Pathophysiology of spontaneous pneumothorax
The abnormal collection of air within the pleural space between the chest wall and lungs is considered as pneumothorax. When air leaks into the pleural space it pushes the outside of the lungs and resulted in collapse. Pneumothorax can be caused due to a blunt chest injury or due to some underlying damage from lung disease (Ashby et al., 2014). Spontaneous pneumothorax can be described as primary spontaneous pneumothorax (PSP) and secondary spontaneous pneumothorax (SSP). There are many risk factors of pneumothorax as well, for example, smoking, sex age, genetics, mechanical ventilation, lung disease or a previous case of pneumothorax. Symptoms include chest pain, shortness of breath, pain during inhaling, loss of consciousness, increased heart rate, blue discoloration of lip and skin and rapid breathing (Bintcliff et al., 2015). The disease can be diagnosed using X-ray, CT scan and other radiography. In order cure the illness proper medical attention is most important. Effective medication, oxygen therapy, even surgical treatment is required for some cases (Hussain et al., 2012). According to a study the annual age-adjusted incidence rate of PSP is 3 to 6 times high (Papagiannis et al., 2015). Thus it is important to provide effective focus to address the issue of the illness by improving the medical service.
In this regards, the assignment will focus to provide a brief discussion regarding pneumothorax. The following paper will provide the detail information about the Pathophysiology, epidemiology, radiographic projection and appearance of pneumothorax. In addition the paper will discuss about the further steps that are required for a patient with pneumothorax to manage the illness in an effective manner.
The abnormal collection of air in the pleural space that is between the lungs and chest wall (visceral pleura and the parietal pleura) leads to the consequence of pneumothorax (Ashby et al., 2014).The negative pressure of pleural cavity will disappear when any communication will develop: through alveolus intrapulmonary air space or chest cavity. The incident results in the lung collapse (Walke et al., 2018).Spontaneous pneumothorax is diagnosed when no trauma (accidental or iatrogenic) has been present (Thomsen et al., 2014). Spontaneous pneumothorax can be divided into two types: primary spontaneous pneumothorax (PSP) and secondary spontaneous pneumothorax (SSP) (Ashby et al., 2014). The potential risk factors of PSP include sex, past family history of pneumothorax and smoking. High intake of tobacco increases the risk of PSP (Walker et al., 2018). On the other hand, SSP occurs due to the setting different lung diseases. It has been found that in 70% cases COPD especially in combination with emphysema and lung bullae has increased the risk of SSP (Bintcliff et al., 2015). Other severe disease that could lead to the development of SSP include-
- obstructive airway disease (asthma)
- Lung and pleural malignancy (carcinoma),
- Infection (tuberculosis, pneumonia – especially caused by Pneumocystis jiroveci),
- Suppurative lung disease (cystic fibrosis, bronchiectasis, lung abscess),
- Interstitial lung disease (sarcoidosis, idiopathic pulmonary fibrosis, hypersensitivity pneumonitis) (Papagiannis et al., 2015).
Epidemiology and symptomatology of spontaneous pneumothorax
It has been found that the epidemiology and demographics are different for subtypes of spontaneous pneumothorax (PSP and SSP). Most of the reported cases have indicated that, around 80 to 90 percent cases of spontaneous pneumothorax is due to the ruptured sub-pleural bleb (air-filled space between the lung parenchyma and the visceral pleura) or bullae (air-filled space within the lung parenchyma itself) (Papagiannis et al., 2015). The peak incidence of PSP occurs in early 20s. It has been found that the most vulnerable demography is the people aged between 20 to 30 years old. PSP is rarely diagnosed in the people aged 40 years old or more. Research has indicated that the age adjusted incidence rate for male and female for PSP is 7.4 to 18 cases per 100,000 and 1.2 to 6 cases per 100,000 cases respectively. The ratio of age adjusted incidence rate for PSP in male and female is 6.2:1. On the other hand the development of SSP is found more frequently in the people with 60 to 65 years age. The age adjusted incidence rate for male and female for SSP is 6.3 cases per 100,000 and 2 cases per 100,000 cases respectively. The ratio of age adjusted incidence rate for SSP in male and female is 3.2:1. The data has clearly indicated that risk of spontaneous pneumothorax is higher in male as compare to female (Bobbio et al., 2015).
The onset of the disease is usually acute and presents as sudden chest pain of pleuritic character concomitant with dyspnoea (even at rest). In addition to breathlessness, symptoms may include tachypnoea and tachycardia, more silent breath sound as well as reduced chest expansion hyper-resonanceonto the affected side (Tschopp et al., 2015). In general severity of the symptoms depends on existence of underlying lung disease, size of pneumothorax, speed of its development and level of interpleural pressure (Henry et al., & British Thoracic Society, 2003). Dyspnea, cutting-like pain and dry cough are the most common symptoms which develop due to the pleural stimulation by the air. Other common symptoms include pain during inhaling, loss of consciousness, increased heart rate, blue discoloration of lip and skin and rapid breathing (Bintcliff et al., 2015).
Chest radiography is one of the most effective choices of imaging spontaneous pneumothorax. Posterior-anterior x-ray provides the most common view of spontaneous pneumothorax. In this radiography, X-rays are coming from the behind of the patient and are interpretedfromthe front. In case of digital radiography, a 2.5-lp/mm spatial resolution is usually enough in order to detect a pneumothorax (Silva et al., 2010).
Radiographic projection of spontaneous pneumothorax
The figure is showing the PA view, a complete bilateral pneumothorax without evidence of pneumomediastinum, pneumopericardium, or subcutaneous emphysema.(Garrido& Aguilera, 2012)
In case of strong clinical suspicion of SSP, an additional view is performed. However, the PA x-ray radiography appears normal. Anteroposterior (AP) X-ray is another effective radiography used for detecting spontaneous pneumothorax. In this case x-rays are coming from front of the patient and are interpreted from behind. The x-rays are harder to interpret and the radiography is performed only under specific circumstances, for example when the patient is unable to leave the bed and for most “supine films” when patient is lying (Silva et al., 2010).
Another important radiography is lateral radiography in which left arm of the patient is raised and flat panel is pressed against the left side of the chest (Connor et al., 2005).
Expiratory chest X-ray is also performed in order to diagnose spontaneous pneumothorax. When the volume of air in the pleural cavity is bigger as compare to the volume of lung the radiography provides clearly visible image of the pleural separation renders the visceral surface (Salazar et al., 2014).
The figure is showing the example of comparing images of expiratory radiography in order detect spontaneous pneumothorax. The picture in the right side is showing presence of spontaneous pneumothorax.
Source: (Garrido& Aguilera, 2012)
Decubitus radiography is usually used to diagnose spontaneous pneumothorax, when patient fails to stand up. In this radiography, the lack of composite shadows makes small volumes of free air easily visible parallel to the chest wall on the suspected side. It is a specialized projection that helps to define small pleural effusion (Tschopp et al., 2015).
The figure is showing the illustration of pneumothorax confirmed by the left decubitis chest x-ray.
Source: (Silva et al., 2010)
In addition horizontal beam radiography could be used as alternative radiography to detect pneumothorax. It helps to diagnose pneumothorax, as well as pleural effusion. The process of detecting pneumothorax could be improved through horizontal directed x-ray beam by positioning the patient in such a way so that x-ray beam could strike the accumulation tangential area (Thomsen et al., 2014).
The radiographic appearance of spontaneous pneumothorax depends on the radiographic projection, the patient’s position, and the presence or absence of pleural adhesion and subsequent loculation. (Silva et al., 2010)It is based on the identification of a visceral pleural line separated from the parietal pleura by a radiolucent airspace. Pulmonary vessels can be followed to the visceral pleural line, but they do not cross it. When the underlying lung disease is absent, the pleural line of pneumothorax is usually parallel to the chest wall (Connr et al., 2005).
Discussion of Radiographic Appearance and Pathology
According to the British Thoracic Society the distance between lung edge and chest wall on PA chest radiograph) should be measured at the level of helium – not apex. If the result detect a distance that is smaller than 2 cm it is considered as small pneumothorax and if the distance is greaterthan 2 cm. it is considered as large (Henry et al., & British Thoracic Society, 2003 )
The American College of Chest Physicians considers smallpneumothoraxes with less than 3-cm apex-to-cupola distance and large pneumothoraxes with greater thanor equal to 3-cm apex-to-cupola distance (Baumann et al., 2001).
It has been found that main appearance of pneumothorax include white visceral pleural line that is separated from the parietal pleura through a collection of air. The appearance of visceral pleural line may be straight or convex towards the chest wall. The amount of gas visible in the radiograph is 50 ml approx. In addition pneumothorax is identified with significant loss of lung volume (collapsed lung). This is due to the reduction in the blood flow in the collapsed lung (Thomsen et al., 2014).
Differential diagnosis should include presence of: medial border of the scapula, skin folds, companion’s shadows (for example rib’s grooves), scarring material usually after pleurectomy, the outline of oxygen reservoir bag, clothes or bedsheets (Tschopp et al., 2015).
Fig: AP erect film, 80M. Bilateral skin folds mimics pneumothorax.
Source: (Salazar et al., 2014)
Further diagnosis may include CT scan, MRI and Ultrasonography (Tschopp et al., 2015). In order to identify the Lung CT scan is a gold standard for the diagnosis of spontaneous pneumothorax. It helps to identify pneumothorax and measurements as well. When X-ray images are hard to interpret or when specific drain placement is required, lung CT scan is performed. One of the main requirements for using CT scan is to distinguish an emphysematous bulla from a pneumothorax, which can be difficult on standard radiographs. CT scan is also a gold standard for pneumothorax size quantification ( Thomsen et al., 2014).
The figure is showing CT’s coronal lung window. Loculated pneumothorax due to pleural adhesions with apical lung bullae or blebs.
Source: (Tschopp et al., 2015)
The figure is showing CT axial, 50M. Signs of bullous emphysema of apical predominance, and presence of right secondary spontaneous pneumothorax.
Source: (Thomsen et al., 2014)
One of the fast and reliable method pneumothorax imaging is Ultrasonography. It is mostly done with the critical patients that are suffering from life threatening condition. Sonographic signs, including ‘lung sliding’, ‘B-lines’ or ‘comet tail artifacts’, ‘A-lines’, and ‘the lung point sign’ could help in the diagnosis of a pneumothorax. However, it is hard to measure the size of pneumothorax with Ultrasonography ( Kirkpatrick et al., 2001)
Significance and Implications of Pneumothorax
The figure is showing lung point of transthoracic sonography image.
Source: (Kirkpatricket al., 2001)
Use of MRI has progressed effectively due to its speed and clear imaging. Mri revealed the presence of pneumothorax with the indication of rounded nodules on pleural surface. It has been found that MRI provides more clear image than CT scan thus make it easy to detect pneumothorax (Tschopp et al., 2015).
The figure is showing MRI sequence indicating right hydropneumothorax.
Source: (Thomsen et al., 2014)
Treatment ranges from 24-hour observation in hospital settings to video-assisted thoracoscopic surgery (VATS). Common clinical surgical rule is if pneumothorax is greater than 25% , chest tube drainage is required. If decided on aspiration up to 2.5 l of air can be aspirated on the first attempt. Only smoking cessation is recommended as a method of preventing the risk of pneumothorax (Vuong et al., 2018).
Conclusion:
From the above discussion it can be said that, pneumothorax is considered as the abnormal collection of air within the pleural space between the chest wall and lungs. Secondary spontaneous pneumothorax is related to life threatening situation, thus it is more severe than the primary spontaneous pneumothorax. It has been found that people aged between 20 to 30 years old are vulnerable to primary spontaneous pneumothorax and people aged between 60 to 65 years old are vulnerable to secondary spontaneous pneumothorax. Study has indicated that male are more vulnerable to pneumothorax as compare to female. Effective radiography such as PA x-ray, lateral x-ray, expiratory chest radiography and decubitus radiography could be used to diagnose pneumothorax. Alternative radiography such as horizontal beam radiography could be used. In addition, CT scan, MRI and ultrasonography could be used in severe cases. Effective treatment is present including surgical intervention and smoking cessation is considered as the only prevention method.Such findings related to the patient outcomes of pneumothorax would help to create awareness in individual. So that people could provide focus to their health status and reduce the risk of suffering from pneumothorax or any lung disease that could lead to life threatening condition.
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Further Role of imaging modalities – CT, MRI, US
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