Recruiting

Observational Study

Sponsor:

Simon Fraser University

Code:

NCT05621460

Conditions

Orthostatic Hypotension

Syncope

Vasovagal Syncope

Eligibility Criteria

Sex: All

Age: 19 - 50

Healthy Volunteers: Accepted

Interventions

500mL carbonated water

500mL still water

50mL still water

Study Details

Brief summary:

The primary purpose of this investigation is to determine whether water carbonation can improve orthostatic tolerance in healthy control volunteers. Orthostatic tolerance refers to the ability to maintain an adequate blood pressure when standing. In some individuals blood pressure can fall when standing, predisposing to dizzy spells or fainting episodes. Drinking water can boost blood pressure and making fainting episodes less likely. However, it is not clear whether the carbonation of the water has any further impact on the blood pressure response. This is important because it may be that carbonated water expands the stomach (gastric distension), provoking an increase in sympathetic activity. The increase in sympathetic nervous system activity boosts blood pressure. Resolving this question would have important implications for patients with syncope. This study will test whether carbonated water will have any further impact on blood pressure than the already known effect of non-carbonated water.

Conditions

Orthostatic Hypotension

Syncope

Vasovagal Syncope

Study ID

NCT05621460

Start date

Sep 1, 2023

Status verified date

Apr, 2026

Completion date

Apr, 2027

Anticipated

Primary completion date

Apr, 2027

Anticipated

Eligibility Criteria

Eligibility Criteria

Sex: All

Age: 19 - 50

Healthy Volunteers: Accepted

Inclusion Criteria:

  • healthy, English-speaking

Exclusion Criteria:

  • pregnancy or suspected pregnancy, history of cardiovascular disease, history of neurological disease, history of recurrent fainting (≥ 2 episodes of fainting with loss of consciousness in the prior 6 months)

Study Design

Enrollment

25 participants

Anticipated

Allocation

Randomized

Intervention Model

Crossover

Primary purpose

Treatment

Interventions and Outcome Measures

Arms

experimental: 500mL carbonated water first, then 500mL of still water, then 50mL of still water

Participants will undergo this test on three separate days. On each day participants will be asked to drink a glass of water: either a 50mL drink of still water (control condition), a 500mL drink of still (non-carbonated) water, or a 500mL drink of carbonated water. In this arm of the study, participants will receive 500mL carbonated water on the first test day, 500mL still water on the second test day, then 50mL still water on the third day.

experimental: 500mL still water first, then 500 mL carbonated water, then 50mL still water

Participants will undergo this test on three separate days. On each day participants will be asked to drink a glass of water: either a 50mL drink of still water (control condition), a 500mL drink of still (non-carbonated) water, or a 500mL drink of carbonated water. In this arm of the study, participants will receive 500mL still water on the first test day, 500mL carbonated water on the second test day, then 50mL still water on the third day.

experimental: 500mL carbonated water first, then 50mL of still water, then 500mL of still water

Participants will undergo this test on three separate days. On each day participants will be asked to drink a glass of water: either a 50mL drink of still water (control condition), a 500mL drink of still (non-carbonated) water, or a 500mL drink of carbonated water. In this arm of the study, participants will receive 500mL carbonated water on the first test day, 50mL still water on the second test day, then 500mL still water on the third day.

experimental: 500mL still water first, then 50mL still water, then 500 mL carbonated water

Participants will undergo this test on three separate days. On each day participants will be asked to drink a glass of water: either a 50mL drink of still water (control condition), a 500mL drink of still (non-carbonated) water, or a 500mL drink of carbonated water. In this arm of the study, participants will receive 500mL still water on the first test day, 50mL still water on the second test day, then 500mL carbonated water on the third day.

experimental: 50mL still water first, then 500mL still water, then 500 mL carbonated water

Participants will undergo this test on three separate days. On each day participants will be asked to drink a glass of water: either a 50mL drink of still water (control condition), a 500mL drink of still (non-carbonated) water, or a 500mL drink of carbonated water. In this arm of the study, participants will receive 50mL still water on the first test day, 500mL carbonated water on the second test day, then 500mL carbonated water on the third day.

experimental: 50mL still water first, then 500mL carbonated water, then 500 mL still water

Participants will undergo this test on three separate days. On each day participants will be asked to drink a glass of water: either a 50mL drink of still water (control condition), a 500mL drink of still (non-carbonated) water, or a 500mL drink of carbonated water. In this arm of the study, participants will receive 50mL still water on the first test day, 500mL still water on the second test day, then 500mL still water on the third day.

Interventions

500mL carbonated water

Drink 500mL carbonated water immediately prior to head-up tilt test

500mL still water

Drink 500mL still water immediately prior to head-up tilt test

50mL still water

Drink 50mL still water immediately prior to head-up tilt test

Primary outcome measure

  • Orthostatic tolerance [ Time Frame: 0-50 minutes ]

Central Contacts and Locations

Central contacts

Victoria E Claydon, PhD

7787828513victoria_claydon@sfu.ca

Vera-Ellen M Lucci, PhD

7787828560vlucci@sfu.ca

Locations

Simon Fraser University

Recruiting

Burnaby, British Columbia, Canada, V5A 1S6

Contacts

Vera-Ellen M Lucci, PhD

7787828560vlucci@sfu.ca

Principal Investigator:

Victoria E Claydon, PhD

More Information

Sponsor

Simon Fraser University

Last update posted

Apr 23, 2026

Last verified

Apr, 2026

Keywords

  • Tilt table
  • Osmopressor reflex
  • Gastropressor reflex

Trial information was received from ClinicalTrials.gov and was last updated on 2026-09-10. This information was provided to ClinicalTrials.gov by Simon Fraser University on 2026-04-23.