This article requires a subscription to view the full text. If you have a subscription you may use the login form below to view the article. Access to this article can also be purchased.
Abstract
BACKGROUND: High-flow nasal cannula (HFNC) is increasingly used for the management of respiratory failure. Settings include 
, total gas flow, and temperature target. Resulting absolute humidity (AH) at the nasal cannula may affect clinical tolerance, and optimal settings with respect to hygrometry remain poorly documented.
METHODS: A bench study was designed to assess AH delivered by 4 HFNC devices (Optiflow, Airvo 2, Precision Flow, and Hydrate) according to flow, ambient temperature, and other available settings. Clinical tolerance of different levels of hygrometry (20, 30, and 40 mg H2O/L) was evaluated in 15 healthy volunteers.
RESULTS: With 
set at 1.0, normal ambient temperature, and settings made accordingly to the manufacturers’ recommendations, mean ± SD AH was 42.2 ± 3.1, 39.5 ± 1.8, 35.7 ± 2.0, and 32.9 ± 2.7 mg H2O/L for the Airvo 2, Optiflow, Hydrate, and Precision Flow, respectively, (P < .001). AH dropped from −3.5 to −10.7 mg H2O/L (P <. 001) with high ambient temperature, except for the Precision Flow. Increasing flow did not significantly affect AH except for the Precision Flow (from 36.4 ± 1.6 to 29.8 ± 0.2 mg H2O/L at 10 and 40 L/min, respectively, [P < .001]). The lowest AH was encountered with the Optiflow set with noninvasive ventilation (NIV) mode, without compensation algorithm, and at high ambient temperature (14.2 ± 1.5 mg H2O/L). In studied subjects, AH significantly affected breathing comfort, reduced from 7.0 ± 1.0 to 3.0 ± 2.0 at 40 and 20 mg H2O/L, respectively, (P < .001). Comfort was similar at 30 and 40 mg H2O/L.
CONCLUSIONS: When used according to manufacturer’s recommendations and at normal ambient temperature, all the HFNC devices evaluated achieved satisfactory hygrometric output with respect to breathing comfort evaluated in healthy subjects (≥ 30 mg H2O/L). Substantial differences exist between devices, and optimal knowledge of their working principles is required as inappropriate usage may dramatically alter efficacy and clinical tolerance.
Footnotes
- Correspondence: François Lellouche MD PhD, Centre de Recherche de l’Institut Universitaire de Cardiologie et de Pneumologie de Québec, 2725, Chemin Sainte-Foy, Québec, Canada G1V4G5. E-mail: francois.lellouche{at}criucpq.ulaval.ca
Supplementary material related to this paper is available at http://www.rcjournal.com.
Dr Lellouche presented a version of this paper at the European Society of Intensive Care Medicine Congress, held in Berlin, Germany, in 2015, and at the American Thoracic Society Congress, held in San Francisco, California, in 2016.
Devices and consumables were provided by Fisher & Paykel Healthcare, Vapotherm, and Hydrate, who had no other involvement in the study. The study was supported by the Groupe de Recherche en Santé Respiratoire de l’Université Laval (GESER).
Mr Delorme is a former employee of ResMed SA, which had no involvement in the current study. Dr Lellouche discloses a relationship with Fisher & Paykel Healthcare. The remaining authors have no conflicts to disclose.
- Copyright © 2021 by Daedalus Enterprises
Pay Per Article - You may access this article (from the computer you are currently using) for 1 day for US$30.00
Regain Access - You can regain access to a recent Pay per Article purchase if your access period has not yet expired.
Log in using your username and password
