THE DEFINITION AND ASSESSMENT OF RESPIRATORY FUNCTION*

Journal/Book: Reprinted from the Brititsh MEDICAL JOURNAL February 21 and 28 1953 vol. i. pp. 415 and 473. 1953;

Abstract: (Reader in Medicine in the University of Birmingham) General Summary The function of the lungs is defined. The importance of lung ventilation and circulation bringing blood and gas in close contact in all alveoli so that efficient gas exchange occurs is emphasized. The various methods of assessing ventilatory function are discussed. The determination of the lung volumes and ventilatory capacity is described and the greater value of the more dynamic measurements emphasized. The relationship of the volumes ventilated to the ventilatory capacity present in the causation of ventilatory discomfort or dyspnoea is discussed. The important features of the pulmonary circulation are detailed and the disturbances of this circulation in lung disease and their effect upon the right ventricle are described. Finally the problem of oxygen transfer and blood oxygenation is considered. It is emphasized that this depends upon the efficient distribution of gas and blood and the proper correlation of alveolar ventilation and circulation throughout the lungs. The diffusion of oxygen across the pulmonary membrane is considered. The theoretical concept of ideal distribution of blood and gas is elaborated and the application of this concept to the measuring of the efficiency of the lungs in this respect both in health and in disease is described. The diffusion gradients in the alveoli and the diffusing capacity of the lungs are also considered in both normal and abnormal subjects. The value and future of arterial blood studies in pulmonary disease is discussed. . . .

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