Hypercapnia and Orthostatic Tolerance in Postural Orthostatic Tachycardia Syndrome
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ClinicalTrials.gov Identifier: NCT04271878 |
Recruitment Status :
Recruiting
First Posted : February 17, 2020
Last Update Posted : February 21, 2022
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The mechanism behind postural orthostatic tachycardia syndrome (POTS) involves many causes including a sympathetic nervous system problem. Blood gases, like carbon dioxide (CO2), have an important effect on sympathetic activation.
The purpose of this research study is to determine if higher CO2 levels have any effect in lowering heart rate and reducing POTS symptoms when upright/standing. The investigators are also searching for the ideal CO2 concentration to achieve the most effective response
Condition or disease | Intervention/treatment | Phase |
---|---|---|
Postural Tachycardia Syndrome Orthostatic Intolerance | Other: RespirAct™ system (Thornhill Research Inc., Toronto, Canada) | Not Applicable |

Study Type : | Interventional |
Estimated Enrollment : | 26 participants |
Allocation: | N/A |
Intervention Model: | Single Group Assignment |
Intervention Model Description: | All participants must have been diagnosed with POTS, they will all complete up to 6 head-up tilt tests (HUTTs) on a single day. They will all receive the following interventions:
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Masking: | None (Open Label) |
Masking Description: | All participants will be fitted with a face mask connected to a tube supplied with gas from the RespirAct™ system. The participants will not be informed about the concentration of gases during the tilt tests. After the study completion they will be informed about the order of interventions. |
Primary Purpose: | Other |
Official Title: | Hypercapnia and Orthostatic Tolerance in Postural Orthostatic Tachycardia Syndrome |
Actual Study Start Date : | February 2, 2022 |
Estimated Primary Completion Date : | December 2026 |
Estimated Study Completion Date : | December 2026 |
Arm | Intervention/treatment |
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All participants
All participants will receive the same interventions
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Other: RespirAct™ system (Thornhill Research Inc., Toronto, Canada)
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- Heart Rate (HR) variation [ Time Frame: difference between HR from supine to peak HR during tilt test for each intervention (mean value HR between the 8th and 9th minute of supine; peak parameters, during HUTT, mean value during the first min and between the 3rd and 8th min) ]Magnitude of ΔHR
- Cerebral blood flow velocity (CBFv) variation [ Time Frame: difference between CBFv from supine to peak during tilt test for each intervention (mean value CBFv between the 8th and 9th min of supine; peak parameters, during HUTT, mean value CBFv during the first min and between the 3rd and 8th min) ]Magnitude of ΔCBFv
- VOSS symptom score [ Time Frame: VOSS will be accessed at the 8th minute of each HUTT, comparing the intensity of symptoms in each intervention ]Vanderbilt Orthostatic Symptoms Score (VOSS) - patients will rate the severity of 9 symptoms on a scale of 0 to 10 (0 reflects absence of symptoms). The sum of the scores at each time point is used as a measure of symptom burden (lower score reflects reduced symptom burden). The 9 symptoms are mental clouding, blurred vision, shortness of breath, rapid heartbeat, tremulousness, chest discomfort, headache, lightheadedness, and nausea.

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Ages Eligible for Study: | 18 Years to 60 Years (Adult) |
Sexes Eligible for Study: | All |
Accepts Healthy Volunteers: | No |
Inclusion Criteria:
- Physician diagnosis of Postural Tachycardia Syndrome (POTS)
- Age 18-60 years
- Male and Female
- Non - smokers.
- Able and willing to provide informed consent.
- Ability to travel to Libin Cardiovascular Institute of Alberta Autonomic Testing Lab at the University of Calgary, Calgary, AB.
Exclusion Criteria:
- Overt cause for postural tachycardia, i.e., acute dehydration
- Participants with somatization or severe anxiety symptoms will be excluded
- Pregnant
- Inability to tolerate mask for the duration of the study
- Subjects who require portable oxygen at rest or with exercise
- Subjects with chronic heart failure or severe pulmonary disease who are unable to climb one flight of stairs due to shortness of breath.
- Other factors which in the investigator's opinion would prevent the participant from completing the protocol, including poor compliance during previous studies.

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.
Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT04271878
Contact: Shaun Ranada, BSc | 403-210-6152 | shaun.ranada@ucalgary.ca | |
Contact: Rasha Hamza, RN | 403-210-6152 | autonomic.research@ucalgary.ca |
Canada, Alberta | |
University of Calgary | Recruiting |
Calgary, Alberta, Canada, T2N 4Z6 | |
Contact: Satish R Raj, MD MSCI 403-210-6152 autonomic.research@ucalgary.ca | |
Contact: Robert S Sheldon, MD PhD 403-220-8191 autonomic.research@ucalgary.ca |
Principal Investigator: | Satish R Raj, MD, MSCI | University of Calgary, Cardiac Science |
Other Publications:
Responsible Party: | University of Calgary |
ClinicalTrials.gov Identifier: | NCT04271878 |
Other Study ID Numbers: |
REB20-0135 |
First Posted: | February 17, 2020 Key Record Dates |
Last Update Posted: | February 21, 2022 |
Last Verified: | February 2022 |
Individual Participant Data (IPD) Sharing Statement: | |
Plan to Share IPD: | No |
Studies a U.S. FDA-regulated Drug Product: | No |
Studies a U.S. FDA-regulated Device Product: | No |
postural tachycardia autonomic orthostatic intolerance dysautonomia |
Postural Orthostatic Tachycardia Syndrome Orthostatic Intolerance Tachycardia Syndrome Hypercapnia Disease Pathologic Processes Arrhythmias, Cardiac |
Heart Diseases Cardiovascular Diseases Cardiac Conduction System Disease Signs and Symptoms, Respiratory Primary Dysautonomias Autonomic Nervous System Diseases Nervous System Diseases Neurologic Manifestations |