Table 1: Indications for the DLCOsb test.

1. Obstructive diseases:

a. COPD (decreased proportionally to the degree of emphysema)

b. Asthma (usually normal or increased)

c. Cystic fibrosis (decreased in advanced stage)

d. Chronic bronchitis (usually normal or slightly decreased)

2. Evaluation and follow-up of restrictive diseases:

a. Interstitial diseases (frequently decreased)

b. Extrapulmonary restrictive diseases (usually normal)

3. Pulmonary vascular diseases (frequently decreased):

a. Chronic pulmonary thromboembolism

b. Pulmonary hypertension

c. Pulmonary vasculitis

4. Preoperative evaluation:

a. Resection for lung cancer

b. Volume reduction surgery

c. Lung transplantation

5. Impairment and disability evaluation:

a. COPD, interstitial diseases, others

b. Prediction of arterial desaturation during exercise in some patients with lung disease

c. Assessment of pulmonary effects of chemotherapeutic agents and other drugs known to cause lung damage, as well as radiotherapy

6. Other useful clinical applications of DLCO measurement:

a. Evaluation of pulmonary hemorrhage (usually elevated)

b. Evaluation of some diffuse pulmonary infectious diseases (e.g., Pneumocystis pneumonia)

c. Timely diagnosis and follow-up in respiratory surveillance programs in occupational medicine, especially in subjects exposed to inorganic dust

DLCO = pulmonary diffusion of carbon monoxide.

COPD = chronic obstructive pulmonary disease.