Trachea deviation in spontaneous pneumothorax - USMLE Forums
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Old 12-25-2013
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Lungs Trachea deviation in spontaneous pneumothorax

Guys any help here?

FA says trachea deviates to Same side of pathology in spontaneous pneumothorax whilst it deviates to opposite side in tension pneumothorax why?

I am thinking in spontaneous pneumothorax the lungs collapse at the affected side right? and ofcourse in tension pnuemothorax the tension created shd push/ shift the mediastinum.
I hope am thinking right?
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Old 12-25-2013
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In real life, there is little to no deviation of the trachea in spontaneous pneumothorax...but for the purposes of the exam let's just go with FA. This discussion is really technical but from what I know it has to do with intrapleural pressure vs atmospheric pressure. Tension pneumo has a higher intrapleural pressure so that pushes the mediastinum to the opposite side. Spontaneous has a lower intrapleural pressure so that in theory would cause the mediastinum to shift towards the affected side.
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Think of it this way:

Tension: You have a stab wound that creates a one way valve, air comes in but cant leave, increased pressure on the side of the lesion displaces the trachea to the opposite side. No, stab wounds arent the only method of getting tension pneumothorax, but just remember that example as USMLE loves it and it makes the reasoning easier to understand.

Spontaneous: You have a bullae or multiple blebs that rupture causing the lung to collapse. When the lung collapses, there is now more free space in the cavity thus creating a more negative pressure. This negative pressure acts pull the trachea towards its side thus the tracheal displacement to the side of the lesion.

Atleast thats how I understand it :P
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The above post was thanked by:
32019 (12-26-2013), bunny1410 (12-26-2013), CisternaChyli (12-25-2013), nsesereso (12-25-2013), Osayimwen (10-01-2015), singular (12-27-2013)
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Quote:
Originally Posted by SeraphimMD View Post
Think of it this way:

Tension: You have a stab wound that creates a one way valve, air comes in but cant leave, increased pressure on the side of the lesion displaces the trachea to the opposite side. No, stab wounds arent the only method of getting tension pneumothorax, but just remember that example as USMLE loves it and it makes the reasoning easier to understand.

Spontaneous: You have a bullae or multiple blebs that rupture causing the lung to collapse. When the lung collapses, there is now more free space in the cavity thus creating a more negative pressure. This negative pressure acts pull the trachea towards its side thus the tracheal displacement to the side of the lesion.

Atleast thats how I understand it :P
that make sense to me . Bassically the collapsing lung drags the mediastinum along with it. But in real life situations, tracheal deviation is often the last sign seen with any pneumothorax. I think this tracheal deviation stuff is more of an exam concept.
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Quote:
Originally Posted by CisternaChyli View Post
that make sense to me . Bassically the collapsing lung drags the mediastinum along with it. But in real life situations, tracheal deviation is often the last sign seen with any pneumothorax. I think this tracheal deviation stuff is more of an exam concept.
Well I have seen several tracheal deviations in practice.
I don't think it's just exams concept it happens more often in practice. I wanted to get the whys to its happening!

Thanks guys you hv been helpful. Wishing u great scores!
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Quote:
Originally Posted by nsesereso View Post
Well I have seen several tracheal deviations in practice.
I don't think it's just exams concept it happens more often in practice. I wanted to get the whys to its happening!

Thanks guys you hv been helpful. Wishing u great scores!
Oh interesting, hmmn...because the discussion over on Student Doctor concluded with people saying that deviations were often the last thing that would occur, and those people had asked attendings and other senior doctors. Maybe you just got lucky and saw a few .
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Quote:
Originally Posted by CisternaChyli View Post
Oh interesting, hmmn...because the discussion over on Student Doctor concluded with people saying that deviations were often the last thing that would occur, and those people had asked attendings and other senior doctors. Maybe you just got lucky and saw a few .
Yea! Depending on ur setting of practice u may not see many probably in developed countries. But in developing countries they do come with such, more of pleural effusion causing the deviations as for the pnuemos in particular not much just a few.
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Quote:
Originally Posted by nsesereso View Post
Yea! Depending on ur setting of practice u may not see many probably in developed countries. But in developing countries they do come with such, more of pleural effusion causing the deviations as for the pnuemos in particular not much just a few.
ah okay; yeah then i guess in the US its a rare thing to see deviations. Even in India, i never saw one...well then again i never saw a pneumothorax.
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