Respiratory distress severity grading mainly assesses the tolerance of patients with chronic obstructive pulmonary disease and pulmonary heart disease after activity as well as lung function, and can be classified into grade I-V. Grade I: Except for strenuous activities, the usual daily work, walking and climbing stairs are the same as those of healthy people in the same age. Grade Ⅱ: walking on flat ground is the same as that of the same year, but slightly shortness of breath when walking sharply on flat ground or climbing uphill or stairs. Grade III: Can walk more than 1 km slowly on a flat road, but at a slower speed than people of the same age. Grade Ⅳ: When walking, shortness of breath and chest tightness often require several breaks, and 50 meters cannot be walked in one breath. Grade V: unable to take care of themselves in daily life, such as getting in and out of bed, dressing, eating, and speaking with force, etc., they feel difficulty in breathing. The higher the level, the worse the lung function and the more obvious the degree of breathing difficulty.