Chest

Chest

Volume 130, Issue 5, November 2006, Pages 1496-1502
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Original Research
Impact of Impaired Inspiratory Muscle Strength on Dyspnea and Walking Capacity in Sarcoidosis

https://doi.org/10.1378/chest.130.5.1496Get rights and content

Background

Dyspnea and fatigue are frequent but poorly understood symptoms in sarcoidosis patients. This study was aimed at assessing the clinical impact of inspiratory muscle impairment on dyspnea and exercise tolerance. This is the first study using nonvolitional tests that are independent of the patient's cooperation and motivation in addition to volitional tests of inspiratory muscle strength in patients with sarcoidosis.

Methods

Peak maximal inspiratory mouth pressure (Pimaxpeak), maximal inspiratory pressure sustained for 1.0 s (Pimax1.0), twitch mouth pressure (TwPmo), lung function test results, blood gas measurements, 6-min walking distance (6MWD), and Borg dyspnea scale (BDS) scores were assessed in 24 male sarcoidosis patients and 24 healthy male control subjects matched for age and body mass index.

Results

Mean (± SD) Pimaxpeak (95.2 ± 25.3% vs 124.6 ± 23.4% predicted, respectively; p < 0.001) and Pimax1.0 (85.6 ± 31.4% vs 125.8 ± 26.8% predicted, respectively; p < 0.001) were lower in sarcoidosis patients compared to control subjects. TwPmo tended to be lower in sarcoidosis patients, and there were three patients who had TwPmo values of < 1.0 kPa, which is a strong indicator of inspiratory muscle weakness. The mean 6MWD was 582 ± 97 m in sarcoidosis patients and 638 ± 65 in control subjects (p = 0.025). The mean BDS score was higher in sarcoidosis patients (3.3 ± 1.7 vs 0.2 ± 0.5, respectively; p < 0.001). Compared to maximal inspiratory pressure, lung function parameters, and blood gas levels, TwPmo was the strongest predictor for 6MWD (r = 0.663; p = 0.003) and BDS score (r = 0.575; p = 0.012) in sarcoidosis patients following multiple linear regression analysis.

Conclusions

Impairment of inspiratory muscle strength occurs in sarcoidosis patients, and has been suggested to be an important factor causing dyspnea and reduced walking capacity, but this is only reliably detectable when using nonvolitional tests of inspiratory muscle strength.

Section snippets

Materials and Methods

The study protocol was approved by the institutional review board for human studies of the Albert-Ludwig University (Freiburg, Germany) and was performed in accordance with the ethical standards laid down in the Declaration of Helsinki, 2000. Informed written consent was obtained from all subjects.

Results

Demographic data and lung function parameters are given in Table 1. Ten patients had an FVC of < 80% predicted, and 5 patients had an FEV1/FVC ratio of < 70% predicted. Blood gas values and parameters of the 6-min walk test are shown in Table 2. Pao2 and arterial oxygen saturation (Sao2) both at rest and after exercise were significantly lower compared to those values in control subjects (Table 2). In addition, sarcoidosis patients presented with a significantly higher degree of dyspnea and a

Discussion

This is the first study in which nonvolitional tests of respiratory muscle strength have been used to quantify inspiratory muscle strength in sarcoidosis patients. The assessment of TwPmoIn showed no clear difference in sarcoidosis patients compared to age-matched and BMI-matched control subjects. This indicates that inspiratory muscle strength is, on average, not substantially reduced in sarcoidosis patients. However, there were three patients in whom inspiratory muscle weakness was diagnosed

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    Copyright © 2006 The American College of Chest Physicians. Published by Elsevier Inc. All rights reserved.