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Sat Oct 18 12:32:09 BST 2008

Late to this thread, but have tried to read back through the archives.
Still, apology if I cover something already stated by someone else, but it's a favourite topic of mine (hence the length)

Some points:

1. We should heed the experience of people like Ross H. on this. He (and others on this list - I'm sure) have the exposure to an environment such as is in South Africa, where an Emergency Physician at any level can easily perform an average of 1 chest drain per hour of ED time!!! You get to see A LOT of these over a few months and this allows you to pick up patterns others miss. You also get to SEE stuff so rare that others only hear/read about it. As a med student in South Africa I recall having a log book, where I kept track of chest drains among other items. I had filled up all spaces for chest drains before the end of my 5th year (thus stopped counting at 100) - in my 6th/final med school year, it was my job to teach chest drain insertion to 4th year students...

2. From: Sahaj Khalsa
> trained that when we decompress a chest ... and get blood flow back, we should pull the catheter. Why?

> Assuming that I have put the dart in correctly (and have not hit the vessels

--> I cannot, of course, be certain why your trainers tell you this, but consider...
Your patient is supine...
The chest wall in the "right place" for decompression is, say 3-4cm thick...
Your 14G, even inserted to the hilt, will likely reach 1-2cm deeper to that, i.e. barely into the pleural cavity...
But WHERE? Well, it's antrior on the chest, but the patient is supine, so it's at the "top" actually...

If you have blood all the way "up" there in a supine patient, there are likely around 1.5-2 litres of blood in that hemithorax to get blood to reach that high. And, if you've just reached this person, pre-hospital, you'd be able to pick that up on percussion as a MASSIVE HAEMOTHORAX and know your patient is abouut to die from haemorrhagic shock or has just died while you were putting the needle in...

But you're very good, so you would not have missed that, which means that likely you have your needle in a vessel after all! Even though you know where to go, you may still hit an unusually-placed internal thoracic/mammary artery, or intercostal vessel, or (seen it!) subclavian vessel.

In South Africa, when I worked there, I saw a few patients with TB-related fibrosis or adhesions related to previous chest drains (but can be post-pneumonectomy or other) whose pericardium has been dragged by fibrosis/adhesion to the anterior chest wall... So you may well have your 14G in a coronary vessel! And we all know traumaic pneumos due to penetrating wounds are usually a recurrent disease...

3. YES, tracheal shift is a late sign. No-one argues that!
But what does "late" mean?
First, with a tension pneumo picked up early in the pre-hospital phase, you know it's developing rapidly (not unusual) and soon your patient will be "late" as well! The point is that it's often a rapid process and, as you pick it up, by the time you get your needle ready to "shoot", you may well be quite "late" in the pathogenesis. If this tension is about to kill your patient, then IT IS LATE in the process - you may well pick up the shift!

Second, Ross was being generous when he gave us 5 seconds to feel for it - 2 seconds is enough, especially for someone as experienced as he is. But 5 seconds made the point just as well.

4. As explained already, when present, a tracheal shift is a very good clue to the presence of a pneumo.
If you think about point 3 above, pre-hospital you may well pick up "some" signs WITHOUT a shift, and move on. But then, a minute late, there suddenly IS a shift and suddenly you KNOW what's going on. So is it not worth a look for it?

5. I am often asked about this about tracheal shift (and distended neck veins) when teaching ATLS:
"You teach us that the mere SUSPICION of a tension pneumo or of a pneumo-which-may-later-tension, as shown by trauma + decreased air entry + hyper-resonance, is enough to stick a needle in. So why bother to waste time looking for the neck signs? And we may have to open the C-collar for that as well!"

Good question!

Here's an answer:
Trauma + decreased air entry + hyper-resonance = pneumo...
It MAY BE a tension. If it's not, it may become one, so needle is indicated...
Many people will simply pick up the 14G needle/cath, find the right place, and shove it in...
What should happen? With tension, there will be a hiss as pressure is relieved. Then the hiss will eventually cease...

"Nice one," you say...
Well, actually, there are 2 options. Either the problem has been solved OR the needle is now blocked/kinked!
"No problem," you say - I'm going to reassess anyway and see whether I've made a difference!

Well, on reassessment, what have you got? A badly multiply injured trauma patient with a pneumo which was big and then developed tension, but the tension is now (I hope) relieved.
So what's left? A big pneumo!
What does that look like on re-exam? Crap! It's still trauma + decreased air entry + hyper-resonance! From these you cannot tell anything's changed! Patient's still in trouble from all his injuries, still tachycardic, still tachpnoeic, still has a crappy hemi-thorax with not much air entry, if any. And a tension-free pneumo sounds just as resonant!

NOW you begin to kick yourself gently... If only I had checked the neck AND was "lucky" enough to find distended neck veins and/or tracheal shift, then NOW I could check they have been resolved and know the tension is gone!

Go ahead - Kick away!

6. Can you have a tension with some lung still visible in the hemithorax on X-ray?
YES. Easy to explain...
As lung collapses rapidly, certain parts of it may well be mucus-plugged sufficiently to NOT collapse. There may also be some kinking of airways and/or blood/secretions causing further failures of collapse... (I wonder - do you call it "telectasis"?)

7. "One should never see a CXR of someone with a tension pneumo"...
Heard that one?
Easy to achieve - all you need to do is keep your eyes tightly shut and you never will!
Otherwise, join the real world... One should never see patients lying in corridors... One should never see patients being given 10 times the dose of a drug prescribed...

Think back to a case like:
Tall young man, seen after 2 hours in the busy Saturday night waiting room, having been triaged as pleuritic chest pain after a minor upper resp illness. Looks well. Vitals OK. Sats 98%. You examine and you THINK there is a pneumo... Maybe... So you give him an X-ray form and tell him to go to X-ray... Where he waits 2 hours and gets slightly breathless, then strains up from his chair to finally go stand in front of the X-ray machine...

Is there some rule which guarantees he cannot develop a worse pneumo during these 2 hours and begin to tension as he gets up to have the picture taken?

>From experience, I can tell you this rule, if it exists, can be broken. I have in the past been called to radiology for just such a patient, who collapsed in front of the camera! De-tensioned him on the floor of the X-ray room. Got him transferred back to the ED and onto monitors and oxygen and then, while we all brown our underwear, trying to get a pulse back, the radiographer walks in and hangs up on the screen this 8th wonder of the modern world - an erect PA CXR with a 100% pneumo with visible mediastinal shift.

What do you say?
Well... What I said was "here we go AGAIN"! Because that was my second one of those. The first time I can even claim the "honour" of being the nasty person who SENT him walking to X-ray! As I had sent dozens like him before and since.

As F. Gump says - "it happens".
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