Aline pressure verses cuff in sepsis

[Darkfield]

Question for all you ICU friends out there. I received a severely septic pt (source unknown) maxed on Levophed and shortly later on neosynephrine. Within a few hours of admission her temp was dropping and she was mottled and cool. Could not get an O2 sat reading for anything (even on her forehead), it didn't correlate with the blood gas-the sat on the monitor was labile and and inaccurate even when the waveform correlated. Her extremities were cool, but her pressure was running with maps in the 60s from a femoral artline with good waveform. Yet when I did a curiosity peripheral bp, I got more like 40/20, which would explain the spo2 monitor problem. Is that even possible? Could a central pressure be different than a peripheral pressure?

[Be_Moore]

The pressures could be different, but usually you would see the opposite pattern. The fem a-line would have a crap pressure while the brachial cuff pressure would be okay. That's when you are thinking something like aortic dissection. I would almost never trust a cuff pressure if the systolic is reading lower than say..70mmhg. They just lose accuracy really quickly. The first diagnostics you have to check are your square-wave form test on your line. Get a good square? Squiggles not over or under damped? If not, trust your a-line.

Perhaps she was mottled and cool because she was so constricted by being maxed on norepi and neo that blood couldn't get to her periphery? Such is the danger of high dose pressors is that it creates a large quantity of core-shunting. And if you have a person on that much support, rare is the case that you will ever have a sat with a waveform...and when you have one, it will usually be off by at least 5% (and usually closer to 12%) in my experience.

[sandyteele]

Central pressures are more reliable for sure. A cuff pressure would be part of the picture, but the femoral art line pressures would be the one I would go with. Levophed could likely be the culprit in the lower cuff pressures, but the picture still doesn't look very pretty. I would still take both values very seriously.

Sounds like this patient is in total septic shock. In our SICU, this patient would probably be on 10 IV drips , (including Xigris), be swaned and have CRRT going around the clock because her kidneys have probably have shut down by now. An O2 sat monitor placed on the bridge of the nose could pick up a value if all else fails.

[Flying ICU RN]

Could a central pressure be different than a peripheral pressure?

Very much so.

Look at the usual patients in this scenario, usually a mix of severe edema and obesity which is hard for the cuff module (a pneumatic device) to give an accurate reflection of systemic pressure.

Your key here in this scenario is the quality of the waveform.