An interventional study of 500mL carbonated water and 500mL still water in Orthostatic Hypotension, Syncope and Vasovagal Syncope, sponsored by Simon Fraser University. Recruiting at 1 site in Canada. Open to participants aged 19 Years to 50 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-04-23.
Sponsored by Simon Fraser University · Not applicable, Interventional, and Treatment
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.
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 [1]. In some individuals blood pressure can fall when standing, predisposing to dizzy spells or fainting episodes [1]. Drinking water can boost blood pressure and making fainting episodes less likely [2-8]. However, it is not clear whether the carbonation of the water has any further impact on the blood pressure response [9,10]. 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.
Volunteers (n=25) will be asked to undergo a "tilt test" to assess cardiovascular reflex control and orthostatic tolerance (measured as time to presyncope, or near fainting, in minutes). It has been previously shown that this technique to be reproducible, reliable, and to have high sensitivity and specificity for differentiating persons with differing orthostatic tolerance, or for examining the effects of interventions aimed at improving orthostatic tolerance [4,6,11-18].
Volunteers 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 room temperature water (control condition), a 500ml drink of flat (non-carbonated) room temperature water, or a 500ml drink of carbonated room temperature water. The study will be conducted in a randomised, single-blind fashion. The investigator responsible for terminating the test will be blinded as to the water condition on each test day, rendering the study single blind. It will not be possible to blind participants as to the carbonation of the water, however, participants will not be informed as to the hypothesised impact of the water conditions.
159 studies on the registry are indexed under Hypotension, Orthostatic; 35 are open to participants now.
This study's planned enrollment of 25 is below the median of 28 across 113 interventional studies indexed under Hypotension, Orthostatic.
Browse Hypotension, Orthostatic studies →Simon Fraser University is the lead sponsor of 29 studies on the registry; 6 are open to participants now.
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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.
Other: 500mL carbonated water · Other: 500mL still water · Other: 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.
Other: 500mL carbonated water · Other: 500mL still water · Other: 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 carbonated water on the first test day, 50mL still water on the second test day, then 500mL still water on the third day.
Other: 500mL carbonated water · Other: 500mL still water · Other: 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, 50mL still water on the second test day, then 500mL carbonated water on the third day.
Other: 500mL carbonated water · Other: 500mL still water · Other: 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 50mL still water on the first test day, 500mL carbonated water on the second test day, then 500mL carbonated water on the third day.
Other: 500mL carbonated water · Other: 500mL still water · Other: 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 50mL still water on the first test day, 500mL still water on the second test day, then 500mL still water on the third day.
Other: 500mL carbonated water · Other: 500mL still water · Other: 50mL still water
Drink 500mL carbonated water immediately prior to head-up tilt test
Drink 500mL still water immediately prior to head-up tilt test
Drink 50mL still water immediately prior to head-up tilt test
Orthostatic tolerance
The time, in minutes, to presyncope (near-fainting) after the initiation of head-up tilt
Time frame: 0-50 minutes
Plan to share: No — Data will be presented in aggregate form and no identifiers will be included.
Started Sep 2023 (actual). Primary completion is estimated for Apr 2027, 43 months after the start.
Of 34 interventional studies with no phase under Hypotension, Orthostatic, half reached primary completion within 54 months of starting (the median), counting those still running; a quarter within 32 and three quarters within 70. This study's planned 43 months is below that.
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