Pneumothorax Svenska

[Bessie Murrillo]

A pneumothorax is an abnormal collection of air in the pleural space between the lung and the chest wall.[3] Symptoms typically include sudden onset of sharp, one-sided chest pain and shortness of breath.[2] In a minority of cases, a one-way valve is formed by an area of damaged tissue, and the amount of air in the space between chest wall and lungs increases; this is called a tension pneumothorax.[3] This can cause a steadily worsening oxygen shortage and low blood pressure. This leads to a type of shock called obstructive shock, which can be fatal unless reversed.[3] Very rarely, both lungs may be affected by a pneumothorax.[6] It is often called a "collapsed lung", although that term may also refer to atelectasis.[1]

A primary spontaneous pneumothorax is one that occurs without an apparent cause and in the absence of significant lung disease.[3] A secondary spontaneous pneumothorax occurs in the presence of existing lung disease.[3][7] Smoking increases the risk of primary spontaneous pneumothorax, while the main underlying causes for secondary pneumothorax are COPD, asthma, and tuberculosis.[3][4] A traumatic pneumothorax can develop from physical trauma to the chest (including a blast injury) or from a complication of a healthcare intervention.[8][9]

Diagnosis of a pneumothorax by physical examination alone can be difficult (particularly in smaller pneumothoraces).[10] A chest X-ray, computed tomography (CT) scan, or ultrasound is usually used to confirm its presence.[5] Other conditions that can result in similar symptoms include a hemothorax (buildup of blood in the pleural space), pulmonary embolism, and heart attack.[2][11] A large bulla may look similar on a chest X-ray.[3]

A primary spontaneous pneumothorax (PSP) tends to occur in a young adult without underlying lung problems, and usually causes limited symptoms. Chest pain and sometimes mild breathlessness are the usual predominant presenting features.[12][13] In newborns tachypnea, cyanosis and grunting are the most common presenting symptoms.[14] People who are affected by a PSP are often unaware of the potential danger and may wait several days before seeking medical attention.[15] PSPs more commonly occur during changes in atmospheric pressure, explaining to some extent why episodes of pneumothorax may happen in clusters.[13] It is rare for a PSP to cause a tension pneumothorax.[12]

Upon physical examination, breath sounds (heard with a stethoscope) may be diminished on the affected side, partly because air in the pleural space dampens the transmission of sound. Measures of the conduction of vocal vibrations to the surface of the chest may be altered. Percussion of the chest may be perceived as hyperresonant (like a booming drum), and vocal resonance and tactile fremitus can both be noticeably decreased. Importantly, the volume of the pneumothorax may not be well correlated with the intensity of the symptoms experienced by the victim,[15] and physical signs may not be apparent if the pneumothorax is relatively small.[13][15]

Tension pneumothorax is generally considered to be present when a pneumothorax (primary spontaneous, secondary spontaneous, or traumatic) leads to significant impairment of respiration and/or blood circulation.[16] This causes a type of circulatory shock, called obstructive shock. Tension pneumothorax tends to occur in clinical situations such as ventilation, resuscitation, trauma, or in people with lung disease.[15] It is a medical emergency and may require immediate treatment without further investigations (see Treatment section).[15][16]

The most common findings in people with tension pneumothorax are chest pain and respiratory distress, often with an increased heart rate (tachycardia) and rapid breathing (tachypnea) in the initial stages. Other findings may include quieter breath sounds on one side of the chest, low oxygen levels and blood pressure, and displacement of the trachea away from the affected side. Rarely, there may be cyanosis (bluish discoloration of the skin due to low oxygen levels), altered level of consciousness, a hyperresonant percussion note on examination of the affected side with reduced expansion and decreased movement, pain in the epigastrium (upper abdomen), displacement of the apex beat (heart impulse), and resonant sound when tapping the sternum.[16]

Tension pneumothorax may also occur in someone who is receiving mechanical ventilation, in which case it may be difficult to spot as the person is typically receiving sedation; it is often noted because of a sudden deterioration in condition.[16] Recent studies have shown that the development of tension features may not always be as rapid as previously thought. Deviation of the trachea to one side and the presence of raised jugular venous pressure (distended neck veins) are not reliable as clinical signs.[16]

Spontaneous pneumothoraces are divided into two types: primary, which occurs in the absence of known lung disease, and secondary, which occurs in someone with underlying lung disease.[17] The cause of primary spontaneous pneumothorax is unknown, but established risk factors include being of the male sex, smoking, and a family history of pneumothorax.[18] Smoking either cannabis or tobacco increases the risk.[3] The various suspected underlying mechanisms are discussed below.[12][13]

Secondary spontaneous pneumothorax occurs in the setting of a variety of lung diseases. The most common is chronic obstructive pulmonary disease (COPD), which accounts for approximately 70% of cases.[18] The following known lung diseases may significantly increase the risk for pneumothorax.

In children, additional causes include measles, echinococcosis, inhalation of a foreign body, and certain congenital malformations (congenital pulmonary airway malformation and congenital lobar emphysema).[19]

A traumatic pneumothorax may result from either blunt trauma or penetrating injury to the chest wall.[13] The most common mechanism is the penetration of sharp bony points at a new rib fracture, which damages lung tissue.[18] Traumatic pneumothorax may also be observed in those exposed to blasts, even when there is no apparent injury to the chest.[9]

Traumatic pneumothoraces may be classified as "open" or "closed". In an open pneumothorax, there is a passage from the external environment into the pleural space through the chest wall. When air is drawn into the pleural space through this passageway, it is known as a "sucking chest wound". A closed pneumothorax is when the chest wall remains intact.[23]

Pneumothorax was reported as an adverse event caused by misplaced nasogastric feeding tubes. Avanos Medical's feeding tube placement system, the CORTRAK* 2 EAS, was recalled in May 2022 by the FDA due to adverse events reported, including pneumothorax, leading to 60 injuries and 23 patient deaths as communicated by the FDA.[24]

Medical procedures, such as inserting a central venous catheter into one of the chest veins or taking biopsy samples from lung tissue, may also lead to pneumothorax. The administration of positive pressure ventilation, either mechanical ventilation or non-invasive ventilation, can result in barotrauma (pressure-related injury) leading to a pneumothorax.[13]

Divers who breathe from an underwater apparatus are supplied with breathing gas at ambient pressure, which results in their lungs containing gas at higher than atmospheric pressure. Divers breathing compressed air (such as when scuba diving) may develop a pneumothorax as a result of barotrauma from ascending just 1 metre (3 ft) while breath-holding with their lungs fully inflated.[25] An additional problem in these cases is that those with other features of decompression sickness are typically treated in a diving chamber with hyperbaric therapy; this can lead to a small pneumothorax rapidly enlarging and causing features of tension.[25]

Pneumothorax is more common in neonates than in any other age group. The incidence of symptomatic neonatal is estimated to be around 1-3 per 1000 live births. Prematurity, low birth weight and asphyxia are the major risk factors, and a majority of newborn infant cases occur during the first 72 hours of life.[26][27][14]

The thoracic cavity is the space inside the chest that contains the lungs, heart, and numerous major blood vessels. On each side of the cavity, a pleural membrane covers the surface of lung (visceral pleura) and also lines the inside of the chest wall (parietal pleura). Normally, the two layers are separated by a small amount of lubricating serous fluid. The lungs are fully inflated within the cavity because the pressure inside the airways (intrapulmonary pressure) is higher than the pressure inside the pleural space (intrapleural pressure). Despite the low pressure in the pleural space, air does not enter it because there are no natural connections to air-containing passages, and the pressure of gases in the bloodstream is too low for them to be forced into the pleural space.[13] Therefore, a pneumothorax can only develop if air is allowed to enter, through damage to the chest wall or to the lung itself, or occasionally because microorganisms in the pleural space produce gas.[13] Once air enters the pleural cavity, the intrapleural pressure increases, resulting in the difference between the intrapulmonary pressure and the intrapleural pressure (defined as the transpulmonary pressure) to equal zero, which cause the lungs to deflate in contrast to a normal transpulmonary pressure of 4 mm Hg.[28]

Chest-wall defects are usually evident in cases of injury to the chest wall, such as stab or bullet wounds ("open pneumothorax"). In secondary spontaneous pneumothoraces, vulnerabilities in the lung tissue are caused by a variety of disease processes, particularly by rupturing of bullae (large air-containing lesions) in cases of severe emphysema. Areas of necrosis (tissue death) may precipitate episodes of pneumothorax, although the exact mechanism is unclear.[12] Primary spontaneous pneumothorax (PSP) has for many years been thought to be caused by "blebs" (small air-filled lesions just under the pleural surface), which were presumed to be more common in those classically at risk of pneumothorax (tall males) due to mechanical factors. In PSP, blebs can be found in 77% of cases, compared to 6% in the general population without a history of PSP.[29] As these healthy subjects do not all develop a pneumothorax later, the hypothesis may not be sufficient to explain all episodes; furthermore, pneumothorax may recur even after surgical treatment of blebs.[13] It has therefore been suggested that PSP may also be caused by areas of disruption (porosity) in the pleural layer, which are prone to rupture.[12][13][29] Smoking may additionally lead to inflammation and obstruction of small airways, which account for the markedly increased risk of PSPs in smokers.[15] Once air has stopped entering the pleural cavity, it is gradually reabsorbed.[15]

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