Mechanical insufflation-exsufflation for airway mucus clearance.

Cough is an important component of airway clearance, particularly in individuals with intrinsic pulmonary disease, weakness of respiratory muscles, or central nervous system disease that impairs breathing. The use of assisted cough to enhance airway clearance in individuals with neuromuscular disease is essential to produce and maintain peak cough flow above a minimum and thereby avoid retained secretions that cause infection, inflammation, and respiratory failure. Periodic insufflation of the lung above a reduced vital capacity is also important, to maintain range of motion of the thoracic cage and avoid progressive respiratory disability. Mechanical insufflation-exsufflation is a therapy in which the device (the CoughAssist In-Exsufflator is the only currently marketed insufflation-exsufflation device) gradually inflates the lungs (insufflation), followed by an immediate and abrupt change to negative pressure, which produces a rapid exhalation (exsufflation), which simulates a cough and thus moves secretions cephalad. Mechanical insufflation-exsufflation is used with patients with neuromuscular disease and muscle weakness due to central nervous system injury. Insufflation-exsufflation decreases episodes of respiratory failure, particularly during upper-respiratory-tract infection, and provides greater success in weaning from mechanical ventilation than do conventional methods. Alternatives to insufflation-exsufflation that can produce sufficient peak cough flow for airway clearance include (1) insufflation to maximum insufflation capacity (via breath-stacking with a bag and mask, a volume ventilator, or glossopharyngeal breathing) followed by a spontaneous cough, and (2) manually assisted cough with an abdominal thrust. The effectiveness of insufflation-exsufflation in patients with obstructive lung disease, such as chronic obstructive pulmonary disease or asthma, and in pediatric patients, is less clear.