Chronic bronchitis is characterized by increased sputum production with decreased sputum clearance. Several studies have shown that the amount of bronchial surfactant is decreased in persons with chronic bronchitis. Anzueto and associates conducted a prospective randomized double-blind study to determine whether aerosolized exogenous surfactant could improve pulmonary function by increasing sputum clearance in patients with chronic bronchitis.

Patients were included in the study if they had a diagnosis of chronic bronchitis, had at least a 10-pack-year history of smoking and had a forced expiratory volume in one second (FEV₁) of 40 to 70 percent of normal. Patients were excluded if they had asthma, a pulmonary disease other than bronchitis or a recent acute pulmonary infection. Patients received nebulized isotonic saline or synthetic surfactant in a dosage of 202.5 mg per day, 607.5 mg per day or 1,215 mg per day for two weeks. Pulmonary function testing (including FEV₁ and forced vital capacity [FVC]) was performed and respiratory symptoms were reviewed during the study. Sputum analysis was performed three times, on day zero, day 14 and day 21.

Sixty-six patients were in the surfactant group and 21 were in the control group. Of these, 79 completed the study. No significant changes in spirometry were reported in patients taking placebo or the 202.5 mg per day of surfactant. The group taking 607.5 mg per day of surfactant showed significant improvement in FEV₁ and FVC by days 14 and 21. Similarly, the group taking 1,215 mg per day of surfactant showed an increase of 18 percent in the FEV₁ by day 21. Respiratory symptoms (cough frequency, sputum production and global condition) improved in all groups, but not significantly more in the surfactant group than in the placebo group. Sputum analysis showed a dose-dependent increase in mucociliary transportability.

The authors conclude that use of aerosolized surfactant, especially at a dosage of 607.5 mg per day, improved FEV₁ and FVC before and after use of the bronchodilator. This improvement lasted for at least one week after treatment. The effect was most likely a result of improved sputum clearance, and larger studies are needed to verify the usefulness of this treatment in patients with chronic bronchitis.