equations Flashcards
Alveolar Air equation
PAO2 = FiO2(PB-PBH20) - PaCO2/.8
Calculate CaO2
(Hgb x 1.34 x SaO2) + (PaO2 x 0.0031)
Volume %
take out to 2 decimals
how is HGB calculated?
Gram percent
Grams of HGB in 100 mL of blood
Volume percent
volume of solute/volume of solution
CvO2
(HGB x 1.34 x SvO2) + (PvO2 x 0.0031)
take out to 2 decimals
C(a-v)O2
CaO2 - CvO2
should be about 5%
Oxygen delivery
DO2
CaO2 x CO x 10
mL per minute
oxygen uptake
VO2 = DO2 (from heart) - DO2(from tissues)
venous admixture
Qs/Qt
(CcO2 -CaO2) / (CcO2 - CvO2)
expressed in percent, whole number
CcO2
(HGB x 1.34 x SAO2) + (PAO2 x 0.0031)
mean systemic arterial pressure
(systolic + (2 x diastolic))/3
whole numbers
ventilation perfusion ratio
Alveolar ventilation (L) / Cardiac output (L)
Normal is 0.8-1.0
VD/DT ratio
(PaCO2 - PeCO2) / PACO2
P/F ratio
PaO2/FiO2
Normal 400-500
equation of motion
P(mus) + P (aw) = Pe + Pr
Charles law
V1/T1 = V2/T2
Pressure constant
Gay-lusac law
P1/T1=P2/T2
Volume is constant
combined ideal gas law
P=nRT/V
P = pressure
N =number of molecules
R = a constant
V = volume
modified ideal gas law
P1xV1/T1 = P2V2/T2
ficks law
V(gas) = A/T x D(gas)(P1-P2)
Vgas = volume of gas diffusing across a membrane
A = surface area tension
T = thickness
Dgas = diffusibility constant
P1-P2 = prcessure gradient
Laplace law for sphere
P = 2T/r
P = distending pressure
T = tension creating tendency to collapse
r = radius
Frank starling law
J = K(Pc-Pi) - (3.14c - 3.14i)
J = net fluid movement out of capillary
K = capillary ability to leak water
Pc = hydrostatic pressure in capillary
Pi = hydrostatic pressure in interstitium
3.14c = oncotic press in capillary
3.14i = oncotic pressure in interstitium
Driving force for gas
F = NvA/Z
F = force
N = viscousity
v =velocity
A = cross sectional area
Z = distance between plates
Reynolds number
Re = vrp/N
v = velocity
R = radius
p = density
N = viscousity
