Alveolar-capillary membrane permeability for early prediction of response of inhaled steroid on patients with chronic obstructive pulmonary disease

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Abstract

Background and objective

Glucocorticosteroid reversibility-testing is undertaken over a period of 3 months to identify whether patients with chronic obstructive pulmonary disease (COPD) would benefit from long-term inhaled corticosteroids. This study assessed whether alveolar-capillary membrane (a/c) permeability testing can be used as an early alternative test method for the same purpose.

Methods

Fourteen patients with severe and symptomatic moderate COPD (group S) were prescribed inhaled steroid 800 μg/day for 3 months. Before inhalation and 4 weeks after inhalation therapy, forced expiratory volume in 1 s (FEV1) and a/c permeability using 99mTc-DTPA were performed. FEV1 was recorded again at the end of the third month. Another 10 patients with COPD of comparable severity (group B) prescribed with inhaled bronchodilators were examined and studied as controls.

Results

In group S, the permeability decreased in eight patients (group D) and increased in six patients (group I). No significant change was noted in FEV1 at the end of the first month. However, seven patients in group D showed significant improvement in FEV1 at the end of the third month, whereas in patients in group I no significant changes were observed. In group B, no significant change in a/c permeability was observed, although the FEV1 increased by 12–17%.

Conclusion

With steroid inhalation, the a/c permeability at 4 weeks predicts future changes in lung functions. Long-term inhaled corticosteroids are likely to be useful if permeability decreases. This test, which needs further validation, appears to provide much earlier prediction of response than glucocorticoid reversibility testing.

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