Investigation of non-uniform airflow signal oscillation during high frequency chest compressionReport as inadecuate




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BioMedical Engineering OnLine

, 4:34

First Online: 19 May 2005Received: 10 March 2005Accepted: 19 May 2005

Abstract

BackgroundHigh frequency chest compression HFCC is a useful and popular therapy for clearing bronchial airways of excessive or thicker mucus. Our observation of respiratory airflow of a subject during use of HFCC showed the airflow oscillation by HFCC was strongly influenced by the nonlinearity of the respiratory system. We used a computational model-based approach to analyse the respiratory airflow during use of HFCC.

MethodsThe computational model, which is based on previous physiological studies and represented by an electrical circuit analogue, was used for simulation of in vivo protocol that shows the nonlinearity of the respiratory system. Besides, airflow was measured during use of HFCC. We compared the simulation results to either the measured data or the previous research, to understand and explain the observations.

Results and discussionWe could observe two important phenomena during respiration pertaining to the airflow signal oscillation generated by HFCC. The amplitudes of HFCC airflow signals varied depending on spontaneous airflow signals. We used the simulation results to investigate how the nonlinearity of airway resistance, lung capacitance, and inertance of air characterized the respiratory airflow. The simulation results indicated that lung capacitance or the inertance of air is also not a factor in the non-uniformity of HFCC airflow signals. Although not perfect, our circuit analogue model allows us to effectively simulate the nonlinear characteristics of the respiratory system.

ConclusionWe found that the amplitudes of HFCC airflow signals behave as a function of spontaneous airflow signals. This is due to the nonlinearity of the respiratory system, particularly variations in airway resistance.

List of abbreviationsHFCCHigh Frequency Chest Compression

FRCFunctional Residual Capacity

TLCTotal Lung Capacity

RVResidual Volume

LVLung volume

AVAlveolar volume

Rresistor

Ccapacitor

Linductor

AZAirway cross sectional area in airway generation Z

AmaxZMaximum Airway cross sectional area in airway generation Z

AZ75Airway cross sectional area in airway generation Z when LV is 75% of TLC

CasAlveolar capacitance

CgzTotal airway capacitance in airway generation Z

CsZSingle airway capacitance in airway generation Z

FinZIncoming airflow in airway generation Z

FoutZOutgoing airflow in airway generation Z

FuaAirflow in the upper airway

LgzTotal inductance inertance of air in airway generation Z

LsZSingle inductance inertance of air in airway generation Z

lZThe length of an airway branch in airway generation Z

NZNumber of airway branches in airway generation Z

PalvAlveolar pressure

PawZAirway pressure in airway generation Z

PplPleural pressure or intrapleural pressure

Ptm iniThe initial value of transmural pressure

PtmZTransmural pressure in airway generation Z

PtpTranspulmonary pressure

Ptp iniThe initial value of transmural pressure

RgzTotal airway resistance in airway generation Z

RsZSingle airway resistance in airway generation Z

rzThe radius of an airway branch in airway generation Z

Electronic supplementary materialThe online version of this article doi:10.1186-1475-925X-4-34 contains supplementary material, which is available to authorized users.

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Author: Kiwon Sohn - Warren J Warwick - Yong W Lee - Jongwon Lee - James E Holte

Source: https://link.springer.com/



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