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Critical Care Paramedic > 2.2.2: Mechanical and Circulatory Assist Devices > Flashcards

2.2.2: Mechanical and Circulatory Assist Devices Flashcards

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1
Q

What are the 5 major stages of the cardiac cycle?

A
  1. late diastole / ventricular filling
    - the AV valve and mitral valves are open
    - blood enters into RA from VC
    - blood enters into LA from PV
  2. atrial systole
  3. isovolumetric ventricular contraction
    - the amount of blood in the ventricles remains the same
    - Tricuspid valve, pulmonary (semilunar) valve, aortic (semilunar) valve, and mitral valve are all closed
    - pressure in ventricles increases significantly
    - “lub” sound
  4. ventricular ejection
    - semi-lunar valve opens
    - pulmonary valve opens
  5. isovolumetric ventricular relaxation
    - pressure in ventricles drops significantly
    - semilunar valves close
    - “dub” sound
    - AV valve opens up (ventricular pressure drops below atrial pressure)
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2
Q

What are the valves doing and what is the heart doing during late diastole / ventricular filling

A
  • the semilunar valves are closed
  • the AV valves are open
  • the heart is relaxed
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3
Q

What is happening during atrial systole?

A
  • the atria contract
  • AV valves are open
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4
Q

what happens during isovolumetric ventricular contraction

A

-ventricles contract
- all valves in the heart are closed

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5
Q

what happens during ventricular ejection?

A
  • semilunar valves open
  • AV valves are shut
  • blood flows out of the ventricles
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6
Q

what happens during isovolumetric ventricular relaxation?

A
  • all valves are closed
  • ventricles stop contracting and begin to relax
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7
Q

What is preload?

A

the amount of stretch on the ventricles prior to contraction
- starling’s law
-

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8
Q

What is afterload?

A

the resistance to ventricular ejection
- the mass of blood that must be moved

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9
Q

What is aortic end diastolic pressure (AEDP)?

A

the pressure that the left ventricle must push against in order to open the aortic valve and generate blood flow

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10
Q

what are the 4 measurements of cardiac performance?

A
  • cardiac output
  • cardiac index
  • fick principle
  • systemic vascular resistance
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11
Q

What is the equation for CI

A

SV x HR / BSA

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12
Q

What are the three components of the A&P of a failing heart?

A
  • left ventricular failure
  • hypervolemia
  • tissue hypoxia
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13
Q

What is the value range for systemic vascular resistance (SVR)?

A

800-1200

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14
Q

What is the definition of SVR?

A

The resistance to blood flow from all of the systemic vasculature excluding the pulmonary vasculature.

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15
Q

What will happen to the SVR when there is vasoconstriction?

A

The SVR will go up

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16
Q

What will happen to the SVR when there is vasodilation?

A

The SVR will go down

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17
Q

What does hypertrophy of the mycoardium lead to?

A

stiffness of the ventricle and decreased ability to relax during diastole

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18
Q

When does the balloon pump inflate and when does it deflate?

A

Inflation during diastole and deflation during systole

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19
Q

What is the primary benefit of an IABP?

A

that it corrects supply vs demand mismatch

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20
Q

What does inflation of the IABP do to the supply?

A

increased supply

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21
Q

What does deflation of the IABP do to the demand?

A

decreased demand

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22
Q

What is the range for a typical IABP catheter?

A

25-50 mL

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23
Q

What are the hemodynamic effects of an IABP?

A
  • increases diastolic arterial pressure
  • increases coronary blood flow
  • increases CO, EF, and forward flow
  • increases cerebral and renal blood flow
  • increases systemic perfusion
  • increases coronary and systemic oxygen supply
  • increases hemodynamic pulse rate
  • decreases systolic arterial pressure
  • decreases afterload
  • decreases LV wall tension
  • decreases preload congestion
  • decreases heart rate
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24
Q

What is the placement for an IABP?

A

1-2 cm below the subclavian artery,
proximal to the renal and mesenteric arteries

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25
Q

What percentage of the aorta foes the balloon occlude when properly placed? Why doesn’t it fully occlude?

A

80-90%
full occlusion will damage the walls of the aorta and cause hemolysis

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26
Q

How far inferior to the aortic arch should be tip of the IAB be?

A

2-3 cm

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27
Q

What are the absolute contraindications for IABP?

A
  • severe aortic valve insufficiency
  • dissecting aortic aneurysm
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28
Q

How often should the hematocrit of a patient with an IABP be monitored?

A

daily

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29
Q

What does apparent rust in the IABP tubing mean ?

A

it means the balloon may have burst or torn and there is blood in the tubing

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30
Q

Where would limb ischemia occur in the case of an IABP?

A

In the leg it is put in or in the left arm (because the balloon could advance and block blood flow)

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31
Q

What are the risk factors for limb ischemia with an IABP?

A
  • female
  • diabetic
  • peripheral vascular disease
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32
Q

CSM should be checked ___ min after IABP insertion and every ___ hours after

A

30, 2

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33
Q

What should you do if the IABP machine has failed?

A

inflate and deflate the balloon every 5-10 minutes by hand using the syringe and stopcock filled with 40-60cc air or helium

34
Q

Approximately how many mLs of helium are pumped into the IAB

A

35-40 mL

35
Q

When the IAB is inflated, which way is blood pushed?

A

superiorly and inferiorly
- superior blood is pushed into the coronary arteries, increasing perfusion to the myocardium and the brain
- inferior blood is forced into distal organs

36
Q

What are the goals of IAB inflation?

A
  • increase coronary perfusion pressure
  • increase systemic perfusion pressure
  • increase peripheral oxygen supply
  • decreases SVR
  • decreases HR
37
Q

When the IAB deflates, pressure in the aorta rapidly decreases. What does this do to afterload?

A

reduces afterload

38
Q

What are the goals of IAB deflation?

A
  • decreases afterload
  • decreases oxygen consumption of the left ventricle
  • decreases assisted peak systolic pressure
39
Q

What does the IABP use to know when to inflate and deflate?

A

it uses the central aortic pressure waveform and the EKG to identify the dichrotic notch

40
Q

What can a pacer spike do to an IABP?

A

it can result in loss of capture, which may result in loss of balloon deflation during systole

  • the pump may continue to follow the pacing rate rather than the ventricular contraction rate
41
Q

During cardiac arrest, the IABP must be taken out of ____ mode and placed into ___ mode

A

EKG, pressure

42
Q

What are the four types of timing errors that can occur with an IABP?

A
  • early inflation
  • late inflation
  • early deflation
  • late deflation
43
Q

When does the IAB inflate in early deflation?

A

prior to the dichrotic notch

44
Q

What physiologic effect can early inflation of the IAB have?

A
  • increase in aortic pressure causing regurgitation of blood into the left ventricle
45
Q

What are the clinical implications of late IABP inflation?

A
  • decreased perfusion pressure
  • decreased volume to the coronary arteries
46
Q

What will the assisted end-diastolic wave look like in early deflation of the IABP?

A

it may be equal or less than the unassisted aortic end-diastolic pressure

47
Q

What will the end-diastolic wave look like in late deflation of the IABP?

A

it may be equal or greater than the unassisted aortic end-diastolic pressure

48
Q

What are the physiologic effects of late IABP deflation?

A
  • there is no afterload reduction now… now there is a blockage
  • increased MVO2 consumption
  • balloon may impede left ventricular ejection and increase afterload
  • potential reduction in cardiac output
49
Q

What can cause a low plateau pressure on IABP?

A
  • low balloon volume
  • too small of a balloon
  • balloon placement too low in the aorta
50
Q

What can cause balloon pressure waveform artifact on IABP?

A
  • balloon still in sheath
  • suture too tight
  • partial kink
  • slow helium speed
  • tortous vessels
51
Q

What can cause an elevated baseline on IABP waveform?

A
  • kinked catheter
  • partially wrapped balloon
  • balloon in sheath
  • overfill
  • balloon too low in aorta
  • balloon too large
52
Q

What can cause the baseline to be below zero on IABP waveform?

A
  • blood in tubing
    -leak in tubing
  • kinked catheter
  • ectopy
53
Q

What can cause a square or rounded plateau on IABP waveform?

A
  • high pressures
  • partially wrapped balloon
  • balloon in sheath
  • too large of balloon
  • inaccurate balloon placement
54
Q

Transvenous pacing serves as a bridge to:

A

permanent cardiac pacemaker implantation

55
Q

If the HR is greater than what the pacer is set at, the sensitivity is too ____ (high/low)

A

low (failure to sense)

56
Q

If the HR is less than what the pacer is set at, the sensitivity is too ____ (high/low)

A

high (failure to pace)

57
Q

ECMO can assume up to ___% of cardiac output

A

75

58
Q

Which vessels are the cannulae placed into in ECMO?

A

internal jugular and carotid artery

59
Q

What are the absolute contraindications of ECMO?

A
  • unable to systemically anticoagulate the patient
  • terminal disease with short survival
  • underlying moderate to severe chronic lung disease
  • advanced multiple organ failure syndrome
  • unresponsive septic shock
  • uncontrolled metabolic acidosis
  • central nervous system injury
60
Q

What medication is contraindicated for patients on ECMO and why?

A

Protamine, it can cause serious circuit-related thrombosis

61
Q

What type of patient is a TAH designed for?

A

patients waiting for a heart transplant who do not respond to other treatments and who are at risk for imminent death from non-reversible bi-ventricular failure

62
Q

What is a VAD and what does it do?

A

ventricular assist device, can replace the LV, RV, or both (BIVAD)

It decreases the workload of the heart while maintaining adequate flow and blood pressure

63
Q

Is bleeding from VAD surgery common? what % of patients experience it?

A

very common, 30-50%

64
Q

What do VADs depend on to function?

A

VADs are preload dependent, they need the preload
they are afterload sensitive

65
Q

What are three major concerns to be aware of with a VAD patient?

A
  • bleeding
  • clotting
  • infection
66
Q

What is suckdown in a VAD patient and why does it happen?

A

suckdown is LV collapse due to hypovolemia or VAD overdrive- happens when the preload isn’t there

67
Q

What is a sign that suckdown is occurring

A

you can hear knocking/grinding sounds when auscultating the device

hypotension
PVCs/vtach
RV failure

68
Q

Are all VAD patients pulseless?

A

No, it is not uncommon for a VAD patient to have a carotid pulse

69
Q

Besides blood pressure (which can be inaccurate in a VAD patient) what other measurement is important?

A

MAP

70
Q

When should a VAD patient be defibrillated or cardioverted?

A

when they are unstable
sometimes VAD patients have an apparent life-threatening arrhythmia, but that is normal for them

71
Q

When should CPR be initiated on a VAD patient

A

per medical control or if instructed by someone at the VAD center

72
Q

What is the first line therapy in an unstable VAD patient and why?

A

volume resuscitation because all VADs are preload dependent

73
Q

Can VAD patients receive nitro?

A

no, silly goose

74
Q

Which VAD device unloads blood from the left ventircle and expels it into the ascending aorta?

A

the Impella

75
Q

What type of device is the intra-aortic balloon pump?

A

a volume displacement device

76
Q

What is the primary benefit of a balloon pump?

A

it corrects the supply vs. demand mismatch

77
Q

What are the contraindications to impella use?

A
  • mural thrombus in LV
  • mechanical aortic valve or heart constrictive device
  • aortic valve stenosis/calcification
  • moderate to severe aortic insufficiency
  • severe PAD that precludes placement
78
Q

What triggers the IABP balloon?

A
  • EKG
  • pressure
  • pacer spike
79
Q

When does the IABP deflate?

A

at the r wave

80
Q

What mode should the IABP be put into if the pt goes into arrest?

A

art line or pressure mode

Critical Care Paramedic (20 decks)

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