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Nasal high‐frequency oscillatory ventilation impairs heated humidification: A neonatal bench study
Author(s) -
Ullrich Tim L.,
Czernik Christoph,
Bührer Christoph,
Schmalisch Gerd,
Fischer Hendrik S.
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.23824
Subject(s) - medicine , anesthesia , high frequency ventilation , airway , ventilation (architecture) , continuous positive airway pressure , relative humidity , respiratory system , tidal volume , mechanical ventilation , meteorology , physics , obstructive sleep apnea
Objective Nasal high‐frequency oscillatory ventilation (nHFOV) is a novel mode of non‐invasive ventilation used in neonates. However, upper airway obstructions due to viscous secretions have been described as specific adverse effects. We hypothesized that high‐frequency oscillations reduce air humidity in the oropharynx, resulting in upper airway desiccation. Therefore, we aimed to investigate the effects of nHFOV ventilatory settings on oropharyngeal gas conditions. Methods NHFOV or nasal continuous positive airway pressure (nCPAP) was applied, along with heated humidification, to a previously established neonatal bench model that simulates oropharyngeal gas conditions during spontaneous breathing through an open mouth. A digital thermo‐hygro sensor measured oropharyngeal temperature (T) and humidity at various nHFOV frequencies (7, 10, 13 Hz), amplitudes (10, 20, 30 cmH 2 O), and inspiratory‐to‐expiratory (I:E) ratios (25:75, 33:66, 50:50), and also during nCPAP. Results Relative humidity was always >99%, but nHFOV resulted in lower mean T and absolute humidity (AH) in comparison to nCPAP ( P < 0.001). Specifically, decreasing the nHFOV frequency and increasing nHFOV amplitude caused a decline in T and AH ( P < 0.001). Mean T and AH were highest during nCPAP (T 34.8 ± 0.6°C, AH 39.3 ± 1.3 g · m −3 ) and lowest during nHFOV at a frequency of 7 Hz and an amplitude of 30 cmH 2 O (T 32.4 ± 0.3°C, AH 34.7 ± 0.5 g · m −3 ). Increasing the I:E ratio also reduced T and AH ( P = 0.03). Conclusion Intensified nHFOV settings with low frequencies, high amplitudes, and high I:E ratios may place infants at an increased risk of upper airway desiccation. Future studies should investigate strategies to optimize heated humidification during nHFOV.