Formulas Flashcards
Qp/Qs
Ao-RA/PV-PA
Laplace
Wall tension = pressure * radius / 2*h
h= wall thickness
Wall tension = determinant of myocardial oxygen deman
Valve area
Valve area = CO/HR * SEP * K (44.3) * sqr (mPG)
sqr: square root
mpg: mean pressure gradient
Fick
CO = oxygen consumption / arteriovenous difference O2 consumption (ml/min) AV diff (ml O2/L blood) = O2 sat * theoretical oxygen carrying capacity of Hg AV diff = Art sat - venous sat (%) * Hg (g/dL) * 10 * 1.36 ml O2/g Hg
Strain:
Langragian formula
E = L-L0/L0 E = strain L = length (current) L0 = initial length
Poiseuille
Vascular resistance: R = 8nl/pi*r^4 n = viscosity l = vessel length 8/pi = constant r= radius
R = P/Q Q = P/R P = Q*R
Ohm
R = dP/CO
SVR
SVR = Ao-RA/Qs (mean systemic arterial pressure, mean RA pressure, systemic blood flow).
PVR
PVR = PA - LA/Qp (mean PA pressure, mean LA pressure, pulmonary blood flow)
Hemisphere surface
2pir^2
Doppler
V = (C x fd)/[2(f0) x cos θ] Fd - frequency shift (reflected frequency minus transmitted frequency) F0 - frequency of the transducer Cos - angle (cos 0 = 1) C - constant
Strain rate
(V2-V1)/D
v: velocity
d: distance
Gorlin for aortic valve
AVA (cm^2)= CO (ml/min) / (SEP * HR * 44.3 * sqrmPG)
CO has to be in ml
Gorlin for mitral valve
MVA (cm^2) = CO (ml/min) / (DFP * HR * 0.85(44.3) * sqrmPG)
CO has to be in ml
Simplified Gorlin for valve area
VA = CO/sqrmPG
