A 73 year-old man presents with progressive dyspnea on exertion over the past one year. He reports a dry cough but no wheezes, sputum production, fevers or hemoptysis. He is a life-long non-smoker and worked as a lawyer until retiring 3 years ago. His pulmonary function testing is as follows. What is the most probable diagnosis? Pre-Bronchodilator (BD)TestActualPredicted% PredictedFVC (L)1.574.4635FEV1 (L)1 283.3938FEV1/FVC (%)8276 FRC1 733.8045RV (L)1.122 5943TLC (L)2.706.4542RV/TLC (%)4142 DLCO corr5.0631.6416

Ans. C. Idiopathic Pulmonary Fibrosis.a. This patient has a reduced FEV1 and FVC with a preserved FEV1/FVC ratio.b. The total lung capacity is reduced and the patient, therefore, has a restrictive defect.c. The flow-volume loop also has the characteristic appearance of a restrictive process - tall, narrow and a short expiratory phase.d. Based on the fact that his TLC is below 50% predicted, this would be classified as a "severe" restrictive defect.e. His DLCO is also markedly reduced indicating he has a reduced alveolocapillary interface for gas exchange and suggesting that the cause of his restrictive process lies within the lung parenchyma.f. Idiopathic pulmonary fibrosis might be a cause in this case.