Performing the cardiopulmonary exercise test
dyspnea
BLOOD
An incremental, symptom-limited CPET was performed on a cycle ergometer (Jaeger, German model: MasterScreen CPX)) with continuous measurements of oxygen consumption, carbon dioxide production, minute ventilation, heart rate, 12-lead electrocardiography, and oxygen saturation measured by pulse oximetry. Average resting indices were measured for 30 s prior to initiation of exercise. Blood pressure was calculated at rest and then every 2 min. Gas exchange data were measured breath-by-breath during the four stages of exercise at a pedaling rate of 60 revolutions per minute (rpm): (1) 3 min of rest, (2) 3 min of unloaded exercise, (3) a maximum incremental ramp (15 or 25 Watt/min), and (4) recovery with 5 min of unloaded cycling. The Borg 6–20 Rating of Perceived Exertion (RPE) scale was used to assess the perceived exertion and dyspnea.The main exercise parameters were obtained at peak exercise points, corresponding to the highest work rate achieved and maintained for 30 s, consist of (a) load at peak, (b) peak oxygen consumption (VO