Orthostatic Hypotension: JACC State-of-the-Art Review.
Roy Freeman, Ahmad R Abuzinadah, Christopher Gibbons...
https://pubmed.ncbi.nlm.nih.gov/30190008Actively Recruiting
Phase Not Applicable
Age: 18Years - 100Years
All Genders
ID05908760
CO2 Rebreathing to Increase Blood Pressure in Neurogenic Orthostatic Hypotension: A Proof-of-Concept Pilot Study
Led by University of Calgary · Updated on 2026-05-05
28
Participants Needed
1
Research Sites
52 weeks
Total Duration
On this page
AI-Summary
What this Trial Is About
Neurogenic orthostatic hypotension (nOH) is a chronic condition where standing causes a significant drop in blood pressure, often leading to symptoms like dizziness and fainting. This condition affects older adults and those with neurodegenerative diseases, neuropathies, or neural injuries. The study is evaluating whether a CO2 rebreathing device can improve blood pressure and reduce symptoms in patients with nOH by increasing carbon dioxide levels in the blood. Participants will undergo two head-up tilt tests at a 70-degree angle, breathing either normal room air or using a CO2 rebreather device that captures and re-inhales exhaled CO2 to raise arterial CO2 levels. Each test lasts up to five minutes, during which blood pressure and other heart and brain blood flow measurements are taken. The order of breathing conditions is randomized to compare the effects of the rebreather versus room air. During the study visit, participants will be monitored with blood pressure cuffs, heart rate electrodes, transcranial Doppler ultrasound, and respiratory measurements. They will be asked to avoid certain substances like alcohol and caffeine before testing. The main outcome is the change in blood pressure between lying down and standing with and without the rebreather. Symptoms and cerebral blood flow are also evaluated. The study aims to understand if CO2 rebreathing can improve orthostatic tolerance safely and effectively in nOH patients.
CONDITIONS
Brief Title
CO2 Rebreathing in nOH: A Proof-of-Concept Pilot Study
Who Can Participate
Age: 18Years - 100Years
All Genders
Eligibility Criteria
You may qualify if you...
- Age 18 years or older
- Male and female participants
- Physician diagnosis of Neurogenic Orthostatic Hypotension
- Non-smokers
- Able and willing to provide informed consent
- Ability to travel to the testing laboratory at the University of Calgary
You will not qualify if you...
- Use of medical therapies or medications that interfere with autonomic function testing
- Pregnant or breastfeeding females
- Chronic heart failure or severe lung disease causing inability to climb one flight of stairs due to shortness of breath
- Other organ failure or systemic illnesses affecting autonomic function or ability to cooperate, including dementia, alcohol/drug abuse, cerebrovascular disease, kidney or liver disease, or nerve surgery affecting sympathetic nerves
- Any other factors judged by investigators that would prevent completing the study protocol, including poor compliance during previous studies
AI-Screening
AI-Powered Screening
Complete this quick 3-step screening to check your eligibility
1
2
3
Your Study Journey
Screening
Duration - 2 to 4 weeks
Participants are screened for eligibility to participate in the trial.
1 visit (in-person) for eligibility assessment and informed consent
Treatment
Duration - 1 day
Participants undergo two randomized 5-minute head-up tilt (HUT) tests while breathing either normal room air or using a CO2 rebreathing device to increase CO2 levels. This involves instrumentation and monitoring of blood pressure, heart rate, cerebral blood flow velocity, respiratory patterns, and other vital signs during supine baseline and upright tilt positions.
1 in-person visit including preparation, instrumentation, and two tilt tests
Trial Site Locations
Total: 1 location
1
University of Calgary
Calgary, Alberta, Canada
Actively Recruiting
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Research Team
J
Jacquie Baker, PhD
A
Angela Qi, MD
How is the study designed?
Study Type
INTERVENTIONAL
Masking
NONE
Allocation
RANDOMIZED
Model
CROSSOVER
Primary Purpose
TREATMENT
Number of Arms
2
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Published Research Related To This Trial
Combined hypoxia and hypercapnia evokes long-lasting sympathetic activation in humans.
B J Morgan, D C Crabtree, M Palta...
https://pubmed.ncbi.nlm.nih.gov/7559221Consensus statement on the definition of orthostatic hypotension, neurally mediated syncope and the postural tachycardia syndrome.
Roy Freeman, Wouter Wieling, Felicia B Axelrod...
https://pubmed.ncbi.nlm.nih.gov/21431947Peripheral chemoreceptor contributions to sympathetic and cardiovascular responses during hypercapnia.
J K Shoemaker, A Vovk, D A Cunningham
https://pubmed.ncbi.nlm.nih.gov/12564639Treatment of acute migraine by a partial rebreathing device: A randomized controlled pilot study.
Cecilia H Fuglsang, Troels Johansen, Kai Kaila...
https://pubmed.ncbi.nlm.nih.gov/30134739