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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Many of the complications related to prolonged ventilation are related to inappropriate handling of endotracheal tube (ETT) cuff. This article reviews the possible complications associated with the ETT cuff, and the landmark development made in that field. The article challenges the present paradigm of cuff use and reviews the current clinical practice in that area.
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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.