Abstract des Autors

Assessment of breathing pattern at maximal exercise in patients is limited because the range of ventilatory responses (minute ventilation; tidal volume; respiratory rate) at maximal exercise in normal humans is unknown. We studied 231 normal subjects (120 women; 111 men) equally distributed according to age from 20 to 80 years. Each subject performed a progressive incremental cycle ergometer exercise test to their symptom-limited maximum. Mean ventilation at the end of exercise (VEmax) was significantly higher in men (mean+/-SD, 97+/-25 L/min) than in women (69+/-22 L/min) (p<0.001). Minute ventilation at the end of exercise as a fraction of predicted maximal voluntary ventilation (VEmax/MVV) for all subjects was 0.61+/-0.14 (range, 0.28 to 1.02). There was no difference in VEmax/MVV between men (0.62+/-0.14) and women (0.59+/-0.14). Tidal volume at the end of exercise (VTmax) was higher in men (2.70+/-0.48 L) than in women (1.92+/-0.41 L) (p<0.001). Any differences in VTmax between men and women disappeared when VTmax was corrected for baseline FVC. Respioratory rate at the end of exercise (RRmax) was 36.1+/-9.2 breaths per minute for all subjects. There was no difference in RRmax between men and women. The VEmax correlated best with carbon dioxide output at the end of exercise (r=0.91; p<0.001) and with maximal oxygen uptake (r=0.90; p<0.001) for all subjects. This study of a large group of subjects has demonstrated the wide range of possible breathing patterns which are adopted during exercise and has provided a wide range of "normal" responses which must be taken into consideration when maximal ventilatory data from exercise tests are analyzed. Verf.-Referat