Transfer function analysis of respiration of laboratory animals.
Reynolds-J; Stolarik-B; Friend-K; Frazer-D
Ann Biomed Eng 2000 Oct; 28(Suppl 1):S-48
A transfer function analysis technique was developed to measure the resistance-compliance time constant (RC) of the lungs of laboratory animals. The change in volume of the thorax with respect to time (thoracic flow) was taken as the system input, and the flow from the nares was taken as the output. Fourier analysis was used to calculate the transfer function from thorax to nares. These data were fit to a parametric model yielding the RC time constant. In order to determine the transfer function, it is necessary that the system input contain enough energy at frequencies of interest to sufficiently excite the system. Spectra of thoracic flow were examined, and were shown to contain a noise component that decreases monotonically with frequency, in addition to a periodic component. Furthermore, the thoracic flow spectra indicate energy over a wide band of frequencies. Coherence was calculated from input to output in order to test system linearity and the input excitation. Coherence was shown to be good well beyond the fundamental breathing frequency for each animal. The coherence values were also shown to be useful in frequency weighting when the measured response was applied to the model.
Animal-studies; Laboratory-animals; Laboratory-testing; Respiration; Lung; Thorax; Statistical-analysis
Conference/Symposia Proceedings; Abstract
Annals of Biomedical Engineering