CO2 Rebreathing in nOH: A Proof-of-Concept Pilot Study
Trial statusRecruiting
Trial phaseNot applicable
Trial typeInterventional
Biological sexAll
Age18-100
SponsorUniversity of Calgary
About this trial
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 A previous study (unpublished) showed that hypercapnia significantly increases standing BP in patients with nOH.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 criteria
This trial does not accept healthy volunteersQualifiers
Age ≥18 years
Male and Female
Physician diagnosis of Neurogenic Orthostatic Hypotension
Non-smokers.
Disqualifiers
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.
Trial design
Design model
Crossover
Treatments tested in this trial
CO2 ReHaler
DeviceThe ReHaler captures expired CO2, which is then re-inhaled. The net effect is a transient increase in CO2.
Treatment groups
28 Participants
are divided into 2 treatment groupsGroup A: CO2 RebreathingExperimental treatment 1 intervention
Group B: Room AirNo intervention 0 interventions
Trial outcomes
Primary outcomes
1
Δ Blood Pressure (BP)
Magnitude of ΔBP (HUT-Supine) breathing room air vs CO2 rebreathe
Time frame
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 rebreatheSecondary outcomes
1
Δ Vanderbilt Orthostatic Symptom Score [Range: 0 (absent) to 10 (worst)]
Magnitude of Δ Vanderbilt Orthostatic Symptom Score (HUT-Supine) breathing room air vs CO2 rebreathe
Time frame
The Δ Vanderbilt Orthostatic Symptom Score (symptoms at the 5th minute of HUT - symptoms at the 5th minute of supine rest) will be compared between room air vs CO2 rebreathe2
Δ Cerebral Blood Flow Velocity (CBFv)
Magnitude of ΔCBFv (HUT-Supine) breathing room air vs CO2 rebreathe
Time frame
The ΔCBFv (HUT-Supine) calculated as the average CBFv in the final two minutes of supine baseline and the average CBFv between minute 3 and 5 of HUT will be compared between room air and CO2 rebreatheSponsors and contacts
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Source ClinicalTrials.gov