Figure 4
Plot of Unpleasantness (A 1 ) as a function of air hunger rating for the 10 COPD subjects who completed daily questionnaires at home. Open circles connected by line represent dyspnea during moderate and high PETCO2 during restricted ventilation in the laboratory; closed circle represents dyspnea experienced during activities of daily living, such as walking or climbing stairs. Scale maxima were defined as ‘Unbearable’ for unpleasantness and ‘as intense as I can imagine’ for air hunger. Error bars reflect standard errors.