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NCT Number: NCT06674629

Asymmetrical High Flow Nasal Cannula and End-Expiratory Lung Impedance

Objective: The primary aim is to assess end-expiratory lung impedance (EELI) changes during the application of high-flow oxygen therapy using asymmetric nasal cannulae, comparing conditions with the mouth closed and open in healthy volunteers in various positions. The secondary objective includes evaluating respiratory rate, shortening fraction, and diaphragm excursion via ultrasound.

Study Design: This is a prospective observational cohort study conducted in the Critical Care Unit of Sanatorio Parque Rosario from November 5 to December 31, 2024. It will involve 20 healthy adult volunteers without respiratory conditions, with informed consent obtained from all participants. Volunteers with contraindications for electrical impedance tomography (EIT) will be excluded.

Methods: Equipment Used: PulmoVista 500 Dräger (EIT), AIRVO 2 (high-flow oxygen generator), asymmetric nasal cannula (Optiflow OPT 966), Toshiba iStyle ultrasound machine.

Procedures: The study includes EELI measurements in different positions (semi-seated, supine Fowler, prone, and prone Fowler) with various high-flow oxygen settings (40 and 60 L/min). Diaphragm excursion and thickening will be assessed using ultrasound.

Scenarios and Measurements: 17 different testing scenarios will be conducted, with 16 intervals for washout breathing at room air between scenarios. Data on EELI, respiratory rate, and diaphragm measurements will be collected.

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Key information

Conditions

End-Expiratory Lung Impedance Diaphragm Excursion Diaphragm Thickness Fraction Respiratory Rate

Age range

18 year–50 year

Sex eligibility

All sexes

Study type

Observational

Primary location

Hospital Británico de Buenos Aires

Buenos Aires, 1425, Argentina

About this study

Methodology:

Procedures: EELI, respiratory rate, and diaphragm measurements will be taken in various body positions while using high-flow oxygen therapy (HFNC) set at 40 and 60 L/min. Diaphragm excursion and thickening will be evaluated with ultrasound.

Data Collection and Analysis: Volunteers will participate in 17 different testing scenarios, with intervals of 5-minute washout periods breathing room air in a semi-seated position between each measurement. Continuous variables will be expressed as mean ± standard deviation or median and interquartile range. Repeated measures ANOVA will be used for statistical comparisons, with significance set at p < 0.05.

17 Testing Scenarios:

Semi-seated at 45° breathing room air. Semi-seated at 45° with asymmetric HFNC at 40 L/min, mouth closed for 5 minutes.

Semi-seated at 45° with asymmetric HFNC at 40 L/min, mouth open for 5 minutes. Semi-seated at 45° with asymmetric HFNC at 60 L/min, mouth closed for 5 minutes.

Semi-seated at 45° with asymmetric HFNC at 60 L/min, mouth open for 5 minutes. Supine in Fowler position (60°) with asymmetric HFNC at 40 L/min, mouth open for 5 minutes.

Supine in Fowler position (60°) with asymmetric HFNC at 40 L/min, mouth closed for 5 minutes.

Supine in Fowler position (60°) with asymmetric HFNC at 60 L/min, mouth open for 5 minutes.

Supine in Fowler position (60°) with asymmetric HFNC at 60 L/min, mouth closed for 5 minutes.

Prone at 180° with asymmetric HFNC at 40 L/min, mouth open for 5 minutes. Prone at 180° with asymmetric HFNC at 40 L/min, mouth closed for 5 minutes. Prone at 180° with asymmetric HFNC at 60 L/min, mouth open for 5 minutes. Prone at 180° with asymmetric HFNC at 60 L/min, mouth closed for 5 minutes. Prone Fowler position with asymmetric HFNC at 40 L/min, mouth open for 5 minutes.

Prone Fowler position with asymmetric HFNC at 40 L/min, mouth closed for 5 minutes.

Prone Fowler position with asymmetric HFNC at 60 L/min, mouth open for 5 minutes.

Prone Fowler position with asymmetric HFNC at 60 L/min, mouth closed for 5 minutes.

Duration per Participant: Approximately 2 hours and 15 minutes.

Ethical Considerations: All data will be anonymized and kept confidential. Participants' rights to withdraw at any time will be respected, and no personal identifying information will be disclosed.

This comprehensive approach aims to elucidate the physiological impacts of using asymmetric HFOT on end-expiratory lung volume and related respiratory parameters in various positions and conditions.

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • healthy volunteers between 18 and 50 years of age who sign the informed consent form, without respiratory pathology.

Exclusion criteria

  • contraindication to implement electrical impedance tomography or high flow oxygen therapy

Treatment and study plan

High flow oxygen therapy

Device

Application of high flow oxygen therapy through asymmetric cannula at 40 and 60 L/m

Primary outcomes

  1. End-Expiratory Lung Impedance

    Time frame: From enrollment to the end of treatment at 2.30hours

    Variation of end-expiratory lung impedance in different positions and with different flows.

Secondary outcomes

  1. Respiratory Rate

    Time frame: From enrollment to the end of treatment at 2.30hours

    Number of respiratory cycles per minute while breathing in a quiet manner at rest.

  2. Diaphragm Thickness Fraction

    Time frame: From enrollment to the end of treatment at 2.30hours

    Diaphragm Thickness Fraction (DTF) is a measure used to assess diaphragm function by comparing the change in diaphragm thickness from end-expiration to end-inspiration expressed as a percentage

  3. Diaphragm excursion

    Time frame: From enrollment to the end of treatment at 2.30hours

    Diaphragm excursion refers to the movement or displacement of the diaphragm during the respiratory cycle, measured from its lowest position at end-expiration to its highest position at end-inspiration. This parameter is assessed using ultrasound and reflects the diaphragm's ability to contract effectively, with greater excursion indicating stronger respiratory muscle function.

Sponsors and collaborators

Lead sponsor

Argentinian Intensive Care Society

Other

Registry information

Official study title

Effects of an Asymmetrical High Flow Nasal Cannula Interface on End-Expiratory Lung Impedance

Acronym: EELI and AHFNC

Important dates

Study start
2024
Primary completion
2024
Study completion
2025
First posted
Nov 5, 2024
Registry last updated
Jul 2, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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