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Trial registered on ANZCTR


Registration number
ACTRN12622000720718
Ethics application status
Approved
Date submitted
12/05/2022
Date registered
19/05/2022
Date last updated
10/11/2024
Date data sharing statement initially provided
19/05/2022
Type of registration
Prospectively registered

Titles & IDs
Public title
Optimising heat therapy for treating high blood pressure
Scientific title
The effect of acute passive heat therapy on 24-h ambulatory blood pressure in patients with hypertension
Secondary ID [1] 307008 0
None
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Hypertension 326129 0
Condition category
Condition code
Cardiovascular 323452 323452 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) 20-min hot-water immersion (40°C), 2) 40-min hot-water immersion (40°C), 3) 40-min thermoneutral-water immersion (~36°C, to establish the role of the water temperature specifically).

There will be a 7-day washout between exposures.

1. 20-min 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 20-min hot water immersion session in 40 °C water. Participants will be seated upright with water approximately nipple level.
Duration: 20 min.

2. 40-min 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 40-min hot water immersion session in 40 °C water. Participants will be seated upright with water approximately nipple level.
Duration: 40 min.

3. 40-min thermoneutral-water immersion (~36°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 40-min thermo-neutral water immersion session in ~36 °C water. Participants will be seated upright with water approximately nipple level.
Duration: 40 min.
Intervention code [1] 323454 0
Treatment: Other
Comparator / control treatment
40-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 40-min resting session (i.e., no exposure/water immersion). Participants will be seated upright in a chair.
Duration: 40 min.
Control group
Active

Outcomes
Primary outcome [1] 331191 0
Blood pressure (assessed via ausculatory method and ambulatory method)
Timepoint [1] 331191 0
Pre-exposure, during exposure, immediately post-exposure and across 24-h post exposure.
Secondary outcome [1] 409131 0
Blood pressure regulatory markers (antidiuretic hormone, atrial natiruetic peptide, haemaglobin, haematocrit; collected via venous blood sample)
Timepoint [1] 409131 0
Pre-exposure, immediate post-exposure and 24-h post exposure
Secondary outcome [2] 409195 0
Physical activity (assessed via accelerometery)
Timepoint [2] 409195 0
Across the 24-h post exposure.
Secondary outcome [3] 409196 0
Heart rate (assessed via chest strap)
Timepoint [3] 409196 0
Pre-exposure, during exposure and immediately post-exposure.
Secondary outcome [4] 409198 0
Body composition (assessed via bioimpedence analysis)
Timepoint [4] 409198 0
Pre-exposure and 24-h post-exposure.
Secondary outcome [5] 409421 0
Vascular function (assessed via ultrasound)
Timepoint [5] 409421 0
Pre-exposure, during exposure and immediately post-exposure.

Eligibility
Key inclusion criteria
Participants will be screened as per criteria listed below:
Inclusion criteria:
- Aged > 35 y or older
- Prescribed and regularly taking at least 1 anti-hypertensive medication
- Patient gives written consent
- Patient is 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
Exclusion criteria:
- Aged < 35 y
- Contraindication to maximal exercise testing (see Appendix)
- Unstable angina
- Recent myocardial infarction (< 3 months ago)
- History of orthostatic intolerance/hypotension
- Current pregnancy
- New anti-hypertensive pharmaceutical initiated recently
- 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)
Methods used to generate the sequence in which subjects will be randomised (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
Completed
Date of first participant enrolment
Anticipated
1/06/2022
Actual
5/09/2022
Date of last participant enrolment
Anticipated
2/12/2022
Actual
2/12/2022
Date of last data collection
Anticipated
23/12/2022
Actual
23/12/2022
Sample size
Target
16
Accrual to date
Final
16
Recruitment outside Australia
Country [1] 24739 0
New Zealand
State/province [1] 24739 0

Funding & Sponsors
Funding source category [1] 311320 0
Government body
Name [1] 311320 0
Putahi Manawa | Healthy Hearts for Aotearoa NZ Centre of Research Excellence
Country [1] 311320 0
New Zealand
Funding source category [2] 311375 0
University
Name [2] 311375 0
University of Otago
Country [2] 311375 0
New Zealand
Primary sponsor type
University
Name
University of Otago
Address
362 Leith Street
Dunedin North
Dunedin 9016
Country
New Zealand
Secondary sponsor category [1] 312697 0
None
Name [1] 312697 0
Address [1] 312697 0
Country [1] 312697 0

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 310822 0
Southern Health and Disability Ethics Committee
Ethics committee address [1] 310822 0
Ministry of Health
Health and Disability Ethics Committees
PO Box 5013
Wellington 6140
Ethics committee country [1] 310822 0
New Zealand
Date submitted for ethics approval [1] 310822 0
27/04/2022
Approval date [1] 310822 0
25/05/2022
Ethics approval number [1] 310822 0
2022 EXP 12392

Summary
Brief summary
The purpose of this study is to examine the effect of heat therapy on taha tinana (physical health; specifically, 24-h blood pressure) in patients with hypertension. Secondary outcomes will assess the effect on taha wairua (spiritual wellbeing), taha whanau (family health) and taha hinengaro (mental health). A randomised cross-over study will recruit 10 participants who are currently taking at least one anti-hypertensive medication. They will complete 4 sessions: 1) 20-min hot water immersion (40°C), 2) 40-min hot water immersion (40°C), 3) 40-min thermoneutral water immersion (~36°C, to establish the role of the water temperature specifically), and 4) control (no exposure). Physiological measures will be taken during exposure to characterise the stimulus. Following each exposure participants will be fitted with an ambulatory blood pressure monitor (and accelerometer to standardise 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 118986 0
Dr Kate Thomas
Address 118986 0
Department of Surgical Sciences
Level 4, Dunedin Public Hospital
201 Great King Street, Central Dunedin, Dunedin 9016
Country 118986 0
New Zealand
Phone 118986 0
+64273527990
Fax 118986 0
Email 118986 0
[email protected]
Contact person for public queries
Name 118987 0
Brendon Roxburgh
Address 118987 0
Department of Surgical Sciences
Level 4, Dunedin Public Hospital
201 Great King Street, Central Dunedin, Dunedin 9016
Country 118987 0
New Zealand
Phone 118987 0
+64274632376
Fax 118987 0
Email 118987 0
[email protected]
Contact person for scientific queries
Name 118988 0
Jim Cotter
Address 118988 0
School of Physical Education, Sport and Exercise Sciences
55 Union Street West
North Dunedin
Dunedin 9016
New Zealand
Country 118988 0
New Zealand
Phone 118988 0
+64 3 479 9109
Fax 118988 0
Email 118988 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.