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Hypercapnia and Orthostatic Tolerance in Postural Orthostatic Tachycardia Syndrome

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Know the risks and potential benefits of clinical studies and talk to your health care provider before participating. Read our disclaimer for details.
 
ClinicalTrials.gov Identifier: NCT04271878
Recruitment Status : Not yet recruiting
First Posted : February 17, 2020
Last Update Posted : February 17, 2020
Sponsor:
Information provided by (Responsible Party):
University of Calgary

Brief Summary:

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

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Study Type : Interventional
Estimated Enrollment : 26 participants
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:

  1. Normal not coached breathing and room air
  2. Normal not coached breathing with ETCO2 clamped at baseline levels - The baseline CO2 levels will be defined from the mean end-tidal CO2 (ETCO2) measured through the mask over the last 5 min of the first baseline phase (ETCO2 normal values range between 35mmHg and 45mmHg).
  3. Normal not coached breathing with mild ETCO2 levels (45mmHg)
  4. Normal not coached breathing with high ETCO2 levels (55mmHg)
  5. Fast breathing and resultant low ETCO2 levels (target ETCO2 19-24mmHg);
  6. Fast breathing and ETCO2 clamped at baseline levels
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
Estimated Study Start Date : March 2020
Estimated Primary Completion Date : March 2021
Estimated Study Completion Date : March 2021

Arm Intervention/treatment
All participants
All participants will receive the same interventions
Other: RespirAct™ system (Thornhill Research Inc., Toronto, Canada)
  1. HUTT with Normal Breathing in Room Air (No gas interventions will be applied)
  2. HUTT with Normal Breathing and ETCO2 clamped at baseline levels
  3. HUTT with Normal Breathing and Mild Hypercapnia (the ETCO2 will be clamped at 45mmHg )
  4. HUTT with Normal Breathing and High Hypercapnia (the ETCO2 will be clamped at 55mmHg)
  5. HUTT with Fast, Deep Breathing and resultant Hypocapnia Participant will be coached to breath around 15 breath per min.No gas interventions will be applied
  6. HUTT with Fast, Deep Breathing and ETCO2 clamped at baseline levels. Participant will be coached to breath around 15 breath per min, with ETCO2 clamped to baseline levels.




Primary Outcome Measures :
  1. 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


Secondary Outcome Measures :
  1. 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

  2. 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
Criteria

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.

Information from the National Library of Medicine

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


Contacts
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Contact: Juliana G Jorge, MD 403 210 7399 juliana.jorge@ucalgary.ca
Contact: Karolina Kogut, BSc 403-210-6152 autonomic.research@ucalgary.ca

Sponsors and Collaborators
University of Calgary
Investigators
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Principal Investigator: Satish R Raj, MD, MSCI University of Calgary, Cardiac Science

Publications of Results:
Other Publications:
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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 17, 2020
Last Verified: February 2020
Individual Participant Data (IPD) Sharing Statement:
Plan to Share IPD: No

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Studies a U.S. FDA-regulated Drug Product: No
Studies a U.S. FDA-regulated Device Product: No
Keywords provided by University of Calgary:
postural tachycardia
autonomic
orthostatic intolerance
dysautonomia
Additional relevant MeSH terms:
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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
Signs and Symptoms
Primary Dysautonomias
Autonomic Nervous System Diseases
Nervous System Diseases
Neurologic Manifestations