ABSTRACT
Pulmonary function testing typically demonstrates a “ restrictive” pattern, a reduced vital capacity and a proportionately decreased FEVb and a reduced total lung capacity with its subdivisions. Airflow rates (FEVļ/FVC ratio, peak flow, FEF25_75%) are usually normal. Measures of gas exchange (P02, 0 2 saturation, D l Co) are typically decreased at rest but may be normal. Oxygen desaturation with exertion may be striking and may appear to be out of proportion to the degree of other physiological or radiographic abnormalities. For this reason, it is very useful to routinely test oxygen saturation with walking in patients with suspected or confirmed HP.
