Are the Respiratory Responses to Changes in Ventilatory Assist Optimized

The input-output relationship of the CO2 respiratory controller can be described in two different ways. The first method is to describe the output as a function of the inputs; this type of controller model may be called a reflex controller model. The other method is to describe the relationship by an operating principle. The operating principle is often the minimization of a certain criterion or parameter; in this case, the controller is called an optimal controller. Several investigators have proposed that the respiratory controller responds to various stimuli in order to minimize certain criteria, which represent the energetic cost of breathing (3,4,9,13). In the concept proposed by Poon (9), the maintenance of arterial blood gas tensions and mechanical work are competing priorities for the respiratory controller, and the controller functions to minimize the net operating cost of both work and deviations of the blood gas tensions from given set points.