Origin and Classification
The spontaneous pneumothorax was first described in 1933 by Kjaergaard with the pathophysiological mechanism of a rupture of a peripheral lung bleb and escape of air. (1) Free air in the pleural space was first diagnosed in 1910 by Laennec in connection with other diseases, often tuberculosis. The incidence is currently stated as 22 cases per 100,000 inhabitants per year, with the ratio of men to women being 3:1. (2)
Clinical Classification
- Primary Spontaneous Pneumothorax
By definition, primary spontaneous pneumothorax affects otherwise healthy individuals without external influence and spontaneously, with a peak age below the 30th year of life. There is no association with other known lung diseases. Clinically relevant special forms to be distinguished are tension pneumothorax and spontaneous hemopneumothorax. Both forms occur in up to 5% of cases with spontaneous pneumothorax and require immediate treatment. (3, 4)
- Secondary Spontaneous Pneumothorax
In secondary spontaneous pneumothorax, a lung disease is found in the patient's history. This form of pneumothorax therefore occurs more frequently in older age as a manifestation of severe pulmonary emphysema, bronchial carcinoma, and other lung diseases. Here, tension pneumothorax occurs significantly more frequently than in spontaneous pneumothorax (15-30%). (3)
- Traumatic Pneumothorax
Traumatic pneumothorax is defined by an external influence, with the most common cause being a medical procedure, for example iatrogenic after puncture. A penetrating or blunt thoracic trauma can also cause a pneumothorax through direct lung injury or severe contusion with tearing of the lung parenchyma.
- Catamenial Pneumothorax
Catamenial pneumothorax is a rare special form of spontaneous pneumothorax, in which endometriosis foci on the lung surface trigger a cycle-dependent pneumothorax.
Symptomatology
The clinical symptomatology of a pneumothorax is very variable, but usually consists of a combination of chest pain and shortness of breath. An anamnestic connection to physical activity plays no role and is not documented in the literature. In tension pneumothorax, a valve mechanism develops, leading to a continuous increase in intrathoracic pressure with compression of the venous return to the heart. From this, the clinical symptoms can be derived, consisting of tachycardia, drop in blood pressure, tachypnea, dyspnea and shortness of breath, as well as in late stages upper jugular vein congestion, hypoxia, and cardiogenic shock. In spontaneous hemopneumothorax, tearing of a well-vascularized adhesion strand and the combination of negative intrathoracic pressure and good perfusion of the pleura lead to rapid blood loss of 1-3 liters. In addition to typical imaging, hemopneumothorax can additionally be diagnosed with a drop in hemoglobin and, in the course, hypovolemic shock. (4)
Imaging Diagnostics
With variable symptomatology, imaging plays a crucial role in diagnostics. Chest X-ray is contrasted with chest ultrasound. With appropriate experience, ultrasound is superior to simple X-ray and achieves similar sensitivity to computed tomography. Due to bedside availability, quick feasibility, and absence of any radiation exposure, ultrasound is the ideal examination for this condition. Ultrasound can also be used for later therapy with drainage to determine the incision height and, for example, to rule out diaphragmatic elevation. In cases of pronounced pre-existing lung diseases or previous thoracic surgery, ultrasound assessment is much more difficult, which is why an X-ray and possibly a computed tomography are often useful here.
Treatment
The treatment of any form of pneumothorax usually requires the placement of a chest drain and connection to a continuous drainage system to support lung re-expansion. Conservative non-interventional therapy is much discussed and practiced differently internationally. In patients with small pneumothorax (under 20% of hemithorax volume) and clinical absence of symptoms, observation is also adequate.
Recurrence and Surgery
The recurrence risk for patients with spontaneous pneumothorax is 20-30%. (6) In large pneumothorax, bullous changes at the lung apex, or history of recurrence, this risk can increase to 70-100%. (7)
Surgery for pneumothorax is therefore indicated not only in persistent air fistula or insufficient drainage, but also as recurrence prophylaxis in a corresponding risk constellation. Using video-assisted thoracoscopy, lung apex resection, and pleurectomy, the risk can be reduced to 2-8%. (8)