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Trial registered on ANZCTR


Registration number
ACTRN12623001312639
Ethics application status
Approved
Date submitted
22/11/2023
Date registered
15/12/2023
Date last updated
25/04/2024
Date data sharing statement initially provided
15/12/2023
Type of registration
Prospectively registered

Titles & IDs
Public title
Blood pressure response to differing modes of hot-water immersion in people with hypertension
Scientific title
Blood pressure response to differing modes of hot-water immersion in people with hypertension
Secondary ID [1] 311010 0
None
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Hypertension 332121 0
Condition category
Condition code
Cardiovascular 328849 328849 0 0
Hypertension

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
All participants will complete 3 water immersion sessions and a control session (in a randomised order): 1) 30-min whole-body hot-water immersion (40°C; chest depth), 2) 30-min waist deep hot-water immersion (40°C), 3) 30-min lower-limb hot-water immersion (~40°C; below knee depth).

There will be a 4-day washout between exposures.

1. 30-min whole-body hot-water immersion (40°C)
Location: School of Physical Education, Sport and Exercise Sciences Aquatic Facility (University of Otago, Dunedin).
Supervision: This session will be supervised by an American College of Sports Medicine (ACSM) registered clinical exercise physiologist (CEP), and the primary investigator (PI) or a research assistant; all supervising researchers are first aid trained. Attendance and session particulars (e.g., physiological indices etc.) will be recorded at each session by the supervising researcher.
Exposure: Participants will complete a single 30-min hot water immersion session in 40 °C water. Participants will be seated upright with water approximately nipple level.
Duration: 30 min.

2. 30-min waist-deep hot-water immersion (40°C)
Location: School of Physical Education, Sport and Exercise Sciences Aquatic Facility (University of Otago, Dunedin).
Supervision: This session will be supervised by an American College of Sports Medicine (ACSM) registered clinical exercise physiologist (CEP), and the PI or a research assistant; all supervising researchers are first aid trained. Attendance and session particulars (e.g., physiological indices etc.) will be recorded at each session by the supervising researcher.
Exposure: Participants will complete a single 30-min hot water immersion session in 40 °C water. Participants will be seated upright with water approximately waist deep level.
Duration: 30 min.

3. 30-min lower-limb hot-water immersion (40°C)
Location: School of Physical Education, Sport and Exercise Sciences Aquatic Facility (University of Otago, Dunedin).
Supervision: This session will be supervised by an American College of Sports Medicine (ACSM) registered clinical exercise physiologist (CEP), and the PI or a research assistant; all supervising researchers are first aid trained. Attendance and session particulars (e.g., physiological indices etc.) will be recorded at each session by the supervising researcher.
Exposure: Participants will complete a single 30-min hot water immersion session in 40 °C water. Participants will be seated upright with water approximately at below knee level.
Duration: 30 min.
Intervention code [1] 327449 0
Treatment: Other
Comparator / control treatment
30-min control (no exposure).

Location: School of Physical Education, Sport and Exercise Sciences Aquatic Facility (University of Otago, Dunedin).
Supervision: This session will be supervised by an American College of Sports Medicine (ACSM) registered clinical exercise physiologist (CEP), and the PI or a research assistant; all supervising researchers are first aid trained. Attendance and session particulars (e.g., physiological indices etc.) will be recorded at each session by the supervising researcher.
Exposure: Participants will complete a single 30-min resting session (i.e., no exposure/water immersion). Participants will be seated upright in a chair.
Duration: 30 min.
Control group
Active

Outcomes
Primary outcome [1] 336645 0
Blood pressure
Timepoint [1] 336645 0
Pre-exposure, during exposure (every 10 mins), immediately post-completion of exposure and every hour across 24-h post-completion of exposure.
Secondary outcome [1] 429151 0
Physical activity
Timepoint [1] 429151 0
Across the 24-h post-completion of exposure
Secondary outcome [2] 429152 0
Heart rate
Timepoint [2] 429152 0
Pre-exposure, during exposure (every 5 mins) and immediately post-completion of exposure.

Eligibility
Key inclusion criteria
- Aged > 35 y or older;
- Prescribed and regularly taking at least one anti-hypertensive medication;
- Able to give written consent;
- Able to travel to the study centre to complete all sessions.
Minimum age
35 Years
Maximum age
85 Years
Sex
Both males and females
Can healthy volunteers participate?
No
Key exclusion criteria
- Aged < 35 y;
- Contraindication to maximal exercise testing;
- Unstable angina;
- Recent myocardial infarction (< 3 months ago);
- History of orthostatic intolerance/hypotension;
- Current pregnancy;
- New anti-hypertensive pharmaceutical initiated recently (i.e., > 30 days since initiation);
- Any other medical condition deemed a significant risk to study participation.

Study design
Purpose of the study
Treatment
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Allocation will not be concealed
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
Who is / are masked / blinded?



Intervention assignment
Other design features
Phase
Not Applicable
Type of endpoint/s
Statistical methods / analysis

Recruitment
Recruitment status
Recruiting
Date of first participant enrolment
Anticipated
18/12/2023
Actual
18/12/2023
Date of last participant enrolment
Anticipated
20/12/2024
Actual
Date of last data collection
Anticipated
Actual
Sample size
Target
10
Accrual to date
2
Final
Recruitment outside Australia
Country [1] 25982 0
New Zealand
State/province [1] 25982 0

Funding & Sponsors
Funding source category [1] 315274 0
University
Name [1] 315274 0
University of Otago
Country [1] 315274 0
New Zealand
Primary sponsor type
University
Name
University of Otago
Address
PO Box 56 Dunedin 9054 New Zealand
Country
New Zealand
Secondary sponsor category [1] 317311 0
None
Name [1] 317311 0
Address [1] 317311 0
Country [1] 317311 0

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 314193 0
Southern Health and Disability Ethics Committee New Zealand
Ethics committee address [1] 314193 0
PO Box 5013. Wellington 6140
Ethics committee country [1] 314193 0
New Zealand
Date submitted for ethics approval [1] 314193 0
11/10/2023
Approval date [1] 314193 0
08/12/2023
Ethics approval number [1] 314193 0
2023/EXP/18988

Summary
Brief summary
This 4x4 randomised crossover study will aim to recruit 10 participants taking at least one anti-hypertensive medication. Participants will complete 4 sessions: 1) 30-min whole-body (chest deep) hot-water immersion (40°C), 2) 30-min waist deep hot-water immersion (40°C), 3) 30-min lower-limb hot-water immersion (below knee depth deep in 40°C), and 4) 30-min control (no exposure). Physiological measures will be taken during each exposure to characterise the stimulus (e.g., beat-to-beat blood pressure, heart rate). Following each exposure participants will be fitted with an ambulatory blood pressure monitor (and accelerometer to confirm standardisation of activity levels) for the following 24 h to quantify the magnitude and duration of post-session hypotension.
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 130742 0
Dr Brendon Roxburgh
Address 130742 0
Department of Surgical Sciences Level 4, Dunedin Public Hospital 201 Great King Street, Central Dunedin, Dunedin 9016
Country 130742 0
New Zealand
Phone 130742 0
+64 274632376
Fax 130742 0
Email 130742 0
[email protected]
Contact person for public queries
Name 130743 0
Brendon Roxburgh
Address 130743 0
Department of Surgical Sciences Level 4, Dunedin Public Hospital 201 Great King Street, Central Dunedin, Dunedin 9016
Country 130743 0
New Zealand
Phone 130743 0
+64 274632376
Fax 130743 0
Email 130743 0
[email protected]
Contact person for scientific queries
Name 130744 0
Brendon Roxburgh
Address 130744 0
Department of Surgical Sciences Level 4, Dunedin Public Hospital 201 Great King Street, Central Dunedin, Dunedin 9016
Country 130744 0
New Zealand
Phone 130744 0
+64 274632376
Fax 130744 0
Email 130744 0
[email protected]

Data sharing statement
Will individual participant data (IPD) for this trial be available (including data dictionaries)?
No
No/undecided IPD sharing reason/comment


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.