PURPOSE: Improvement in pulmonary function test (PFT) after bronchodilator administration (BD) is characteristic of airway diseases such as asthma which are associated with an obstructive pattern of dysfunction. However, one occasionally encounters a patient with a restrictive pattern on testing that improves after BD. The aim of this study was to determine the clinical significance of this reversible restrictive defect.
METHODS: Patients with restrictive spirometry who had a bronchodilator study were identified by review of all PFTs done at the Oklahoma City VAMC between January 2004 and August 2006. Restriction was defined as a decreased FVC, with a normal FEV1/FVC. Responsiveness to BD was defined as an improvement in FEV1 and/or FVC of at least 12% and 200 ml. Patients were divided into BD responders and non-responders. Clinical records of these patients were reviewed.
RESULTS: A total of 2344 PFTs were reviewed, with 1593 undergoing BD including 87 patients (4%) who had a restrictive pattern and BD evaluation. Forty-one (47%) of these had a response to bronchodilator. Both groups had similar baseline FVC (2.92±0.77 vs. 3.12±0.8 L) and FEV1 (2.03±0.55 vs. 2.22±0.63 L). A higher prevalence of wheezing (63% vs. 17%, p<0.01) was seen in the BD responsive group. There was no difference in age, sex, body mass index, symptoms of cough or dyspnea, or co-morbidities including clinical diagnosis of asthma between the two groups of patients. Using a logistic regression model, a response to bronchodilators was strongly associated with wheezing (LR+ 28.0; p < 0.01), history of reactive airways disease (LR+ 8.7; p < 0.01) and inhaled anticholinergics (LR+ 7.2; p < 0.01), theophylline (LR+ 4.8; p = 0.02) and beta 2 agonist (LR+ 4.0; p=0.04) use.
CONCLUSION: Reversible restrictive pattern appears to be a variant of obstructive lung disease in which complete closure of terminal lung units by contraction of alveolar ducts leads to low FVC.
CLINICAL IMPLICATIONS: In symptomatic patients, a therapeutic trial of BD may be of potential benefit.
DISCLOSURE: Marwan Elya, No Financial Disclosure Information; No Product/Research Disclosure Information