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Old 01-11-2011
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Lungs Pneumothorax: mediastinal shift away or towards

This is what I understand from Goljan Audio.
Spontaneous pneumothorax commonly caused by blebs will cause trachea to shift TOWARDS side of pneumothorax.

Tension pneumothorax because of the one way valve will cause trachea to shift AWAY from the side of the pneumothorax

However I have seen several qbanks where they seem to think that regardless of the cause of the pneumothorax trachea will shift away to the opposite side. (This is also what I was taught in med school).
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Old 01-11-2011
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Isn't it suppose to shift away in case of a bleb? I understand it this way: Its just a blob of air that has gotten inside the thoracic cavity because of the rupture, therefore naturally the lung will be compressed against it, and along with that, deviation of trachea in the same direction of the lung will occur, in that case, with it.. so shifting away.
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Old 01-12-2011
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Quote:
Originally Posted by prim View Post
This is what I understand from Goljan Audio.
Spontaneous pneumothorax commonly caused by blebs will cause trachea to shift TOWARDS side of pneumothorax.

Tension pneumothorax because of the one way valve will cause trachea to shift AWAY from the side of the pneumothorax


However I have seen several qbanks where they seem to think that regardless of the cause of the pneumothorax trachea will shift away to the opposite side. (This is also what I was taught in med school).
pneumothorax = automatic cancellation of negative intrapleural pressure thus - that side of the mediastinum now has pressure = 0 , or pressure = +x (tension pneumothorax).

Meanwhile the other unaffected side always has a -ve intrapleural pressure (-5 odd..if m nt mistaken) - so the negative pressure will always exert a pull towards it.
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Old 01-12-2011
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Arrow Pneumothorax always push

Any type of pneumothorax (tension or traumatic) would shift the mediastinum to the opposite side. Likewise, any air trapping (blebs, emphysema, ruptured bronchus, ..etc) also shift the mediastinum towards the opposite side.

A shift towards the side of the lesion is seen in lung collapse.
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Old 01-12-2011
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In rapid review pathology and goljan audio it indicates that rupture of the blebs will cause areas of affected lung to collapse and if the collapse is big enough trachea will deviate to side of the collapse

I was also taught what you guys are saying in med school. But I thought since goljan is the pathology god he knows best?
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Old 01-13-2011
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Default I think that Dr. Goljan is right.

We have to understand that he is talking about “SPONTANEOUS PNEUMOTHORAX”. In this context; there is a bleb which ruptured into the pleural cavity. This supposedly leads to “loss of contact between visceral and parietal pleural layers, leading to collapse of that part of the lung (during relaxation of airways on expiration)”, which is known as RELAXATION ATELECTASIS. (Seen in Spontaneous pneumothorax and pleural effusion.)
Apical lobe is more prone to relaxation atelectasis in spontaneous pneumothorax. (In pleural effusion, middle and lower lobes are more prone to relaxation atelectasis.)
In Atelectasis, trachea deviates towards the ipsilateral side. So, in spontaneous pnemothorax, if the collapse is big enough, there will be ipsilateral tracheal deviation.
In "TENSION PNEUMOTHORAX", due to ONE-WAY-VALVE mechanism (either external or internal), there is a positive pressure built up in the pleural cavity. This pushes the lung and mediastinum contra-laterally. Thus, trachea markedly deviates to the opposite side.

Correct me if i am wrong. To err is human...
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Physiology-, Radiology-, Respiratory-

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