art line vs cuff pressure

[maverick_pkg]

what do u do in situations where after zeroing the art line etc, its pressure is significantly higher/lower than cuff pressure in both arms? any guidelines anywhere?

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[46&2]

what do u do in situations where after zeroing the art line etc, its pressure is significantly higher/lower than cuff pressure in both arms? any guidelines anywhere?

This is taken from the ACS textbook on BP (and having an attending very interested in the subject):

Cuff pressure reads falsely high in patients who are:
1. obese
2. calcified arteries (i.e. diabetics)

All cuff readings (done with a stethoscope or oscillation) can be off regarding diastolic pressure, especially in hypovolemic patients. There isn't enough change in flow (i.e. turbulence) to make the stethoscope or oscillator sensitive enough.

MAPs from a cuff are junk unless done by oscillometric cuffs (1/3 SBP + 2/3 DBP can be way off). These are also off during hypovolemia.


On art lines:
Overall, irregardless of other problems, the art line should give an accurate representation of MAP.

The snap test can be used to test the accuracy of the art line.

"In this test, a square pressure wave is introduced into the catheter-tubing-transducer system by pulling on the tab that allows fluid to flow from the high-pressure bag into the transducer and the artery. The tab is then snapped shut, and the pressure in the system returns abruptly to baseline levels. If the system is adequately matched to the vasculature, the pressures in the transducer will abruptly return to baseline with minimal oscillation. If the measuring system is too stiff, the snap test will result in hyperresonance, evidenced by prolonged and exaggerated oscillation. If the measuring system is too compliant or if the catheter or tubing is obstructed, the snap test will lead to a slow and slurred descent toward baseline."


In the end, the whole clinical picture is important. If the cuff pressure is reading much higher than the art line, and the patient is otherwise showing signs of hypovolemia (e.g. tachycardia, low CVP, low urine output, under resuscitated in the OR), well, I'd go with the number that makes more sense.

If the art line seems flaky (e.g. reading 75/55), hopefully the MAP is above >60. In general trust the art line, esp. for MAP, but the whole picture is most important. I usually disregard cuff pressure if an art line is available.

 

[maverick_pkg]

well yesterday on call i had a patient of another service on POD 1 with lobectomy with art line reading 190/45 and cuff reading 120s/40s for most of the day. He had been extubated the same day. Gave metoprolol and hydralazine IV and restarted home BP meds. The chief on call (not considered very good) at 11pm when I called her the third time (1st time she wanted metoprolol and 2 nd time hydralazine) just wanted me to d/c the art line. What would you have done?

PS: I had not done the snap test

 

[Miyagi]

I have done a few months of SICU and have ran into this problem more than once.
One of the most important things on the a-line is to be able to tell if the wave form is a good one or not.If you don't know what I am talking about, you should not be giving meds. to txt HTN to those pts.
If all else fails, I roll out the out manual BP cuff and pump it up until the a-line wave form disappears...there u go u have ur SBP...let it down and watch for the wave form you have the DBP....there u go...not more guessing....just takes a little time and some elbow grease. works 100% of the time...unless the pt. has B/L UE Amps.