Formulas

Question 1

How do you convert Celsius to Fahrenheit?

Answer 1

F = (C x 1.8) + 32

Question 2

How do you convert Fahrenheit to Celsius?

Answer 2

Celsius = (F - 32) / 1.8

Question 3

What is the formula for arterial oxygen content and the normal values?

Answer 3

Formula: CaO2 (mL/dL) = (Hb [g/dL] x 1.36 x SaO2 + (PaO2 [mmHg] x 0.003)

Values: 19-21mL/dL

CaO2 = (Hb x 1.36 x SaO2) + (PaO2 x 0.003)

Question 4

What is the formula for cardiac output?

Answer 4

Formula: HR (beats/min) x SV (mL/beat)

CO = HR x SV

Question 5

What is the formula for cardiac index?

Answer 5

Formula: CI (mL/kg/min) = CO (mL/min) / BW (kg)

Values: 100-200mL/kg/min (dog)
200mL/kg/min (cat)

Question 6

What is the formula for oxygen delivery index?

Answer 6

Formula: DO2 (mL/kg/min) = Cl (mL/kg/min) x CaO2/100

Values: 20-35mL/kg/min

Question 7

What is the formula for stroke volume and normal values?

Answer 7

Formula: SV (mL/beat/min) = CI (mL/kg/min) / HR

Values: 1.5-2.5 mL/beat/kg)

Question 8

What is the formula for mean arterial blood pressure and normal values?

Answer 8

Formula: MAP (mmHg) = ([systolic - diastolic / 3) + diastolic

Values: 80-120 mmHg (dog)
100-150 mmHg (cat)

OR: diastolic x2 + systolic / 3

Question 9

What is the formula for calculated plasma osmolality?

Answer 9

2 (Na + K) + BUN / 2.8 + Glu / 18

Question 10

What is the formula for effective plasma osmolality?

Answer 10

2 (Na + K) + Glu / 18

Question 11

What is the formula for blood pressure?

Answer 11

BP = SVR x CO

Question 12

The delivery of oxygen to tissue is the product of cardiac output and arterial oxygen content and is expressed by what formula?

Answer 12

DO2 = CO x CaO2

Question 13

What is the formula for correcting dehydration?

Answer 13

% dehydrated x body weight (kg) x 1000 = mL to replace

Question 14

What are the two formulas for maintenance fluids?

Answer 14

For patients between 2-40kg
(Body weight [kg] x 30) + 70 = mL/day

For patients >40kg or <2kg
(Body weight [kg] to the 0.75 power) x 70 = mL/day

Question 15

What is the formula for the big A in PAO2?

Answer 15

PAO2 = (Pb - PH2O) x FiO2 - PaCO2 / R

Pb is barometric pressure = 760
PH20 is pressure of water = 47
R is respiratory quotient = 0.8

This is the calculated alveolar oxygen pressure vs PaO2 which is measured arterial blood oxygen pressure.

Question 16

What is the equation for A-a gradient?

Answer 16

A-a gradient = PAO2 - PaO2

This is done on ROOM AIR

Question 17

What is the equation for P/F ratio?

Answer 17

P/F ratio = PaO2 / FiO2

This is done ON OXYGEN support via arterial
blood gas.

Question 18

What is the Henderson-Hasselbalch equation?

Answer 18

pH = 6.1 + log (HCO3 - / PCO2 x 0.03)

6.1 is the logarithmic dissociation constant (pKa) of carbonic acid.

0.03 is the solubility constant of CO2 in plasma which converts PCO2 to CO2.

pH measures the tendency of carbonic acid to break down into bicarbonate and H+

Question 19

What is the equation for anion gap (AG)?

Answer 19

(Na + K) - (HCO3 + Cl)

N: 12-24 mEq/L

*albumin is highest source of negative ions
*to better define a metabolic acidosis
*DUEL

Question 20

What does DUEL stand for?

Answer 20

DKA
Uremia
Ethylene glycol
Lactic acidosis

Question 21

Formula for patient albumin deficit

Answer 21

10 x (serum albumin goal) - current albumin x kg x 0.3 = patient albumin deficit

Question 22

Free water deficit formula

Answer 22

([Current Na+ / 140] - 1) x 0.6 x kg

Question 23

What is the carbonic acid equation?

Answer 23

Outlines the relationship of all elements of the buffering system as it operates in the body:

CO2 + H2O <-> H2CO3 <-> HCO3- + H+

Question 24

Corrected chloride formula

Answer 24

[Normal Na+ / Measured Px Na+] x measured Px Cl-

Question 25

Sodium bicarbonate formula

Answer 25

mEq of bicarb needed = 0.3 x kg x base excess

Question 26

Formula for compliance (pertaining to lungs)

Answer 26

Compliance (C) = change in volume divided by amount of pressure applied

Question 27

Alveolar ventilation formula

Answer 27

VA = (VT - VD) x RR

Alveolar ventilation = (tidal volume - anatomical dead space) x respiratory rate