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[atelo- + -ectasis]
1. A collapsed lung; an airless lung.
2. A condition in which the lungs of a fetus remain partially or totally unexpanded at birth.
SEE: respiratory distress syndrome of the preterm infant
It also may be caused by obstruction of one or more airways with mucus plugs; by hypoventilation secondary to pain, e.g., from fractured ribs or related to surgery, or to ventilation with inadequate tidal volumes; by inadequate surfactant production; or by compression of the lung externally or the lung or bronchi by tumors, aneurysms, or enlarged lymph nodes. It is sometimes a complication following abdominal or thoracic surgery, caused by splinting. Thoracic and high abdominal surgery poses extra risks because of the location of the incision. It occurs in patients with chronic obstructive pulmonary disease, bronchiectasis, or cystic fibrosis, and also in those who smoke tobacco heavily.
SEE: middle lobe syndrome
Symptoms may not be present if the atelectasis is minor and the patient has previously healthy lungs. Dyspnea is common when the atelectasis is severe.
Treatment varies with the cause. The patient with atelectasis due to persistent ventilation with small tidal volumes is given lung expansion therapy such as incentive spirometry. During mechanical ventilation, the patient should receive appropriate tidal volume, and positive end-expiratory pressure (PEEP) to increase increase functional residual capacity. Oxygen should be administered at the lowest setting that will prevent hypoxemia. The patient should be weaned from the ventilator and extubated as soon as possible. The patient with atelectasis due to mucus plugging needs bronchial hygiene therapy to assist with mucus removal. Artificial surfactant may be useful for the infant with premature lungs and atelectasis.
Patients at risk (esp. those who have had chest or high abdominal surgeries or those with underlying chronic problems with ventilation) are evaluated for dyspnea, decreased chest wall movement, inspiratory substernal or intercostal retractions, diaphoresis, tachypnea, tachycardia, and pleuritic chest pain. Lung fields are percussed for decreased resonance, and the chest is auscultated for abnormal breath sounds (diminished breath sounds, bronchial breath sounds in areas of consolidation, and fine, late-inspiratory crackles). Pulse oximetry and arterial blood gas values are monitored for evidence of hypoxemia. Bronchial hygiene therapies are useful for the patient with atelectasis due to retained pulmonary secretions. Positioning the patient in semi-Fowler’s and occasionally high-Fowler’s position (unless specifically contraindicated) helps increase lung capacity and encourage deeper breathing. The patient should also be encouraged and helped to sit in a chair and walk as soon as possible. The nurse or respiratory therapist instructs and monitors the patient on the use of incentive spirometry to prevent or correct existing atelectasis. Using this calibrated device, the patient takes slow, sustained maximal inspirations to total lung capacity, holds the breath for 5 seconds, and exhales passively to help keep the alveoli open. This should be done about 10 times an hour while the patient is awake. Adequate pain control, frequent coaching, reinforcement, and praise are essential to be sure that the appropriate technique is employed. Patients anticipating surgery should be taught correct use of incentive spirometry preoperatively to allow time for practice.
SEE: incentive spirometry
Adequate fluid intake is encouraged, inspired air is humidified as necessary, and the patient is assisted to mobilize and clear secretions. Intubated or obtunded patients are suctioned as necessary.