What factors affect pulmonary ventilation function test

When doing lung ventilation examination, it is necessary to pinch the nose without air leakage, bite the mouth and blow with the mouth. The influencing factors include the psychological environment of the examinee, the specific environment of the hospital, the cognitive ability of the patient, the coordination ability, the coordination of movements, etc. If the patient eats too much before the examination, the detected data will also be affected.