Research On Cardiopulmonary Coupling Analysis

Object:Cardiopulmonary coupling(CPC) means internal coordination mechanism and interactions between the cardiovascular and respiratory system. Now univariate time series analysis techniques widely used to research cardiovascular regulation system. Recent advances in nonlinear dynamics and information theory have allowed the multivariate study of information transfer between time series.They might be able to provide additional diagnostic and prognostic information in medicine.This paper analyzes the physiological phenomenon of cardiopulmonary coupling and the methods to quantify the strength of cardiopulmonary coupling.Method:First, we analyzes the physiological signals during a stepwise paced breathing (PB)procedure, use empirical mode decomposition method to extraction PTT (pulse transit time) to baseline components and amplitude components;then do statistical analysis of systolic, diastolic and mean pressure under each guided breathing rate. This article also studies the method to determine the optimum order of autoregressive models in heart rate variability analysis.We used FPE (Final Prediction Error) Criterion to estimate the optimum model order for autoregressive models, then used prediction error whiteness test to test the reliability of the model. To quantify cardiopulmonary oscillations during stepwise paced breathing, using CPC analysis based on coherence and cross-spectral power.To improve the accuracy of CPC analysis based on respiratory signal EDR (ECG-Dirived Respiration) and RR Interval from ECG, we try to use adaptive filtering to improve the quality of EDR signal,then analyzes the ECG and Respiration data from Fantasia database on the physionet site to verify the effectiveness of adaptive filtering to improve the accuracy of cardiopulmonary coupling analysis, after obtained the product of coherence and coherence and cross-spectral power calculation the CPC value of each frequency band, and compare the value to the results obtained directly from EDR and RR Interval.Finally, use the data of sleep apnea syndrome patient from Apnea ECG Database performed cardiopulmonary coupling analysis to detect sleep stages and sleep apnea events.Results:The results indicated that the stepwise PB procedure produce an accumulative effect of PTT baseline increase. As increase of PTT baseline indicates the decrease of blood pressure, stepwise paced breathing procedure can lead to blood pressure reduction significantly (p<0.05),Our experiment also shows that the stepwise PB procedure can reduce the strength of RSA. And also the CPC analysis shows the value of cardiopulmonary oscillations index significantly greater than the value before PB procedure. We analysis the cardiopulmonary coupling of ECG and respiration data from Fantasia database, the results of power spectrum value of each band obtained from enhanced EDR signal is closer to the results obtained from real respiration compared to the results obtained the original from EDR signal.Conclusion:It was found that during the stepwise paced breathing procedure, along with the decreasing of the breathing rate, amplitude of the heart rate and PTT increases,indicating the reduction of blood pressure.Meanwhile the cardiopulmonary coordination increases significantly. The results of cardiopulmonary coupling index of Fantasia data indicate that enhanced EDR can improve the quality of EDR signal and accuracy of CPC analysis. Use the ECG and enhanced EDR signal of sleep apnea syndrome patient from Apnea ECG Database performed cardiopulmonary coupling analysis, obtained the maker of sleep apnea events, which also close to the results marked based on real respiration.Discussion:We use adaptive filtering to enhance the quality of EDR signal, for different ages or sleep-disordered patients,whether this method can effectively improve the accuracy of CPC analysis need to be verified. And whether the correlation between CPC index based on enhanced EDR and sleep apnea or sleep stage is the sanme as the criterion based on real respiration or original EDR is also needed to study further.