What finding on physical examination is common in acute hypersensitivity pneumonitis?

In acute hypersensitivity pneumonitis, also known as acute interstitial pneumonitis, a common finding is the presence of tachypnea and fine crackles during physical examination. This condition usually arises due to an immune response to inhaled organic dusts or chemicals, leading to an inflammatory reaction in the lungs.

Tachypnea indicates the body’s compensatory response to decreased oxygen exchange, while fine crackles, often described as "velcro" rales, are indicative of interstitial lung involvement due to the edema and inflammation occurring in the alveoli and interstitial spaces. These crackles are typically heard during inspiration and suggest that there is a disruption in normal lung mechanics, which is characteristic of this condition.

The other options describe findings that are not commonly associated with acute hypersensitivity pneumonitis. For instance, while peripheral cyanosis can indicate significant respiratory distress, it is not a typical finding specifically linked to this condition. Consolidation on lung auscultation might suggest a different pathology, such as pneumonia, and increased tactile fremitus often relates to lung consolidation or pleural effusion, which are not typical findings in hypersensitivity pneumonitis. Therefore, the presence of tachypnea and fine crackles is the defining characteristic in