Table 2: Contraindications to the DLCOsb test.

Absolute

1. Severe hypoxemia (SpO2 < 75%)

In this case its performance can be evaluated according to the altitude where the test is being performed, and always under medical supervision

2. Elevated carboxyhemoglobin levels (COHb > 10 to 15%)

Relative

1. Confusion or poor muscle coordination that prevents the proper maneuver from being performed

2. Acute or decompensated cardiovascular disease (infarction, heart failure, cerebrovascular disease)

3. Pneumothorax in the last three months

4. Risk of bleeding due to hemoptysis or aneurysms

5. Surgery (thorax, abdomen, eye, ear) in the last month

6. Acute respiratory infections in the last two weeks (influenza, common cold)

7. Active pulmonary tuberculosis

8. Advanced or complicated pregnancy

9. Patients with tracheostomy or pleural probes

10. Patients who cannot withhold supplemental oxygen for

at least 10 minutes

11. Patients with VC or FVC less than the minimum volumes required by the equipment

COHb = carboxyhemoglobin.

DLCOsb = single-breath carbon monoxide lung diffusion.

FVC = forced vital capacity.

SpO2 = pulse oximetry oxygen saturation.

VC = vital capacity.