# know any formulas to calculate systolic and diastolic bp?

Discussion in 'Allopathic' started by cliquesh, Apr 24, 2012.

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1. ### cliqueshEstablished Member

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I got pimped today about this and the only thing I could think of was rearranging map = 2/3 Dbp + 1/3 Sbp. Any other suggestions?
2. ### RafaTechEstablished Member

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You can't calculate systolic and diastolic pressures. Its something you measure (ie with a BP cuff). You can calculated Mean Arterial Pressure.
3. ### CaptainSSOEstablished Member

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Yea that would give you one equation with 2 unknown variables. You can't do that.
4. ### cliqueshEstablished Member

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It was a cardiologist that asked me this question. He said he is going to ask me again tomorrow and he wants specific equations, but i cannot find anything. he wants two equations, one for DBP and one for SBP
5. ### QuizzicalApeEstablished Member

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bp cuff plus arm = SBP/DBP
6. ### jcushould have been dr. who

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Are you sure you understood him correctly? Does he have an accent?
7. ### IschiowhatNew Member

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Yea. Press Start BP cuff on the f*cking monitor.

Seriously, you should have said that.
8. ### DrSnipsMS4

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SBP = 110 + 2sqrt(age) + 20x, where x is number of antihypertensives pt. should take but doesn't

No but seriously, your cardio attending should publish his miraculous method of calculating BP. We could save tons of money on BP cuffs.

Actually wait, troll attending can be counter-trolled, observe:

SBP = DBP + PP

DBP = SBP - PP
Last edited: Apr 24, 2012
9. ### mjl1717Senior Member

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Fun-ny.

But in all seriousness it could be a trick question..
10. ### CaptainSSOEstablished Member

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Thanks, I bet he hadn't deduced that yet from the 15 prior responses.
11. ### PMPMD4G MD

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12. ### SpecterGT260Catdoucheus

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Find 2 theoretical calculus proofs on fluid dynamics. \$20 says he can't tell you you're wrong
13. ### DrSnipsMS4

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\$20 says he asks you to explain those proofs
14. ### pkwraithAvatar of Boris

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DBP = Force of Blood in Brachial Artery / Area of Brachial Artery during Diastolis

There you go.
15. ### PMPMD4G MD

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You can calculate systolic pressure with the modified Bernoulli equation: P = 4 * v^2. This is usually used with echo to estimate RVSP (right ventricular systolic pressure), but I suppose it could be used to estimate systemic pressure. You would have to add the result to the LAP (left atrial pressure), which you would have to measure or estimate.
16. ### PMPMD4G MD

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Hope your attending's not an SDNer.
17. ### DrSnipsMS4

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Hmmm. I see OP getting a paper out of this. Let me start it for you:

Title: A new method for determining systolic blood pressure by combined use of Doppler ultrasound and cardiac catheterization.

Abstract: Blah Blah insert statistics. The study showed that the new method of BP determination is non-inferior to use of conventional BP cuff when compared with arterial line measurements.

Methodology: We took 300 people who presented to a health fair for BP screening...

There you go OP, all I ask is that you not make me an author.
18. ### PMPMD4G MD

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I should add that you would need to assume there is no significant AS (aortic stenosis) in this case.

The original concept is used in echo to estimate pulmonary arterial pressure:

PA ~ RVSP + RAP (or CVP) assuming no significant pulmonic stenosis
19. ### SurfingDoctorNew Member

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Also, the Dinamap (the typical automated BP cuffs you will see) or other automated BP cuffs use arterial pressure oscillation to get a mean arterial pressure, then calculate the measurements during the cycle to estimate a systolic and diastolic blood pressure. I'm sure if you read the technical specs of the Dinamap, they would show you how they derive a systolic and diastolic BP from a mean arterial pressure, though I doubt it is very straightforward.

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How did it go OP?
21. ### PMPMD4G MD

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Typically, the pressure resulting in the maximal oscillations is the MAP. Algorithms are used to calculate SBP and DBP from the MAP but these are generally proprietary.

I did find one published algorithm:

The Algorithm used by DINAMAP:

1. It first determines the amplitude at MAP, which is the lowest cuff pressure at which maximum amplitude is sensed

2. It then reviews the data above MAP and find the pressure that generates amplitude by 0.5 of the amplitude of MAP --> that is systolic blood pressure

3. Finally it reviews the data below MAP and find the pressures that generates amplitude by 0.625 of the amplitude of MAP --> that is diastolic blood pressure
22. ### SurfingDoctorNew Member

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I was wrong, that is totally straightforward.