Cardiac Physiology - Normal Values and Equations Flashcards
1
Q
How to approximate the mean arterial pressure at a normal heart rate?
A
MAP = diastolic P + 1/3 pulse pressure
2
Q
Normal BP for an adult?
A
120/80
3
Q
Pulse pressure?
A
Systolic P - Diastolic P
4
Q
What equation relates flow, pressure, and resistance?
A
Q = ΔP/R
5
Q
Equation to calculate cardiac output?
A
CO = HR x SV
6
Q
Normal CO value?
A
5L/min
7
Q
Normal SV for a 170 lb person?
A
70 mL
8
Q
Formula for CI?
A
CI = CO / m^2
9
Q
CI for 170 lb person?
A
CI = 5/1.5 = 3.3 L/min/m^2
10
Q
Formula for SI?
A
SI = SV/ m^2
11
Q
What is the unit of resistance?
A
mmHg/mL/min
12
Q
Normal resistance of the systemic circulation?
A
0.02 PRU
13
Q
1 m3 = x L?
A
1 L
14
Q
1 L = x cm3?
A
1,000 cm3
15
Q
1 L = x mm3?
A
1,000,000 mm3
16
Q
Equation for ejection fraction?
A
Ejection fraction = SV/EDV
17
Q
Equation for end diastolic volume?
A
EDV = SV + ESV
18
Q
% of cardiac output going to the brain? VO2?
A
13%
VO2: = 21%
19
Q
% of cardiac output going to the coronary circulation? VO2?
A
4%
VO2 = 11%
20
Q
% of cardiac output going to the liver and GIT? VO2?
A
24%
VO2 = 23%
21
Q
% of cardiac output going to skeletal muscles? VO2?
A
21%
VO2 = 27%
22
Q
% of cardiac output going to the kidneys? VO2?
A
20%
VO2 = 7%
23
Q
% of cardiac output going to the skin and other organs? VO2?
A
18%
VO2 = 11%
24
Q
What vessels account for most of the resistance of the CV system? What to note?
A
- Small arteries/arterioles: 47%
- Capillaries: 27%
- Large arteries: 19%
- Veins: 7%
Highest resistance in arterioles though
25
Breakdown % of blood in systemic vs pulmonary circulation?
Systemic circulation => 90% of the blood
| Pulmonary circulation => 10% of the blood
26
Pulmonary arterial pressure?
25/10 mmHg
27
Pulmonary MAP?
15 mmHg
28
Where is the largest pulse pressure found in the CV system? What is it?
LV: 120
29
Where is the lowest pulse pressure found in the CV system? What is it?
RV: 20
30
Normal venous pressure?
2-6 mmHg
31
Normal RA pressure?
9/4 mmHg (5)
32
Normal LA pressure (wedge)?
12/5 mmHg (10)
33
Normal RV end-diastolic pressure?
< 6 mmHg
34
Normal LV end-diastolic pressure?
4-12 mmHg
35
What is the actual equation to measure CO using the indicator-dilution technique?
I/C.T
```
I = mass of indicator injected
C = mean dye concentration
T = duration of 1st circulation
```
36
What is the Fick principle?
Amount of substance added or removed to or from an organ = blood flow x (a-v)
(a-v) = difference in concentration across the organ between arteries and veins
37
How is Fick's principle used to calculate CO?
CO = blood flow across the lungs = amount of oxygen consumed (mL/min) / (a-v)O2
```
a = systemic arterial oxygen concentration (sampled from any artery)
v = pulmonary arterial oxygen concentration
```
38
How to use the indicator dilution technique when all you have is the curve produced?
CO = amount of indicator added / area under first circulation curve
39
Normal RV pressure?
25/0 mmHg
40
Normal LV pressure?
120/0 mmHg
41
BV for 170 lb patient?
5L
42
List the distribution of BV throughout blood vessels.
1. Veins: 64%
2. Lungs: 9%
3. Small arteries and arterioles: 8%
4. Large arteries: 7%
5. Heart in diastole: 7%
6. Capillaries: 5%
43
Velocity of blood in aorta?
~30 cm/s
44
Velocity of blood in capillaries?
~0.1 cm/s
45
Equation to relate velocity, flow, and area of blood in vessels?
Flow (Q) = V x A
```
V = blood velocity
A = cross-sectional area
```
46
Largest vessel in body? A?
Aorta
A = 4 cm^2
47
What is Poiseuille's Law?
Flow equation, that expands on the original Q = ΔP/R:
Q = π.(P1 - P2).r^4/(8.η.L)
```
r = vessel radius
η = fluid viscosity
L = length of the vessel
```
48
Rearranging Poiseuille's Law, what is the equation for resistance?
R = 8.η.L/π.r^4
49
How does doubling the radius of the vessel affect flow rate?
16x
50
Equation to calculate total peripheral resistance?
TPR = (aortic P - CVP)/CO
CVP = central venous P
51
Equation to calculate total pulmonary resistance (PVR)?
PVR = Pulmonary artery P - LA P/CO
52
Normal PVR?
0.002 PRU
53
How can TPR be approximated in a clinical situation?
TPR = MAP/CO
54
How to measure total resistance in series circuit?
RT = R1 + R2 + R3 + ... + Rn
55
What is the pressure gradient Pi-Po equal to in series and parallel circuits?
The sum of all the pressure gradients: (Pi-P1)+(P1-P2)+(P2-Po)
56
What is the equation of the total flow of a circuit in parallel?
Qtotal = Q1 + Q2 + Q3 + ... + Qn
57
How to measure total resistance in parallel circuit?
1/RT = 1/R1 + 1/R2 + 1/R3 + ... + 1/Rn
58
Equation for Reynold's number?
Re = ρ.D.v/η
```
ρ = fluid density
D = vessel diameter
v = mean velocity
η = fluid viscosity
```
59
How can Reynold's number predict flow?
- Re<2000 => laminar flow
| - Re>2000 => turbulent flow
60
What is the density of blood?
1 g/mL
61
Equation for wall tension? What is this called?
La Place's Law:
T = P.r
```
P = transmural pressure
r = vessel radius
```
62
BP in capillary?
35 mmHg
63
How does tripling the radius of the vessel affect flow rate?
81x
64
Combined pressure of ejection of RV and LV?
125 mmHg
65
Duration of average cardiac cycle?
70 beats/min => 0.85 second cardiac cycle => 0.28 systole and 0.58 diastole
66
What is the aortic pressure during the isometric contraction of the LV?
80 mmHg
67
What % of ventricular filling does atrial contraction account for AT REST?
20-25%
68
What is LV EDV at rest?
140 mL
69
Normal ejection fraction at rest?
0.5
70
What is the CO during maximal aerobic exercise?
25 L/min
71
Max HR?
180 bpm
72
What is the SV during maximal aerobic exercise?
100-130 mL
73
What diastolic pressure is considered HT?
Above 90 mmHg
74
Normal PO2 of arterial blood?
95-100 mmHg
75
Normal PCO2 of arterial blood?
40 mmHg
76
Normal pH?
7.4
77
What is stroke work?
SV x systolic pressure
78
How many mL of blood need to be added to the artery for the pressure to go up 40 mmHg?
70 mL = SV to go from diastolic to systolic pressure
79
What is CVP at rest?
2 mmHg
80
Combined, what fraction of the CO do the liver and the GIT receive?
1/3
81
Normal arteriolar transmural pressure?
100 mmHg
82
What max % of CO can skeletal muscles get during exercise?
80% of 25 L/min CO
83
Normal MAP?
95 mmHg
84
Systolic RA and CVP pressure?
5 mmHg
85
Systolic RV and PA pressure?
25 mmHg
86
Systolic LA and PA occlusion pressure?
10 mmHg
87
Systolic LVP?
125 mmHg
88
Normal CI?
2.6-4.2 L/min/m^2
