Journal of clinical monitoring and computing
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J Clin Monit Comput · Feb 2012
Respiratory and non-respiratory sinus arrhythmia: implications for heart rate variability.
The quantity of blood arriving at the left side of the heart oscillates throughout the breathing cycle due to the mechanics of breathing. Neurally regulated fluctuations in the length of the heart period act to dampen oscillations of the left ventricular stroke volume entering the aorta. We have reported that stroke volume oscillations but not spectral frequency variability stroke volume measures can be used to estimate the breathing frequency. ⋯ Both respiratory and non-respiratory sinus arrhythmia was observed amongst healthy adults. This observation at least partly explains why heart period parameters and heart rate variability parameters are not reliable estimators of breathing frequency. In determining the validity of spectral heart rate variability measurements we suggest that it is the position of the spectral peaks and not the breathing frequency that should be the basis of decision making.
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J Clin Monit Comput · Feb 2012
Developing an algorithm for pulse oximetry derived respiratory rate (RR(oxi)): a healthy volunteer study.
The presence of respiratory information within the pulse oximeter signal (PPG) is a well-documented phenomenon. However, extracting this information for the purpose of continuously monitoring respiratory rate requires: (1) the recognition of the multi-faceted manifestations of respiratory modulation components within the PPG and the complex interactions among them; (2) the implementation of appropriate advanced signal processing techniques to take full advantage of this information; and (3) the post-processing infrastructure to deliver a clinically useful reported respiratory rate to the end user. A holistic algorithmic approach to the problem is therefore required. We have developed the RR(OXI) algorithm based on this principle and its performance on healthy subject trial data is described herein. ⋯ These data indicate that RR(oxi) represents a viable technology for the measurement of respiratory rate of healthy individuals.
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J Clin Monit Comput · Feb 2012
Classification of sleep apnea types using wavelet packet analysis of short-term ECG signals.
Obstructive sleep apnea (OSA) causes a pause in airflow with reduced breathing effort. In contrast, central sleep apnea (CSA) event is not accompanied with breathing effort. The aim of this study is to differentiate CSA and OSA events using wavelet packet analysis and support vector machines of ECG signals over 5 s period. ⋯ The classification result indicates the possibility of non-invasively classifying CSA and OSA events based on shorter segments of ECG signals.