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

Authors :: Garofalo E
Bruni A
Pelaia C
Cammarota G
Murabito P
Biamonte E
Abdalla K
Longhini F
Navalesi P
Source :: Respiratory care [Respir Care] 2019 Oct; Vol. 64 (10), pp. 1231-1239. Date of Electronic Publication: 2019 Jun 04.
Publication Year :: 2019
Abstract: Background: This study assessed the effects of a new interface that combined CPAP 10 cm H <subscript>2</subscript> O 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.<br />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 H <subscript>2</subscript> O 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.<br />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.<br />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.<br /> (Copyright © 2019 by Daedalus Enterprises.)