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Background <p>High-flow nasal cannula is widespread in patients with hypoxemic and hypercapnic respiratory failure, but physiological data concerning influence of the combination of breathing pattern, preset flow rate (PFR), and inspiratory oxygen fraction (F<sub>D</sub>O<sub>2</sub>) on end-expiratory pressure (EEP), capnogram, oxygram, and exhaled tidal volume (VTe) remains insufficient.</p> Methods <p>The study included 20 healthy subjects with 12 combinations of PFR (30–60-80 L/min) and F<sub>D</sub>O<sub>2</sub> (40–60-80–100%) multiplied by 4 breathing patterns: mouth closed (CM), mouth open (OM), and combination of the CM and OM with hyperpnea (HCM and HOM). Pressure, capnogram, oxygram were measured from hypopharyngeal catheter, VTe, and subject’s comfort were assessed.</p> Results <p>Inspiratory oxygen fraction (FiO<sub>2</sub>) were close to F<sub>D</sub>O<sub>2</sub> at the PFR of 30 L/min (CM), and 60 L/min (HCM). FiO<sub>2</sub> during the OM and HOM were much less than F<sub>D</sub>O<sub>2</sub>, variable and unpredictable. PFR of 60 L/min was sufficient to keep FiO<sub>2</sub> close to F<sub>D</sub>O<sub>2</sub> during the CM and HCM. End-expiratory carbon dioxide (F<sub>E</sub>CO<sub>2</sub>) decreased with an increase in the PFR and F<sub>D</sub>O<sub>2</sub>, reaching 1.4 (1.1–1.7)% at F<sub>D</sub>O<sub>2</sub> 100% and PFR of 80 L/min. EEP had grown a lot with the PFR increase and were highly variable reaching 11.1 (7.7–14.8) cmH<sub>2</sub>O at the PFR of 80 L/min. VTe at the PFR of 60 and 80 L/min were 948.0 (715.0–1204.8) and 948.0 (869.0–1422.0) ml, respectively. PFR of 60 L/min and 80 L/min were associated with discomfort.</p> Conclusion <p>HCM, OM, and HOM in healthy subjects decreased FiO<sub>2</sub> and F<sub>E</sub>CO<sub>2</sub> (more pronounced during OM and HOM). HFNC within the CM and HCM provided flow-dependent CPAP-effects over a wide range and could be associated with lung hyperinflation. An excessive PFR led to discomfort.</p> Trial registration <p>ClinicalTrials.gov identifier: <a href="https://clinicaltrials.gov/study/NCT06189716?term=NCT06189716&amp;rank=1">NCT06189716</a>, registered on 19/12/2023.</p>

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Gas composition and pressure in the hypopharynx during high-flow oxygen therapy through a nasal cannula in healthy volunteers with different breathing patterns

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  • 发表日期：

    2025年8月23日

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  • Andrey I. Yaroshetskiy,
  • Anna P. Krasnoshchekova,
  • Fedor D. Tkachenko,
  • Alina V. Rubashchenko,
  • Daniil D. Zubarev,
  • Vasiliy D. Konanykhin,
  • Maxim I. Savelenok,
  • Maxim M. Nosenko,
  • Zamira M. Merzhoeva,
  • Sergey N. Avdeev

摘要

Background

High-flow nasal cannula is widespread in patients with hypoxemic and hypercapnic respiratory failure, but physiological data concerning influence of the combination of breathing pattern, preset flow rate (PFR), and inspiratory oxygen fraction (FDO2) on end-expiratory pressure (EEP), capnogram, oxygram, and exhaled tidal volume (VTe) remains insufficient.

Methods

The study included 20 healthy subjects with 12 combinations of PFR (30–60-80 L/min) and FDO2 (40–60-80–100%) multiplied by 4 breathing patterns: mouth closed (CM), mouth open (OM), and combination of the CM and OM with hyperpnea (HCM and HOM). Pressure, capnogram, oxygram were measured from hypopharyngeal catheter, VTe, and subject’s comfort were assessed.

Results

Inspiratory oxygen fraction (FiO2) were close to FDO2 at the PFR of 30 L/min (CM), and 60 L/min (HCM). FiO2 during the OM and HOM were much less than FDO2, variable and unpredictable. PFR of 60 L/min was sufficient to keep FiO2 close to FDO2 during the CM and HCM. End-expiratory carbon dioxide (FECO2) decreased with an increase in the PFR and FDO2, reaching 1.4 (1.1–1.7)% at FDO2 100% and PFR of 80 L/min. EEP had grown a lot with the PFR increase and were highly variable reaching 11.1 (7.7–14.8) cmH2O at the PFR of 80 L/min. VTe at the PFR of 60 and 80 L/min were 948.0 (715.0–1204.8) and 948.0 (869.0–1422.0) ml, respectively. PFR of 60 L/min and 80 L/min were associated with discomfort.

Conclusion

HCM, OM, and HOM in healthy subjects decreased FiO2 and FECO2 (more pronounced during OM and HOM). HFNC within the CM and HCM provided flow-dependent CPAP-effects over a wide range and could be associated with lung hyperinflation. An excessive PFR led to discomfort.

Trial registration

ClinicalTrials.gov identifier: NCT06189716, registered on 19/12/2023.