Evaluation of Clinical Dyspnea Ratings and Magnitude Scaling
Dyspnea is a common and disabling symptom in patients with chronic respiratory disease. Yet many issues concerning the routine measurement of unpleasant respiratory sensations in patients with lung disease remain unresolved. For example, both clinical dyspnea ratings and psychophysical scaling techniques have implications for the assessment of dyspnea in patients. On the one hand, clinical rating instruments provide objective measures of the impact of symptoms on activities of daily living. In contrast, magnitude scaling techniques provide insight into stimuli affecting the perceived magnitude of respiratory sensations. At the present time, however, there is little information about either the relationships among, or the clinical utility of, these two approaches to the measurement of respiratory sensation in patients with lung disease. more
In a previous investigation we examined relationships among clinical dyspnea ratings, the perceived magnitude of added resistive loads, and lung function in patients with obstructive airway disease. Dyspnea scores were significantly correlated with lung function, but neither clinical dyspnea ratings nor lung function were significantly related to the perception of added loads. Because these interrelationships are likely influenced by the underlying pathophysiologic condition, other investigations are required to determine the limits of these observations. Currently, few data exist about the problem of breathlessness in patients with ILD.
The purpose of our study was to compare clinical dyspnea ratings and the perception of added loads in stable, symptomatic patients with ILD. In this investigation, we evaluated the hypothesis that ratings from clinical instruments designed to measure the severity of breathlessness are independent of results from psychophysical scaling tasks in ILD patients. This consideration is important because the most appropriate tool for assessing the impact of dyspnea on a patients daily life remains to be established in these patients. Magnitude scaling of added pulmonary elastic loads was selected for comparison with clinical dyspnea ratings in these patients because these loads can mimic the type of pressure-volume alterations experienced by patients with ILD during daily physical activities. We also explored the relationships between these two approaches for the assessment of respiratory sensation and measures of physiologic function at rest and during exercise.