tpchristifulli
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Does an Art Line have to be zeroed at the phlebostatic axis, or does it not matter?
Arterial Lines
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ricardoj
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Yes, it does, same as a CVP
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For every cm of vertical distance between the transducer and the RA, the SBP moves in the opposite direction 0.5 - 1 mmHg. DBP changes much less, so the measured MAP is affected very little.
So it doesn't have to be exact by any means. As long as you aren't leveling the thing 2 feet above or below the patient, it shouldn't matter much at all.
For transport, taping the transducer to the arm or a stretcher rail that is within a few inches of the target works just fine.
So it doesn't have to be exact by any means. As long as you aren't leveling the thing 2 feet above or below the patient, it shouldn't matter much at all.
For transport, taping the transducer to the arm or a stretcher rail that is within a few inches of the target works just fine.
Angel
Paramedic
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Are you guys RT folks?
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I am not a RRT.
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You done it now!
Angel
Paramedic
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Ruh roh!
Not sure what you mean that diastolic pressure "changes much less". That's not correct. It changes the same as the systolic BP does for each cm +/- the phleblostatic point. MAP changes as well. This is not all that big a deal in a-lines, but more important in swans and central lines where the pressures are lower to begin with. A change of 5-10mmHg, about 3-5 inches of transducer placement, could mean a significant difference clinically on the venous side, not so much on the arterial side. The main point is to measure from the correct point and be consistent - taping it to a stable point is a good idea.
This assumes that the patient is supine. Raising or lowering the head relative to the heart makes a difference in the pressure perfusing the brain, which, in the end, is what you're interested in perfusing. I do a lot of anesthetics for patients in a semi-sitting position, particularly for shoulder procedures, which are often done in older patients. The blood pressure at the level of the heart can be clinically significantly less than the pressure perfusing the brain when the patient is sitting up at an 80deg angle. If I happen to have an arterial line on these patients, I'm going to be placing my transducer at the approximate level of their Circle of Willis once they're positioned.
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[QUOTE="jwk, post: 552518, member: 12218
Not sure what you mean that diastolic pressure "changes much less". That's not correct. It changes the same as the systolic BP does for each cm +/- the phleblostatic point. MAP changes as well.[/QUOTE]
You are right. I meant that the further down the arterial tree the invasive BP is measured, the greater SBP is but DBP and MAP remain relatively unchanged. Not pertinent to the question but in my hurried response I guess I errantly combined some related yet different concepts.
The overall point is that minor deviations from the phlebostatic are probably not clinically significant.
Not sure what you mean that diastolic pressure "changes much less". That's not correct. It changes the same as the systolic BP does for each cm +/- the phleblostatic point. MAP changes as well.[/QUOTE]
You are right. I meant that the further down the arterial tree the invasive BP is measured, the greater SBP is but DBP and MAP remain relatively unchanged. Not pertinent to the question but in my hurried response I guess I errantly combined some related yet different concepts.
The overall point is that minor deviations from the phlebostatic are probably not clinically significant.