4.4 - Pneumothorax Flashcards
What is/causes a pneumothorax?
- Pneumothorax occurs when air is introduced into the pleural space causing complete or partial collapse of the lung.
- It may be caused by blunt trauma, mechanical ventilation, central venous access devices, rib fracture and bleb rupture
What is/causes a hemothorax?
- Hemothorax occurs when blood accumulates in the pleural space. If the amount that collects is more than 1500 cc it is considered massive.
- This may be a result of blunt or penetrating trauma, lung cancer or as a complication of anticoagulation
What is/causes an open pneumothorax?
- Occurs when air freely flows from the atmosphere to the pleural space and back again, “sucking chest wound”.
- It can lead to a tension pneumothorax if covered with an occlusive dressing or if the skin flap does not allow air to escape.
- Caused by penetrating trauma, such as gunshot wounds or knife wounds
What is/causes a tension pneumothorax?
- It is a collapse of the lung caused by a one-way entrance of air flow into the pleural space. This results in increased pressure on the heart, causes a mediastinal shift to the unaffected side, and it can eventually cause circulatory collapse
- It is a potentially life threatening condition
- Can be caused by: barotrauma due to mechanical ventilation, a chest wound that allows air in but not out or a defect in the visceral pleura that behaves in the same “ball-valve” effect
What is/causes a primary spontaneous pneumothorax?
- It occurs without a precipitating event in a person who does not have known lung disease.
- In actuality, most individuals with a primary spontaneous pneumothorax (PSP) have unrecognized lung disease and the pneumothorax occurs when a subpleural bleb ruptures.
- The incidence of PSP is less in women
- Factors that have been proposed or shown to predispose patients to PSP include smoking, family history, Marfan syndrome, homocystinuria and thoracic endometriosis
What is a secondary spontaneous pneumothorax?
A pneumothorax that results from underlying parenchymal lung disease including COPD and emphysema, interstitial lung disease, necrotizing lung infections, and cystic fibrosis.
What is an Iatrogenic pneumothorax?
A pneumothorax that occurs after thoracentesis, central line placement, transbronchial biopsy, thoracic needle biopsy and barotrauma from mechanical ventilation
What are the risk factors associated with developing a pneumothorax?
- Smoking - risk increases with the duration and number of cigarettes smoked
- Gender (men are 3.3 times more likely than woman to experience this)
- Age (18 to 40 years old)
- Stature (tall, thin) men are more prone to developing pneumo’s
- Familial pneumothorax
- Mechanical ventilation
- Genetic disorders
What are the subjective/physical exam findings associated in a patient with a pneumothorax?
Subjective:
- Commonly complain of ipsilateral chest or shoulder pain with acute onset
- A history of recent chest trauma or medical procedure
- Respiratory distress, hypoxia and tachypnea are likely to be seen in patients with a large pneumothorax in a patient with underlying lung diseases
Physical Exam:
- Hyperresonace to percussion on the affected side
- Decreased level of consciousness (LOC) if hypoxemia is extreme
- Hypotension
- Cyanosis
- Tachycardia
- Shallow respirations
- Decreased or absent breath sounds on the affected side
- Deviation of the trachea to the unaffected side with severe pneumothorax
- Subcutaneous emphysema may be felt if the pneumothorax is the result of a penetrating trauma or pneumomediastinum
- A tension* pneumothorax may cause severe respiratory distress leading to circulatory collapse due to decreased cardiac output and decreased blood pressure
- An open pneumothorax: a sucking sound may be heard on inspiration*
What findings are seen in a chest x-ray of a patient with a pneumothorax?
A chest x-ray reveals collapsed lung and possible mediastinal shift depending on the size of the pneumothorax. You will see a separation of the pleural shadow from the chest wall. A chest x-ray with an AP view taken on expiration is mostly likely to show a possible pneumothorax. As patients expire and the lung volume decreases, it is replaced by air caused by a pneumothorax. But, an AP film may be also be erroneously normal so if your suspicion for a pneumothorax is high a lateral or decubitus film may assist. Remember, in a tension pneumothorax may show a mediastinal and tracheal shift toward the contralateral side and depression of the ipsilateral diaphragm.
What diagnostic tests are used to diagnose a pneumothorax?
- ABGs may reveal respiratory acidosis
- A chest x-ray reveals collapsed lung
- An EKG - may show heart strain. The changes will depend on the side that is involved. There may be diminished QRS amplitude and an anterior axis shift. In extreme cases you may see electromechanical dissociation.
- Chest U/S - can be done at bedside for the diagnosis of pneumothorax. This is extremely helpful in patients that may need to remain supine or who cannot travel safely to the radiology department. This will be helpful in critical ICU patients. Placement of the probe in the intercostal spaces provides information regarding the pleura and underlying lung parenchyma. Normal findings would include the presence of a “sliding sign” that demonstrates the movement of the visceral and parietal pleural moving against each other during inspiration. Another normal finding is “comet tails”, or a ray like opacity produced by the air filled parenchyma below the pleura. If these normal signs do not exist, a pneumothorax can be diagnosed with high reliability at the point of the probe.
- Chest CT - is the gold standard for the diagnosis of a pneumothorax as well as determining the size. It may also be useful in differentiating a pneumothorax from bullous lung disease.
How do you manage a patient with a pneumothorax?
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Small primary spontaneous pneumothorax - smaller than 15% to 20% requires only observation and serial chest x-rays to confirm that it is not getting larger.
- The air is likely to be reabsorbed and can do so within 10-14 days. If the
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Tension pneumothorax - rapid insertion of large bored (14 to 16 gauge) needle into the second intercostal space, midclavicular line of the affected side to decompress.
- An obese person or a patient with a large amount of breast tissue may not have complete resolution with a standard catheter due to inability to reach the area. These patients may require a longer needle or larger gauge needle to stent the area open to allow air to escape
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Regular peumothorax or Hemothorax - Chest tube insertion to low wall suction (- 20 cm)
- Massive hemothorax requires fluid resuscitation with lactated Ringer solution before thoracostomy due to the loss of tamponade effect. May consider an auto transfusion
- Secondary pneumothorax - may develop a large defect and may require lung expansion. Consult a pulmonologist if, in the presence of a chest tube in place, pleural sclerosis may be indicated. If there is a persistent leak around the tube, surgery may need to perform the pleural sclerosis in the OR
- Consider mechanical ventilation - with a positive end expiratory pressure of + 5, a pressure support of 10 and a tidal volume set at 6 ml/kg
- Open pneumothorax - treatment includes application of a three sided dressing leaving one side unsecured to allow air to escape
