Findings of pneumothorax and CT
In general, pneumothorax can be treated with X-ray or CT imaging to help with treatment. X-rays and CT scans are different in their role in pneumothorax and are not substituted for each other. Next, let's introduce the characteristics of pneumothorax X-ray and CT examination.
Symptoms of pneumothorax
Closed pneumothorax: small closed pneumothorax can have no obvious symptoms, if it is a large pneumothorax, causing air to enter the subcutaneous tissue, it can cause subcutaneous emphysema in the chest and neck, a large number of pneumothorax, lung tissue compression, chest tightness, shortness of breath symptoms, physical examination trachea can be moved to the opposite side, percussion is tympanum, breath sounds are weakened.
Open pneumothorax: because the outside air can freely enter and exit the pleural space, the negative pressure in the pleural space on the injured side completely disappears, and the lungs are compressed and atrophy, resulting in impaired gas exchange.
Because the pleural cavity on the unaffected side is still under negative pressure, the pressure on both sides is unbalanced, and the mediastinum moves to the unaffected side, which can also compress the lung on the unaffected side to a certain extent in severe cases, seriously affecting the ventilation function. Air enters the pleural space through the wound during inspiration, and the mediastinum is pushed toward the unaffected side, and during exhalation, air exits through the wound and the mediastinum shifts toward the affected side. The mediastinum oscillates back and forth with breathing, hindering venous blood return, causing circulatory dysfunction, and can also stimulate the mediastinum and hilar nerve, resulting in pleural pulmonary shock. At the same time, the residual air in the injured lung is sucked into the healthy side during inhalation, and the residual air in the healthy lung is expelled from the body during exhalation, and some of it is discharged into the affected lung, forming residual gas convection, affecting gas exchange, and aggravating hypoxia and carbon dioxide accumulation. Patients present with shortness of breath, dyspnea, irritability, purple severity, weak pulse, decreased blood pressure, and even shock. Physical examination may reveal an open wound on the chest wall, and the sound of air entering and exiting the pleural space with breathing may be heard—the trachea moves to the unaffected side, the injured side is pomming with a tympanum, and the breath sounds are decreased or absent on auscultation.
Tension pneumothorax: After chest trauma, the patient develops acute dyspnea, cyanosis, decreased blood pressure, and irritability. On physical examination, the jugular veins are distended, the trachea and heart are displaced to the side, and the chest wall bulge on the affected side is weakened. Percussion shows tympanum, absent tremor and breath sounds, and often subcutaneous emphysema in the chest wall and neck. Diagnosis is confirmed by thoracentesis lateral to the midclavicular line of the second rib and the syringe core can be pushed out due to intrathoracic hypertension.
So, how do x-rays and CT show pneumothorax?
Findings of pneumothorax and CT
X-rays show the preferred test for diagnosing pneumothorax. It may show the degree of lung compression, lung condition, and the presence or absence of lung compression
pleural adhesions, pleural effusion, and mediastinal displacement.Typical x-rays of pneumothorax show a convex arc of thin line-shaped shadows, compressed lung tissue within the line, no lung markings outside the line, and a marked increase in translucency. When the pneumothorax extends to the lower part, the costo-diaphragmatic angle is sharp. Small amounts of gas tend to be confined to the apex of the lungs and are often masked by the bones. When the patient is asked to exhale deeply, the atrophied lungs are smaller and more dense, in contrast to the area of external air translucency, thus showing a pneumothorax band. Localized pneumothorax is easily missed on posterior anterior x-ray, and the pneumothorax can be seen by turning the body position under x-ray. In the case of a large pneumothorax, the lungs are compressed and gathered in the hilar area in a spherical shadow. If there is a lesion or pleural adhesion in the lungs, it is lobulated or irregularly shaded. Massive pneumothorax or tension pneumothorax shows mediastinum and heart shift to the unaffected side. When a pneumothorax is combined with pleural effusion, there is a fluid gas surface, and the fluid level also moves when the body position changes under fluoroscopy. If there is a translucent band around the cardiac margin, mediastinal emphysema should be considered.
Basic CT of pneumothorax shows a very low-density gas shadow in the pleural cavity with varying degrees of compression and atrophy of the lung tissue. Generally, it should be observed in the condition of the lung window in a low window, and the diagnosis of pneumothorax with a very small amount of gas and localized pneumothorax mainly located in the anterior middle pleural cavity can be missed on plain X-ray, while there is no disadvantage of image overlap on CT, and the diagnosis is very easy. CT can also distinguish a pneumothorax adjacent to the mediastinum from pneumomediastinum and a pulmonary balloon, and in patients with extensive subcutaneous emphysema, CT often reveals a pneumothorax with negative plain x-rays.
The above is an introduction to pneumothorax and CT examination, I hope it will be helpful to you.