What counts as a modern scanner! I think we still have a 4 slice scanner?
Another great subject for discussion SAH, and I can agree with Pauls
approach for informed consent. Unfortunately because of entrenched
opinions if you do miss something there is going to be some "expert" out
there willing to bury you for not doing the LP.
I believe there is a difference between PE and SAH though. Miss an early
warning bleed, next time likely to have severe disability or death. Send
home a ?PE they may die, but more likely to return more
breathless/unresolved pain. It is the neurological damage and inability
to work that scares the hospitals and lawyers. All that extra money for
providing ongoing nursing care and loss of earnings if negligence can be
proved. We either have to prove that it is reasonable not to LP everyone
or be watertight with our informed consent.
Andy Webster
Coats Tim - Professor of Emergency Medicine wrote:
> Andy
> The 98% sensitivity was before modern scanners - I haven't seen any
> data about the sensitivity of the latest generation of scanners. There
> is no data for sensitivity for first bleed compared with later bleeds.
> Tim.
>
> -----Original Message-----
> *From:* Accident and Emergency Academic List
> [mailto:[log in to unmask]]*On Behalf Of *Andrew Webster
> *Sent:* 26 February 2006 18:25
> *To:* [log in to unmask]
> *Subject:* Re: SAH
>
> Listening to Jerry Hoffman on one of the Emergency Medicine
> Abstracts he believes sensitivity for CT for the early warning
> bleed is far lower than 98%. Also how many of us have the latest
> 64 slice CT scanners, and neuroradiologists interpreting the films?
>
> Andy Webster
>
> ------------------------------------------------------------------------
>
> *From:* Accident and Emergency Academic List
> [mailto:[log in to unmask]] *On Behalf Of *Coats Tim -
> Professor of Emergency Medicine
> *Sent:* 26 February 2006 17:55
> *To:* [log in to unmask]
> *Subject:* Re: SAH
>
> Paul,
>
> I don't think that we have the data to give absolute answers to
> the interesting questions that you pose.
>
> 1) Role of LP when CT negative - depends on the pre-test
> probability of SAH. About 5% of the scans that we do for LASH show
> SAH (so we know that Emergency Physicians's threshold for CT
> scanning is about a 5% risk - you can work out your own threshold
> by looking back at what proportion of the scans you have recently
> ordered are positive). With this 5% pre-test probability and a
> negative likelihood ratio of 0.02 for CT scanning the post-test
> probability of SAH means that it is likely that about 1000 LPs
> will need to be performed to find each CT negative SAH. (Assuming
> that CT is as good a test in low probability patients as in high
> probability patients). (Article with the details due to be
> published in the European Journal, March edition). As CT scanning
> is a good test for SAH, we maybe should be talking to our patients
> about their post test probability, their attitude to risk and
> whether they wish to have any further investigations (LP is
> probably not to be undergone lightly).
>
> 2) CT angio has limited resolution and is answering a different
> question from a LP. If you want to know if there is an operable
> structural abnormality CT angio may provide the answer, however
> the question usually is 'has the patient had an SAH'. If I was a
> patient I think that I would want to know if I had suffered a SAH,
> even if no structural abnormality could be found. (Maybe I would
> give up my hobby of bungee jumping and be just that bit more
> appreciative of life!).
>
> 3) The influence of new generation CT scanners is interesting -
> you are correct about technology running ahead of us. All of the
> published data (the 98% sensitivity etc) seems to be from more
> than 5 years ago - therefore before the current generation of
> multi-slice scanners. How does this alter the negative likelihood
> ratio? Not sure, but it probably makes a CT scan a more sensitive
> test.
>
> We risk stratify and accept 'low risk' rather than 'no risk' in
> many areas of emergency care (a PE can be just as fatal as a SAH).
> It is therefore a bit anomalous that we strive for 'no risk' in SAH.
>
> My views on investigation of LASH come with a health warning - the
> dogma that every patient who has a CT for LASH must have an LP is
> very well entrenched. There is insufficient data to support any
> other approach, so deviate from the current 'norm' at your
> medico-legal peril. However, I will bet my hat that in 10 years
> time we will be risk stratifying and limiting the number of LPs
> that we perform.
>
> Tim
>
> Tim Coats.
>
> Professor of Emergency Medicine.
>
> Leicester University.
>
> -----Original Message-----
> *From:* Accident and Emergency Academic List
> [mailto:[log in to unmask]]*On Behalf Of *Paul Bailey
> *Sent:* 25 February 2006 03:44
> *To:* [log in to unmask]
> *Subject:* SAH
>
> I am beginning to wonder if I am still subscribed to the list
> as I haven’t heard much from you all of late.
>
> I wanted to bring up the topic of subarachnoid haemorrhage.
>
> I find myself, as time goes on, becoming increasingly
> interested in patient safety, uniformity in the delivery of
> emergency medicine (or complete lack thereof), the concept of
> ‘risk assessment’ as the core of our specialty, the concept of
> acceptable miss rates for particular conditions, and finally
> the approach to low prevalence high mortality conditions such
> as SAH. In a lot of imaging related areas we have the
> additional problem of the wavefront of imaging technology
> being significantly ahead of the literature on most subjects –
> eg CTPA for PE and the role / sensitivity / accuracy of
> multislice CT – creating an evidence vacuum for a lot of the
> things that we do.
>
> With that out of the way I have been thinking a lot about SAH
> recently.
>
> In particular, two things:
>
> the role of LP when a high quality (ie no movement or artifact
> issues) multislice CT is negative.
>
> Why we aren’t just doing CT angiograms on everyone (and
> perhaps obviating the need for LP) given that this is what
> happens in a lot of centres when xanthochromia is positive.
>
> Out of interest, I am sure it occurs, but no-one in my
> institution has seen a 16 slice CT Head negative xanthochromia
> positive patient actually end up having a procedure – ie the
> CT angiogram / MR angiogram is always normal in this situation
> and no-one can really figure out where the blood came from.
>
> So, I’m opening it up to the collective wisdom of acad-ae-med.
> What are all of your thoughts on the matter?
>
> Kind regards
>
>
> Paul Bailey
>
> Emergency Physician
>
> Western Australia
>
>
> This e-mail, including any attached files, may contain
> confidential and / or privileged information and is intended for
> the exclusive use of the addressee(s) printed above. If you are
> not the addressee(s), any unauthorised review, disclosure,
> reproduction, other dissemination or use of this e-mail, or taking
> of any action in reliance upon the information contained herein,
> is strictly prohibited. If this e-mail has been sent to you in
> error, please return to the sender. No guarantee can be given that
> the contents of this email are virus free - The University
> Hospitals of Leicester NHS Trust cannot be held responsible for
> any failure by the recipient(s) to test for viruses before opening
> any attachments. The information contained in this e-mail may be
> the subject of public disclosure under the Freedom of Information
> Act 2000 - unless legally exempt from disclosure, the
> confidentiality of this e-mail and your reply cannot be
> guaranteed. Copyright in this email and any attachments created by
> us remains vested in the University Hospitals of Leicester NHS Trust.
>
> ________________________________________________________________________
>
> National Patient Safety Agency - supporting Doctors.net.uk members in safe practice.
>
> http://www.doctors.net.uk/NPSA
>
> ________________________________________________________________________
>
>
> This e-mail, including any attached files, may contain confidential
> and / or privileged information and is intended for the exclusive use
> of the addressee(s) printed above. If you are not the addressee(s),
> any unauthorised review, disclosure, reproduction, other dissemination
> or use of this e-mail, or taking of any action in reliance upon the
> information contained herein, is strictly prohibited. If this e-mail
> has been sent to you in error, please return to the sender. No
> guarantee can be given that the contents of this email are virus free
> - The University Hospitals of Leicester NHS Trust cannot be held
> responsible for any failure by the recipient(s) to test for viruses
> before opening any attachments. The information contained in this
> e-mail may be the subject of public disclosure under the Freedom of
> Information Act 2000 - unless legally exempt from disclosure, the
> confidentiality of this e-mail and your reply cannot be guaranteed.
> Copyright in this email and any attachments created by us remains
> vested in the University Hospitals of Leicester NHS Trust.
> ________________________________________________________________________
> National Patient Safety Agency - supporting Doctors.net.uk members in safe practice.
> http://www.doctors.net.uk/NPSA
> ________________________________________________________________________
>
|
