Math Flashcards
Volume of PRBC
(Target Hct - current Hct)/ Hct of PRBC x blood volume
Estimated blood volume in a one year old is 80 ml / kg and ~ Hct of PRBC is 60 for calculation
Maximal allowable blood loss =
EBV x (starting Hct -Target Hct)/starting Hct
Bohr equation
Used to quantify the ratio of physiological dead space to the total tidal volume, and gives an indication of the extent of wasted ventilation.
VD/VT = (PaCO2 - PECO2)/PaCO2
*PECO2 = the mixed expired gas collected using a Douglas bag (NOT ETCO2 - common exam mistake)
During albeit oxygenation, CO2 rises by … in the first minute and then … in subsequent minutes
6 mmHg
Then 3 mmHg for every minute after the first minute
Calculating the % vapor delivered when you accidentally fill wrong gas in a different vaporizer
Vapor pressure of the wrong agent/vapor pressure of the wrong vaporizer
% vapor delivered at high altitude =
Atmospheric pressure at sea level / Barometric pressure at high altitude
Calculating vaporizer output and % delivered
Important keyword
VO = CG x VP / BP -VP
CG: carrier gas
VP: vapor pressure of agent
BP: barometric pressure
When a syringe of blood with O2 sat of 100% and another syringe with 2% O2 sat are mixed, the mixture has ~ 50% O2 sat. The P50 is 27 mmHg. So the PaI2 of the mixture will be …
27 mmHg
Calculating O2 content of the blood
O2 content per 100 ml of blood = 1.39 x Hb x O2 sat + (0.003 x PaO2)
O2 = 1
In order to calculate the O2 delivered, multiple the obtained value from above equation by 10 which gives O2 content In litter and the multiple by cardiac output (as CO is usually given by litters)
Calculating PaO2
102 - (age/3)
Equation for PAO2
(PB - PBH2O) x FiO2 - (PaCO2/R)
SEM
SD/square root of n
SVR =
(MAP-CVP) x 80 / CO
PVR =
(PAP-PCWP) x 80 / CO
