Equations

Question 1

Total arterial Oxygen content equation (CaO2)

Answer 1

CaO2= SaO2 (Hb)(1.34) + PaO2 (.003)

Question 2

Total Venous Oxygen content equation (CvO2)

Answer 2

CvO2=SvO2 (Hb)(1.34) + PvO2 (.003)

Question 3

Fick Equation

Answer 3

oxygen consumption + cardiac output
-oxygen consumption (VO2) can be determined by calculating the difference in arterial O2 content and venous content

CO= VO2/ (CaO2-CvO2) X 10

Question 4

Delivery of Oxygen (DO2)

Answer 4

DO2=(CaO2)(CO)(10)

Question 5

What is tissue perfusion MOSTLY dependent on?

Answer 5

SaO2 and hemoglobin concentration

Question 6

Pressure of Inspired Oxygen (PiO2)

Answer 6

PiO2= FiO2 (atmospheric pressure- water vapor pressure)

@sea level, barometric pressure= 760 mmHg
Water vapor pressure = 47 mmHg

PiO2= FiO2 (716 mmhg)

Question 7

Alveolar gas equation (PAO2)

Answer 7

PAO2= FiO2 (atmospheric pressure-water vapor pressure) -PaCO2 (1.2)

Question 8

Estimation of PAO2

Answer 8

102- age/3

Question 9

Alveolar Ventilation Equation (VA)

Answer 9

VA= (Vt-Vd)(RR)

tidal volume includes dead space ventilation
dead space= 1/3 of tidal volume (2mL/kg)

Question 10

Alveolar volume

Answer 10

Vt-Vd

Question 11

PaCO2 equation

Answer 11

PaCO2= (VCO2)(0.863)/ Va

If alveolar ventilation is low, PaCO2 will increase

Question 12

Alternative to the A-a gradient equation

Answer 12

PaO2/FiO2

Normal = >400
~5X the patients FiO2

PaO2/FiO2 ration <300= ALI
PaO2/FiO2 ration <200= ARDS

Question 13

Systemic vascular resistance equation (SVR)

Answer 13

SVR= MAP- CVP/CO X 80

Question 14

Pulmonary vascular resistance (PVR)

Answer 14

PVR= PAP-PCWP/ CO X 80

Question 15

Volatile anesthetic calibration

Answer 15

Dial setting @ sea level X Pressure where it was calibrated/ new atmospheric pressure

Question 16

Transpulmonary gradient

Answer 16

mean PAP- PCWP

Question 17

find the total gas flow through a vaporizing chamber

Answer 17

Total FGF X (dial setting/100) / (Volatile VP/ atm P)

Question 18

Average weight for a child

Answer 18

age X 2 + 10

Question 19

coronary perfusion pressure

Answer 19

CPP= DBP-LVEDP or CVP

Question 20

calculating the anion gap

Answer 20

anion gap= measured cations-measured anions

measured cations: Na+ and K+
measured anions: Cl- (28) and HCO3- (102)

Question 21

calculate the Fi02 of nasal cannula

Answer 21

21% + 4% for every liter of O2

Question 22

predicted VO2

Answer 22

kg to the .75 power X10