Intubation post GM seizure: when ?

[Bill Griggs]

I have been interested to read the posts on intubating patients with GCS 
less than 8 or 9.  Thank you all for some interesting posts.

As I understand it the logic in the head injured patient is not just that 
they need to have their airway protected but rather that they need to avoid 
the effects of respiratory depression including potentially both 
desaturation and high CO2.  These are reportedly bad for the injured brain. 
The practice that I usually see is to follow intubation of a head trauma 
case with positive pressure ventilation with the aim of both improving 
oxygenation and also to control CO2.

I see this as potentially different to the non-trama case where the brain 
has not been physically injured.

Of note, in Recovery wards / PACUs patients frequently have GCS less than 9 
yet are left to wake up without an ETT being reinserted. Very occasionally 
some aspirate. The vast majority dont.

Now specifically the post ictal patient?
To me he/she is "usually" going to improve their conscious state over the 
next few minutes - maybe 10-15 mins but maybe quicker.
Despite a GCS of less than 9 they often have a gag reflex (as in fact do 
some/many of the head injured patients).
In this setting the risk balance equation seems to me to favour watching 
them for a period to see if they do improve and start to rouse.

Another issue is that we sometimes see patients immediately after their fits 
because they fit in hospital.  However, we do not see head injured patients 
with a low GCS immediately after their head injury.  Even paramedics rarely 
see them within 4 minutes and hospital ED / ER staff rarely within 20 
minutes.    While doing my basic medical and specialist training I worked 
part time as a paramedic (I did this for 15 years) and I observed that 
patients' clinical state including GCS can change a lot fairly quickly in 
the prehospital phase.Thus to me a head injured patient with a low GCS at 
hospital is more likely to have that GCS remain low for longer with the 
associated theoretical risks of low oxygen, high CO2 and aspiration risk 
(which I suspect may be the least of these three) because GCS has already 
been low for a while.

Now what about the data?  Many groups including as I understand it, ATLS, 
teach that "the head injured patient with low GCS should be intubated within 
10 minutes".  Some centres have this as a performance indicator / KPI.  But 
why 10 minutes?  Logic aside, I have struggled to find data to support 10 
minutes over 5 minutes or 15 minutes or even 30 minutes.  If anyone knows of 
any please feel free to share it.

We also know that hypotension is bad for head injuries - current data 
suggest it may be the worst thing post injury that can happen.
To intubate a trauma patient in hospital we often need to use drugs (hmm is 
this because they are "protecting" their airway??)
and most of our anaesthetic drugs are known to cause hypotension especially 
in the hypovolaemic patient.
And trauma that causes head injuries - often blunt and diffuse truama - may 
have caused other injuries which may have bled leading to relative 
hypovolaemia.
So in deciding to intubate we are potentially risking causing the worst 
thing that can happen to a head injured patient.....

Also we intubate the head injured patient but rarely with continuous 
arterial waveform analysis available (because we "have to" do it quickly...) 
and so maybe we miss the hypotension we could be causing?  If  we don't see 
it then we didn't cause it?

Maybe we need to think this through very carefully.

Personally I try to use the first few minutes after the (blunt trauma) 
patient arises to get some fluid into them to minimise the risk of 
hypotension from my anaesthetic drugs.  I also use the time to watch the GCS 
which we know can fluctuate especially when drugs or alcohol are involved, 
which strangely enough is fairly common.  I ask the paramedics about 
fluctuations they have seen.  When I do intubate, to minimse the hypotension 
risk (and also because it is not usually anaesthesia for someone to 
immediately burrow into the belly), I give very low doses of the anaesthetic 
drugs in this circumstance.  I give full doses of relaxants.  I would much 
rather apologise afterwards than kill the patient directly or indirectly.

So in summary,

Patient A with GCS 6 post a fit that I have witnessed in the ED/ER/ward - 
all things being equal I will sit and watch this patient for a while.  The 
natural history is that usually they wake.

Patient B with GCS 6 and head injury now 40 minutes post event after being 
brought in by ambulance - I will try to minimise hypovolaemic risk and watch 
for fluctation in GCS while I do this, but I will probably intubate fairly 
quickly using drugs (low dose amnesic/anaesthetic agents with full dose 
relaxant) and a rapid sequence technique.  In a major trauma centre with a 
large trauma team, if one team member gets a line into an artery while we 
are getting set up to intubate then I feel an added comfort because I will 
be able to be certain I did not cause hypotension, or be able to react 
quickly if the pressure does drop.  Inserting an A line should not slow 
other things down at all though.

A million variations in individual cases could change any or all of this but 
I am trying to demonstrate my concepts.

In the absence of additional data I hope I am being logical and acting in my 
patient's best interests.  However medicine changes all the time so I would 
appreciate it if anyone can demonstrate to me that I should change this 
practice.

My 2 cents worth

regards

Bill

A/Prof William Griggs AM
MBBS, PGDipAvMed, FANZCA, FJFICM
Director Trauma Service
Royal Adelaide Hospital
South Australia
william.griggs at health.sa.gov.au