Leveling art line to tragus for cpp??? - page 3

by jimmy_hat

17,937 Views | 33 Comments

Hello all. I am taking a class that stated in a sitting/semi-fowlers patient that we have concerns with CPP, we should level the art line at the tragus (or where every you would level your ICP monitor). I have never done that... Read More


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    I work in a SICU that takes all neuro and trauma pts, all of our neuro pts have their art line leveled at the external auditory canal, although I couldn't figure out why until reading all these posts. We treat for a CPP <60 generally, using 3% saline. Also take our readings with the ventric closed.
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    very interesting. Like I said, from the research I have seen it seems to be about 33% level at the EAC, and the rest at the phleb axis. All seem to use the same numbers/criteria for treatment. As posted before, I asked the AACN via thier website/email. The response I got was that the art line should always be leveled at the phleb axis and those numbers used for CPP calc, though she gave me no reference to research or a formal publication saying such.

    I find it shocking that there is such a variation in practice. No one else seems to care By my rough estimations the cpp would be a 14 point different. HUGE! I would love to see a formal document or position of an organization to defend either practice.
    IckuRN likes this.
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    Wow, am I glad to see this being discussed!

    I work in an SICU that has many neuro patients. About a year ago, one of our attending doctors who is an anesthesiologist, did a whole bunch of "teaching" on Rounds about leveling art lines at the tragus for neuro pts. This was based on one article he had and the fact that this was the practice on the OR. Before that, we always leveled at phleboststic axis, nobody ever questioned it.

    It had never been the practice in our unit before. Because our hospital policy states to level art line at phlebostatic axis, if the docs want us to level the art line at the tragus, we have to get the doctor to write a specific order for that. (and then d/c that order once the ICP monitor is out - we had an instance where a pt was sent to a non-neuro step-down unit and the nurses were still following the order to level at tragus, with no understanding of what it was all about).

    It "went viral". The neuro docs went to the neuro step-down and said "the nurses in ICU are leveling at the tragus for their art lines, why don't you do that?" - all with NO real basis for this practice change. It's all been very upsetting.

    We haven't been able to find any concrete evidence as to why the practice of leveling an art line at the tragus would be a good thing. All the "norms" and safe pressures in texts (CPP, etc) are calculated using the central pressure at the aortic root. We are taught to shoot for MAP of a certain level because this has been shown to generally perfuse all organs.

    Are the proponents of leveling art lines at tragus suggesting that we my be under-perfusing the brains of our non-neuro patients?

    If you move your transducer up, really all you are doing is manipulating your zero point. Yes, it may give you different CPP values, etc. But as we say "treat the patient, not the numbers".... The danger is (as stated in the pdf presentation linked on the first page of this thread) of when you do start to treat the numbers and use fluids inotropes, etc.

    I haven't been able to find any real clinical research as to the exact pressures found the the COW, how this relates to artline readings at either level point, and how much of a difference this makes.

    I agree, it is potentially huge. There are many centers practicing leveling at tragus on the assumption that it reflects cerebral perfusion pressure - but what if their assumption is not actually correct. My centre is one of those places, and it's gone to all sorts of practice committees and physician committees because to make a practice change unless you have decent evident makes no sense at all.
    fiveofpeep likes this.
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    With regard to the question about drainage and checking ICP. It depends on your surgeons preference for that particular patient. Some patients, the really sick ones, require having the ICP open to continuous drain at XXcmH2O. On these patients, we close it every hour to get an accurate ICP.

    On other patients, the surgeon may only order drainage of XmL for an ICP >YYcmH2O. Either way, we never record ICP on an open drain. It's off my about 15mmHg too low. I hope this answers your side question.
    Last edit by kvsherry on May 7, '10
    fiveofpeep likes this.
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    I'm currently working in a SICU that does a lot of head trauma. The TBI protocol states that we level the A-line transducer at the external auditory meatus. I follow the protocol and we treat with hypothermia, 3% saline, Mannitol, and pressors. Sometimes we drain CSF and sometimes we only monitor with the Camino.

    I previously worked in a NICU that required we level it at the phlebostatic axis. I had understood this to be the proper place to measure MAP. I'm not sure if you can find any research or textbook that will tell you to measure MAP anywhere else. I would think that an accurate MAP would be important since CPP=MAP-ICP.

    I follow the policy of the facility where I now work, but do not agree with it.

    Penthes
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    I've just done a placement in one of the biggest and most specialized, well regarding neuro ICUs in the country. They leveled their art transducer at the tragus. With regard to the EVD/ICP these were most often open to the drain (& therefore the icp on the monitor would be grossly inaccurate) and clamped hourly to transduce an accurate ICP. obviously drainage orders were per neurosurg however.
    IckuRN likes this.
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    We level our art lines to the phlebostatic axis. We level our EVDs to the tragus. I haven't heard of leveling art lines to the tragus before.
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    I'm in a level II trauma center and we level ABP at the tragus when they have an ICP to calculate CPP. I've been there 7 yrs and thats how I was trained to do it.
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    We're phleb axis people on our NICU. I'll be interested to see what research comes out to support zeroing at the tragus. We also use 3% saline and mannitol; I've never seen a higher concentration of saline ordered. We don't have a standard practice regarding ventrics; we require orders be written for every one. Typically what I see is a pop off around 12 mmH2O and then clamp after a certain amount of drainage for an hour, then open depending on the ICP/CPP. My unit is small and specialized; trauma has their very own floor so our practice might be different because of that.

    ETA that I clamp every hour to get the reading.
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    My unit does not transduce art lines at the tragus for cerebral perfusion nor at the kidneys, colon or anything other than the phlebostatic axis. I'm curious to see the evidence based practice or something on this.


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