Chapter 32. Spontaneous and Iatrogenic Pneumothorax

Pneumothorax occurs when air enters the potential space between the parietal and visceral pleura, leading to partial lung collapse. Smoking is the most common risk factor for spontaneous pneumothorax, which most likely results from subpleural bulla rupture. Primary pneumothorax occurs in patients without known lung disease and secondary pneumothorax occurs most often in patients with chronic obstructive pulmonary disease, but other underlying diseases such as asthma, cystic fibrosis, interstitial lung disease, cancer, and Pneumocystis carinii pneumonia have been implicated. Iatrogenic pneumothorax occurs secondary to invasive procedures such as needle biopsy of the lung, placement of a subclavian line, nasogastric tube placement, or positive pressure ventilation. Tension pneumothorax results from positive pressure in the pleural space leading to decreased venous return, hypotension, and hypoxia. Hemopneumothorax occurs in 2% to 7% of patients with spontaneous pneumothorax.

Symptoms resulting from a pneumothorax are directly related to its size, rate of development, and the health of the underlying lung. Acute onset of pleuritic pain is found in most patients, whereas a large volume pneumothorax may cause dyspnea, tachycardia, hypotension, and hypoxia. Decreased breath sounds on the affected side have a positive predictive value between 86% and 97%. Hypotension, tracheal deviation, and hyperresonance of the affected side are the hallmarks of tension pneumothorax.

Pneumothorax is usually diagnosed by posteroanterior chest x-ray which has a sensitivity of 83%. Expiratory films are no more helpful than inspiratory films. Chest CT is more sensitive and may be useful in patients with bullous changes on x-ray. Ultrasound can be used and has a sensitivity approaching 100%. Ultrasound signs include absence of lung sliding in real-time (100% sensitive but not specific), the demonstration of a “lung point” (66% sensitive and nearly 100% specific), and absence of normal vertical comet-tail artifacts. The clinician should be aware that a pneumothorax can be associated with ST changes and T wave inversion on EKG.

1. In patients with unstable vital signs and clinical features suggestive of tension pneumothorax, immediate needle thoracostomy followed by tube thoracostomy is indicated. X-rays should not be obtained before treatment.

2. In stable patients, oxygen 2 to 4 L/min by nasal canula helps increase resorption of intrapleural air.

3. Patients with small primary pneumothoraces may be observed for 6 hours and discharged with surgical follow-up if there is no enlargement on repeat x-ray. However, many eventually require tube thoracotomy.

4. A catheter or needle may be used to simply aspirate a small pneumothorax with success rates from 37% to 75%. The patient can be discharged with surgical follow-up at 6 hours postaspiration if there is no pneumothorax recurrence.

5. A small catheter can be used to aspirate the pleural space and then attached to a Heimlich valve and left secured in place. The patient may be discharged at 6 hours postaspiration with surgical follow-up if there is no pneumothorax recurrence.

6. Tube thoracostomy and admission are indicated for failed aspiration, large pneumothorax, recurrent pneumothorax, bilateral pneumothoraces, hemothorax, abnormal vital signs, or severe dyspnea. The ...