Pneumothorax: Clinical sciences

Pneumothorax refers to an abnormal presence of air within the pleural space that can result in a deflated or collapsed lung. The pleural space has a parietal layer, which lines the chest wall, and a visceral layer, which lines the parenchyma of the lung. Disruption of either of the pleural layers can allow air to enter the pleural space.

This can occur spontaneously, usually due to rupture of anatomic lung defects called blebs and bullae, or traumatic, which might occur after a penetrating chest injury or even a medical procedure. Based on the underlying cause, pneumothorax can be classified as spontaneous pneumothorax, which is further subdivided into primary- and secondary spontaneous pneumothorax; and non spontaneous pneumothorax.

Now, if you suspect pneumothorax, you should first perform an ABCDE assessment to determine if your patient is unstable or stable. If the patient is unstable, stabilize the airway, breathing, and circulation. This means that you’ll need to assess the need for ventilatory support and might need to intubate the patient. Next, obtain IV access, provide supplemental O2 to maintain SaO2 >92% and put your patient on continuous vital sign monitoring, such as pulse oximetry, blood pressure, and heart rate.

Next, perform a focused history and physical and get a chest x-ray as soon as possible. Your patient might report sudden chest pain and shortness of breath while your exam will reveal an asymmetric chest and tracheal deviation away from the affected side, as well as hypotension, respiratory distress, and decreased or absent breath sounds on the affected side. Keep in mind that tension pneumothorax is a clinical diagnosis and doesn’t need further testing.

However, if you were to perform a chest x-ray, it would show a distinct visceral pleural edge with an absence of lung markings distally, often with a depressed hemidiaphragm ipsilateral to the collapsed lung, known as a deep sulcus sign. In severe cases, you’d see shifting of the mediastinum contralateral to the collapsed lung.

Okay, listen up! Here’s a clinical pearl… Since tension pneumothorax is so dangerous, it should be diagnosed based on clinical suspicion, and treatment should not be delayed, even if imaging has not been performed or results are not yet available. In fact, you’ll want to perform immediate decompression with needle thoracostomy. Identify the second intercostal space where it intersects with the midclavicular line, then insert an angiocatheter through the chest wall, just above the rib. If effective, you will release the trapped air, allowing the lung to reinflate and relieve any mediastinal compression. You will later need to proceed with tube thoracostomy, or placement of a chest tube connected to continuous low pressure suction to allow full reinflation and decrease chances of recurrence.

Now, let’s jump back to the ABCDE assessment and take a look at stable patients. If your patient is stable, proceed with a focused history and physical examination. Your patient is likely to report the sudden onset of pleuritic chest pain, or pain that gets worse with deep breathing, as well as shortness of breath. Common examination findings include tachypnea, shallow breathing, and decreased or absent breath sounds on the affected side of the chest. If these findings are present, suspect pneumothorax and order a chest x-ray.

Look for a visceral pleural edge, absence of lung markings, and a deep sulcus sign, while keeping in mind that a mediastinal shift is less likely to be present in a stable patient. At this point, you can be sure that the diagnosis is pneumothorax. On other hand, if you notice findings that are inconsistent with pneumothorax, you should consider an alternative diagnosis.

Now that you’ve diagnosed pneumothorax, the next step is to assess the underlying cause. Ask about a history of trauma to the chest wall and any recent medical procedures where inadvertent trauma may have occurred. If neither of these is present, then the pneumothorax is said to be spontaneous.

If spontaneous pneumothorax occurs in the absence of trauma or known lung condition, the pneumothorax is said to be primary. Risk factors for primary spontaneous pneumothorax include young age, tall height, thin body habitus, and being a biologically male individual. Now, the first step in management of a patient with a primary spontaneous pneumothorax is to assess the size of the pneumothorax.