內科Cheng, Y. P.Y. P.ChengWu, H. D.H. D.WuWang, C. Y.C. Y.WangJan, G. J.G. J.Jan2008-12-292018-07-112008-12-292018-07-111999http://ntur.lib.ntu.edu.tw//handle/246246/95092Oesophageal pressure (P-es) measurements are important in medical research and useful in clinical diagnosis. Measurements, however, are contaminated heavily by cardiac artifacts. The spectrum and waveform of the P-es signal is obtained from the oesophageal balloon. Adaptive finite impulse response (AFIR) filter and modified adaptive noise cancellation ( MANC) methods are adopted to filter out cardiac beat interference. These results are compared. In the frequency domain, frequency variations and spectral overlap between the P-es components and cardiac beat signal components impact on the performance of the filter. From our experimental results on power strength, the fourth or higher harmonics did not have any significant effect on the filter performance. However, the second harmonics of these signals had a significant effect on the filtering result Thus, in the design of AFIR filters, attention is needed to minimise these effects. In frequency analysis, these harmonics or overlapping frequencies do not affect MANC. MANC was the better method for eliminating cardiac beat artifact in P-es measurement. The dynamic compliance (C-dyn) was also used to evaluate the performance of MANC and AFIR. The standard deviation of C-dyn was less than 0.15 using MANC, compared with standard deviations as high as 0.57 for AFIR. We conclude that MANC performs better than AFIR.en-USadaptive filterfinite impulse response (AFIR)adaptive noise cancellation (ANC)oesophageal pressure signal (P-es)least mean square (LMS)dynamic compliance (C-dyn)journal article