Clearance of mucus produced in the tracheobronchial tree in chronic bronchitis secondary to smoking may:

A. Be hampered by the fact that the amount of mucus is increased by the number of mucus-producing cells at the expense of ciliated cells.

DISCUSSION: Chronic bronchitis may have an acute component, and in these patients therapy with antibiotics and bronchodilators may improve the flow rate as measured by pulmonary function tests within 3 or 4 days of the cessation of smoking and treatment of the acute condition. However, the chronic bronchitic will continue to produce large amounts of mucus, most evident in the morning, even after the acute process has been resolved. Clearance of these secretions is hampered by the inability to cough, perhaps secondary to the pain of thoracotomy or abdominal surgery or by a decrease in the number of ciliary cells that help move mucus up the tracheobronchial tree. This causes plugging of small airways and atelectasis, which may progress to pneumonia. For this reason, cessation of smoking for 3 to 5 days before surgery is very beneficial in preventing pulmonary complications during the postoperative period.