Cardio Equations Flashcards Preview

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Flashcards in Cardio Equations Deck (21)
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1
Q

velocity of blood flow in a given vessel

A

v=Q/A. Velocity equals output over cross-sectional area

2
Q

Ohm’s law: cadiac output

A

Q=deltaP/R. Output equals change in pressure over resistance

3
Q

Law of Laplace: wall stress

A

T=Pr/2H. Wall stress equals pressure time radius over two times wall thickness

4
Q

Poiseuille’s: resistance to flow

A

R=8nl/pi*r^4. Resistance equals eight times viscosity times vessel length over pi times radius to the fourth.

5
Q

calculation for caridac output

A

CO=(MAP-RAP)/TPR. Output equals mean arterial pressure minus right atrial pressure over total peripheral resistance

6
Q

calculate mean arterial pressure

A

MAP=(SBP+2DBP)/3=DBP+1/3PP. Mean arterial pressure equals systolic plus two times diastolic over three, or diastole plus one-third of peripheral pressure.

7
Q

calculate oxygen consumption

A

CO=(O2consumed)/(O2PA-O2PV). Assume consumption is 250 mL/min, so output equals 250 over pulmonary artery oxygen content minus pulmonary vein oxygen content

8
Q

convert mmHg min/L to dynes

A

multiply by 80

9
Q

Normal TPR

A

700-1600 dynes, 9-20 mmHg min/L

10
Q

Normal O2 consumption

A

250 mL/min

11
Q

PVR

A

PVR=(MPAP-PCWP)/CO

12
Q

Stroke Volume

A

SV=EDV-ESV
Stroke volume equals end-diastolic volume minus end-systolic volume

13
Q

ejection fraction

A

EF=SV/EDV

ejection fraction equals stroke volume over end diastolic volume

14
Q

cardiac output from stroke volume

A

CO=HR*SV

cardiac output equals heart rate times stroke volume

15
Q

stroke volume from PV loop

A

distance between ESV (left) and EDV (right)

16
Q

Compliance

A

C=V/P

change in volume for a relative change in pressure
corresponds inversely to EDPVR

17
Q

Slope of ESPVR corresponds to

A

contractility

18
Q

the load on the ventricle after diastole

A

preload

19
Q

important measures of preload

A

end-diastolic pressure, end-diastolic volume

20
Q

load on the ventricle after ejection, determined by arterial system

A

afterload

21
Q

important measures of afterload

A

aortic pressure, total peripheral resistance