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Respir Care. 2019 Jun 4. pii: respcare.06871. doi: 10.4187/respcare.06871. [Epub ahead of print]

Evaluation of a New Interface Combining High-Flow Nasal Cannula and CPAP.

Author information

1
Intensive Care Unit, University Hospital Mater Domini, Department of Medical and Surgical Sciences, Magna Graecia University, Catanzaro, Italy.
2
Anesthesia and Intensive Care, "Maggiore della Carità" Hospital, Novara, Italy.
3
Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy.
4
Intensive Care Unit, University Hospital Mater Domini, Catanzaro, Italy.
5
Intensive Care Unit, University Hospital Mater Domini, Department of Medical and Surgical Sciences, Magna Graecia University, Catanzaro, Italy. longhini.federico@gmail.com.

Abstract

BACKGROUND:

This study assessed the effects of a new interface that combined CPAP 10 cm H2O by using a helmet with high-flow nasal cannula (HFNC) at varying flows in healthy volunteers. Outcome measures included pharyngeal pressures, diaphragm kinetics, breathing frequency, the temperature inside the helmet, and comfort.

METHODS:

After baseline assessment during spontaneous breathing, HFNC was applied at flows of 30, 40, and 50 L/min. Successively, the volunteers underwent helmet CPAP at 10 cm H2O and CPAP + HFNC at flows of 30, 40, and 50 L/min. We measured the variations of pharyngeal pressures at end-expiration and end-inspiration, referenced to spontaneous breathing for HFNC and to CPAP for CPAP + HFNC, diaphragm displacement and thickness at end-expiration and thickness at end-inspiration, breathing frequency, the temperature inside the helmet, the occurrence of the fog effect, and comfort.

RESULTS:

Variations of pharyngeal pressures at end-inspiration changes were small overall and clinically unimportant. With the mouth closed, at increasing HFNC flow, variations of pharyngeal pressures at end-expiration increased during both HFNC (from 2.8 up to 7.7) and, to a lesser extent, CPAP + HFNC (from 2.7 up to 3.8) (P < .001 for all comparisons). These variations were attenuated during open-mouth breathing. HFNC ≥ 40 L/min and CPAP + HFNC ≥ 40 L/min compared with spontaneous breathing and CPAP, respectively, increased diaphragm displacement (P = .001), thickness at end-inspiration and thickness at end-expiration (P < .003 for both). At all flows, breathing frequency was slightly, although significantly, lower with CPAP + HFNC than with HFNC alone (P < .003). The temperature inside the helmet increased slightly and insignificantly at flows of ≤ 40 L/min with CPAP + HFNC compared with CPAP alone. The fog effect never occurred, whereas comfort was always rated as optimal, without differences between trials.

CONCLUSIONS:

CPAP + HFNC was well tolerated, with no adverse effects. Based on our findings, there was no need to vary the CPAP level when adding HFNC. At least in healthy subjects, CPAP + HFNC at 30 L/min seemed to be the best combination.

KEYWORDS:

breathing pattern; comfort; continuous positive airway pressure; diaphragm contractility; diaphragm ultrasound; healthy volunteers; high-flow nasal cannula; pharyngeal pressure

PMID:
31164484
DOI:
10.4187/respcare.06871

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