Leveling art line to tragus for cpp???

[jimmy_hat]

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 in any of my neuro units. Art was at phleb axis and ICP at tragus and we used those numbers to calculate the CPP. That big of a difference would give you about a 20-30 mmhg difference (lower) pressures. These are huge differences. Anyone doing this? Does it modify your reference numbers for goal cpp?

Jimmy

The only articles I am able to find are ones from journals that state that the transducer should not be leveled to insertion site. I am shocked because I thought that was old news but the research based ones are from 2001 in CHEST. I was practicing back then but it was never taught to me as anything other that the phleb axis.

[IDoNotGiveOut]

I work in a large and respected academic hospital in SICU which takes all neuro and trauma patients, and we always level the ICP transducer and a-line transducer at external auditory canal (EAC). We actually have the two transducers clicked together so wherever you level them they are at the same level.

I'm really intrigued by your question because I have never even questioned it. Everybody else is at phlebostatic axis except neuro pt. with bolt or ventric. I am always careful to use the bed's inclinometer and keep HOB at exactly 30 to avoid falsely affecting the measurements.

With our method, the ICP and MAP are together so no matter how you level them, the CPP is going to be the same. i.e. if you level too high MAP will be lowered but so will ICP, so CPP will be about the same. But it will definately be a lower CPP than the one you get by leveling the a-line lower. What CPP do you treat for? We only treat to keep CPP>60 in most patients. (And 7.5% for any ICP >20). If it's a patient they want to be hypertensive for perfusion they will just order MAP 80-110 or whatever.

It seems like this is the type of answer you are looking for, what bedside nurses in other NICUs do.

[jimmy_hat]

Interesting. Thanks for the reply. That is what i was looking for. I have been unable to identify a unit NICU or SICU that actually does this until now. Like i had said before. I contacted the AACN and they said no one does this and did not understand my concern or really what my question was. I doubt the person was a specialist but she was CCRN (not that it means a lot). I would be happy to give you her name and contact info.

What CPP do you treat for? We only treat to keep CPP>60 in most patients. (And 7.5% for any ICP >20)

We would treat to the same CPP. greater than 60 or 65. Depended on the case. That was the CPP calculated with the MAP at the phleb axis and ICP leveled at the EAC. I have worked at a few different ICUs as a traveler and have never seen what you describe. I only learned about this in my current CRNA education. I am considering calling some of my contacts at Hopkins and seeing what they do there. Just kind of busy these days.

We would use NEO to elevate the MAP to obtain that CPP. We had some pretty high BPs in attempt to obtain the CPP. What did you mean about the 7.5%? I do not understand your reference.

I like you never thought of asking about this. Now I am finding different info. Europe already noted that they have a problem with this, but they did not come to a solution. I imagine if we did a survey here, we would see much the same info. I have a feeling about 30-40% of the hospitals level the art line to the EAC with the rest at the phleb axis. I think this is a pretty major confusion if someone wants to take the wheel and run with it.

[jimmy_hat]

idonotgiveout,

I wanted to PM you but it seems that neither of us the ability. I was wondering where you worked. Email me if you do not mind.

[IDoNotGiveOut]

About 7.5%, I was referring to hypertonic saline which we use for ICP >20, I assume everybody does this? Or do you use mannitol or something? So, for CPP of 60 all we need is MAP of 60-80 depending on closed ICP, and if CPP is low d/t high ICP we of course treat ICP first with 7.5%. Even leveled at EAC it is usually not terribly hard to keep a MAP of 60 to 80 with just phenylephrine. Sometimes we have to add another pressor because of either propofol or if the patient just happens to be very sick. But that's not really a huge problem either since most of these patients have a central line anyway just in case they need 7.5%.

On a semi-unrelated note, do you monitor with your ventrics open all the time and just close each hour to check ICP? Just curious.

[IDoNotGiveOut]

I emailed you.

lol at the addy.:)

[jimmy_hat]

We used both mannitol and hypertonic. We would also hyperventilate to fight spikes in ICP. BP is not our first choice but we often end up there when their sodium and serum osmolarity limit our ability to give the hypertonics or mannitol. It has been a couple years since I have done neuro. When I left they were thinking about chilling the patients heads, but I never saw it. I honestly can not remember what % saline we used. I want to say it was 5%. I will not swear to it.

[fiveofpeep]

On a semi-unrelated note, do you monitor with your ventrics open all the time and just close each hour to check ICP? Just curious.

At the insistence of the neurointerventionalist, we check ICP hourly. At another hospital I've worked at they did continuous monitoring w/ continuous drainage by turning the stopcock completely up so that the monitor and drain are open simultaneously.

[IDoNotGiveOut]

Yeah, we have the monitor and drain open simultaneously, but that's the open ICP, and then we close it and the closed ICP is the "real" one. As you know they're way way different. The reason I asked is because one of the nurses I work with said some places monitor it closed all the time and open hourly for drainage, the opposite of what we do. So I'm just wondering if others do it this way or they do it like we do.

[nursepercy]

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

[jimmy_hat]

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.

[pebbles, BSN, RN]

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.

[kvsherry]

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.