Basics of CPB

Question 1

Fill in the blank: Centrifugal pumps are ____ dependent.

Answer 1

afterload

Question 2

What does it mean when centrifugal pumps are afterload dependent?

Answer 2

Centrifugal pump consists of impellers/stacked cones within housing. When rotated rapidly, negative pressure is created at one inlet, and positive pressure at the other, thus propelling the blood forward. They are afterload dependent, so if the patient’s systemic vascular resistance (SVR) increases, the cardiac output generated will drop unless the flow through the pump is increased.

Question 3

A vent is required to drain the left side of the heart for blood draining through the ____ and ____ veins.

Answer 3

• bronchial

* thebesian

Question 4

The arterial cannula is inserted in the aorta, list 3 alternate sites that may be used.

Answer 4

Alternate sites include the femoral, innominate or axillary artery in situations such as emergency, redo surgery, minimally invasive surgery or to achieve regional perfusion in procedures that involve the ascending aorta and arch.

Question 5

List 3 things conventional heparin bonded circuits have been shown to do.

Answer 5

Covalently-bonded heparin circuits have shown evidence in many studies of reduced inflammation and platelet activation resulting is lesser bleeding and transfusions

Question 6

Fill in the blank: The arterial line filter can remove particulate matter that is more than _ micrometers in size.

Answer 6

20-40

Question 7

Why do we do an arterial line check?

Answer 7

We do an arterial line check to look for forward flow. Pressure of 100 give flows of 1 L/min. Looking for pressure spike then drop.

Question 8

Normal ACT range?

Answer 8

80-120 s

Question 9

ACT needed to go on bypass?

Answer 9

480 s

Question 10

How often do you check an ACT on pump?

Answer 10

every 30-40 mins on CPB

Question 11

If a patient has heparin resistance and has an AT3 deficiency what 2 things can be given to assist in elevating the ACT?

Answer 11

Treatment is the administration of antithrombin III concentrates (1000 units) or fresh frozen plasma (2–4 units).

Question 12

List 4 heparin alternatives:

Answer 12

Lepirudin, argatroban, danaparoid, and bivalirudin, all which have no specific reversal agents

Question 13

Perfusion pressures should be maintained between __ and __ mmHg.

Answer 13

50 and 70

Question 14

Mixed venous saturations should be maintained at > __ %.

Answer 14

> 70 percent

Question 15

Hypothermia reversibly inhibits ___ and ___.

Answer 15

• clotting factors

* platelets

Question 16

The alpha in alpha stat refers to the alpha imidazole ring of histidine, why is this important?

Answer 16

Cause it is an important intracellular buffer.

Question 17

Carbon dioxide is added to the oxygenator in ____ stat.

Answer 17

pH stat

Question 18

Ultrafiltration removes 2 things, what are they?

Answer 18

Inflammatory mediators and excess fluid

Question 19

What nasopharyngeal temperature should you not exceed when rewarming a patient?

Answer 19

37 degrees when rewarming (although authors accept 35.5-36.5)

Question 20

Low SVR is treated with vasopressors, list 3.

Answer 20

Phenylephrine, noradrenaline or vasopressin

Question 21

If a patient fails to wean what mechanical support devices could be used? List 3.

Answer 21

Intra-aortic balloon pump, ventricular assist device or extracorporeal membrane oxygenation should be considered.

Question 22

What are the 3 types of protamine reactions?

Answer 22

Type I (hypotension, due to fast infusion), type II (anaphylaxis) and type III (pulmonary hypertensive crisis).

Question 23

What can be done to manage a protamine reaction?

Answer 23

Reactions can be managed with stopping protamine, fluids, vasoconstrictors/inotropes or return to bypass

Question 24

What are 3 risk factors for acute kidney injury?

Answer 24

Risk factors are prolonged bypass time, sepsis and diabetes