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
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
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
4
Q
medications your patient may be on
A
- antiarrhythmics
- calcium channel blockers
- beta blockers
- nitrates
5
Q
cardiac anesthesia goals
A
- decrease cardiac oxygen utilization
- maintain oxygen supply
- anticoagulation
- maintain BP in target range
6
Q
ways to decrease cardiac oxygen utilization
A
- anesthesia
- hypothermia
- electrical silence, cardioplegia use
- empty cardiac chambers, specifically LV
7
Q
ways to maintain oxygen supply
A
- maximize oxygen carrying capacity and flow
- hemodilution and acceptable perfusion pressure and flow
8
Q
myocardial protection strategies
A
- cardioplegia
- hypothermia
- hemodilution
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
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
11
Q
hemodilution for myocardial protection
A
-not really a protection strategy but flow increases due to decreased blood viscosity
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
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
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
15
Q
contraindications for TEE
A
- esophageal pathology (alcoholic varices)
- empty stomach before placing probe
16
Q
what can you not see in TEE
A
- distal segment of ascending aorta
- proximal segment of aortic arch
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
18
Q
RA/CVP pressure
A
0-5 mmHg
19
Q
RV pressures
A
15-25/0-8
20
Q
PA pressures
A
15-25/8-15
“quarter over a dime”
21
Q
PAOP
A
6-12 mmHg
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)
23
Q
pre-bypass hemodynamics
A
keep BP within +/- 20% of baseline pressure; HR between 40-80 are generally fine depending on clinical situation
24
Q
stenotic valve repair hemodynamics
A
maintain SVR; maintain lower than normal HR
25
Q
regurgitant valve repair hemodynamics
A
maintain SVR, higher than normal HR to maintain forward flow of blood
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)
27
Q
common cardiac drips
A
- NTG/NTP
- epi/norepi
- phenylephrine/ephedrine
- dopamine and dobutamine as needed
- antiarrythmis (esmolol, lidocaine, magnesium, amiodarone)
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
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
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
