Respiratory analyzer system

Abstract

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.