Chest
Volume 96, Issue 4, October 1989, Pages 767-771
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Clinical Investigations
Measurement of Respiratory Sensation in Interstitial Lung Disease: Evaluation of Clinical Dyspnea Ratings and Magnitude Scaling

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To evaluate measurements of respiratory sensation in ELD, we compared ratings of breathlessness from three clinical scales with the perceived magnitude of added elastic loads in 20 symptomatic ELD patients. Dyspnea ratings were obtained by two independent observers for each clinical method. Perceived magnitude of four elastic loads was selected from the Borg category scale; these estimates were summarized using the psychophysical power function equation. Ten age-matched healthy subjects also scaled the magnitude of added elastic loads. Dyspnea ratings from the three clinical scales were significantly interrelated. Mean exponents for mouth pressure developed during elastic loading were similar in the patient and control groups. Dyspnea ratings and exponents for elastic loads were not significantly correlated in ILD patients. Of the physiologic parameters examined, Dsb and gas exchange during exercise correlated significantly with clinical dyspnea ratings; none correlated with the exponent for added elastic loads. These data demonstrate that clinical dyspnea ratings provide valid measures of breathlessness in patients with ILD which are independent of the perception of respiratory loads.

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MATERIALS AND METHODS

Twenty patients with ILD and ten healthy control subjects recruited from employees of the medical center participated in the study. The diagnosis of ILD was based on a chest radiograph showing bilateral interstitial markings and normal heart size, pulmonary function tests, and histologic confirmation of an infiltrative process. The following different types of ILD were represented: idiopathic pulmonary fibrosis (n = 11); connective tissue disease (n = 2); sarcoidosis (n = 2); hypersensitivity

RESULTS

Anthropometric data and results of lung function and exercise parameters for both the patient and control groups are presented in Table 1. Age, gender, height and weight were comparable in the two groups. Patients with ILD exhibited significantly lower levels of lung function (FVC and FEV1) compared with control subjects.

The values for the clinical rating of breathlessness represented a wide spectrum in the ILD patients. The range of ratings was 0 to 3 for the MRC scale, 25 to 95 mm for the

DISCUSSION

The data from this investigation increase our understanding of respiratory sensations in ILD. In two previous reports different clinical systems have been described for grading dyspnea during the course of idiopathic pulmonary fibrosis.11, 12 In addition, psychophysical experiments using both threshold detection and magnitude scaling techniques have been conducted in small numbers of patients with ILD.13, 14 More recently, we have demonstrated modest correlations between respiratory function

ACKNOWLEDGMENT

The authors thank T. Lentine, J. McGovern, and J. Ward for their technical assistance.

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  • Cited by (0)

    This study was supported by a Biomedical Research Support Grant from the National Institute of Health, Training Grant No. HL-07449 from the National Heart, Lung, and Blood Institute, and by a grant from the New Hampshire Affiliate of the American Heart Association.

    Manuscript received September 29; revision accepted February 16.

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