Aerosol Delivery Using Jet Nebulizer and Vibrating Mesh Nebulizer During High Frequency Oscillatory Ventilation: An In Vitro Comparison

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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Effect of I/E ratio on mean alveolar pressure during high-frequency oscillatory ventilation

Journal of Applied Physiology ◽

10.1152/jappl.1999.87.1.407 ◽

1999 ◽

Vol 87 (1) ◽

pp. 407-414 ◽

Cited By ~ 45

Author(s):

J. J. Pillow ◽

H. Neil ◽

M. H. Wilkinson ◽

C. A. Ramsden

Keyword(s):

High Frequency ◽

High Frequency Oscillatory Ventilation ◽

Lung Model ◽

Alveolar Pressure ◽

Expiratory Time ◽

Oscillatory Ventilation ◽

Airway Opening ◽

Mean Pressure ◽

High Frequency Oscillatory

This study investigated factors contributing to differences between mean alveolar pressure ([Formula: see text]) and mean pressure at the airway opening (Pao) during high-frequency oscillatory ventilation (HFOV). The effect of the inspiratory-to-expiratory time (I/E) ratio and amplitude of oscillation on the magnitude of [Formula: see text] −Pao (Pdiff) was examined by using the alveolar capsule technique in normal rabbit lungs ( n = 4) and an in vitro lung model. The effect of ventilator frequency and endotracheal tube (ETT) diameter onPdiff was further examined in the in vitro lung model at an I/E ratio of 1:2. In both lung models,[Formula: see text] fell belowPao during HFOV when inspiratory time was shorter than expiratory time. Under these conditions, differences between inspiratory and expiratory flows, combined with the nonlinear relationship between resistive pressure drop and flow in the ETT, are the principal determinants of Pdiff. In our experiments, the magnitude of Pdiff at each combination of I/E, frequency, lung compliance, and ETT resistance could be predicted from the difference between the mean squared inspiratory and expiratory velocities in the ETT. These observations provide an explanation for the measured differences in mean pressure between the airway opening and the alveoli during HFOV and will assist in the development of optimal strategies for the clinical application of this technique.

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Fluid Dynamics of Gas Exchange in High-Frequency Oscillatory Ventilation: In Vitro Investigations in Idealized and Anatomically Realistic Airway Bifurcation Models

Annals of Biomedical Engineering ◽

10.1007/s10439-008-9557-1 ◽

2008 ◽

Vol 36 (11) ◽

pp. 1856-1869 ◽

Cited By ~ 20

Author(s):

Kevin B. Heraty ◽

John G. Laffey ◽

Nathan J. Quinlan

Keyword(s):

Fluid Dynamics ◽

Gas Exchange ◽

High Frequency ◽

High Frequency Oscillatory Ventilation ◽

Oscillatory Ventilation ◽

Airway Bifurcation ◽

High Frequency Oscillatory

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Nitric oxide and Nitrogen dioxide Concentrations During In Vitro High Frequency Oscillatory Ventilation † 1970

Pediatric Research ◽

10.1203/00006450-199804001-01993 ◽

1998 ◽

Vol 43 ◽

pp. 336-336

Author(s):

Bala R Totapally ◽

Andre Raszynski ◽

Jeff Sussmane ◽

Karl Hultquist ◽

Javier Hernandez ◽

...

Keyword(s):

Nitric Oxide ◽

Nitrogen Dioxide ◽

High Frequency ◽

High Frequency Oscillatory Ventilation ◽

Oscillatory Ventilation ◽

High Frequency Oscillatory

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Assessment of Respiratory System Resistance during High-Frequency Oscillatory Ventilation Based on In Vitro Experiment

Applied Sciences ◽

10.3390/app112311279 ◽

2021 ◽

Vol 11 (23) ◽

pp. 11279

Author(s):

Jan Matejka ◽

Martin Rozanek ◽

Jakub Rafl

Keyword(s):

Physical Model ◽

Respiratory System ◽

High Frequency ◽

Gas Flow ◽

High Frequency Oscillatory Ventilation ◽

Oscillatory Ventilation ◽

Airway Opening ◽

Respiratory System Resistance ◽

High Frequency Oscillatory

High-frequency oscillatory ventilation (HFOV) is a type of mechanical ventilation with a protective potential characterized by a small tidal volume. Unfortunately, HFOV has limited monitoring of ventilation parameters and mechanical parameters of the respiratory system, which makes it difficult to adjust the continuous distension pressure (CDP) according to the individual patient’s airway status. Airway resistance Raw is one of the important parameters describing the mechanics of the respiratory system. The aim of the presented study was to verify in vitro whether the resistance of the respiratory system Rrs can be reliably determined during HFOV to evaluate Raw in pediatric and adult patients. An experiment was performed with a 3100B high-frequency oscillator, a physical model of the respiratory system, and a pressure and flow measurement system. The physical model with different combinations of resistance and compliance was ventilated during the experiment. The resistance Rrs was calculated from the impedance of the physical model, which was determined from the spectral density of the pressure at airway opening and the spectral cross-density of the gas flow and pressure at airway opening. Rrs of the model increased with an added resistor and did not change significantly with a change in compliance. The method is feasible for monitoring respiratory system resistance during HFOV and has the potential to optimize CDP settings during HFOV in clinical practice.

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