Recent developments in the physiological assessment of sarcoidosis: clinical implications

This review emphasizes key findings in physiologic research of sarcoidosis reported over the past year.

Sarcoidosis, a multiorgan disease involving the formation of epithelioid-cell granulomas, is characterized by reduced lung volumes, compliance, and diffusion capacity (D(L)CO), and, in a small number of cases, by airflow limitation. Recent studies do not show a close relationship between changes in lung volume and radiographic stage. Fatigue and exercise limitation are characteristic of this condition, and can be assessed by health-related quality of life (HRQOL) instruments. Recent investigations have focused on the evaluation of the extent of parenchymal and nodal inflammatory activity by PET using 18F-fluorodeoxyglucose (FDG-PET imaging). Pulmonary hypertension in advanced cases of sarcoidosis contributes to increased physical impairment, and decreased HRQOL and survival. It is best associated with ambulatory desaturation, reduced D(L)CO, and abnormal cardiopulmonary exercise testing findings indicative of pulmonary vascular disease. If pulmonary hypertension is suspected, it should be screened for by echocardiography and confirmed by right heart catheterization. Selected patients with progressive disease unresponsive to medical therapy or with severe pulmonary hypertension should be considered for lung transplantation. Current criteria for lung transplantation include New York Heart Association functional class III-IV, pulmonary hypertension, and/or right atrial pressure at least 15  mmHg.

Periodic assessment of HRQOL measures, exercise-induced hypoxemia, and right-sided cardiac pressures for pulmonary hypertension provides, to date, the best insight into the magnitude of physiologic impairment, serving as guideposts for management (including lung transplantation) and prognosis.