The letters dlco have a specific meaning in respiratory medicine and are an abbreviation for diffusion function in the pulmonary function test. Diffusion function in pulmonary function tests is mainly to check the ventilation function, which is the function of oxygen uptake by the body. A decrease in oxygen uptake by the lungs is usually seen in cases of pneumonia, interstitial lung disease, or restrictive ventilation dysfunction combined with diffusion dysfunction. With this condition, doing strenuous activities will produce shortness of breath, such as feeling dizzy when climbing high or low, and one can often feel headache or panic and heartbeat, which are all symptoms of hypoxia.