Blue Book

Question 1

volume concentration formula

Answer 1

V1 x C1 = V2 x C2

Question 2

The predicted hematocrit of a 75 kg patient with a hematocrit of 30% and a circuit priming volume of 2200mL would be determined by:

Answer 2

V1 = 70 ml x 75 kg = 5250 blood volume
V2 = 5250 +2200 = 7450 total volume on bypass
C1 is .30 (present hematocrit)

V1 x C1 = V2 x C2 
5250 x .30 = 7450 x C2 
1575 = 7450 x C2 
.211 = C2 
the concentration or hematocrit on bypass is 21.1%

Question 3

If a desire hematocrit is 25% on a 75 kg patient with a starting hematocrit of 30% and a priming volume of 2200. What formula can we use to see how much PRBCs need to be given?

Answer 3

V1 x C1 = V2 x C2

V1 x C1 = 5250 x .30 = 1575 patients RBC volume
v2 x C2 = 7450 [this is v1 + priming volume] x .25 = 1862.5 RBC volume for 25 hct

186.25 - 1575 = 287.5 RBCs needed
hematocrit of packed RBC is 70%
287.5/.70 = 410.7 mL of packed RBCs needed for hct of .25

Question 4

what is the hematocrit of PRBC

Answer 4

70%

Question 5

If it is necessary to add crystalloid solution to a patient and you wanted to find out new hct. What formula would you use?

75 kg patient with hct of 30% and a circuit priming volume of 2200 mL and you add 500 mL crystalloid to patient

Answer 5

V1 = (70 mL x 75kg) + 2200 = 7450 volume on bypass
C1 = .35 Hct on bypass
V2 = (70mL x75 kg)+2200+500 = 7950 volume after adding
C2 = ? 

7450 x .25 = 7950 x C2
.23 = C2 the new hct after adding 500 mL crystalloid

Question 6

If a 350 mL of packed RBCs is added to a patient. How would you find out the new hct?

Answer 6

the RBC volume divided by the total volume equals the hct. The hct of PRBC is usually 70%

.70 x 350 = 245 mL RBCs
7450 [volume on bypass] x .25 = 1862.5
7950 [volume after adding 500]

1862.5 +245 [how many RBCs we added] / 7950+350 [volume]
= .25 new hct after adding 350 ml of packed RBCs

Question 7

the goal of adequate heparinization is to maintain the patient’s ACT at

Answer 7

480 seconds

Question 8

Why might a patient require additional heparin doses after the initial administration?

Answer 8

AT3 deficiency due to long hospital stays and heparinization

Question 9

If additional heparin is given and does not help the anticoagulation status, what may be necessary?

Answer 9

give FFP containing AT3 or the specific component

Question 10

why might the arterial line pressure rise greatly during test transfusion?

Answer 10

• cannula may be occluded by the aortic wall

- may be protruding into the media which could cause a dissection

Question 11

Why might blood from the patient be removed after cannulation via the venous cannula?

Answer 11

• preserve platelets and clotting factors that would be lost during bypass for reinfusion at the end since blood has platelets, clotting factors, and red blood cells

Question 12

what is the disadvantage of removing blood from the patient after cannulation but before going on bypass?

Answer 12

the hct of the patient drops for the bypass run

Question 13

causes of aortic cannula high line pressure when initiating bypass

Answer 13

• kink in arterial cannula or line
• cannula improperly positioned
• clamp too near cannula when cross clamp applied
• cannula too small
• arterial systemic blood pressure very high
• aortic dissection
• blockage in arterial filter

Question 14

what is the maximum acceptable electrical leakage?

Answer 14

100 microamperes

Question 15

what is normal pulmonary artery pressure

Answer 15

25/8

Question 16

where does the swan-ganz catheter go?

Answer 16

through the internal jugular vein, into the right atrium and out into the pulmonary artery

Question 17

what are the circulating catecholamines

Answer 17

epinephrine and norepinephrine

Question 18

what are catecholamines secreted by?

Answer 18

adrenal medulla

Question 19

why does the blood pressure drop when going on bypass?

Answer 19

• circulating catecholamines due to dilution

- reduced systemic vascular resistance

Question 20

what happens later in the surgery in terms of catecholamines?

Answer 20

large amounts of catecholamines are released by the reaction of the sympathetic nervous system due to stress of surgery

Question 21

what can hypertension cause when on pump?

Answer 21

• leaking around suture and cannulation sites

- pump line pressure may rise

Question 22

what can help fix hypertension on pump?

Answer 22

• lowering flow

- sometimes giving anesthetic agents is all that is needed

Question 23

for every __ C that the patient is cooled, the oxygen consumption is decreased by __

Answer 23

7C that the patient is cooled, the oxygen consumption is decreased by 50%

Question 24

pros and cons of normothermic bypass

Answer 24

• less platelet dysfunction

- requires higher flows that may increase blood trauma

Question 25

if cooling is used as a temperature gradient less than ___C between the arterial and venous blood is maintaned

Answer 25

less than 10 C

Question 26

why do we keep a gradient when cooling the patient

Answer 26

prevents the formation of micro bubbles

Question 27

why might oxygen saturations are falling?

Answer 27

• not adequately paralyzed and may be experiencing subclinical shivering: more paralyzing agents
• blood flow may not be high enough
• may need to cool patient if oxygen saturations cannot be sustained

Question 28

average adult’s blood flow to the brain is about

Answer 28

750 ml/min

Question 29

blood flow to the coronary arteries is about

Answer 29

225 ml/min

Question 30

blood flow to various organs while at rest or on bypass are:

Answer 30

brain - 15%
heart - 4-5%
kidneys - 27%
liver - 29%

Question 31

the kidneys receive about _% of the cardiac output but only require __% of the body’s oxygen

Answer 31

25% of cardiac output but only require 7% of the body’s oxygen

Question 32

how does retrograde cardioplegia travel

Answer 32

travels through the coronary veins, capillaries, arteries, and then exits into the aorta where it must be removed by venting

Question 33

how does antegrade cardioplegia travel?

Answer 33

exits into the right atrium where it is removed by the venous cannula

Question 34

why is warm cardioplegia used prior to cross clamp removal?

Answer 34

• uniformly warm the heart and provide arrest during the early reperfusion period
• warm dose flushes the coronary arteries of detrimental metabolic products and air accumulated during the cross clamp period
• replenishment of high energy phosphates

Question 35

warming the blood too rapidly could cause what?

Answer 35

red blood cells to absorb fluid causing hemolysis

Question 36

what is one of the problems with femoral bypass?

Answer 36

lack of venting and decompression of the heart

Question 37

the hct on bypass is kept from

Answer 37

22-29%

this reduced hct circulating solution perfuses the capillaries and tissues better than blood with normal hct

Question 38

why is a lower than normal hct better for perfusing arterioles and capillaries?

Answer 38

arterioles have an average critical closing pressure of 20 mmHg and this reduced viscosity helps to maintain flow and pressure

Question 39

what does adding large amounts of crystalloid cause and what should be done to fix it?

Answer 39

large amounts of crystalloid solution may decrease the colloid osmotic pressure and cause third spacing of fluid

• 25% albumin should be added
• patients with decreased serum albumin and colloid pressure become edematous, often preventing closure of sternum