Investigating Hypercapnia to Treat Neurogenic Orthostatic Hypotension

REB20-1322

The Autonomic (or "automatic") Nervous System (ANS) regulates internal processes, including control of heart rate and blood pressure (BP). When someone stands, and gravity tries to pull blood away from the brain, the ANS works to maintain BP and brain blood flow. Neurogenic Orthostatic Hypotension (NOH) occurs when our "fight-or-flight" part ("sympathetic") of the ANS fails. BP can drop a lot when upright, reducing blood flow and oxygen delivery to the brain, and this can cause symptoms of light-headedness, nausea, and fainting. One solution to help counter the effects of NOH may be to increase sympathetic activity by breathing higher levels of carbon dioxide. In healthy volunteers, small increases in the amount of inhaled carbon dioxide has been shown to increase BP in the upright position, and this improves symptoms! The objectives of the current study are to apply carbon dioxide in patients with NOH and healthy controls to: (a) evaluate the effects of breathing carbon dioxide on BP and brain blood flow, and (b) determine if a device that increases carbon dioxide while standing will work as a new therapy

2022-03-01

2025-12-31

2026-05-31

Recruiting

80

Inclusion Criteria: * Age ≥18 years * Male and Female * Non - smokers. * Able and willing to provide informed consent. * Ability to travel to Libin Cardiovascular Institute Autonomic Testing Lab at the University of Calgary, Calgary, AB. Exclusion Criteria: * Medical therapies or medications which could interfere with testing of autonomic function * Participants with somatization or severe anxiety symptoms will be excluded * Pregnant or breast-feeding females * 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. * Presence of failure of other organ systems or systemic illness that can affect autonomic function or the participant's ability to cooperate. These include: dementia, alcohol and/or drug abuse, cerebrovascular disease, kidney or liver disease, surgical procedures where the nerves of the sympathetic nervous system have been cut. * Other factors which in the investigator's opinion would prevent the participant from completing the protocol, including poor compliance during previous studies.

{'studyType': 'INTERVENTIONAL', 'phases': ['NA'], 'designInfo': {'allocation': 'RANDOMIZED', 'interventionModel': 'CROSSOVER', 'interventionModelDescription': 'Male and female NOH patients (n=40) will be recruited from the Calgary Autonomic Clinic, along with sex and age-matched controls from the community. Participants will complete five Active Stand Tests during which they will be asked to target different end-tidal (ET) CO2 levels. Participants will complete the following breathing protocol during an active stand test:\n\n1. Breathing normal room air (ETCO2 free to fluctuate),\n2. ETCO2 clamped at baseline,\n3. ETCO2 clamped at +5mmHg,\n4. ETCO2 clamped at +10mmHg,\n5. ETCO2 clamped at +10mmHg with ETO2 clamped at 50mmHg.', 'primaryPurpose': 'TREATMENT', 'maskingInfo': {'masking': 'NONE', 'maskingDescription': '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 each active stand test. After the study completion they will be informed about the order of interventions.'}}, 'enrollmentInfo': {'count': 80, 'type': 'ESTIMATED'}}

2023-11-29