Respironics, Inc.

The University of Texas System

Khosrow Bebehani

John R Burk

Edgar A Lucas

John R Axe

Fu-Chung Yen

Respiratory rhythms of a subject are derived from measured ECG signals utilizing leads placed for significant influence of chest movement on the ECG signals. The QRS pulses within ECG signals measured in two substantially orthogonal planes are located by applying a sequence of filters. The knot and period of the QRS pulses are then determined, with adjustments made during a learning phase of data sampling. The QRS pulse areas in both planes is then calculated. These pulse areas are employed to determine the angle of orientation of the depolarization wave's mean electrical axis (MEA) at the QRS pulse locations. Cubic spline interpolation of the data points for the MEA angle provides a smooth breathing curve, which may be scored for sleep disordered breathing events. The ECG-derived respiratory (EDR) signal may be employed in lieu of airflow measurements where such measurements are not available, or may be employed in conjunction with airflow measurements and/or measured cardiac activity data to discriminate between arrhythmias associated with disordered breathing versus those associated with cardiac malfunction, reducing misdiagnosis. The additional processing of ECG data required for derivation of respiratory rhythms may be easily automated and implemented at nominal incremental cost per unit.

ECG derived respiratory rhythms for improved diagnosis of sleep apnea

A method and device for controlling sleep disorder breathing utilizes variable multiple level pressures. A pressure source supplies compressed breathable gas at a relatively low pressure to the user's airway. Pressure transducers monitor pressures and convert them into electrical signals. The electrical signals are filtered and processed to extract specific features such as duration and energy levels. If these features exceed selected threshold values for duration and energy level over a minimum period of time, then the microprocessor declares the presence of sleep disorder breathing. If a selected number of these events occur within a selected time period, then the microprocessor adjusts the pressure delivered by the pressure source. If sleep disorder breathing is not detected within a certain time period, then the microprocessor lowers the pressure level gradually. The device and method disclosed in this patent is capable of detecting apnea, hypopnea, and pharyngeal wall vibration. Further, it is able to distinguish between obstructive, central and mixed apnea and hypopnea.

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Arlington, TX, United States of America

Khosrow Bebehani