CO2 Rebreathing in nOH: A Proof-of-Concept Pilot Study

NCT05908760 · tracked via the Priya Life Science Canada tracker

Sponsor

University of Calgary

Phase

Not applicable

Started

2024-07-30

Last updated

2026-05-05

Condition(s) studied

Neurogenic Orthostatic HypotensionAutonomic Failure

Investigational drug(s) / intervention(s)

CO2 ReHaler

CO2 ReHaler: The ReHaler captures expired CO2, which is then re-inhaled. The net effect is a transient increase in CO2.

Study summary

Neurogenic orthostatic hypotension (nOH) is a chronic condition associated with increased cardiovascular risk and reduced quality of life. On standing, patients with nOH experience a large reduction in blood pressure (BP; at least ≥20/10mmHg, but often much more), which is often accompanied by debilitating symptoms and syncope. A previous study (unpublished) showed that hypercapnia significantly increases standing BP in patients with nOH. Human bodies naturally produce and exhale CO2. Rebreathe devices offer a simple, cost-effective technology to increase arterial CO2. In brief, rebreathe devices work by capturing expired CO2, which is then re-inhaled. The net effect is a transient increase in CO2. A CO2 rebreathing device may offer a novel hemodynamic therapy for patients with nOH.

This is a pilot, proof-of-concept study to evaluate a CO2 rebreather to improve blood pressure and orthostatic tolerance in patients with nOH. The hypothesis is that a rebreather will increase CO2 sufficiently enough to improve BP in patients with nOH.

Male and female patients (n=28) will be asked to complete two randomized 70° head-up tilt (HUT) tests breathing either room air or using a CO2 rebreather. Hemodynamics (BP, heart rate, stroke volume, brain blood flow) and orthostatic symptoms will be assessed throughout. Breath-by-breath data will include O2, CO2, respiration rate and tidal volume.

The primary outcome measure will be the magnitude of the BP response (ΔBP = HUT - Supine) during Room Air vs. Hypercapnia. The primary outcome will be compared between room air and hypercapnia using a paired t-test.

Eligibility

Sex

ALL

Min age

18 Years

Max age

100 Years

Healthy volunteers

Inclusion Criteria: * Age ≥18 years * Male and Female * Physician diagnosis of Neurogenic Orthostatic Hypotension * 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 * Pregnant or breast-feeding females * 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.

Primary outcome measure(s)

Δ Blood Pressure (BP) — The ΔBP (HUT-Supine) calculated as the average BP in the final two minutes of supine baseline and the average BP between minute 3 and 5 of HUT will be compared between room air and CO2 rebreathe
Magnitude of ΔBP (HUT-Supine) breathing room air vs CO2 rebreathe

Trial sites (1)

Facility	City	Region	Status
University of Calgary	Calgary	Alberta	Recruiting

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Official registry record

This page summarises publicly available registry data for informational purposes — not medical advice. Eligibility is determined by each study team; patients should discuss participation with their clinician.

View NCT05908760 on ClinicalTrials.gov ↗ ← All trials in Canada