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Patient Monitoring/Instrumentation & SIM > Advanced Hemodynamic Monitoring > Flashcards

Advanced Hemodynamic Monitoring Flashcards

1
Q

Normal value for cardiac index

A

2.2-4.2 L/min/m2

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2
Q

Normal value for central venous pressure

A

5-12 mmHg

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3
Q

When is CVP most accurate?

A

When measured at the end of expiration

If the backrest position is between 0 to 60 degrees

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4
Q

Normal value for coronary perfusion pressure

A

Autoregulated between 50-120 mmHg

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5
Q

Normal value for mixed venous oxygen saturation (mvO2)

A

60-80% in an awake patient

Roughly equal to central venous oxygen saturation (ScvO2)

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6
Q

Normal value for pulmonary artery pressure (PAP)

A

15-30/10 mmHg

Accurate if backrest position is between 0-60 degrees

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7
Q

Normal value for pulmonary hypertension (mild, moderate and severe)

A

Mild: 36-49 mmHg systolic
Moderate: 50-59 mmHg systolic
Severe: >60 mmHg systolic

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8
Q

Normal value for pulmonary capillary wedge pressure

A

<12 mmHg (mean pressure)
1-4 mmHg less than pulmonary artery diastolic pressure
Accurate if backrest position is between 0-60 degrees

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9
Q

Normal pulmonary vascular resistance (PVR)

A

100-300 dynesseccm^-5

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10
Q

Normal value for stroke volume in adults

A

60-90 mL/beat

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11
Q

Normal value for stroke volume index

A

20-65 mL/beat/m2

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12
Q

Normal value for systemic vascular resistance (SVR)

A

700-1200 dynesseccm^-5

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13
Q

Normal value for central venous oxygen saturation (ScvO2)

A

25-30% below SaO2 OR 70-75% if pt’s SaO2 is normal

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14
Q

Baroreceptor reflex

A
  • Responds to changes in blood pressure in carotid sinus and aortic arch
  • When BP is low, HR increases
  • When BP is high, HR decreases
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15
Q

Bainbridge reflex

A

-Responds to changes in blood volume in the heart
-If R atrial pressure increases, the Bainbridge reflex causes increased HR and vasodilation
(try to get excess blood out of R atrium and causes venous pooling in legs, which decreases venous return)

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16
Q

What causes an increase in HR in the Bainbridge reflex and Baroreceptor reflex?

A

Low CVP through Baroreceptor reflex

High CVP through Bainbridge reflex

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17
Q

Why is a cardiac output of 5L/min not accurate?

A

It may be normal for a 70kg patient, but it is too low for a 200 kg patient and too high for a 30 kg patient

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18
Q

What is the cardiac index equation?

A

Cardiac output/surface area

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19
Q

Stroke volume index equation

A

stroke volume/surface area

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20
Q

Coronary perfusion pressure equations

A
  1. CPP = DBP - LVEDP
  2. CPP = DBP - CVP
  3. CPP = DBP - Pulmonary artery diastolic pressure
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21
Q

How do you estimate Left Ventricular Diastolic Pressure? (LVEDP)

A
  1. LVEDP = left atrial pressure
  2. Left atrial pressure = PCWP
  3. PCWP = Pulmonary artery diastolic pressure
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22
Q

What is the thermodilution technique?

A
  1. Inject 10ml cold saline in the R atrium through the Swan Ganz catheter CVP port in <4 seconds
  2. The cold fluid travels to the PA where it encounters the thermistor (the fluid is warmed to a degree before encountering the thermistor)
  3. The monitor produces a waveform depending on how cold it is
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23
Q

If cardiac output is high, what happens to the temperature of the fluid at the thermistor?

A

It warms up quickly

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24
Q

What does the thermistor curve look like for high cardiac output?

A

The area under the curve is lower than normal (small wave)

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25
Q

If cardiac output is low, what happens to the temperature of the fluid at the thermistor?

A

It will stay cold for a longer period

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26
Q

What does the thermistor curve look like for low cardiac output?

A

The area under the curve is larger than normal (large wave)

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27
Q

What happens if the saline is injected too slowly to the thermistor?

A

The curve would be larger than normal, underestimating cardiac output

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28
Q

A patient has a right to left intracardiac shunt. Would thermodilution lead to an overestimation or underestimation of cardiac output, and why?

A

Overestimation; Some cold fluid is lost to the L side, so blood in the pulmonary artery will be warmer and the curve will be smaller

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29
Q

A patient has a left to right intracardiac shunt. Would thermodilution lead to an overestimation or underestimation of cardiac output, and why?

A

Overestimation; Cold fluid is diluted by warm blood in the L side, so fluid will be warmer and the curve will be smaller

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30
Q

A patient has tricuspid regurgitation. Would thermodilution lead to an overestimation or underestimation of cardiac output, and why?

A

Underestimation; The blood at the thermistor will stay colder for a longer period and the curve will be larger

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31
Q

What has replaced thermodilution?

A
  1. Continuous cardiac output pulmonary artery catheters

2. Transesophageal echocardiography (TEE)

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32
Q

Oxygen saturation of superior vena cava

A

Central venous O2 saturation

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33
Q

How is ScvO2 drawn?

A

Central venous line port

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34
Q

What is a mixed venous oxygen saturation?

A

Blood from the SVC, IVC and coronary sinus taken at the distal tip of the pulmonary artery catheter

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35
Q

What is the difference between ScvO2 and mvO2?

A

mvO2 will be slightly lower because it has venous blood from the heart (coronary sinus blood)

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36
Q

How do ScvO2 and mvO2 relate to low cardiac output, and why?

A

Low CO = low mvO2/ScvO2
Blood is more deoxygenated by the time it reaches the heart because it traveled slowly through the body and had more time to unload oxygen to the tissues

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37
Q

How do ScvO2 and mvO2 relate to high cardiac output, and why?

A

High CO = high mvO2/ScvO2
Blood is less deoxygenated by the time it reaches the heart because it traveled quickly throughout the body and had less time to unload oxygen to the tissues

38
Q

Why are ScvO2 and mvO2 rarely used to estimate cardiac output now?

A
  1. It requires drawing blood from central line or Swan catheter
  2. Cardiac output can be estimated through other effective methods such as TEE, CCO Swan, FloTrac sensor
39
Q

What is the equation for Ohm’s law and what is each variable?

A

V= IR
Voltage
I: Current
Resistance

40
Q

What part of Ohm’s law is analogous to cardiac output?

A

The current (I)

41
Q

What part of Ohm’s law is analogous to peripheral and systemic vascular resistance?

A

Resistance (R)

42
Q

What in the body is analogous to voltage in Ohm’s law?

A

The difference between the blood pressure at the arterial end of the body and the blood pressure at the venous end of the body
MAP- CVP

43
Q

What is Ohm’s law in terms of cardiac output systemically?

A

(MAP-CVP) = (SVR)(CO)

44
Q

Rewrite Ohm’s law to solve for cardiac output

A

CO = [(MAP-CVP)/SVR]*80

45
Q

Rewrite Ohm’s law to solve for SVR

A

SVR= [(MAP-CVP)/CO] *80

46
Q

Why use the number “80” in the equations for cardiac output and SVR?

A

80 converts the units for blood pressure and SVR into units for cardiac output

47
Q

How can you calculate PVR using Ohm’s law?

A

PVR = [(PAP-PCWP)/CO] *80

48
Q

How can you calculate cardiac output with pulmonary pressures?

A

CO= [(PAP-PCWP)/PVR] *80

49
Q

What are factors that affect pulse pressure?

A
  1. Stroke volume (increased stroke volume = increased systolic pressure)
  2. SVR (increased SVR/vasoconstriction = increased systolic pressure)
  3. Aortic compliance (good compliance = decreased systolic pressure)
50
Q

Will pulse pressure be wide or narrow in a hypovolemic patient, and why?

A

Narrow

Low SV and vasoconstriction

51
Q

Will pulse pressure be wide or narrow in a patient with CHF, and why?

A

Narrow

Low SV and vasoconstriction

52
Q

Will pulse pressure be wide or narrow after running 3 miles on the treadmill, and why?

A

Wide

Inc SV and vasodilation

53
Q

Will pulse pressure be wide or narrow in a patient with cardiac tamponade, and why?

A

Narrow

Low SV and vasoconstriction

54
Q

Will pulse pressure be wide or narrow in a patient with aortic stenosis, and why?

A

Narrow

Low SV and vasoconstriction

55
Q

Will pulse pressure be wide or narrow in a patient with a milrinone drip, and why?

A

Wide

Increases cardiac contractility and decreases SVR

56
Q

Will pulse pressure be wide or narrow in a patient with aortic regurgitation, and why?

A

Wide

Inc SV and dec DBP

57
Q

What causes high CVP?

A
  1. Fluid overload
  2. Heart failure
  3. Pulmonarty HTN
  4. Trendelenburg
  5. High intrathoracic pressure (tension PNX)
58
Q

What causes low CVP?

A
  1. Hypovolemia

2. Sitting position

59
Q

Causes of low SVR

A

Vasodilation

60
Q

Causes of high SVR

A

Vasoconstriction

61
Q

Causes of low cardiac index

A
  1. Decreased cardiac contractility
  2. Bradycardia
  3. Hypovolemia
  4. Hypervolemia (in CHF patient)
  5. Increased afterload (aortic stenosis or high SVR)
62
Q

Causes of high cardiac index

A
  1. Increased contractility/stroke volume
  2. Tachycardia
  3. Vasodilation
63
Q

Types of hypotension

A
  1. Hypovolemia
  2. Vasodilation
  3. Heart failure (dec contractility)
64
Q

Treatments for hypovolemia

A

Fluids and/or blood products

65
Q

Treatments for vasodilation

A
  1. Vasopressors

2. Reversing of vasodilation such as decreasing level of anesthetic

66
Q

Treatments for heart failure

A
  1. Inotropes

2. Diuretics

67
Q

What happens to cardiac index, CVP and SVR when a patient is hypotensive due to hypovolemia?

A

Cardiac index: Decreased
CVP: Decreased
SVR: Increased

68
Q

If a patient has hypotension due to vasodilation, what happens to cardiac index and SVR?

A

Cardiac index: Increased

SVR: Decreased

69
Q

If a patient has hypovolemia due to decreased contractility, what happens to cardiac index, CVP and SVR?

A

Cardiac index: Decreased
CVP: Increased
SVR: Increased

70
Q

What would be best to treat this patient with a BP of 88/40, HR of 98, cardiac index of 3.0 and SVR of 400?

A

Vasopressor

71
Q

What would be best to treat this patient with a BP of 85/40, HR of 65, SVR of 1100, and cardiac index of 1.8?

72
Q

What would be best to treat this patient with a BP of 170/105, HR of 60, SVR of 1700, cardiac index of 2.8 and PVR of 350?

A

Vasodilator

73
Q

What would be the best treatment for a patient with a BP of 84/55, HR of 100, SVR of 1500, PVR of 100, cardiac index of 2, CVP of 2, and PAP of 20/5?

A

Fluid bolus

74
Q

Stroke volume and systolic blood pressure fluctuating during inspiration and expiration

A

Stroke volume variation or pulse pressure variation

75
Q

How much does systolic blood pressure decrease during inspiration in spontaneously ventilating patients?

76
Q

Why does systolic blood pressure decrease during inspiration in spontaneously ventilating patients?

A

It decreases 5-10 mmHg due to:

  1. Pulmonary vessels vasodilating
  2. Vasodilation causes blood to pool in lungs
  3. Less blood is available to pump to the body
  4. Slight drop in BP during inspiration
77
Q

What is the expected effect on HR if the patient is hypervolemic? Hypovolemic? and why?

A

HR increases due to the Bainbridge reflex

78
Q

In healthy mechanically ventilated patients, how much does the systolic blood pressure change during inspiration and why?

A

Increases 5-10%

  1. Displaces L ventricular wall inward during systole, assisting ventricular contraction (increasing ejection fraction)
  2. Squeezes blood out of the pulmonary capillaries, into the L atrium and increasing blood volume and stroke volume during inspiration
79
Q

When the stroke volume/systolic blood pressure has wider than expected fluctuations during inspiration and expiration

A

Pulsus paradoxus

80
Q

How do you detect pulsus paradoxus?

A

SpO2 and arterial line waveforms

81
Q

Most common cause of pulsus paradoxus

A

Hypovolemia

82
Q

Other causes of pulsus paradoxus

A

cardiac tamponade, tension pneumothorax, vasodilation, CHF, hypervolemia, and PEEP

83
Q

Cardiac tamponade mechanism for pulsus paradoxus

A
  1. During normal inspiration, blood volume in the R ventricle increases
  2. With cardiac tamponade, the R ventricular wall cannot expand, so it forces the interventricular septum to bulge to the L
  3. This causes a decrease in the volume of the L ventricle, decrease in SV and greater decrease in BP during inspiration
84
Q

Tension PNX mechanism for pulsus paradoxus

A
  1. R ventricular wall cannot expand, causing the interventricular septum to bulge into the L
  2. This causes a decrease in the volume of the L ventricle, decrease in SV and greater decrease in BP during inspiration
85
Q

What does the FloTrac sensor do?

A

Tells us exact stroke volume variation

86
Q

“Cool things” about the FloTrac sensor

A
  1. Noninvasive
  2. Gives real time blood pressure
  3. Measures stroke volume variation, stroke volume and SV index, SVR (from waveform downstroke)
  4. Can calculate cardiac index
87
Q

Disadvantages of FloTrac sensor

A
  1. Arterial lines give access for drawing labs while EV1000 does not
  2. EV1000 is not always accurate
88
Q

Common methods to assess volume status

A
  1. Urine output
  2. hypotension/tachycardia
  3. CVP monitoring
89
Q

How do you manage fluids with the FloTrac sensor?

A

The FloTrac Sensor can give us stroke volume variation. When stroke volume increases by >10-15% on mechanically ventilated patients, hypovolemia is expected.
Titrate until the stroke volume variation is closer to 10%

90
Q

Limitations of the FloTrac Sensor?

A
  1. Patient must be 100% mechanically ventilated for accurate stroke volume variation
  2. Respiratory rate needs to be constant
  3. Tidal volume needs to be >8ml/kg
  4. Regular heart rhythm
  5. PEEP and vasodilators can alter SVV
91
Q

Fluid management protocol for hypotensive patients

A
  1. Give fluids until SVV <10%
  2. If SVV does not respond to therapy, look at the SVI
    - if SVI is <20%, give inotropes
    - if SVI is 40-50%, give vasopressors
    - if SVI is >50%, give diuretics

Patient Monitoring/Instrumentation & SIM (12 decks)

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