Cardiac Intraop Mgmt

Question 1

Initial (pre CPB) and subsequent heparin doses

Answer 1

Initial pre bypass dose 30,000 units

then dose off of ACT, usually 300-350units/kg

Question 2

where is heparin obtained?

Answer 2

mast cells or commercially made

Question 3

Heparin Mech of action

Answer 3

binds to AT3 (protease inhibitor) > potentiates the actions of AT3 1,000 fold, inhibits thrombin and factor 9a, 10, 11a, and 12a

inhibition of thrombin requires heparin to bind to AT3 and thrombin whereas the other factors just require heparin to bind to AT3

Question 4

how fast does heparin peak?

Answer 4

1min

Question 5

how is heparin eliminated?

Answer 5

dose-dependant

via kidneys or metabolized via reticuloendothelial system

low dose 100-150units/kg half life is 1 hr
CPB dose of 300-400 units/kg is 2hr

Question 6

why is heparin initial dose so high at 35-40k units?

Answer 6

because it distributes primarily into the plasma

Question 7

Heparin is ALWAYS GIVEN when? when do you draw ACT?

Answer 7

prior to aortic cannulation, draw ACT 3 min later

Question 8

Normal ACT and goal ACT?

Answer 8

normal 110-140
goal 400-450

Question 9

what two things can prolong ACT?

Answer 9

hypothermia and hemodilution

Question 10

side effects of heparin administration?

Answer 10

hypotension, anaphylaxis, HIT (usually after 5-9 days of continuous admin)

Question 11

is protamine basic or acidic?

Answer 11

basic, so it neutralizes acidic heparin

Question 12

how much protamine to neutalize 100 units of heparin?

Answer 12

1mg

Question 13

how do you physically give protamine?

Answer 13

1-2 cc then wait 30-60 sec. You can’t give it too slow, but can give it too quickly.

Question 14

what do you announce to the room regarding protamine?

Answer 14

when it is halfway in, this is when they will start pulling cannulas

Question 15

what do you draw 3 min after full dose of protamine is in?

Answer 15

ACT and ABG

Question 16

S/S of anyphylaxis to protamine?

Answer 16

HoTN, bronchospasm, pul edema,

Question 17

s/s anaphylactoid reaction to protamine?

Answer 17

HoTN, 3x elevation in PA pressures, RV failure

Question 18

post protamine ACT should return to _____ patients baseline ACT?

Answer 18

<10% above

Question 19

What med is a lysine analog?

Answer 19

Amicar

Question 20

Amicar mech of action

Answer 20

bind to lysine bidning sites of plasmin and plasminogen.

form reversible complex with plasmin whcih then inhibits fibrinolysis (natural breakdown of clots)

Question 21

TXA is how potent compared to Amicar?

Answer 21

5-10x but more expensive too

Question 22

Amicar/TXA is best when used?

Answer 22

prophylactically

Question 23

5 components of bypass

Answer 23

venous reservoir - filled with venous drainage from heart and blood suctioned from surgical field (pump suckers)
main pump - non pulsatile flow via roller pump or centrifugal pump
oxygenator - oxygenates venous blood and removes CO2
heat exchanger
arterial filter - air bubbles trap

Question 24

What is RAP

Answer 24

retrograde autologous priming
perfusionist drains blood out of the patient through aortic cannula to prime the CPB circuit

reduces hemodilution

can cause hypotension, perfusion may request increase in BP to facilitate drainage

Question 25

basic sequence of events for initiating bypass

Answer 25

cannulas in > increase flow of oxygenated blood through arterial cannula, venous clamp gradually relased allowing increasing portion of systemic venous blood to drain into CPB reservoir continue ventilation until full flow achieved lungs down, volatile off, pressors/dilators off confirm perfusion has iso on, confirm NMB empty foley, document UOP a sbypass urine from now on

Question 26

sequence of events once on bypass

Answer 26

on bypass > cool pt > cross clamp aorta > arrest heart > operation > warm patient > unclamp aorta > pacing wires > come off bypass

Question 27

when do you start warming patient?

Answer 27

when final distal anastomosis begin

Question 28

what should you do with rewarming?

Answer 28

start propofol drip d/t increased risk of awareness

Question 29

advantages of OPCAB vs standard CABG?

Answer 29

avoid SIRS, hemodilution, and aortic cross clamping

Question 30

how to treat hemodynamic changes with off pump technique?

Answer 30

fluids (volume), pressors, and steep t burg

Question 31

temp consideration for off pump method?

Answer 31

temp is not corrected, so you must use active warming. Watching for ischemic changes of ECG and TEE

Question 32

most common site of aortic cannulation?

Answer 32

distal ascending aorta

Question 33

where else can you do aortic cannulation?

Answer 33

femoral and axillary arteries

Question 34

ACT must be >? before cannulation?

Answer 34

400

Question 35

why is aortic cannulation inserted first?

Answer 35

to allow for infusion of volume in case of hemorrhage associated with venous cannulation

Question 36

SBP should be what before aortic cannulation?

Answer 36

90-100

Question 37

how could peep be helpful during aortic cannulation?

Answer 37

can help avoid air entrainment during cannulation

Question 38

after aortic cannulation how high should you raise SBP?

Answer 38

to 100-120 so pefusion can RAP

Question 39

complications from aortic cannulation?

Answer 39

embolic phenomoena from air or plauqe dislodgement, Hotn, dysrhythmias, aortic dissection, bleedign, air entrainment

Question 40

where is venous cannulation done?

Answer 40

incision in right atrium, cannula placed into atrium and down into IVC, can also do femoral or BiCaval SVC plus IVC

Question 41

complications associated with venou cannulation?

Answer 41

significant dysrhythmias and HOTN, also air and bleeding

Question 42

are BP goals the same during venous and aortic cannulation?

Answer 42

yes