ABSTRACT
The principles of psychophysics can be applied to allow the patient or
subject to report his/her intensity of dyspnea during the stimulus of a standard exercise test (1). As such, this method enables a direct measure of an
individual’s breathlessness as opposed to the approach based on a patient’s
responses to questions about the impact of activities of daily living on
dyspnea (see Chapter 7 on Clinical Ratings of Dyspnea). Not surprisingly,
Hajiro et al. (2) showed that dyspnea scores obtained at the end of exercise
provide unique information that is different than that obtained from clinical
scales such as the Medical Research Council (MRC) scale or the baseline
dyspnea index (BDI). An exercise test is clearly different for patients than actual perfor-
mance of daily activities. However, the rationale of using a standardized
exercise testing as the stimulus to provoke breathlessness in the laboratory
is that it mimics or simulates physical activities or work. Actual testing in
the exercise laboratory enables the collection of physiological data that can-
not be readily obtained in the home or work environment. One limitation of
exercise testing is the requirement of appropriate equipment to collect and analyze the physiological exercise responses. Physiological variables such
as power production, minute ventilation (VE), and oxygen consumption
(VO2) are important in order to ‘‘match’’ the physiological with the percep-
tual responses of the patient so that the appropriate statistical analyses can
be performed.
