FM Radiology Case - Pneumothorax Flashcards
Radiological criteria for pneumothorax include ___ in the pleural space.
Air (black); in other words, there are no lung markings in the pleural space
Radiological criteria for pneumothorax include recognition of the ___ lung, which recoils to a resting state as negative pressure in the ___ is lost.
Atelectatic; pleura; this is also known as relaxation atelectasis
Radiological criteria for pneumothorax include shift of the mediastinum to the ___ side. Explain how this happens.
Opposite; Normally, the mediastinum is held in the middle by balance between pleural pressures. When negative pressure on the side of the pneumothorax is lost, the mediastinum gets pulled by the normal negative pressure from the opposite side.
There is a misconception that any mediastinal shift means a tension pneumothorax has occurred. How can one be certain of tension radiologically?
Only when the shift is progressive and you see the diaphragms are concave.
Radiological criteria for pneumothorax include a larger ___.When the negative pressure in the pleura is lost, the ___ relaxes to the TLC position.
Hemithorax; chest wall
Radiological criteria for pneumothorax include the ___ ___ sign. Which side is significantly lower?
Deep sulcus; the costophrenic sulcus is significantly lower than on the contralateral side due to the release of chest wall and diaphragm to the TLC position in the absence of negative pressure
Radiological criteria for pneumothorax include increased ___ of vascular markings on the opposite side. Why does this occur?
Prominence; The opposite lung gets the entire cardiac output.
Radiological criteria for pneumothorax include ___ along the lung margins. These are not always present.
Blebs
List 7 possible radiological criteria for pneumothorax.
- Air in the pleural space
- Atelectatic lung
- Shift of mediastinum to the opposite side
- Larger hemithorax
- Deep sulcus sign
- Increased vascular prominence on the opposite lung
- Blebs
True or false - shift of the mediastinum occurs with all pneumothorax irrespective of tension.
True
How can one be certain of a tension pneumothorax based on CXR?
If sequential films show progressive mediastinal shift or if the diaphragms become concave, we can then be certain of tension in a pneumothorax
Presence or absence of tension in a pneumothorax is best determined by ___ parameters - why?
Hemodynamic; pleural negative pressure facilitates venous drainage. When the pleural pressures become positive, it impedes venous return to the heart. Blood pressure falls and tachycardia ensues.
What are the steps in reading a CXR with pneumothorax?
- Indicate that there is dark air in the pleural space (no lung markings). Lung markings do not extend to the chest wall.
- Indicate that you see the outer margin of the atelectatic lung.
- Indicate the position of the mediastinum
How should you assess whether there is tension in the pneumothorax?
- Ask for BP and pulse - falling BP and tachycardia are the most important signs of tension in a pneumothorax.
- Progressive shift of the mediastinum and concave diaphragm are radiological signs of tension (both, not just the mediastinal shift)
When assessing the etiology of a pneumothorax, look for a lesion in the atelectatic lung; all lung diseases can lead to pneumothorax. What are some things to look for on CXR and to assess in the patient’s history?
- Normal lung appears to have the same radiolucency as the opposite lung; blood flow dramatically decreases to the atelectatic lung. An abnormal lung will appear more dense than the opposite lung.
- Do not mistake the increased blood flow to the opposite lung for interstitial disease.
- Look for subclavian lines and a history of procedures that can cause pneumothorax.
- History of trauma and fracture ribs
- Look for blebs on the surface of the atelectatic lung
