2 - Pulmonary function testing for pathologists

Abstract

Pulmonary function testing provides quantification of pulmonary physiologic function. Pulmonary function tests (PFTs) often provide the first diagnostic tool that helps guide a clinical pulmonologist in creating a filing system for a possible differential. This chapter will focus on the basic elements that comprise a full set of PFTs including lung volumes, lung flows by spirometry, airway resistance, and capillary bed assessment. PFTs provide quantification of the severity of the lung impairment and can be used to evaluate for change in lung function over time. This change over time in function may be age related or represent deterioration related to a disease state or, potentially, improvement related to institution of therapy. Fundamentally, lung physiologic function will be normal, restrictive, or obstructive. Restriction implies reduction in lung volumes—size of the lungs. Obstructive implies reduced air flows, mostly secondary to narrowing of the airways, such as in asthma, or reduced elastic recoil, such as from emphysema, leading to greater exhalation times.