The invaluable pressure-volume curve.

We present a case in which the pressure-volume (P-V) curve proved invaluable in the diagnostic workup of a patient. The patient was a 43-year-old man who presented with progressive dyspnea on exertion, restrictive spirometry, exercise desaturation, and an unremarkable CT scan. Because of the unexpected finding of an unremarkable CT scan, we wanted more data assuring the presence of an indication for lung biopsy. Detailed pulmonary function tests, including a P-V curve, were administered. The P-V curve was abnormal, thus prompting a biopsy, which revealed hypersensitivity pneumonitis. In this report, we discuss the use of P-V curves and the clinical presentation of hypersensitivity pneumonitis.