20 40 60 80 100 10 20 30 40 50 60 Vo2 (% predicted max) VT (%predicted VC)
Fig. 5.8 An incremental exercise test in a patient with COPD (solid lines) compared with normal responses in health (dashed lines). Exertional symptoms, ventilation (VE), oxygen saturation, inspiratory capacity (IC), and heart rate (HR) responses are plotted against oxygen consumption (VO2). Breathing patterns [frequency (F) vs. tidal volume (VT)] are plotted on the lower left panel. This patient stopped exercise at 50% of VO2 predicted maximum because of severe breathlessness and leg discomfort. Contributing factors to exercise limitation in this patient included excessive ventilation, arterial oxygen desaturation, progressive lung hyperinflation (i.e. reduced IC), and a rapid shallow breathing pattern. MVC, maximal ventilatory capacity.
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