Breathlessness and blood oxygen tension in patients with chronic bronchitis and emphysema.

The dyspnea grade (MRC scale) was confronted with the arterial oxygen tension (PaO2) measured at rest in a group of 51 patients with chronic obstructive lung disease with moderate or severe impairment of ventilatory function (FEV 1.0 less than 1.5 1). For the group as a whole no correlation was found, but in the "bronchitic" subgroup (clinical-roentgenologic and biologic criteria) a tendency of PaO2 to decrease with the increase in dyspnea severity was apparent. The linear correlation coefficient did not attain the significance threshold owing to the limited number of observations (r = 0.46; p greater than 0.05).