CPR Circulation and Hemodynamics

Question 1

Which vessels have the greatest cross sectional area? Second greatest?

Answer 1

Capillaries

Veins

Question 2

Which vessels hold the greatest blood volume?

Answer 2

Veins (~65%)

Question 3

What does constriction of veins do?

Answer 3

Pushes blood into arteries to increase BP, doesn’t change resistance that much

Question 4

What does constriction of arteries/arterioles do?

Answer 4

Doesn’t shift much blood over to veins but DOES increase resistance

Question 5

What is the equation of velocity of blood flow?

Answer 5

V = Q/A
velocity = flow/area

Question 6

What is the relationship between blood flow, pressure, and resistance?

Answer 6

Q = delta P/R
flow = pressure gradient/resistance

Question 7

How are flow and resistance related?

Answer 7

Flow is inversely proportional to resistance

Question 8

How is vessel radius related to resistance?

Answer 8

R = (8nl)/pi r^4)
R = resistance
r = vessel radius (one of main ways to regulate BP)

Question 9

How is vessel length related to resistance?

Answer 9

As length increases, resistance increases (in parallel circuits total resistance decreases)

Question 10

What is laminar flow?

Answer 10

Even blood flow, not turbulent

Question 11

What is Reynolds number?

Answer 11

Nr = pdv/n
p= density of blood
d= diameter of vessel
v= velocity of blood
n= viscosity of blood

If Nr is >2000 then transition from laminar to turbulent flow

Question 12

What is a bruit

Answer 12

Turbulent flow

Question 13

What is compliance of blood vessels?

Answer 13

How easy it is for a vessel to expand, opposite of elasticity. Higher elasticity = less compliance

Question 14

Which vessel has the highest compliance?

Answer 14

Veins - lowest elasticity
Arteries - lower compliance
Old arteries - very low compliance

Question 15

What does smooth m contraction in veins do to compliance?

Answer 15

Decreases compliance, causes increase in pressure and shift of blood from veins to arteries

Question 16

What is pulse pressure?

Answer 16

Pulse pressure = systolic - diastolic

Question 17

What is mean pressure?

Answer 17

Mean pressure = diastolic + 1/3 pulse pressure

Mean pressure closer to diastolic pressure than systolic pressure

Question 18

What is pulmonary wedge pressure?

Answer 18

Catheter in pulmonary artery with balloon, measure pulmonary venous circulation pressure to find left atrial pressure

Question 19

Why is pulmonary wedge pressure important?

Answer 19

Helps determine extent of cardiac failure