NCT05723679 · University of Texas Southwestern Medical Center
Targeting Breathing Limitations to Improve Functional Outcomes in HFpEF
What this study is about
The overall purpose of this study is to investigate whether pulmonary limitations that increase the oxygen (O2) cost of breathing impact dyspnea on exertion (DOE) and peak exercise capacity in patients with HFpEF and obesity. As per investigator's hypothesis, obesity is likely a significant contributor to DOE and exercise intolerance in patients with HFpEF.
View original scientific description
The overall purpose of this study is to investigate whether pulmonary limitations that increase the oxygen (O2) cost of breathing impact dyspnea on exertion (DOE) and peak exercise capacity in patients with HFpEF and obesity. As per investigator's hypothesis, obesity is likely a significant contributor to DOE and exercise intolerance in patients with HFpEF.
Interventions
OTHER
HeO2 gas mixture
Low-density helium-oxygen gas mixture (HeO2: 21% O2 and 79% He). Participant will be breathing this gas mixture.
OTHER
Room air gas mixture
Normal room air
Primary outcome measures
O2 cost of breathing (Objective 1)
Time frame: Day 2
O2 cost of breathing measured during eucapnic voluntary hyperventilation, and calculated using oxygen uptake and ventilation variables.
Change in DOE during HeO2 breathing (Objective 2)
Time frame: Day 3 or 4
Dyspnea on Exertion (DOE) will be assessed via ratings of perceived breathlessness (RPB) using a 0-10 Borg Scale, and will be compared with that measured during room air breathing.
Change in peak exercise capacity during HeO2 breathing (Objective 2)
Time frame: Day 3 or 4
Peak exercise capacity will be assessed by measuring peak oxygen uptake (in L/min, measured via a breath-by-breath metabolic measurement system), peak power output recorded from a cycle ergometer (Watts), and/or total exercise duration (minutes).
Who can participate
This study lists these criteria on ClinicalTrials.gov. A study coordinator reviews eligibility during screening — this page does not determine whether you qualify.
Inclusion criteria
- signs and symptoms of heart failure
- an ejection fraction \> 0.50;
- objective evidence of diastolic dysfunction. elevated biomarkers (NT-proBNP \>300 ng/dl) or HF hospitalization
- healthy volunteers
Exclusion criteria
- age \< 55 years
- BMI \> 50 kg/m2
- Atrial fibrillation with poorly controlled heart rate
- phosphodiesterase type 5 (PDE5) inhibitor use
- severe valvular disease
- severe Chronic obstructive pulmonary disease (COPD)
- Chronic kidney disease (CKD) 4 or higher
- any restriction of ambulation and mobility.
Where
- Dallas, Texas
Related conditions & keywords
Frequently asked questions
What is a clinical trial?
A clinical trial is a research study that tests new medical treatments, drugs, devices, or procedures to determine their safety and effectiveness. Trials are carefully designed and monitored to protect participants while advancing medical knowledge.
Is it safe to participate?
Clinical trials follow strict safety guidelines and ethical standards. Trials must be reviewed and approved, and participants are closely monitored by medical professionals throughout the study. You can withdraw at any time if you choose.
Will I be compensated?
Many clinical trials offer compensation for your time, travel expenses, and inconvenience. The specific compensation varies by study and will be discussed during the screening process. All study-related medical care is typically provided at no cost to participants.
Will I receive a placebo instead of treatment?
When effective treatment exists, participants typically receive either the standard treatment plus the study intervention, or the standard treatment plus placebo. You would not be denied effective care. Placebos are primarily used when no proven treatment is available, or in addition to standard care. Your trial consent form will clearly explain what treatments you may receive.
Can I leave a trial if I change my mind?
Absolutely. Participation in clinical trials is completely voluntary. You have the right to withdraw from the study at any time, for any reason, without penalty or loss of benefits to which you are otherwise entitled.
How long does a clinical trial last?
Trial duration varies widely depending on the study design and purpose. Some trials last just a few weeks, while others may continue for months or years. The study coordinator will provide specific timeline information during your screening call.
Data: ClinicalTrials.gov · synced May 7, 2026 · Source of record for eligibility and locations