Equations/Lists/etc Flashcards
Kirby’s rule of 20
Fluid balance, oncotic pull, glucose, electrolyte and acid-base balance, oxygenation/ventilation, mentation, perfusion/blood pressure, HR/rhythm/contractility, albumin levels, coagulation, RBC/Hgb concentrations, renal fxn, immune status/abx dose and selection/WBC count, GI motility/mucosal integrity, drug dosages/metabolism, nutrition, pain control, nursing care/mobilization, wound care/bandage change, TLC
Equation for MAP
MAP= diastolic BP - 1/3(Syst-Diast BP)
OR
MAP = CO * SVR
Equation for cardiac output
SV x HR
Starling-Landis equation
Pg 60 silverstein/hopper
Oxygen delivery equation
DO2=Q x CaO2 (Q=cardiac output, CaO2=arterial oxygen content)
Calculation for CaO2 (arterial O2 content)
[1.34 x SaO2 x Hgb] + [PaO2 x 0.003]
alveolar air equation, at 21% room air at sea level
PAO2=150-PaCO2
A-a gradient (simplified)
PAO2-PaO2 Normal is 20 means decreased oxygenating efficiency Should be performed when pt is on room air
P/F ratio
PaO2/FiO2 Normal is >400 mm Hg <200 consistent with ARDS
Strong ion difference
SID=(Na + K + Mg + Ca)-(Cl + A) A=unmeasured strong anions Must use corrected Cl
Corrected Chloride
Cl.corrected=Cl x (Na.normal/Na.meas)
Anion gap
AG= (Na + K)-(Cl + HCO3)
Henderson-Hasselbalch equation
pH=6.1 + log ([HCO3] ÷ [0.03 x PCO2])
Equation for pH
pH=pKa + log (HCO3/[PCo2 x SC]) SC=solubility coefficient of CO2 in blood=0.03
Venous admixture (shunt) calculation
Qs/Qt=(CcO2-CaO2)/(CcO2-CvO2) qs=shunt fraction, qt=cardiac output, cco2=oxygen content of end capilary blood CaO2=oxygen content of arterial blood CvO2=oxygen content of mixed venous blood must obtain from pulmonary artery
Oxygen content using jugular venous blood
(1.34xhgbxSO2) + (0.003 x PO2)
Fluid types/characteristics (transudate, exudate etc) for dogs
Pure transudate: TP 3, TNCC >7000
Fluid types/characteristics (transudate, exudate etc) for cats
Transudates: TP 3.5, TPr >0.56, TNCC >5900, LDHp >226
A-a gradient
[FiO2 x (Patm-Ph2o)-PaCO2/0.8)]-PaCO2
Calculation for PAO2
PAO2=FiO2 (760-47)- PaCO2/0.8
Equation of motion
muscle pressure + ventilation pressure= (tidal volume + compliance) + (resistance x flow)
Criteria for readiness for spontaneous breathing trial in mech ventilation
Improvement in primary disease P/F ratio >150-200 with FiO2 < 5 cm H20 adequate respiratory drive hemodynamic stability absence of major organ failure
Free water deficit
( [current Na/normal Na]-1) x (0.6 x BW) *body weight in kg
Bicarbonate deficit
BWkg x 0.3 x (24-measured HCO3)=meq HCO3 deficit
corrected Cl
=(Nanormal/Nameasured) x Cl measured
Equation for cardiac index?
CO/BSA
BSA in m2
equation for stroke volume?
CO/HR
equation for CO?
MAP/R
R=resistance
equation for stroke volume index?
SVI=SV/BSA
BSA in m2
equation for systemic vascular resistance?
(MAP-RA pressure)/cardiac index
equation for pulmonary vascular resistance?
PVR=(mean PA pressure- PAOP)/cardiac index
Fick’s equation?
CO=VO2/(CaO2-CvO2)
where CaO2-CvO2=arteriovenous O2 content difference
normal CVP values?
0-5 or 0-8 cm H2O
normal mean PAP?
5-12 mm Hg
Normal CO values?
Dog 125-200 ml/kg/min
Cat 120 ml/kg/min
Normal SvO2 & ScvO2?
ScvO2 >65%
SvO2 >75%
normal values for cardiac index?
3.5-5 L/min/m2
shunt fraction calculation?
QS/QT=(CcO2-CaO2)/(CcO2-CvO2)
Qs=shunt flow
Qt=total flow/cardiac output
CcO2=oxygen content of capillary blood
v=venous
a=arterial
alveolar gas equation?
PAO2=PIO2- (PACO2/R)
PIO2= FiO2 x (Patm-Ph2o)
R=0.8 (resp quotient)
Starling’s equation?
Diffusion capacity equation?
DL=VCO/PACO
Alveolar dead space/Bohr equation?
VD/VT=(PACO2-PECO2)/PACO2
PECO2=ETCO2
normal is 0.2-0.35 (or 20-35%)
To get percentage, multiple x 100
what is the Haldane effect?
the deoxygenation of blood increases its ability to carry CO2
Calculation for fractional shortening?
FS=(LVIDD-LVIDS)/LVIDD
equation for Laplace’s law?
pressure=(4 x surface area tension)/radius
what is the equation for compliance?
compliance=(change in volume)/(change in pressure)
shunt fraction equation (for cardiac output)
Qs/Qt=(CcO2-CaO2)/(CcO2-CvO2)
what is the equation for Reynold’s # and what does it represent?
Re=(2rvd)/n
predicts laminar vs turbulent flow
higher #–>turbulent flow
equation for Poiseuille’s law?
R=(8nL)/πr4
equation for oxygen delivery (DO2)?
DO2=CaO2 x CO
equation for abdominal perfusion pressure (APP)
APP=MAP-IAP
how do you convert cm H2O to mm Hg?
1 cm H20 = 0.736 mmHg
1.36 cm H2O = 1 mmHg (torr)
how do you calculate a CVP based on the waveform?
Calculating CVP = (‘a’ wave peak + x descent base)/2
equation for pulse pressure variation?
Pulse pressure variation =
100 X (PPmax- PPmin)/{(PPmax+PPmin)/2}
what is the equation for oxygen extraction?
Oxygen extraction = CaO2 – CvO2
equation for O2 extraction ratio?
O2ER=[CaO2 – CvO2]/CaO2 = VO2/DO2
equation for systemic vascular resistance?
SVR=[(MAP – RA pressure)/CI]
what is the equation for osmolality? what about for effective osmolality?
- Osmolality: 2(Na + K) + (gluc/18) + (BUN/2.8)
- Effective osmolality: 2 (Na) + [gluc/18]
equation to determine amt of HCO3 to give to a patient?
mEq/L HCO3 to give=0.3 x BW x BD
BD=base deficit
BW=body weight
equation for corrected Na in relation to hyperglycemia?
Na(corr)=Na(meas) + 1.6([measured gluc-normal gluc]/100)
equation for Na deficit?
Na deficit=(target Na-patient Na) x (0.6 x BW)
equation for Cl gap? what does a high or low number mean?
Cl gap= Clnormal-Clcorrected
value >4à hypochloremic alkalosis
value < -4 à hyperchloremic acidosis
what is the equation for strong ion difference?
SID= HCO3 + albumin + P
Or
Na-Cl
what is the equation for albumin deficit to calculate the amt of human albumin to give to a patient?
Albumin deficit (gms)= 10 x (desired albumin-pt albumin) x weight (kg) x 0.3
what is the equation for cerebral perfusion pressure?
CPP=MAP-ICP
