Important Equations

Question 1

Q =

Answer 1

Q (flow) = CO (cardiac output)

Q = Change in P/R (resistance)

Question 2

P =

Answer 2

CO x TPR

Question 3

Resistance =

Answer 3

R = 8Ln / pi*r^4
Resistance is inversely proportional to radius 
Rseries = R1 + R2 +. . .Rn
and 
1/Rparalell = 1/R1 + 1/R2 + . . . 1/Rn

Question 4

CO =

Answer 4

HR X SV

Question 5

SV =

Answer 5

(stroke volume) = EDV (end diastolic volume) - ESV (end systolic volume)

Question 6

What is Fick’s Principle?

Answer 6

Used to determine a tissue’s steady-state consumption (or production) of any substance. Xtc is the transcapillary efflux rate of X, [X]a,v is the arterial and venous concentrations of X, and Q is the blood flow rate.

Question 7

Fick’s Equation

Answer 7

Xtc = Q x ([X]a - [X]v)

Question 8

What can approximate P = CO x TPR?

Answer 8

MAP (mean arterial pressure) = Pdiastole + 1/3(Psystolic - Pdiastole)

Question 9

What are two methods for calculating the mean electrical axis?

Answer 9

1. Find the lead with the largest R wave and follow that dipole. (If wave is negative, then dipole is in the opposite direction)
2. Determine what lead contains the most equiphasic QRS complex.
   Then determine which lead lies 90deg away from the most equiphasic lead and look at the tracing (remember if wave is negative, then dipole is in the opposite direction)

Question 10

Cardiac Index =

Answer 10

CO / Body surface area

Question 11

EF (ejection fraction) =

Answer 11

SV/EDV