When air leaks out of the lungs it is generally referred to as a collapsed lung, or scientifically referred to as a pneumothorax.
Defined, a pneumothorax is when air enters the space the surrounds the lungs called the pleural space. Air can enter the pleural space either from a small hole in the lungs (leak), or from the chest wall, as in what might occur from a trauma or bullet or knife wound.
Many times during the course of life a person may have small pneumothoraces that go un-noticed. This can cause pain, but not always. Larger pneumothoraces, however, pain may be the result, but the patient will also become dyspneic (short of breath.).
A patient becomes short of breath because air in the pleural space makes the lung involved much smaller, and the effected part of the lung won't be able to participate in air exchange.
What are causes of an air leak?
1. Spontaneous: No particular reason (idiopathic)
2. Spontaneous: Rupture of bleb (emphysema), cyst or bulla
3. Rupture of esophogus that causes air to leak into pleural region
4. Chronic lung disease: Severe asthma, Severe COPD, Pulmonary Fibrosis (interstitial lung disease)
5. Positive Pressure Ventilation: PEEP or too high volumes
6. Trauma
7. Side effect of thorocentesis or lung biopsy
8. Side effect of insertion of central venous catheters
How to detect an air leak?
1. Patient agitation: Pain, general misery, dyspnea
2. Reduced chest expansion: with each breath
3. Increased resonance with percussion
4. Breath sounds: diminished over leak, or pleural rub (grating sound on expiration)
5. No tactile fremitis over air leak
6. Chest x-ray: The line of the pleural sac can be seen inside the lung where it doesn't belong
7. Low pulse ox (SpO2) or ABG PO2
8. Trachea shift away from the affected side (air pushes mediastinal contents away). This is most evident of a tension pneumothorax (see below)
How do you treat a pneumothorax?
1. Spontaneously: if small the air will be reabsorbed naturally. About 70 percent of pnneumothoracies are of this nature.
2. Chest tube: usually needed for large air leaks, or about 30 percent of pneumothoracies. I have a post about this coming up soon, so stay tuned.
3. Thorocentesis: Inserting a large bore needle into pleural sack to let air out (temporary relief)
Tension pneumothorax: This is where air enters the pleural space on inspiration but cannot escape during expiration. The air in pleural space keeps increasing with each successive breath, and the lung gets more an more squished with each breath. This is most common in ventilated patients when too much pressure is used causing an air leak. This must be relieved immediately with a chest tube. If no time to insert chest tube, a large bore needle should be inserted into pleural space (thorocentesis).
Hemathorax: This is when blood gets into the pleural space. What can cause blood in the pleural space:
- Trauma
- Tuberculosis
- Pulmonary infarction
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