BAL cytology analyses (differential cell counts) should be considered in the evaluation of patients with IPF at the discretion of the treating physician based on availability and experience at their institution. BAL may reveal alternative specific diagnoses: malignancy, infections, eosinophilic pneumonia, histiocytosis X, or alveolar proteinosis. In the evaluation of patients with suspected IPF, the most important application of BAL is in the exclusion of other diagnoses. Prominent lymphocytosis (>30%) generally allows excluding a diagnosis of IPF. Pulmonary function tests
Spirometry classically reveals a reduction in the vital capacity (VC) with either a proportionate reduction in airflows, or increased airflows for the observed vital capacity. The latter finding reflects the increased lung stiffness (reduced lung compliance) associated with pulmonary fibrosis, which leads to increased lung elastic recoil.Measurement of static lung volumes using body plethysmography or other techniques typically reveals reduced lung volumes (restriction). This reflects the difficulty encountered in inflating the fibrotic lungs. The diffusing capacity for carbon monoxide (DLCO) is invariably reduced in IPF and may be the only abnormality in mild or early disease. Its impairment underlies the propensity of patients with IPF to exhibit oxygen desaturation with exercise which can also be evaluated using the 6-minute walk test (6MWT).Terms such as mild, moderate, and severe are sometimes used for staging disease and are commonly based on resting pulmonary function test measurements. However, there is no clear consensus regarding the staging of IPF patients and what are the best criteria and values to use.
Updated international guidelines were published in 2022, which some simplification in diagnosis and the removal of antacids as a possible adjunct therapy. Signs and symptoms
In many people, symptoms are present for a considerable time before diagnosis. The most common clinical features of IPF include the following:
Age over 50 years
Dry, non-productive cough on exertion
Progressive exertional dyspnea (shortness of breath with exercise)
Dry, inspiratory bibasilar "velcro-like" crackles on auscultation (a crackling sound in the lungs during inhalation similar to Velcro being torn apart slowly, heard with a stethoscope). Clubbing of the digits, a disfigurement of the finger tips or toes (see image)
Abnormal pulmonary function test results, with evidence of restriction and impaired gas exchange.Some of these features are due to chronic hypoxemia (oxygen deficiency in the blood), are not specific for IPF, and can occur in other pulmonary disorders. IPF should be considered in all patients with unexplained chronic exertional dyspnea who present with cough, inspiratory bibasilar crackles, or finger clubbing.Assessment of "velcro" crackles on lung auscultation is a practical way to improve the earlier diagnosis of IPF. Fine crackles are easily recognized by clinicians and are characteristic of IPF.If bilateral fine crackles are present throughout the inspiratory time and are persisting after several deep breaths, and if remaining present on several occasions several weeks apart in a subject aged ≥60 years, this should raise the suspicion of IPF and lead to consideration of an HRCT scan of the chest which is more sensitive than a chest X-ray.