Todd Fraser on 12-06-2011
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Alex McKenzie wrote 06-13-2011 09:48:21 am
It is a bit worrying, I agree Todd, but its a single case, and I'm not sure that you can change practice based on that.
Who knows what happened there - perhaps there were unrecognised factors that invalidated that particular examination (though I agree it sounds unlikely given it was repeated 6 hours later). A single case report over decades of experience seems insufficient to me to overhaul the recommendations.
Andrew Donald wrote 06-13-2011 06:09:55 pm
I recall the suggestion in guidelines and reviews of neurological prognostication in HBI in recent years that the use of hypothermia may require deferment of the prognostic value of a poor motor score to day 6.
For example, Young et al. in NEJM, 2009 - "Clinical features predicting a poor outcome are likely to be reliable regardless of whether hypothermia was used, but the motor response may be delayed until 6 days or more in hypothermia-treated patients." No reference apparent.
The effect of hypothermia on outcomes in post-arrest HBI is well documented, and it is plausible on first principles that it may acutely affect brainstem function as well, and impact the sensitivity of brain death testing.
Brain death testing guidelines include the absence of hypothermia, requiring temp >35, as a precondition, but don't specify a time period for this before testing. In this case testing was at 22 and 28 hrs post hypothermia.
We've all observed the delayed recovery of organised higher functions behind metabolic or hypoxic derangements, perhaps this could occur at a brainstem level with hypothermia as well.
Finally, in my experience it would be unusual to proceed to testing and donation in this time period, particularly in a 'young' 55/M. Perhaps our usual multifactorial delays have masked a real phenomenon that we will see more of with more aggressive donation practice.
Todd Fraser wrote 06-15-2011 08:07:56 pm
Thanks Andrew and Alex,
If nothing else this serves as a cautionary tale. While you may be right on the money Andrew that we need to wait longer, there is little literature to guide how long that might be. 24 hours? 72? A week after hypothermia?
The problem with all this is that there is no gold standard, and there is an ongoing problem with self fulfilling prophecy.
Oliver Arkell wrote 06-17-2011 09:52:26 pm
The biggest concern I have is the potential loss of faith in the system that a case report like this can result in. I suspect this type of event published in major press would result in major damage to the donation process.
Claire Cattigan wrote 06-18-2011 02:46:05 pm
Interesting case report. My concerns would be 1. the length of hypothermia, as I would expect most would not cool beyond 24hours, and the effect this may have on neurological function 2. The sedation used to maintain hypothermia for this length of time and whether a sufficient period off sedation was allowed prior to clinical brainstem testing.
Todd Fraser wrote 06-21-2011 10:02:22 am
Sorry, forgot to add the paper :
Webb, Adam C, Samuels, Owen B. Reversible brain death after cardiopulmonary arrest and induced hypothermia. Critical Care Medicine: 39 (6):1538-154
A link to the abstract : http://bit.ly/mC0gGc
Alex McKenzie wrote 06-21-2011 10:05:21 am
I guess the question then is how long is good enough to wait after hypothermia. I agree with Claire that the sedation used could contribute, but this can fairly easily be overcome with reversal agents. It seems (or seemed) hard to believe that hypothermia could so profoundly affect cerebral function that you look brain dead, despite being rewarmed for 22 hours.
Alex McKenzie wrote 06-21-2011 10:07:12 am
The obvious follow on is if you're not going to use clinical testing, what test "should" you use. My understanding is that the research into outcomes with the other modalities is no less imprecise than clinical testing.
Also, what about DCD in this case?
Vikram Masurkar wrote 06-22-2011 02:09:55 pm
Interesting case and I couldn't agree more with all of you. If this patient was in our unit, I don't think he would be managed the way the authors did.
This patient had a PEA arrest from asthma with time to ROSC of 20mins. His sats were 60% even before the arrest. I'm sure everyone would agree that his prognosis was going to be dismal.
I would not have cooled this patient. There is not evidence for hypothermia in this context. More importantly it makes prognositcation so much more complicated.
The next issue I have is the timing of cooling. Evidence exists for cooling either for 12 or 24 hrs post arrest. This pt was cooled from 16 to 50 hrs.
Although one could argue that this shouldn't affect brain death testing, the prerequisites for testing aren't very clear.
I think we need to be more selective about which patients we cool.
This case will definitely not be good for the organ donation movement.
Thanks for highlighting this case Todd.
Chris Anstey wrote 08-15-2011 03:03:06 pm
I have to agree with the above. Cooling was not indicated, particularly for such a long time.
Even though 22 hours had expired since cessation of cooling, there may still have been a residual brain stem effect - you are not dead until you (and all of your bits) are warm and dead ....
Either that, or maybe the US Neurologists need to enlist a Pulmonologist to assess breathing when performing these tests after, of course, the Clinical Pharmacologist has reviewed the drug chart. Beware single organ Doctors (SODs).
Just my 2c.
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