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I & M > Cardiac Assist Devices > Flashcards

Cardiac Assist Devices Flashcards

1
Q

What are the essential functions performed by CPB (cardiopulmonary bypass)? (3)

A

Oxygenation of venous blood

Elimination of CO2

Maintenance of system perfusion

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2
Q

Describe the CPB basic circuit from the patient.

A

Patient→

Reservoir→

Filter→

Oxygenator→

Heat exchanger (hypothermia ~30ºC)→

Roller pump→

Arterial line filter

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3
Q

What is the method commonly used to stop the heart?

What 2 products are used to physically prevent the heart from beating?

A

Cardioplegia

High potassium,

Low potasssium containing cardioplegia solutions

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4
Q

Cardioplegia perfusion of the myocardium may be ________ through the ______ ______ or ________ through the _______ ______.

A

antegrade

coronary arteries

retrograde

coronary sinus

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5
Q

How are the majority of cardiac procedures performed?

A

venous cannulation through the right atrium, with a single “two-stage” cannula

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6
Q

What does this depict?

A

2 vessel cannulation of the right atrium

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7
Q

What does this depict?

A

“Two-stage” cannula

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8
Q

Label:

A

(In green)

  1. Venous reservoir
  2. Heat exchanger, oxygenator (located lower)
    2*. Anesthetic vaporizer
  3. Roller pumps
  4. Heater/cooler, usually proximal to the oxygenator
  5. Arterial filter

A single integrated, disposable unit containing the venous reservoir, heat exchanger, and oxygenator is demonstrated.

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9
Q

A centripetal/centrifugal pump is used in a CPB circuit.

A

centrifugal

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10
Q

What type of oxygenator is used in CPB?

Bubble through or membrane oxygenator?

A

Membrane oxygenator directly connected to the heat exchanger.

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11
Q

KNOW (red-boxed)

An ___-____ blender controls the FiO2 delivered to the membrane oxygenator and therefore the _____ _____ _______ ______ between the gas and blood phases.

This alters the total amount of oxygen transfer by diffusion through the membrane and ultimately the _____.

A

air-oxygen

oxygen partial pressure gradient

PaO2 which equals P(arterial)O2

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12
Q

KNOW (red-boxed)

Arterial PaCO2 is independently controlled by the ____ ____ through the oxygenator, which is often referred to as the “____ ___”.

A

gas flow (L/min)

“sweep rate”

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13
Q

KNOW

Higher rates of gas flow ______ more CO2 from the inner membrane surface establishing a diffusion gradient from the blood to the inside of the membrane _____ the PaCO2.

A

remove

decreasing

Note: This gas flow does not contain CO2.

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14
Q

KNOW

An ______ ______ may be placed in the circuit to provide a set concentration of vapor to the membrane surface where it diffuses into the blood of the patient.

A

anesthetic vaporizer

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15
Q

KNOW

Current membranes have a surface area of approximately ___ to ___ m2.

A

2 - 4

Note: The surface area is 1/20th of the lung, but compensates by increasing contact or transit time to the membrane.

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16
Q

What type of pump maintains pressure but without pulsatile pressure?

A

Roller pump

Note: You will see static electricity on the roller pump, not heart activity on the EKG.

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17
Q

Describe phases A, B, C, D of the roller pump.

A

A. Roller pump B moves fluid ahead of it and suctions fluid behind it

B. The second roller A begins to engage the tubing

C. As rotation continues there is a very brief period with volume trapped between the two rollers and no forward flow, which imparts some pulsatility.

D. Roller B leaves the tubing while the second roller continues to move fluid in the same direction

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18
Q

What type of pump and where does blood enter/exit?

A

Centrifugal pump

Preload is where blood enters.

Afterload is where blood exits.

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19
Q

What type of pump?

A

Impeller

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20
Q

What type of pump depends upon afterload?

A

centrifugal

Note: Roller pump does NOT depend on afterload.

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21
Q

What type of pump involves increased risk of air embolism?

A

Roller pump

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22
Q

What type of pump generates pulsatile flow?

A

roller

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23
Q

What type of pump can generate excessive arterial line pressure?

A

roller

Centrifugal cannot.

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24
Q

What type of pump can you hand crank?

A

roller

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25
Q

What type of pump can cause greater trauma to bypass tubing?

A

roller

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26
Q

What type of pump can cause greater trauma to blood?

A

roller

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27
Q

What type of pump has a superior outcome?

A

Neither are superior to the other (centrifugal/roller)

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28
Q

What type of pump is more expensive and where reverse flow is possible?

A

centrifugal

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29
Q

What are the CPB filter sites? (6)

A

Cardioplegia

Bank blood

Priming fluids

Reservoir

Arterial Filter

Between oxygenator and O2 supply

Essentially, just know there are filters everywhere.

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30
Q

Describe how the endovascular CPB system works.

A

This system uses femoral arterial and venous cannulation sites and femoral access for placement of an endoaortic balloon occlusion.

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31
Q

Identify the phases along the x-axis

32
Q

What change will you notice on the ECG during hypothermia?

A

Osborn wave in V5 lead, or other mid-precordial, inferior leads

33
Q

What are the deleterious effects of hyperthermia during cerebral ischemia?

A

Increases in:

  • excitotoxic neurotransmitter release
  • BBB permeability
  • inflammatory response
  • free radical production
  • intracellular acidosis
34
Q

What is a positive deflection at the J point also called?

A

Osborn wave

35
Q

What is ECMO?

ECLS?

A

Extracorporeal Membrane Oxygenation

Extracorporeal Life Support

36
Q

What is the difference between ECMO, ECLS?

A

ECMO generates flow

ECLS generates pressure

37
Q

What is ECMO?

A

It is a means to provide temporary hemodynamic and/or respiratory support to critically ill patients who cannot be supported by less aggressive means such as inotropes, vasopressors, etc.

38
Q

The highest rate of success with ECMO has been among what pt population?

A

neonates and pediatrics with respiratory failure

39
Q

ECMO is similar to CPB consisting of cannula, pump, and gas exchange. Major differences include site of cannulation and lack or venous reservoir. True or false?

40
Q

What are the indications for ECMO in peds?

A

Respiratory

  • Primary pumonary HTN
  • Congenital diaphragmatic hernia
  • Meconium aspiration
  • Persistent fetal circulation
  • Pneumonia
  • ARDS
  • Pulmonary hemorrhage

Cardiac

  • Cardiac failure after cardiac surgery
  • Cardiomyopathy
41
Q

What are the indications for ECMO in adults?

A

Respiratory

  • ARDS
  • Pneumonia
  • Near drowning
  • Post-lung transplantation

Cardiac

  • Cardiac failure posttransplant
  • Right heart failure
  • Failure to wean from bypass
  • Emergency resuscitation
42
Q

What is venoarterial ECMO?

What are possible arterial sites?

Venous sites?

A

Designed to primarily support a patient with cardiopulmonary failure.

Arterial sites include the right common carotid (neonates) or femoral (adults)

Venous sites include the femoral vein, jugular vein or even the atrium.

43
Q

What is venovenous ECMO?

A

ECMO support for respiratory failure.

The right internal jugular vein is accessed for drainage and the femoral vein is used for return blood.

Or, a tube enters the body through the vena cava down through the heart and delivers/removes blood via 1 tube.

44
Q

Label the ECMO system.

A
  1. Venous reservoir
  2. Membrane oxygenator
  3. Pump
  4. Heat exchanger
45
Q

How does the ECMO system warm fluids?

A

countercurrent warming

46
Q

What is depicted?

How do you want this positioned?

A

Intra-Aortic Balloon Pump

Do not occlude the carotids with the proximal portion.

Want to have distal portion above the renal arteries.

47
Q

What may stress from the intra-aortic balloon cause?

48
Q

What are indications for an intra-aortic balloon pump? (6)

A
  • Cardiogenic shock such as MI, cardiomyopathy
  • Failure to separate from CPB
  • Stabilization of ventricular septal defect
  • Mitral regurgitation (that further complicates MI)
  • Support during coronary angiography
  • Bridge to transplantation
49
Q

What are contraindications to intra-aortic balloon pump?(6)

A
  • Aortic valvular insufficiency
  • Aortic disease like dissection, aneurysm
  • Severe vascular disease
  • Severe noncardiac systemic disease
  • Massive trauma
  • DNR patients
50
Q

When does the IABP (intra-aortic balloon pump) inflate/deflate?

A

Deflates during systole.

Inflates during diastole to improve oxygen supply to the heart.

51
Q

What is normally used as the drive gas for IABP?

A

Helium because low density gives rapid inflation.

NOT CO2 because dissolves in blood quickly.

52
Q

What is the IABP balloon volume and triggers?

A

30 - 50 ml

Triggers: ECG and arterial pressure waveform

53
Q

What are the hemodynamic affects of IABP? (6)

A
  • Increase coronary perfusion (increasing diastolic BP)
  • Decrease afterload (decreasing aortic diastolic pressure)
  • Decreases LVEDP and PCWP
  • Increase CO and EF
  • Increase cerebral perfusion
  • Decrease HR
54
Q

What type of wave does the balloon pump create?

A

square wave

55
Q

What do points D and E indicate?

A

D. Diastolic augmentation

E. Reduced aortic end diastolic pressure

56
Q

Label:

57
Q

What does this waveform indicate?

What are the physiological effects?

A

Premature deflation of the IAB during the diastolic phase (early deflation)

Increased MVO2 demand

Note: MVO2 is myocardial consumption.

58
Q

What does this waveform indicate?

What are the physiological effects?

A

Deflation of the IAB late in diastolic phase as aortic valve is beginning to open (late deflation)

Increased MVO2 consumption due to the LV ejecting against a greater resistance and a prolonged isovolumetric contraction phase.

Note: See widened diastolic augmentation and prolonged rate of rise in systole.

59
Q

What does this waveform indicate?

A

Normal IABP assistance and perfusion

60
Q

What does this waveform indicate?

What are the physiological effects?

A

Inflation of the IAB prior to aortic valve closure (early inflation)

Increased MVO2 demand

61
Q

What does this waveform indicate?

A

Inflation of the IAB markedly after closure of the aortic valve (late inflation)

62
Q

What are IABP complications relating to vascular injury?

A
  • Arterial injury (aortic perforation, dissection)
  • Femoral artery thrombosis
  • Peripheral embolization
  • Pseudoaneurysm of femoral vessels
  • Lower extremity ischemia
  • Compartment syndrome
  • Visceral ischemia
63
Q

What are miscellaneous IABP complications?

A
  • Hemolysis
  • Thrombocytopenia
  • Infection
  • Claudication
  • Paraplegia
  • Spinal cord necrosis
64
Q

What is this waveform called?

A

Intra-aortic balloon counterpulsation

65
Q

What is this arterial pressure waveform a result of?

A

Cardiopulmonary bypass

Small variations due to bypass roller pump.

66
Q

What is depicted?

A

Axial flow assist devices

67
Q

What is a Hemopump?

A

The Hemopump is inserted via the femoral arteries. The inflow to the pump sits in the LV and the outflow in the proximal descending aorta.

Helps pump blood into aorta.

68
Q

What is a NovaCor LVAS?

How does the pump operate?

A

LV assist system

The pump works using dual pusher plates that compress a polyurethane sac.

69
Q

What are special considerations when you are presented with a patient with a LVAS?

A

BP and pulse ox may not work.

Use a cerebral oximeter.

70
Q

What is depicted?

A

Heartmate XVE LVAD

71
Q

What is depicted?

A

Arrow LionHeart implantable LVAD (left ventricular assist device)

72
Q

What is depicted?

A

Abiomed Single or Dual Chamber Support Device

73
Q

What is depicted?

A

Total artificial heart

74
Q

What better bridges pts to tranplantation? BiVAD or total artificial heart?

A

total artificial heart

75
Q

What is depicted?

A

CardioWest Artificial Heart which is powered by air

I & M (37 decks)

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