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Carbon dioxide washout during high flow nasal cannula versus nasal CPAP support: An in vitro study
Author(s) -
Sivieri Emidio M.,
Foglia Elizabeth E.,
Abbasi Soraya
Publication year - 2017
Publication title -
pediatric pulmonology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.866
H-Index - 106
eISSN - 1099-0496
pISSN - 8755-6863
DOI - 10.1002/ppul.23664
Subject(s) - washout , medicine , anesthesia , cannula , nasal cannula , tidal volume , lung volumes , lung , respiratory system , surgery , anatomy
Summary Objective: To compare CO 2 washout time at different levels of HFNC versus NCPAP in a premature infant lung model with simulated mouth‐closed and mouth‐open conditions using two sizes of nasal cannula and full‐ and half‐prong HFNC insertion depths. Design/Methods: A piston‐cylinder lung simulator, having a fixed volume of 30 ml and a 4.8 ml dead space, simulated spontaneous breathing (6.5 ml tidal volume, 50 br/min, Ti = 0.5 sec). Two Fisher & Paykel™ cannulas (Fisher & Paykel Healthcare Ltd., Auckland, New Zealand) (2.8 and 3.2 mm O.D.) and two Infant‐Flow™ (CareFusion, Yorba Linda, CA) NCPAP cannulas (3.4 and 4.1 mm O.D.) were applied to simulated airways having either 3.5 or 4.5 mm I.D. nares. Simulated mouth opening was a 5 mm I.D. side tap below the nasal interface. The lung was primed with 5% CO 2 . Washout times were determined at HFNC settings of 3, 4, 5, 6, and 8 L/min and NCPAP at 3, 4, 5, 6, and 8 cm H 2 O with simulated open and closed‐mouth conditions and full‐ and half‐inserted HFNC prongs. Results: Overall combined mean washout times for NCPAP with mouth‐closed were significantly longer than HFNC over all five pressure and flow device settings by 16.2% ( P < 0.001). CO 2 washout times decreased as flow or pressure device settings were increased. There were negligible differences in washout times between NCPAP and HFNC with mouth‐open. Mouth‐open washout times were significantly less than mouth‐closed for all conditions. Overall closed‐mouth washout times for HFNC half‐prong insertion were longer than for full‐prong insertion by 5.3% ( P < 0.022). Conclusions: Significantly improved CO 2 elimination using HFNC versus NCPAP should be a particularly important consideration in premature infants having very high dead space‐to‐tidal volume ratio compared to larger infants. Pediatr Pulmonol. 2017;52:792–798. © 2017 Wiley Periodicals, Inc.