Resonance frequency of the respiratory system in premature infants receiving high frequency oscillatory ventilation (HFOV)

We appreciate the observation reported by Cheung et al, and agree with their findings. We reported similar results on survival in premature infants with pulmonary interstitial emphysema in 1986. These data show that high-frequency oscillatory ventilation (HFOV) response delineates two groups of infants with different outcomes. It is important to note that most neonates treated with HFOV have improved ventilation, but that a smaller proportion of neonates have improved oxygenation. In our experience improved oxygenation is a better predictor of outcome than improved ventilation.

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In Vitro Estimation of Relative Compliance during High-Frequency Oscillatory Ventilation

Applied Sciences ◽

10.3390/app11030899 ◽

2021 ◽

Vol 11 (3) ◽

pp. 899

Author(s):

Jan Matejka ◽

Martin Rozanek ◽

Jakub Rafl ◽

Petr Kudrna ◽

Karel Roubik

Keyword(s):

Physical Model ◽

Respiratory System ◽

High Frequency ◽

High Frequency Oscillatory Ventilation ◽

Opening Pressure ◽

Respiratory System Mechanics ◽

Oscillatory Ventilation ◽

Airway Opening ◽

High Frequency Oscillatory

High-frequency oscillatory ventilation (HFOV), which uses a small tidal volume and a high respiratory rate, is considered a type of protective lung ventilation that can be beneficial for certain patients. A disadvantage of HFOV is its limited monitoring of lung mechanics, which complicates its settings and optimal adjustment. Recent studies have shown that respiratory system reactance (Xrs) could be a promising parameter in the evaluation of respiratory system mechanics in HFOV. The aim of this study was to verify in vitro that a change in respiratory system mechanics during HFOV can be monitored by evaluating Xrs. We built an experimental system consisting of a 3100B high-frequency oscillatory ventilator, a physical model of the respiratory system with constant compliance, and a system for pressure and flow measurements. During the experiment, models of different constant compliance were connected to HFOV, and Xrs was derived from the impedance of the physical model that was calculated from the spectral density of airway opening pressure and spectral cross-power density of gas flow and airway opening pressure. The calculated Xrs changed with the change of compliance of the physical model of the respiratory system. This method enabled monitoring of the trend in the respiratory system compliance during HFOV, and has the potential to optimize the mean pressure setting in HFOV in clinical practice.

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High-frequency oscillatory ventilation in neonatal RDS: initial volume optimization and respiratory mechanics

Journal of Applied Physiology ◽

10.1152/jappl.1998.84.4.1174 ◽

1998 ◽

Vol 84 (4) ◽

pp. 1174-1177 ◽

Cited By ~ 9

Author(s):

Masendu Kalenga ◽

Oreste Battisti ◽

Anne François ◽

Jean-Paul Langhendries ◽

Dale R. Gerstmann ◽

...

Keyword(s):

Respiratory System ◽

Lung Volume ◽

High Frequency ◽

Distress Syndrome ◽

Respiratory Mechanics ◽

High Frequency Oscillatory Ventilation ◽

Oscillatory Ventilation ◽

Respiratory System Resistance ◽

High Frequency Oscillatory ◽

Good Oxygenation

To determine whether initial lung volume optimization influences respiratory mechanics, which could indicate the achievement of optimal volume, we studied 17 premature infants with respiratory distress syndrome (RDS) assisted by high-frequency oscillatory ventilation. The continuous distending pressure (CDP) was increased stepwise from 6–8 cmH2O up to optimal CDP (OCDP), i.e., that allowing good oxygenation with the lowest inspired O2 fraction. Respiratory system compliance (Crs) and resistance were concomitantly measured. Mean OCDP was 16.5 ± 1.2 cmH2O. Inspired O2 fraction could be reduced from an initial level of 0.73 ± 0.17 to 0.33 ± 0.07. However, Crs (0.45 ± 0.14 ml ⋅ cmH2O−1 ⋅ kg−1at starting CDP point) remained unchanged through lung volume optimization but appeared inversely related to OCDP. Similarly, respiratory system resistance was not affected. We conclude that there is a marked dissociation between oxygenation improvement and Crs profile during the initial phase of lung recruitment by early high-frequency oscillatory ventilation in infants with RDS. Thus optimal lung volume cannot be defined by serial Crs measurement. At the most, low initial Crs suggests that higher CDP will be needed.

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