Cardiopulmonary function testing tools and indicators
In this study, the 6MWT test system (Doctor Walker 6-min walk detection and analysis system WOKE-360, Wuhan Qingyi Yunkang Medical Equipment Co., Ltd.) was used to measure the cardiopulmonary function of the patients. The test involved asking the patients to walk along a straight 20–30-m closed corridor at the fastest possible speed to test their walking distance within a six-minute period. During the test, the patient wore a remote electrocardiogram monitoring and blood oxygen saturation monitoring system, and the patient's cardiopulmonary function and exercise tolerance were determined according to their walking distance (m) and the changes in heart rate, blood oxygen level and breathing during the test. The cardiopulmonary function of the patients was divided into four grades; the lower the grade, the worse the cardiopulmonary function. This test was carried out in the allocated test site of the Cardiac Rehabilitation Center of Hebei Provincial People's Hospital and was completed by the same rehabilitation technician from the cardiac rehabilitation team of our department. The following cardiopulmonary function grades applied: grade 1: < 300 m, grade 2: 300–374 m, grade 3: 375–449.5 m and grade 4: > 450 m.A metabolic equivalent (MET) presents a quantitative value of exercise endurance, which pertains to the maximum exercise load an individual can bear. The larger the value, the greater the exercise load the individual can bear and the stronger the exercise ability.