Asymmetrical versus symmetrical high-flow nasal cannula effects on breathing effort

The Effect of Asymmetrical vs. Symmetrical High Flow Nasal Cannula on the Work of Breathing: A Randomised Cross-over Study

It will test whether an asymmetrical high-flow nasal cannula helps reduce breathing effort compared with a conventional symmetrical cannula in adults who have recovered from a respiratory illness.

Quick facts

• Phase: Not applicable
• Study type: Interventional
• Enrollment: 30 (estimated)
• Ages: 18 Years and up
• Sex: All
• Sponsor: Larissa University Hospital (Academic / other)
• Locations: 1 site (Larissa)
• Trial ID: NCT07066566 on ClinicalTrials.gov

What this trial studies

This is a randomized single-center crossover physiologic study in clinically stable adults recovered from respiratory disease, with each participant receiving both an asymmetrical and a conventional symmetrical nasal high-flow interface at 50 L/min and FiO2 0.21 for 15 minutes in random order. Respiratory mechanics will be measured using esophageal pressure monitoring and minute ventilation, while lung volume changes are tracked by a chest bioelectrical impedance device and flow by a heated pneumotachometer. Vital signs and peripheral oxygen saturation will be continuously recorded during each intervention. The study compares the immediate impact of the two interfaces on work of breathing while participants breathe comfortably seated on room air.

Who should consider this trial

Good fit: Ideal candidates are adults (≥18 years) who are clinically stable after a respiratory illness, maintain SpO2 >95% on room air, and have no contraindication to esophageal pressure monitoring.

Not a fit: People with active respiratory failure or hypoxemia (SpO2 <94% on room air), pregnancy, neuromuscular disease, or contraindications to esophageal pressure monitoring are unlikely to benefit from this protocol.

Why it matters

Potential benefit: If successful, the asymmetrical nasal cannula could reduce patients' breathing effort and improve comfort during high-flow nasal therapy.

How similar studies have performed: Early physiologic studies of asymmetrical high-flow interfaces have suggested reductions in work of breathing compared with conventional interfaces, but clinical outcome data remain limited.

Eligibility criteria

Inclusion Criteria:

1. age ≥18 years old
2. absence of symptoms and signs of respiratory failure (SpO2\>95% at FiΟ2 0.21)

Exclusion Criteria:

1. pregnancy
2. SpO2\<94% at FiΟ2 0.21
3. neuromuscular disease
4. contraindications to esophageal pressure monitoring (e.g., uncontrolled coagulopathy, esophageal disease, nasal trauma, allergy to local lidocaine)

Where this trial is running

Larissa

• University Hospital of Larissa, Department of Pulmonary Medicine — Larissa, Greece (Recruiting)

Study contacts

• Study coordinator: Ioannis Dr. Pantazopoulos, Associate Professor

Conditions Respiratory Disease