Small Airway Involvement in Mixed Connective Tissue Disease.

Abstract

We studied pulmonary functions in 17 female patients with mixed connective tissue disease (MCTD) to detect early pulmonary involvement in this disease; in 8 of the 17 patients followup studies were also performed at 1.2-to 5.9-year intervals. In the first pulmonary function tests, decreases in vital capacity (VC) and diffusing capacity (DL~o) were observed in 6 (35%) and 8 (47%) patients, respectively. The ratio of forced expiratory volume in one second to VC was normal in all the patients, but pulmonary resistance and static compliance were abnormal in 6 (35%) and 10 (59%) patients, respectively. However, frequency dependence of dynamic compliance was found in all 16 patients tested. Moreover, 4 (24%) of the 17 patients had normal DL~o and DL~o-to-alveolar volume ratio (DLCO/VA). Reductions in DL~o and DLCo/VA were significantly correlated with the disease duration. These results suggest that small airway obstruction is an early and frequent indication of functional pulmonary impairment, and that impairment of alveolar gas exchange is progressive in patients with MCTD.connective tissue disease; small airways; frequency dependence of dynamic compliance; diffusing capacity

Frequency of broncho-bronchiolar disease in rheumatoid arthritis: an examination by high-resolution computed tomography

“…22 On the other hand, mN on HRCT directly means a bronchiole disease. Small airways were called the silent zone before; thus, small amounts of mN were not thought able to impair small airway function.…”

Clinical applications of lung function tests: A revisit

“…Chronic pulmonary embolism, primary pulmonary hypertension (PPH) and other pulmonary vascular diseases may also result in a decline in DLCO 34 . There are known associations between reduced DLCO and clinical conditions such as mixed connective tissue disease, 35 gastro‐oesophageal reflux, 36 diabetes mellitus 37 and liver cirrhosis 38 . It is therefore crucial for clinicians to have a clear understanding of how lung function, and in particular DLCO, is affected by these extrapulmonary diseases.…”

The Lung in Mixed Connective Tissue Disease

“…All studies suggest that the measurement of DLCO might serve as the most sensitive marker of pulmonary involvement in MCTD. 42 Pulmonary nodules (different etiologies) 38 Mediastinal adenopathy Co-existing sarcoidosis 41 Pulmonary infections Chronic hypoventilation Diaphragmatic dysfunction Isolated pulmonary capillaritis 27 Alveolar hemorrhage…”

“…Primary obstructive lung disease (bronchiolitis obliterans) has not been described in MCTD. In 1993, Izumiyama 42 and colleagues performed pulmonary function tests in 17 female patients with MCTD but without cardiac or pulmonary symptoms. This included the assessment of small airway involvement by estimation of the frequency dependence of dynamic compliance.…”