Medical Graphics Corporation

Stephen T Anderson

Catherine A Anderson

Terrance J Kapsen

A cardiopulmonary exercise system for real-time, breath-by-breath acquisition, analysis, display and printing of an individual's physiologic parameters. A microprocessor based waveform analyzer receives inputs from a CO.sub.2 analyzer, an ECG monitor, an O.sub.2 analyzer, and a pneumotachograph, and, optionally, can also connect a cycle ergometer, a treadmill, a cardiac stress system, and an ear oximeter. The waveform analyzer provides output data to a host central processor unit to which a CRT display, a graphics copier or hard-copy printer may be connected for providing medical data for assessment of an individual's heart and lungs, on a real-time basis whereby the level of fitness or underlying organic defects which may effect the cardiopulmonary system can be determined. The pneumotachograph, CO.sub.2 analyzer and O.sub.2 analyzer and ECG monitor provide analog signals representing flow, CO.sub.2 and O.sub.2 levels in expired air as well as heart rate. The waveform analyzer, under control of its dedicated microprocessor, performs an A/D conversion with the microprocessor also being used to calculate the tidal volume (V.sub.T), minute ventilation (V.sub.E), breathing frequency (f.sub.B), cardiac frequency (f.sub.C), inspiratory time (T.sub.I) and total time (T.sub.TOT) of last breath, fraction of CO.sub.2 in inspired gas (F.sub.ICO.sbsb.2) and fraction of O.sub.2 in inspired gas (F.sub.IO.sbsb.2), peak CO.sub.2 and O.sub.2 (F.sub.ETCO.sbsb.2 and F.sub.ETO.sbsb.2), and expired volumes of CO.sub.2 and O.sub.2 (VCO.sub.2 and VO.sub.2) breath-by-breath. The system of the preferred embodiment analyzes the individual's expirate at a sample rate of one hundred samples per second per channel with twelve bit resolution.

Cardiopulmonary exercise system

A system for measuring the ventilatory response of the human respiratory system to increased levels of CO.sub.2 and/or decreased levels of O.sub.2. Measured concentrations of CO.sub.2 are introduced into an infant's lungs and the inspired and expired air is passed through a pneumotachograph for developing various electrical analog signals relating to flow. Samples of the expired air are delivered to CO.sub.2 and O.sub.2 analyzers. The resulting electrical analog signals produced by these devices represent inspiratory and expiratory flow, and the CO.sub.2 and the O.sub.2 levels in the expired air. They are applied to a waveform analyzer containing an analog to digital converter and a microprocessor system which is programmed to discriminate between normal breathing patterns and irregular patterns. The microprocessor also computes inspiratory and expiratory tidal volume, ventilation (measured in liters per minute), breathing frequency, inspiratory, expiratory and total times of a preceding breath, minimum CO.sub.2 and O.sub.2, peak CO.sub.2 and O.sub.2 and volume of expired CO.sub.2 and O.sub.2 either on a breath-by-breath basis or over a user selected time interval. The results of these computations are provided in digital form to a digital computer having a graphic display capability. When the ventilation rate is plotted as a function of changes in the inspired CO.sub.2 concentration, the slope of this linear relation is indicative of abnormal ventilatory response, which is deemed helpful in the diagnosis of a number of disease states, e.g., Sudden Infant Death Syndrome.

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Stillwater, MN, United States of America

Stephen T Anderson