KMID : 0372919900110020195
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Journal of Biomedical Engineering Research 1990 Volume.11 No. 2 p.195 ~ p.201
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Theoretical Prediction of Lung Hyperinflation (LH-I) Due to Asymmetric Pressure-flow Characteristics of Human Airways During High Frequency Ventilation(HFV)
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Abstract
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The hypothesis of asymmetric resistance to explain the phenomenon of lung hyperinflation (LHI) during hlgh frequency ventilation (HFV) was quantitatively studied. LHI was predicted by modeling the ism-volume pressure-flow (IVPF) data from 5 human subjects using the empirical Rohrer¡¯¡¯¡¯¡¯s equation. Non-steadiness during HFV was compensated by em- ploying recently proposed volume-frequency diagram. Tidal volume and ventilation frequency were 100 ml and 20 Hz, respectively. Airflow pattern was a symmetric sinusoid. The predic- tion results of mean pressure drop across the airways were averaged for those 5 subjects, and compared with zero by one-sided student¡¯¡¯¡¯¡¯s t-test. A marginally significant (P<0.1) increase in mean pressure drop was observed during HFV at low lung volumes (below FRC) , which could increase mean lung volume up to one liter When the lung volume was above FRC, no significant LHI (P >0.25) was resulted. LHI seemed to be inversely related to the lung volume. These results recommend to clinically apply HFV only at lung volumes above FRC.
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KEYWORD
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