Figure 4: The estimated impedance within the measured frequency range for the symmetric (*) and the asymmetric (o) case against averaged data from healthy subjects-THE RESPIRATORY IMPEDANCE IN AN ASYMMETRIC MODEL OF THE LUNG STRUCTURE
| Main Authors: | Clara Ionescu, Ionut Muntean, Robin de Keyser |
|---|---|
| Format: | info Image |
| Bahasa: | eng |
| Terbitan: |
, 2010
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| Subjects: | |
| Online Access: |
https://www.edusoft.ro/brain/index.php/brain/article/view/171 |
Daftar Isi:
- It is significant to observe that in the frequency interval of clinical interest, ! 2 [25; 300] rad/s, the two impedances tend to behave similarly. For the asymmetric case, we have a decrease of about -10dB/dec and a phase of ap- proximately ¡50o, resulting in a fractional order of n »= This observation suggests that a combined efect of more than one fractal order is present in the lungs and that it leads naturally to values closer to measured data in the low frequency range. In other words, the symmetric tree representation does not suffice to obtain a good fit between the model and the measured impedance data. Another observation is that the constant-phase behavior is emphasized at frequencies below those evaluated standardly in clinical practice, i.e. below 5Hz. However, in the standard clinical range of frequencies for the forced oscil- lation technique, namely 4-48Hz, both symmetric and asymmetric tree models give similar results, as depicted in ̄gure 4