A 62-year-old man is evaluated for shortness of breath. During pulmonary function testing, the patient performs a forceful and complete exhalation after maximal inhalation. The results (red curve) are compared to a healthy individual of the same age and sex (black curve), as shown in the image below: Which of the following is the most likely cause of this patient's dyspnea?

Question

A 62-year-old man is evaluated for shortness of breath.  During pulmonary function testing, the patient performs a forceful and complete exhalation after maximal inhalation.  The results (red curve) are compared to a healthy individual of the same age and sex (black curve), as shown in the image below:  Which of the following is the most likely cause of this patient's dyspnea?

Quizplus · Accepted Answer

11ec160b_3b4b_88b7_9249_5b082db6e4ae_MD0001_00 Pulmonary function testing (PFT) usually involves spirometry, during which the patient completely inhales (to reach total lung capacity) and then forcefully exhales as much air as possible as quickly as possible. The graph in this question depicts the measured results following this procedure. The volume of air expelled during the first second of exhalation is the forced expiratory volume in 1 second (FEV1), and the total volume of air expelled represents the forced vital capacity (FVC). The black curve on the graph depicts normal PFT results with an FEV1 of 4 liters, an FVC of 5 liters, and an FEV1/FVC ratio of 80%. The patient's red curve shows a reduced FEV1 of 3 liters, a reduced FVC of 3.5 liters, and a slightly increased FEV1/FVC ratio of 86%. These findings are consistent with a restrictive pattern; therefore, the patient's dyspnea is most likely due to interstitial lung disease. Neuromuscular weakness and obesity hypoventilation syndrome also demonstrate a restrictive pattern on PFT. (Choices A, B, and D) Asthma and chronic obstructive pulmonary disease (COPD) both demonstrate an obstructive pattern on PFT with reduced FEV1 (eg, 2 liters), normal or reduced FVC (eg, 4.5 liters), and reduced FEV1/FVC ratio (eg, 45%). Bronchodilator testing may be helpful in differentiating asthma and COPD as airway obstruction due to asthma typically has a much higher degree of reversibility than that due to COPD. However, bronchodilator testing does not play a role in evaluating restrictive lung disease. Educational objective: Pulmonary function testing involves having the patient inhale completely and then forcefully exhale as much air as possible as quickly as possible. Restrictive lung disease causes reduced total volume of air expelled (ie, reduced forced vital capacity [FVC]), reduced volume of air expelled in 1 second (ie, reduced forced expiratory volume in 1 second [FEV1]), and a normal or sometimes increased FEV1/FVC ratio.

A 62-Year-Old Man Is Evaluated for Shortness of Breath