Asymmetrical Versus Conventional High-flow Nasal Cannula in Acute Respiratory Failure

April 21, 2026 updated by: Nuttapol Rittayamai, Siriraj Hospital

The Physiologic Effects of Asymmetrical Versus Conventional High-flow Nasal Cannula in Acute Respiratory Failure. A Randomized Crossover Study.

The goal of this randomized crossover physiological study is to evaluate the physiologic effects of asymmetrical nasal cannula and conventional nasal cannula in patients with acute respiratory failure. The main questions it aims to answer are:

  • Does the asymmetrical high-flow nasal cannula reduce the diaphragm and parasternal intercostal work activity of breathing measured by ultrasound compared to conventional high-flow nasal cannula?
  • What is the effect of the asymmetrical high-flow nasal cannula on breathing pattern, gas exchange, and hemodynamic variables compared to conventional high-flow nasal cannula? Participants will received asymmetrical high-flow nasal cannula or conventional high-flow nasal cannula at a flow rate of 40 and 60 L/min in a random order.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

High-flow nasal cannula (HFNC) is increasingly used in patients with acute respiratory failure. The physiologic benefits of HFNC can be explained via several mechanisms. These mechanisms lead to improve alveolar ventilation and decrease patient's inspiratory effort directly or indirectly.

Recent clinical practice guidelines recommended to use HFNC in patients with acute hypoxemic respiratory failure over conventional oxygen therapy (COT) and noninvasive ventilation (NIV). A landmark clinical study demonstrated that patients with acute hypoxemic respiratory failure who received HFNC had better survival than COT and NIV. A systematic review and meta-analysis also demonstrated that HFNC significantly reduced escalation of respiratory support in patients with acute hypoxemic respiratory failure.

HFNC can also be an alternative respiratory support in patients with acute on chronic hypercapnic chronic obstructive pulmonary disease (COPD). Several physiological and clinical studies in COPD patients with exacerbations have also suggested that HFNC was not inferior to noninvasive ventilation (NIV) in COPD patients with mild to moderate exacerbation, in terms of gas exchange, treatment failure, intubation rate, and mortality rate. It may be also be used during NIV interruptions or after extubation.

Recently, an asymmetrical HFNC interface has been developed with a feature of one prong of smaller diameter and the other prong of larger diameter resulting in an increase in the overall cross-sectional area compared to conventional HFNC interface. An experimental study has shown that asymmetrical nasal cannula potentially increased positive end-expiratory pressure (PEEP) and enhanced carbon dioxide washout compared to conventional nasal cannula. Different respective effects in terms of pressure, resistance, and dead space washout between the two types of cannulas may explain different results, according to the population.

The aim of this study is to evaluate the physiologic effects of asymmetrical nasal cannula and conventional nasal cannula on diaphragm and parasternal intercostal activity of breathing measured by ultrasound in patients with acute respiratory failure.

Study Type

Interventional

Enrollment (Actual)

40

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Thailand
    • Bangkok
      • Bangkok Noi, Bangkok, Thailand, 10700
        • Faculty of Medicine Siriraj Hospital

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Patients with acute hypoxemia respiratory failure

Inclusion Criteria:

  • Age > 18 years old
  • Acute respiratory failure within 7 days of hospital admission?
  • Hypoxemia defined by arterial partial pressure of oxygen (PaO2)/FiO2 < 300 mmHg or SpO2/FiO2 < 315
  • Already supported with HFNC device

Exclusion Criteria:

  • Respiratory acidosis: pH < 7.30 and PaCO2 > 45 mmHg
  • Hemodynamic instability requiring vasopressor initiation
  • Diminished level of consciousness or uncooperative
  • Active hemoptysis or pneumothorax requiring a chest tube
  • Chronic severe neuromuscular disease
  • Pregnancy

Patients with acute hypercapnic COPD Inclusion criteria

  • Age > 40 years old
  • Diagnosed COPD according to the Global Initiative for Chronic Obstructive Lung Disease (GOLD) guideline (postbronchodilator forced expiratory volume at 1 second (FEV1)/forced vital capacity (FVC) < 70%)

  • Exacerbation requiring hospitalization; at least 2 of the following criteria

    1. Respiratory rate > 24/min
    2. Use of respiratory accessory muscles or paradoxical motion of the abdomen
    3. Acute respiratory acidosis with arterial or venous pH < 7.35 and/or PaCO2 > 45 mmHg

Exclusion criteria

  • pH < 7.25
  • Hemodynamic instability requiring vasopressor initiation
  • Persistent hypoxemia despite supplemental oxygen therapy
  • Diminished level of consciousness or uncooperative
  • Active hemoptysis or pneumothorax requiring a chest tube
  • Associated severe chronic neuromuscular disease
  • Pregnancy

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Crossover Assignment
  • Masking: Single

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Asymmetrical high-flow nasal cannula
  • Asymmetrical nasal cannula (Optiflow+ Duet nasal cannula)
  • Airvo-2 (Fisher&Paykel)
Device: Experimental: Asymmetrical high-flow nasal cannula
Asymmetrical high-flow nasal cannula will be set at 40 and 60 L/min in a random order. Temperature will be set at 37 degree celsius and inspired oxygen fraction (FiO2) will be adjusted to maintain oxygen saturation by pulse oximetry (SpO2) >/= 94% in acute hypoxemic patients and between 92-94% in acute hypercapnic COPD patients
Active Comparator: Conventional high-flow nasal cannula
  • Conventional nasal cannula (Optiflow+ nasal cannula)
  • Airvo-2 (Fisher&Paykel)
Device: Active comparator: Conventional high-flow nasal cannula
Conventional high-flow nasal cannula will be set at 40 and 60 L/min in a random order. Temperature will be set at 37 degree celsius and FiO2 will be adjusted to maintain SpO2 >/= 94% in acute hypoxemic patients and between 92-94% in acute hypercapnic COPD patients

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Diaphragm thickening fraction
Time Frame: 15 minutes
Diaphragm thickening fraction measured by ultrasound
15 minutes

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Parasternal intercostal thickening fraction
Time Frame: 15 minutes
Parasternal intercostal thickening fraction measured by ultrasound
15 minutes
Parasternal intercostal/diaphragm thickening fraction ratio
Time Frame: 15 minutes
Contribution between parasternal intercostal and diaphragm thickening fraction
15 minutes
Respiratory rate
Time Frame: 15 minutes
Respiratory rate
15 minutes
Oxygen saturation
Time Frame: 15 minutes
Pulse oximetry
15 minutes
Mean arterial pressure
Time Frame: 15 minutes
Blood pressure
15 minutes
Heart rate
Time Frame: 15 minutes
Heart rate
15 minutes
Transcutaneous carbon dioxide (CO2) pressure
Time Frame: 15 minutes
Transcutaneous CO2 monitor
15 minutes

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Siriraj Hospital

Investigators

  • Principal Investigator: Nuttapol Rittayamai, M.D., Siriraj Hospital

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

January 20, 2024

Primary Completion (Actual)

November 30, 2024

Study Completion (Actual)

November 30, 2024

Study Registration Dates

First Submitted

January 3, 2024

First Submitted That Met QC Criteria

January 3, 2024

First Posted (Actual)

January 12, 2024

Study Record Updates

Last Update Posted (Actual)

April 24, 2026

Last Update Submitted That Met QC Criteria

April 21, 2026

Last Verified

April 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 763/2566(IRB4)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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