Hypercapnia in Orthostatic Hypotension

• Status: Recruiting
• Trial end date: 2026-05-31
• Target enrollment: 0
• Participant gender: All

Summary

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

• Phase: N/A
• Accepts Healthy Volunteers?: Accepts Healthy Volunteers

Details

• Lead Sponsor: University of Calgary

Criteria

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.