Calculations Flashcards
A-a Gradient
PAO2 - PaO2
Alveolar Gas Equation
PAO2 = FiO2 • (PATM - Pwater vapor) - PaCO2 / RQ
Dynamic Compliance (Cdyn) =
Tidal Volume /Peak Pressure - PEEP
Minute Ventilation =
RR * Tidal Volume
Predicted PaO2 by Age =
110- (Age *0.4)
Reynold’s Number =
(Velocity * Density * Diameter) / Viscosity
Static Compliance (Cstat) =
TV / (Plateau Pressure - PEEP)
Transpulmonary Pressure =
Alveolar Pressure - Pleural Pressure
Transthoracic Pressure =
Pleural Pressure - Atmospheric Pressure
Dead Space to Tidal Volume Ratio =
Vd/Vt Ratio = Vd / Vt
Cardiac Output =
HR x SV
Coronary Perfusion Pressure =
DBP - LVEDP (or PAOP)
Ejection Fraction =
EDV - ESV / EDV
Fick Principle
Cardiac Output =
(VO2 / CaO2 - CvO2) x 100
Law of LaPlace (Cylinder)
Wall Tension (cylinder) =
(Pressure x Radius) / Wall Thickness
Law of LaPlace (Sphere)
Wall Tension (Sphere) =
(Pressure x Radius) / 2 x Wall Thickness
Maximum Allowable Blood Loss =
EBV x (Starting Hgb - Target Hgb)/ Starting Hgb
MAP =
[SBP + (DBP * 2)] / 3
Oxygen Carrying Capacity / Oxygen Content
CaO2 =
(Hgb x SaO2 x 1.34) + (PaO2 x 0.003)
Oxygen Delivery
DO2 =
(Hgb x SaO2 x 1.34) + (PaO2 x 0.003) x CO x 10
Oxygen Extraction Ratio
ER =
Oxygen Consumption / Oxygen Delivery
Poiseuille’s Law
Flow =
(π • Radius4 • ∆Pressure) /
8 • Viscosity • Length
Pulmonary Vascular Resistance =
[ (Mean PA Pressure - PAOP) / CO ] x 80
Pulse Pressure =
SBP - DBP
Systemic Vascular Resistance =
[ (MAP - CVP) / CO ] x 80
Stroke Volume (Version 1) =
CO x 1000 / HR
Stroke Volume (Version 2) =
End Diastolic Vol - End Systolic Volume
Uncuffed ETT size =
Age / 4 + 4
Cuffed ETT size =
Age / 4 + 3.5
O2 Remaining in Oxygen E-Cylinder:
Step 1
Step 2
Step 1: Tank Capacity (L)/ Full Tank Pressure (psi) = Contents Remaining (L) = Gauge Pressure (psi)
Step 2: Contents Remaining (L) / Flow Rate (L/min) = Minutes Left
Fraction of Inspired Oxygen (FIO2) =
[ (Oxygen Flow Rate x 100) + (Air Flow Rate x 21) ] / Total Flow Rate
Gas Tanks (E)
Air - Volume, Pressure, Pin
Air:
- Vol: 660L
- Pressure: 1900psig
- Pin: 1-5
Gas Tanks (E)
Oxygen- Volume, Pressure, Pin
Oxygen:
- Vol: 660L
- Pressure: 1900psig
- Pin: 2-5
Gas Tanks (E)
N2O- Volume, Pressure, Pin
N20:
- Vol: 1590L
- Pressure: 745psig
- Pin: 3-5
Cerebral Perfusion Pressure =
MAP - ICP (or CVP whichever is higher)
Anion Gap =
[Na+] - ( [Cl-] + [HCO3-])
Plasma Osmolarity =
2 [Na+] + Glucose/18 + BUN/2.8
Boyle’s Law:
P1 x V1 = P2 x V2
Gay Lussac’s Law:
P1/T1 = P2/T2
Charles’ Law:
V1/T1 = V2/T2
Ideal Gas Law:
Pressure x Volume = # moles x 0.0821 x temperature
Celsius =
(F-32) x 5/9
Dalton’s Law:
P total = P1+ P2 + P3 …
Farenheit =
(C x 1.8) + 32
Henderson Hasselbalch pH =
pK + log [HCO3 / (0.03 x PaCO2)]
Henry’s Law =
Partial Pressure = Constant x Concentration
Inverse Square Law
Intensity =
1 / Distance ^2
Volume of Distribution =
Dose / Concentration
Half Life =
Volume of Distribution / Rate of Clearance