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

NCT05908760 · Status: RECRUITING · Phase: NA · Type: INTERVENTIONAL · Enrollment: 28

Last updated 2026-05-05

No results posted yet for this 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 A previous study (unpublished) showed that hypercapnia significantly increases standing BP in patients with nOH.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.

Conditions

  • Neurogenic Orthostatic Hypotension
  • Autonomic Failure

Interventions

DEVICE

CO2 ReHaler

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

Sponsors & Collaborators

  • University of Calgary

    lead OTHER

Principal Investigators

  • Satish R Raj, MD · University of Calgary

Study Design

Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
NONE
Model
CROSSOVER

Eligibility

Min Age
18 Years
Max Age
100 Years
Sex
ALL
Healthy Volunteers
No

Timeline & Regulatory

Start
2024-07-30
Primary Completion
2029-12-31
Completion
2030-12-31

Countries

  • Canada

Study Locations

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Read the full study record

This page highlights key information. For complete eligibility criteria, study locations, investigator contacts, and the full protocol, visit the original record on ClinicalTrials.gov.

View NCT05908760 on ClinicalTrials.gov