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N934 Advanced Principles of Anesthesia II > Cardiac Anesthesia > Flashcards

Cardiac Anesthesia Flashcards

1
Q

cardiac surgical procedures

A
  • CABG (coronary artery bypass grafting)
  • off pump (OP) CABG
  • minimally invasive direct (MID)-CABG
  • valve replacement
  • heart transplant
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2
Q

cards surgery preop evaluation

A
  • cardiac history - severity of disease/hemodynamic status
  • past surgical history - past strenotomy, leg and groin vascular surgery, previous protamine use
  • angina presentation - nausea, fatigue, DOE, SOB
  • dysrhytmias
  • PMH - TIA, CVA
  • comorbid diseases - PVD, DM, HTN, COPD, renal
  • meds - anticoagulants, antianginals, insulin, ACEIs
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3
Q

preop testing for cardiac surgery

A
  • cardiac cath report
  • EKG
  • ECHO
  • hematologic studies - PTT, PT, baseline ACT
  • CXR - look for calcified aorta, cardiomegaly, edema
  • renal fxn - decreased fxn increases post-op mortality
  • liver fxn tests - CPB hypo-perfuses liver
  • T&C - must have PRBCs available
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4
Q

medications your patient may be on

A
  • antiarrhythmics
  • calcium channel blockers
  • beta blockers
  • nitrates
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5
Q

cardiac anesthesia goals

A
  • decrease cardiac oxygen utilization
  • maintain oxygen supply
  • anticoagulation
  • maintain BP in target range
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6
Q

ways to decrease cardiac oxygen utilization

A
  • anesthesia
  • hypothermia
  • electrical silence, cardioplegia use
  • empty cardiac chambers, specifically LV
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7
Q

ways to maintain oxygen supply

A
  • maximize oxygen carrying capacity and flow

- hemodilution and acceptable perfusion pressure and flow

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8
Q

myocardial protection strategies

A
  • cardioplegia
  • hypothermia
  • hemodilution
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9
Q

cardioplegia induced asystole for myocardial protection

A
  • electrical and mechanical activity ceases
  • potassium given continuously during cross clamping
  • must be able to cross clamp aorta - calcifications/clots already present?
  • blood versus clear prime
  • hyperkalemia is an issue with renal patients
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10
Q

hypothermia for myocardial protection

A
  • alters plt function and reduces fibrin enzyme function
  • inhibits initiation of thrombin formation
  • reduces metabolic demands and increases tolerance to ischemia
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11
Q

hemodilution for myocardial protection

A

-not really a protection strategy but flow increases due to decreased blood viscosity

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12
Q

CABG order of events

A
  • preop prep
  • monitors
  • lines
  • induction
  • wait
  • incision
  • drop lungs
  • sternotomy
  • surgical dissection
  • cannulation
  • on-bypass
  • off-bypass
  • dry up - give protamine
  • close chest
  • to ICU
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13
Q

monitors for CV surgery

A
  • pulse ox
  • TEE
  • EKG - leads V5 and II
  • temperature - swan, esophageal, foley (this one is best)
  • ABP - usually radial, sometimes femoral; usually preinduction
  • CVP - mandatory for infusion of drugs
  • PA cath - pts with severe LV dysfunction, pts with profound pulm HTN
  • BIS
  • NIRS
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14
Q

Transesophageal ECHO

A
  • helps to diagnose underlying mechanisms ascribed to several scenarios - eval of ventricular filling, estimation of CO, assess ventricular systolic/diastolic fxn, valvular patho, calcified aorta, cardiac tamponade, artiral thrombus
  • helps to plan case interventions - volume, vasoactive drips, re-examine graft, assessment of surgical repair
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15
Q

contraindications for TEE

A
  • esophageal pathology (alcoholic varices)

- empty stomach before placing probe

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16
Q

what can you not see in TEE

A
  • distal segment of ascending aorta

- proximal segment of aortic arch

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17
Q

PA cath

A
  • used to be standard monitor for cardiac surgery patients but now used less bc high risk and now there is TEE
  • PACs are typically placed in RIJ ( most direct)
  • cordis is placed after induction and PA inserted if needed
  • no evidence to suggest PA caths offer additional information and have inherent risk in ICU patients
  • TEE is better monitor over PAC
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18
Q

RA/CVP pressure

A

0-5 mmHg

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19
Q

RV pressures

A

15-25/0-8

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20
Q

PA pressures

A

15-25/8-15

“quarter over a dime”

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21
Q

PAOP

A

6-12 mmHg

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22
Q

complications of PAC/Swan

A
  • ventricular arrhythmias
  • heart block (esp in those with preexisting LBB)
  • pneumothorax (most common with subclavian approach)
  • unintended arterial puncture (most common injury)
  • valve damage (rare but could happen if balloon not deflated when pulled back)
  • hematoma/thromboembolism
  • vascular injury
  • perforation of thorax leading to hemothorax
  • PA rupture
  • Cardiac tamponade (most common life threatening complication)
  • blood stream infection (late complication)
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23
Q

pre-bypass hemodynamics

A

keep BP within +/- 20% of baseline pressure; HR between 40-80 are generally fine depending on clinical situation

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24
Q

stenotic valve repair hemodynamics

A

maintain SVR; maintain lower than normal HR

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25
Q

regurgitant valve repair hemodynamics

A

maintain SVR, higher than normal HR to maintain forward flow of blood

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26
Q

cardiac OR set up

A
  • usual airway equipment/machine check
  • pacemaker
  • drips (vary by institution)
  • heparin and coag monitoring capability (ACTs usually)
  • emergency drugs (PAGES)
  • PBRCs available in OR (at least 4 units checked and ready to go)
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27
Q

common cardiac drips

A
  • NTG/NTP
  • epi/norepi
  • phenylephrine/ephedrine
  • dopamine and dobutamine as needed
  • antiarrythmis (esmolol, lidocaine, magnesium, amiodarone)
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28
Q

cardiac anesthetic drugs

A
  • inhalation agents
  • fentanyl/sufentanil
  • versed
  • prop/etomidate/ketamine
  • vec/roc/cis
  • succ or roc if RSI
  • abx = cefazolin, vancomycin, clindamycin
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29
Q

other drugs you will likely need in cardiac room

A
  • anti-fibrinolytics = amicar (ACA, aminocaproic acid) or TXA
  • magnesium (good post bypass)
  • insulin drip
  • calcium chloride
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30
Q

why antifibrinolytics during cardiac surgery?

A
  • during CPB, large amounts of circulating tPA are found and increased post-op bleeding due to inappropriate fibrinolysis
  • fibrinolysis is diagnosed with TEG
  • drugs exist that inhibit the binding of plasminogen to fibrin, a step in the fibrinolytic pathway
  • in order for it to be effective, amicar or txa must be started before initiation of CPB
31
Q

pre-induction patient prep

A
  • oxygen via nasal cannula
  • evaluate need for mild sedation (try and limit or avoid versed, maybe fent ok)
  • lines –> PIV x2 + art line
  • baseline ABG and baseline ACT
  • cross matched blood (CHECK EARLY)
  • place external defib pads prior to induction
  • make sure team (esp perfusion/ECMO) here or rolling back to the room
32
Q

intraop prep/positioning for cv patient

A
  • supine with legs padded
  • foam head support
  • arms tucked at sides and padded
  • check lines
  • prep area - from sternal notch to toes
  • foley (hook up to bladder temp)
  • fluid + under boody forced air warmer
  • rapid infuser
  • drips spiked, in line, ready to go!!`
33
Q

prop for CV induction

A
  • used safely in patients with ischemic and valvular heart disease
  • biggest challenge = hypotension
34
Q

etomidate for CV induction

A

-may be less likely to cause hypotension than prop

35
Q

ketamine for CV induction

A
  • CV effects are advantageous

- biggest challenge is CV stimulation (increases workload on heart)

36
Q

volatiles for CV surgery

A
  • produce dose dependent global CV depression
  • negative effects of volatiles are due to alterations in intracellular calcium
  • sensitizes myocardium to effects of EPI in varying degrees
  • may prevent or facilitate atrial or ventricular arrhythmias during myocardial ischemia or infarction
  • produces weak coronary artery dilation and depresses baroreceptor reflex control of arterial pressure
  • you may be turning off your vaporizer - perfusionist has vaporizer on bypass machine
37
Q

induction for CV surgery patient

A
  • proceed slowly and know your plan
  • it is not the drug but the way that it is given that is important
  • technique –> high vs low dose narcs; use prop or other induction agent with narcs
  • airway –> if you anticipate difficult airway, do not hesitate to do difficult intubation
  • post-induction –> central line (if not placed pre-op), OGT, then TEE
  • tuck arms carefully
  • the surgeons are your friend, talk and ask for help and opinions
  • you are A TEAM - best for the patient
38
Q

what usually occurs pre incision in CV surgery patients

A
  • hypotension
  • lack of stimulation
  • systemic pressure support
  • risks involved with vasoconstrictors
  • recall rare at this point unless severe hypotension occurs in face of pure opioid technique
39
Q

incision to bypass part of procedure

A
  • INTENSE surgical stimuli
  • HTN –> deepen anesthetic, vasoactive agents like NTG, NTP
  • handling of heart by surgeon
  • bleeding can be significant
  • ID and localize ischemia
  • drop lungs for strenotomy
  • radial artery and saphenous vein harvested
  • COMMUNICATION V IMPORTANT HERE
40
Q

heparinization pre-bypass

A
  • anticoagulate the patient with heparin before going on bypass
  • binds to ATIII and potentiates its natural anticoagulant properties (x1000)
  • give dose and wait 3-5 min to draw ACT
  • administer via CVP or directly into RA because then it will get there QUICK
41
Q

weight based dosing for heparin

A

300-400 units/kg

42
Q

normal ACT value

A

130 seconds or less (80-120)

43
Q

goal ACT to go on bypass

A

ACT > 400-450 seconds

44
Q

side effects of large heparin dose

A
  • decrease SVR by 10-20%

- decrease BP by 10-20%

45
Q

ATIII deficiency and going on bypass… what do you do?

A
  • patient will be unresponsive to heparin

- FFP can be given or thrombate III

46
Q

heparin induced thrombocytopenia

A
  • antiplatelet antibodies form

- leads to platelet aggregation and potentially life-threatening thromboembolic events

47
Q

cannulation post heparinization and pre-bypass

A
  • cannulation of aorta (arterial) and RA (venous)
  • must drop patient’s BP for aortic cannulation (usually SBP < 90 mmHg)
  • BP might drop and/or arrhythmias can occur when placing venous cannula
  • perfusionist can give fluids via arterial line if hypotension occurs
  • ANESTHESIA - medicate the patient with midaz and fentanyl
48
Q

what is cannulated to administer cardioplegia?

A
  • coronary sinus for retrograde administration of cardioplegia
  • aorta can also be cannulated with this to administer antegrade cardioplegia
  • administered proximal to the cross clamp so the solution stays in the heart and doesn’t go systemically
49
Q

problems than can occur pre-bypass during cannulation

A
  • arrythmias - usually related to cardiac manipulation and cannulation; may be first sign of myocardial ischemia; may also be due to patient getting TOO cold pre bypass
  • HTN - especially during aortic cannulation
  • HoTN - volume given through aortic line
  • heart failure
  • bleeding - strenotomy lacerates RV or aorta
50
Q

what can happen if HTN occurs during aortic cannulation?

A

aortic dissection

51
Q

transition onto CPB after cannulation

A
  • surgeon states “GO ON BYPASS”
  • perfusionist opens venous clamp so blood drains passively into venous reservoir, immediately begins to cool patient
  • arterial trace goes flat
  • ECG still present
  • pull back PAC 2-3 cm so it is no longer in PA
  • look at head for swelling (could indicate improper venous drainage)
  • check pupils and BIS
  • stop ventilator once heart is empty
  • give muscle relaxant (prevent shivering)
  • give amnestic med
  • stop fluids
  • drain urine pre-bypass so you have bypass only urine
52
Q

CPB numbers/goals

A
  • flows = 2.5-3.5 L/min; 50-60 mL/kg
  • mixed venous sat = 70-80%
  • CVP = 0-5 mmHg; may have negative CVP if using vacuum assist to drain blood
53
Q

hemodilution and pump prime

A
  • for adults, CPB machine primed with 1500-2500 mL of balanced electrolyte solution
  • albumin, heparin, mannitol, and sodium bicarb often added to increase osmolality, reduce edema, and promote diuresis
  • significant hemodilution and decrease in oxygen carrying capacity occurs
  • typically Hct 20% is OK
  • hemodiluation associated with decreased viscosity, decreased SVR and promotes forward flow
54
Q

cardioplegia facts

A
  • COLD 4 degrees celcius
  • reduces metabolism of heart
  • v fib occurs at 25-30 degrees celcius
  • contains A LOT OF K+ (26 mEq/L)
  • depolarization of heart
  • heart arrested in diastole then cross clamp applied
55
Q

issues related to CPB

A
  • HoTN related to decreased SVR
  • renal ischemia from hypoperfusion and/or hemodiluation
  • CVA form thrombus in CPB system
  • air emboli introduced into CPB system
  • thrombocytopenia
  • increased inflammatory response
  • altered post-op mental state “pump head”
  • CPB issues may not happen to everyone but team needs to be hypervigilant to detect and intervene early
56
Q

cerebral protection strategies

A
  • hypothermia
  • blood gas management
  • adequate BP
  • cerebral oximetry
57
Q

when do you start rewarming the patient

A

-when the last distal graft is being sewn

58
Q

when to rewarm

A
  • begins prior to aortic cross-clamp removal
  • begins with the last distal anastomosis in angioplasty procedure
  • begins when all the valve sutures are in and knots are being tied down
59
Q

how fast to warm

A

1 degree celcius every 3-5 minutes

60
Q

preparation for coming off bypass

A
  • core temperature must be above 35 degree C (eventual target 37 degree C)
  • correct labs (K+ first, then acid base, and hematocrit)
  • inflate lungs (de air maneuvers)
  • removal of cross clamp
  • debfibrillation
  • HR - paced or SR at sufficient rate (80-90 bpm min)
  • rhythm - a or v paced
  • venous return line SLOWLY clamped, perfusionist will turn down flows and allow RA to fill
  • look for PA and a line pressures to increase
  • when pump comes off and venous cannula clapmed = OFF BYPASS
  • measure CO - watch TEE for LV failure, monitor PA and a line pressures
  • monitor SVO2 - increased demand or decreased delivery
  • shivering - give muscle relaxant
  • airway - turn vent on
61
Q

aortic cross clamp

A
  • prolonged cross-clamp time significantly correlates with major post-op morbidity
  • when cross clamp coming off, reperfusion may paradoxically cause myocardial damage and limit the extent of recovery
  • complications may include hemorrhage (at cannula site), dislodgement of atheromas (clots) and aortic dissection
62
Q

internal defibrillation joules

A

10-30 joules

63
Q

coming off CPB

A
  • contractility (look at the heart; is it vigorously beating; heart needs adequate contractility to come off CPB; look at TEE)
  • inspect for bleeding
  • what is the systemic pressure in relation to PA pressure
  • give protamine (SLOWLY) when cannulas all the way out
  • when chest is closed, cardiac tamponade type schenario (heart squished and may have to re open chest if pt doesnt tolerate)
64
Q

protamine dose

A

1 mg/100 units heparin

65
Q

risk factors for renal injury during CPB

A
  • age
  • bypass time
  • preexisting renal injury
66
Q

post CPB challenges

A
  • recall and neuro changes
  • bleeding
  • organ hypoperfusion
  • non-pulsatile blood flow, emboli, thrombi
  • systemic inflammation response
  • residual hypothermia
  • remember –> extended CPB and cross-clamp time makes it HARDER to wean off bypass
67
Q

points in CV surgery with highest rate of recall

A
  • graft harvest
  • strenotomy
  • rewarming
68
Q

reasons why bleeding is an issue post CPB

A
  • loss of clotting factors
  • fibrinolysis
  • thrombocytopenia
  • surgical blood loss
  • transfusion reaction
  • vessel trauma
  • metabolic byproducts
69
Q

reperfusion interventions

A
  • spend time paying back by re-perfusing the empty heart at adequate perfusion pressure (typically 20-30 min)
  • allows heart time to recover by washing out metabolic by products
  • if exceptionally long clamp time, consider IABP
  • correct metabolic abnormalities
70
Q

protamine

A
  • composed of multiple low molecular weight proteins that are derived from salmon sperm
  • protamine is able to neutralize and reverse effects of heparin so that heparin is unable to form the complex with ATIII
  • can cause pulm HTN and RHF which is why we give SLOWLY
  • half life is shorter than heparin (why heparin re bound can occur)
  • SLOW ADMIN THROUGH PIV
71
Q

type 1 protamine rxn

A
  • histamine release

- treatable with BP med, volume, and slow infusion

72
Q

type 2 protamine rxn

A
  • IgE mediated, anaphylaxis like rxn
  • bronchoconstriction
  • can be treated
73
Q

type 3 protamine rxn

A
  • protamine and heparin complex forms
  • lodges in pulmonary circ
  • causes pulm HTN and/or RV failure
74
Q

transport to ICU post surgery

A
  • ambu bag and oxygen tank (with enough O2)
  • monitor - EKG, art line
  • emergency drugs
  • keep surgical table sterile until out of room in ICU
  • after move to bed, re check breath sounds
  • in ICU attach to vent and re check breath sounds
  • transport assistance will be needed

N934 Advanced Principles of Anesthesia II (17 decks)

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