ABSTRACT
Physical pulmonary function tests are an important noninvasive (NI) means of diagnosing obstructive lung diseases (OLDs). The principal functions of the vertebrate respiratory system are to keep the arterial blood supplied with oxygen, and to allow the dissipation of a metabolic by-product, carbon dioxide, in the exhaled breath. This chapter focuses on the physical side of the respiratory process. That is, the mechanics of breathing and the gas exchange processes taking place at alveolar capillaries. Spirometers basically measure the respiratory volumes, or in the case of modern units, respiratory volume flow rate which is integrated to determine the volume. The chapter describes the uses of gas dilution to measure certain respiratory parameters. An important respiratory parameter is alveolar ventilation (AV). It is also of interest in a medical evaluation of the respiratory system to noninvasively measure the alveolar capillary blood flow.
