2-43
2-43. ATELECTASIS
a. Atelectasis is defined as collapse of the lung. This means the collapse of an alveolus or multiple alveoli. There are two different mechanisms that may cause alveolar collapse.
(1) Pressure on the lung that restricts normal lung expansion of the alveoli. Whenever there is an overcrowding of the thoracic contents, the spongy lung tissue will be the first thing to collapse as a result of the compression. Such pressure may be caused by pleural effusion, pneumothorax, tumor growth, or an upwardly displaced diaphragm.
(2) Obstruction of a bronchus may restrict airflow to and from the communicating alveoli. This may be caused by inhalation of a foreign body, but the most frequent cause is the presence of thick mucous that is not removed by coughing. Postoperative patients and debilitated bedridden patients are susceptible to obstructive atelectasis due to inadequate depth of respiration and the accumulation of bronchial secretions.
b. If a sudden collapse involving sufficient tissue occurs, the following signs and symptoms may be present: dyspnea, tachycardia, anxiety, cyanosis, and pleural pain. The chest wall of the affected side will barely move on respiration.
c. Treatment involves the identification and correction of the underlying cause. If the presence of air or fluid in the pleural space is causing compression, measures should be taken to remove the air or fluid by thoracentesis or chest tube insertion. Bronchial obstruction should be removed by the use of vigorous percussion, coughing, and postural drainage. Secretions may be loosened and liquefied by the use of humidification and increased fluid intake.
d. Postoperative atelectasis can be reduced significantly by the use of early ambulation, incentive spirometery, and a rigorously enforced program of deep breathing and coughing.
