Respiratory sensation in chronic obstructive pulmonary disease.

Previous work has demonstrated that the perception of added resistive loads is blunted in patients with chronic obstructive pulmonary disease (COPD). It is not clear, however, whether this is due to reduced levels of respiratory muscle force during loaded breathing or to a specific abnormality in respiratory sensation. In the present study, the psychophysical technique of magnitude scaling was used to evaluate the sensation of external resistive and elastic ventilatory loads as well as the perception of inspired volume and inspiratory muscle force in 14 patients with COPD and in 12 normal subjects of similar age. The exponents of the power function relationships between load magnitude and sensation intensity for both resistive and elastic loads were significantly reduced in the patients with COPD compared with those in the normal subjects. While breathing against any given ventilatory load, the peak inspiratory mouth pressure and inspiratory duration were comparable in the 2 groups. Thus, the exponents of the power function relationships between peak inspiratory mouth pressure and sensation intensity were significantly lower in the patients with COPD (0.92 +/- SE 0.17 and 0.96 +/- SE 0.17 for resistive and elastic loads, respectively) compared with those obtained in the normal subjects (1.47 +/- SE 0.12 for resistive loads and 1.52 +/- SE 0.17 for elastic loads) (p less than 0.05). In contrast, the perception of inspired volume and of respiratory muscle force during static inspiratory maneuvers as determined by magnitude estimation and production were no different in either group.(ABSTRACT TRUNCATED AT 250 WORDS)