Factors determining maximum inspiratory flow and maximum expiratory flow of the lung

The factors determining maximum expiratory flow and maximum inspiratory flow of the lung are reviewed with particular reference to a model which compares the lung on forced expiration to a Starling resistor. The theoretical significance of the slope of the expiratory maximum flow-volume curve is discussed. A method of comparing maximum expiratory flow with maximum inspiratory flow at similar lung volumes is suggested; this may be applied either to a maximum flow-volume curve or to a forced expiratory and inspiratory spirogram.