A 56-year-old man comes to the office due to progressively worsening exertional dyspnea over the last 4 months. The patient has had no fever, chest pain, orthopnea, cough, or ankle swelling. He does not use tobacco, alcohol, or illicit drugs. The patient works for a home insulation and plumbing company. He has never been abroad and owns no pets. Medications include hydrochlorothiazide and amlodipine for blood pressure control. Temperature is 36.8 C (98.2 F), blood pressure is 130/78 mm Hg, pulse is 76/min, and respirations are 15/min. Examination shows digital clubbing and fine bibasilar end-inspiratory crackles. Jugular venous pressure is 2 cm H2O above the sternal angle. There is no peripheral edema. Which of the following additional findings is most likely to be found in this patient?
Clinical features of asbestosis | |
Clinical presentation |
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Diagnostic evaluation |
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PFT = pulmonary function testing. | |
This patient's presentation suggests interstitial lung disease (ILD), likely due to asbestosis. Asbestosis is a type of pneumoconiosis with an increased incidence in occupations such as mining, shipbuilding, insulation, and pipe work. There is usually a latency period of ≥20 years between initial asbestos exposure and disease presentation. Patients primarily develop progressive dyspnea over a period of months; cough, sputum production, and wheezing are uncommon. Physical examination may show digital clubbing and bibasilar end-inspiratory crackles; each is seen in approximately 50% of affected individuals.
Typical chest imaging findings in asbestosis include interstitial thickening of the lower lung fields in a reticular (ie, net-like) pattern, and pleural plaques (the hallmark of the disease). As in other forms of ILD, pulmonary function testing shows a restrictive pattern with reduced FEV1, reduced FVC, and normal or elevated FEV1/FVC ratio (due to the reduction in FVC being greater than the reduction in FEV1) (Choice E). Interstitial fibrosis also causes decreased diffusion capacity of the lung and decreased pulmonary compliance.
In late disease, chronic lung hypoxia leads to sustained hypoxic pulmonary vasoconstriction and can eventually cause pulmonary hypertension and right ventricular failure (ie, cor pulmonale). Such patients typically have peripheral edema, hepatojugular reflux, right ventricular heave, and jugular venous distension. In this patient, jugular venous pressure is normal, suggesting he has not developed right ventricular failure.
(Choice B) The chronic lung hypoxia in ILD acts to increase, not decrease, pulmonary arterial pressure.
(Choice C) Pulmonary capillary wedge pressure (PCWP) is a reflection of left atrial pressure, and elevated PCWP indicates left ventricular failure or left-sided valvular dysfunction. ILD due to asbestosis can eventually cause right ventricular failure, but the left ventricle is unaffected and PCWP is not elevated.
(Choice D) Residual lung volume is the amount of air remaining in the lung after maximal exhalation. It is increased in obstructive lung diseases (eg, asthma, chronic obstructive pulmonary disease) but decreased in restrictive lung diseases such as asbestosis.
Educational objective:
Asbestosis is a pneumoconiosis resulting from inhalation of particles involved in many industrial processes. Patients typically have progressive dyspnea, clubbing, end-inspiratory crackles, and pleural plaques on imaging (the hallmark of the disease). Pulmonary function testing shows a restrictive pattern with decreased lung volume and normal or increased FEV1/FVC ratio. Diffusion capacity of the lung is decreased.