Nasal high-flow therapy delivers low level positive airway pressure

R Parke, S McGuinness, M Eccleston, R Parke, S McGuinness, M Eccleston

Abstract

Background: The aim of this prospective study was to determine whether a level of positive airway pressure was generated in participants receiving nasal high flow (NHF) delivered by the Optiflow system (Fisher and Paykel Healthcare Ltd, Auckland, New Zealand) in a cardiothoracic and vascular intensive care unit (ICU).

Methods: Nasopharyngeal airway pressure was measured in 15 postoperative cardiac surgery adult patients who received both NHF and standard facemask therapy at a flow rate of 35 litre min(-1). Measurements were repeated in the open mouth and closed mouth positions. Mean airway pressure was determined by averaging the pressures at the peak of inspiration of each breath within a 1 min period, allowing the entire pressure profile of each breath to be included within the calculation.

Results: Low level positive pressure was demonstrated with NHF at 35 litre min(-1) with mouth closed when compared with a facemask. NHF generated a mean nasopharyngeal airway pressure of mean (SD) 2.7 (1.04) cm H(2)O with the mouth closed. Airway pressure was significantly higher when breathing with mouth closed compared with mouth open (P<or=0.0001).

Conclusions: This study demonstrated that a low level of positive pressure was generated with NHF at 35 litre min(-1) of gas flow. This is consistent with results obtained in healthy volunteers. Australian Clinical Trials Registry www.actr.org.au ACTRN012606000139572.

Figures

Fig 1
Fig 1
Optiflow™ system set-up. a, Optiflow™ RT034 cannula; b, heater delivery tube RT241; c, MR880 heated humidifier; d, laptop interface; e, pressure transducer.
Fig 2
Fig 2
Standard facemask set-up. g, Mask adapter (commercially unavailable).
Fig 3
Fig 3
Breathing pressure profile of one participant over 1 min. Nasopharyngeal pressure (cm H2O) generated at 35 litre min−1 using NHF with the mouth closed (NHFMC) is shown in black. Nasopharyngeal pressure (cm H2O) generated at 35 litre min−1 using a facemask with the mouth closed (FMMC) is shown in grey.

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Source: PubMed

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