A pneumothorax is a partial or complete collapse of the lungs, due to an air collection between lungs and chest wall (Fig.1). The lungs collapse due to the loss of physiological negative pressure that usually exists between lungs and chest wall. There are two causes: air can either enter following a traumatic injury of the chest wall - for example caused by a stab or gunshot wound - or due to a rib fracture after a fall. In this case we are talking about an external or open pneumothorax or if the air is leaking through a rupture of a lung of a so-called internal or closed pneumothorax.
Internal or closed pneumothorax
If air is internally leaking through a rupture or the visceralis pleura or the lung tissue, for example due to a medical intervention (iatrogenic) after inserting subclavian vein catheter, after pleural punction, at positive pressure mechanical ventilation, but also at diving and due to operations in the pleural space, this disease entity is termed internal or closed pneumothorax.
An internal pneumothorax is also present in case of leakage of the visceral pleura or the lung surface due to various diseases; such as for example with bronchial asthma, lung emphysema, tuberculosis or lung carcinoma. Whereas the latter is called a secondary pneumothorax, all other cases are called primary pneumothorax.
The primary spontaneous pneumothorax occurs without obvious reasons in per se patients with healthy lungs and is also defined as idiopathic. Typically young, tall and thin man, but also women in the age between approx. 15 and 35 years are affected. Frequently the disease occurs with smokers and at the tip of the lung there are small air bubbles that spontaneously ruptured. A special type of the pneumothorax is the spontaneous pneumothorax. Thereby air is intruding in the pleural space and drained. If this is progressively increasing, what is in particular the case in ventilation with pressure, the chest size is filling with air until it is under heavy pressure and compressing the heart and lung to the contralateral side. This condition is life-threatening and requires a quick pressure release by insertion of a thoracic drainage. In spontaneous breathing this does rarely results in a life-threatening situation.
Abb 1: Partial collapse of the left lung side shows a pneumothorax in X-ray imaging (dark pattern vs whitish pattern on the contralateral side indicates the pneumothorax; standing with a.p. projedtion).
The clinical symptoms of pneumothorax vary significantly. This ranges from slight tickling of the throat or light pressure feeling and pain to strong difficulty in breathing and feelings of suffocation. Basically the rule applies that if a pneumothorax occurs acutely also the probability of strong symptoms is high, whereas at a gradual slow development of a pneumothorax the symptoms are significantly milder. In most of the cases nevertheless a quick breathing (tachypnea) is the first symptom Additionally pressure feelings or pains, partially in intervals, might occur and radiate into the arms, head or back. In severe cases of breathlessness the skin turns blue-gray, which shows the oxygen shortage in the blood (cyanosis).
In case of a traumatic pneumothorax air might leaks subcutaneously; a so-called skin emphysema. At light pressure on the skin a crackling or grinding noise can be heard, similar to pressing against snow. A tension pneumothorax additionally to the mentioned symptoms includes in the beginning phase tachycardia and hypotension and in the late phase bradycardia and hypotension accrue. These symptoms, paired with increasing shortness of breathing, usually are getting worse quickly and can lead to heart failure and rapid death, unless a pressure release is performed.
In case of a unilateral pneumothorax the concerned side is poorly ventilated and an asymmetric respiratory pattern results, why the thorax is not expanding uniformly. At auscultation no or only slight breathing noises can be heard on this side. At percussion a hollow resonance, a so-called box sound, occurs. The percussion should anyhow always be performed in a comparison with the contralateral thorax side. The diagnostic imaging of choice, which usually reliably evidences a pneumothorax, is the thorax X-ray. This should be routinely be performed while standing and in inspiratory posture in two planes.
The pneumothorax is visible in the sense of missing vascular drawing. Ultrasonic examinations are increasingly performed as an alternative method, as small pneumothoraces are recognized quickly, reliably and without radiation exposure. In case of a recurrence of a pneumothorax as well as if an underlying disease is expected (secondary pneumothorax), a computer tomography (CT) should be performed, on the base of which any underlying injuries or diseases can be diagnosed.
If an idiopathic spontaneous pneumothorax is present and it occurs for the first time, it is generally treated conservatively.
The conservative therapy consists with a minor manifestation of a spontaneous pneumothorax (apical expansion smaller than 2 cm) in a strict X-ray progression monitoring. This decision should be made with detailed consideration concerning the clinical symptoms. In all other cases a thoracic drainage should be inserted, so that the negative pressure within the thorax is restored and lungs are expanding again (Fig. 2). This is usually laid under local anesthesic in the central or posterior axillary line at the height of the 5th intercostal space.
If the pneumothorax resulted from a trauma and additional injuries such as for example a rib fracture or a hemothorax (blood in the pleural space) are present, a thoracic drainage needs to be laid in order to drain the pneumothorax and any abnormal existing liquids such as blood or other effusion. In case of a tension thorax highest emergency indication prevails and the drainage needs to be laid immediately.
In case of pneumothorax recurrence, at persistent air loss over 3-4 days or presence of a secondary pneumothorax (i.e. a lung disease), a surgical intervention is recommended. This includes the endoscopy (thoracoscopy) of the affected chest cavity under general anesthetic. To close the leakage of the pleura a small wedge resection in the affected lung section should be performed, which consist of small bulla usually located in the tip area of the upper lobe. Additionally a so-called abrasio of the pleura, i.e. a roughening for bonding the lung with the chest wall is performed. In case of a 2nd recurrence of the pneumothorax after the afore mentioned operative procedures, a talc pleurodesis, a bonding of both tissues with talcum powdering is conducted.
Abb.2: complete expansion of the left lung after a thoracic drainage has been inserted.