Pulmonary function testing is a valuable tool for evaluating
the respiratory system, representing an important adjunct to the patient history, various lung imaging studies, and invasive
testing such as bronchoscopy and open-lung biopsy. Insight into underlying pathophysiology can often be gained by comparing
the measured values for pulmonary function tests obtained on a patient at any particular point with normative values derived
from population studies.
ofpredicted normal is used to grade the severity of
the abnormality. Practicing clinicians must become familiar with pulmonary function testing because it is often used in clinical
medicine for evaluating respiratory symptoms such as dyspnea and cough, for stratifying preoperative risk, and for diagnosing
common diseases such as asthma and chronic obstructive pulmonary disease.
function tests (PFTs) is a generic term used to indicate a battery of studies or maneuvers that may be performed using standardized
equipment to measure lung function. PFTs can include simple screening spirometry, formal lung volume measurement, diffusing
capacity for carbon monoxide, and arterial blood gases.
Before a spirogram can be meaningfully
interpreted, one needs to inspect the graphic data (the volume-time curve and the flow-volume loop) to ascertain whether the
study meets certain well-defined acceptability and reproducibility standards. Tests that fail to meet these standards can
provide useful information about minimum levels of lung function, but, in general, they should be interpreted cautiously.
The interpretive strategy usually involves establishing a pattern of abnormality (obstructive, restrictive, or mixed), grading
the severity of the abnormality, and assessing trends over time.