Campus, Ipswich, 4305
Queensland, Australia
Country 115764 0
Australia
Phone 115764 0
+61 7 3812 6147
Fax 115764 0
Email 115764 0
dean.mills@usq.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?
Anonymous (de-identified) data will be shared upon email request.
When will data be available (start and end dates)?
Data will be available at the completion of the project. Data will be available for 5 years after the completion of the project.
Available to whom?
Researchers from a scientific or academic institute.
Available for what types of analyses?
For the aims approved in the proposal (e.g. for meta-analytical studies).
How or where can data be obtained?
Dr Dean Mills
Phone: +61 7 3812 6147
Email: dean.mills@usq.edu.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.