Cardiac Anesthesia Flashcards
Types of Cardiac Surgical Procedures (5)
CABG Off pump (OP) CABG minimally invasive direct (MID) CABG valve replacement (can be done in cath lab/EP but we are talking about OR in this lecture) (congenital hearts fall here mostly) heart transplant
preoperative evaluation cardiac history assessment should include
severity of disease/hemodynamic status (cath/ECHO/EKG reports)
baseline EF, high LVEDP, pHTN, valvular and congenital lesions, CHF
dysrhythmia history
preoperative evaluation for cardiac surgeries: past surgical history specific for
past sternotomies (scarring around heart)
leg and groin vascular surgery
previous protamine use (yes if previous open heart)
preoperative evaluation for cardiac surgery: ask about angina presentation sx including
nausea, fatigue, DOE, SOB
preoperative evaluation for cardiac surgery: PMH should include (neuro)
TIA/CVA. look for carotid dopplers and ensure they are fixed if need be before open heart surgery
preoperative evaluation for cardiac surgery should include evaluation for these comorbid diseases
PVD DM HTN COPD renal disease (=prepare for postop care)
preoperative evaluation for cardiac surgery: ask about which kinds of meds?
anticoagulants
antianginals
insulin
ACEI’s
what questions should you ask about a previous cardiac catheterization
how many blockages
where they are
how blocked they are
if theres any collateral flow
what questions should you ask about the up to date echocardiogram
EF, valve function, wall abnormalities/diskenisia, calcified aorta, atrial thrombus (no CVA!)
what hematologic labs should be retrieved prior to cardiac surgery
PTT, PT, baseline ACT
clotting studies, especially platelet number and functionality (TEG)
T&C as well (and PRBC’s near OR)
what should you look for on a preop CXR for cardiac surgery
calcified aorta, cardiomegaly, edema
the following drugs should be continued through operative day for cardiac surgery (4)
antiarrhythmics
CCB’s
BB’s
nitrates
how do we decrease cardiac oxygen utilization during cardiac surgery
anesthesia, hypothermia, electrical silence/cardioplegia use, empty cardiac chambers, specifically LV (no LV distention!)
how to we maximize oxygen supply during cardiac surgery
maximize oxygen carrying capacity and flow. check for anemia, make sure PRBC’s are avail
hemodilution and acceptable perfusion and pressure and flow decreases viscosity and promotes flow
what does hypotension or hypertension result in during cardiac surgery
hypotension: decreased organ perfusion
hypertension: disrupts myocardial balance
name 3 myocardial protection strategies employed
cardioplegia induced asystole
hypothermia
hemodilution
how does cardioplegia induced asystole happen
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 (colloid versus crystalloid versus blood prime)
hyperkalemia is an issue with renal patients (and just an issue with this procedure in general)
how does hypothermia induced during cardiac surgery effect the patient
alters platelet function and reduces fibrin enzyme function
inhibits initiation of thrombin formation
reduced metabolic demands and increases tolerance to ischemia
CABG order of events
preoperative prep monitors lines induction wait incision drop lungs sternotomy surgical dissection (not super stimulating, getting heart ready for intervention) cannulation on bypass off bypass dry up: give protamine close chest to ICU
monitors to consider for cardiac procedures
pulse ox (hypothermia and vascular disease may prompt you to try finger, ear lobe, nose)
TEE (in place of swan)
EKG (leads V5/II and ST segment monitoring)
temperature (foley is best)
ABP and cuff (q minute induction pressure if no aline). usually radial, sometimes femoral
CVP: mandatory
PA catheter: for patients with severe LV dysfunction, patients with profound pHTN
BIS and NIRS: put on before induction for baseline
warmer under patient and fluid warmers
OGT in and out and then insert TEE
TEE helps diagnose underlying mechanisms ascribed to several scenarios including (8)
evaluation of ventricular filling (preload)
estimation of CO
assessment of ventricular systolic function
assessment of ventricular diastolic function
valvular pathology
calcified aorta (important for aorta cannulation)
cardiac tamponade
atrial thrombus
TEE helps to plan case interventions including
when to give volume when to start vasoactive drips re examine graft assessment of surgical repair may look for air with it. can move patient around to "de air" or may do needle aspiration
contraindications to TEE include
esophageal pathology (varices) empty stomach before placing probe
which 2 spots are you unable to see with a TEE
distal ascending aorta
proximal part of aortic arch
where does the TEE probe chill for the duration of the case while not being used
esophagus
where are PA catheters usually placed
right IJ
what is placed after induction that a PA cath can be inserted into if needed
cortis
right artery normal PA cath pressures
25/10
right ventricle normal PA cath pressures
15-30/0-8
pulmonary artery normal PA cath pressures
15-30/5-15
wedged normal PA cath pressures
~18? (cant read my handwriting, lit)
complications of PA catheter (swan)
ventricular arrhythmias
complete heart block (especially in patients with preexisting LBB)
pneumothorax (most common with subclavian approach)
unintended arterial puncture (most common acute injury)
valve damage (rare but could happen especially if balloon is not down when pulling back)
hematoma/thromboembolism
vascular injury (localized hematoma=minor and most common)
perforation of thorax leading to hemothorax
PA rupture
cardiac tamponade (most common life threatening complication of CV cannulation. If the heart room can intervene quickly versus placing in ICU)
blood stream infection (late complication)
pre bypass hemodynamics
keep BP within 20% of baseline pressure. heart rates between 40-80 rarer generally fine depending on the clinical situation prior to bypass
valve repair specific recommendations: stenosis
preload: maintain
SVR: higher normal
HR: lower normal
valve repair specific recommendations: regurgitation
preload: maintain
SVR: lower normal
HR: higher normal
cardiac OR set up includes
usual AW/machine check pacemaker (may have to pace post bypass) gtt's heparin and coagulation monitoring capabilities (ACT's via pump team) emergency drugs (PAGES) PRBC's avail in OR (~4U T&C)
cardiac OR set up drips include most commonly:
NTG (nitrate that dilates arteries)/NTP epinephrine/NE phenylephrine/ephedrine dopamine/dobutamine PRRN antiarrhythmics (esmolol, lidocaine, magnesium post bypass, amiodarone) insulin likely (usually a DM patient)
cardiac anesthetic drugs include
inhalation agents fentanyl/sufentanil versed propofol/etomidate/ketamine vecuronium/rocuronium/cisatracurium succinylcholine or rocuronium if RSI antibiotic: cefazolin, vancomycin, clindamycin (pre and post bypass usually)
why not use pancuronium in this surgical population
causes tachycardia/is vagolytic related to blockage of M2 receptors
anti fibrinolytics used (2) and the need they serve during cardiac surgery
during CPB, large amounts of circulating tPA are found and increased postop bleeding due to inappropriate fibrinolysis (dx by TEG)
drugs exist that inhibit the binding of plasminogen to fibrin, a step in the fibrinolytic pathway
to be effective, must be started before going on CPB**
TXA used more than Aminocaproic acid (ACA)
two drugs given post bypass include
magnesium (to help with arrhythmias)
calcium chloride
patient preparation pre induction includes
oxygen via nasal cannula (NRB facemark if respiratory distress)
evaluate need for mild sedation (limit or avoid using versed. fentanyl can be used)
line placement: 14-18g and arterial line (typical cords and SWAN placed after induction in stable patients)
baseline ABG and baseline ACT
cross matched blood (check blood early, at least 2U)
place external defibrillation pads prior to induction
make sure team (especially perfusion team) is rolling back
may do aline in preop with topical lidocaine or pre induction
cardiac surgery intraoperative preparation and positioning
supine with legs padded foam head support arms tucked at sides and padded check lines prep area from sternal notch to toes (especially if harvesting saphenous vein) foley (temp sensing) fluid and upper body forced air warmer rapid infuser drips spiked and ready to go aka plugged into CVC
induction agents: propofol specs
used safely in patients with ischemic and valvular heart disease
biggest challenge is HoTN
induction agents: etomidate specs
may be less likely to cause HoTN than propofol
induction agents: ketamine specs
CV effects are advantageous
biggest challenge is CV stimulation
avoid which drug during induction and on CPB?
N2O
volatile anesthetics in relation to cardiac surgery
produce dose dependent global cardiac depression
negative effects of volatile anesthetics 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
produce weak coronary artery dilation and depress baroreceptor reflex control of arterial pressure
may be turning off your vaporizer: perfusionist has vaporizer on bypass machine
preconditions CV for ischemia
helps with amnesia/recall
induction during cardiac surgery: how to give these drugs
proceed slowly/give slower and allow the slow circulation time to work as well
common induction medication combinations include
propofol and etomidate or
increased narcotic like 5-10cc of fentanyl and ~50mg of propofol
(can do high or low dose narcotic technique for induction aka alot of prop or alot of fent)
induction plan: airway
if you anticipate a difficult airway, do not hesitate to do an awake intubation. a well planned, well topicalized patient provides the smoothest induction
induction plan: post induction plan
CVC if not placed pre op, OG then TEE. tuck arms carefully
pre incision HoTN considerations
its due to lack of stimulation
systemic pressure support
risks involved with vasoconstrictors
recall rare at this point, unless severe HoTN occurs n the face of purely opioid technique
incision to bypass
intense surgical stimuli
HTN can happen (deepen anesthetic, vasoactive agents like NTG or NTP)
heralding of heart by surgeon
bleeding can be signficiant
ID and localize ischemia
drop lungs for sternotomy (DC from circuit completely)
arterial and saphenous veins are usually harvested
what to do with your anesthetic before they open the chest
turn your pressors off and your agent up
heparin MOA
binds to antithrombin III and potentiates natural anticoagulant properties
pre bypass heparinization dosing and route of administration
300-400units/kg, wait 3-5 minutes before ACT
via CVP or directly into RA
normal ACT
<130 seconds (80-120)
ACT goal
<400-450
what can heparinization do to SVR and BP
can decrease them by 10-20%
what to do if patient has antithrombin III deficiency
FFP or thrombate III can be given
pre bypass before canalization of anything, what has to happen?
heparinization with an ACT >400
pre bypass post heparinization cannulation or aorta (arterial) and RA (venous) anesthetic considerations
must drop patients BP for aortic cannulation
BP might drop and/or arrhythmias can occur while placing venous cannula
perfusionist can give fluids via the arterial line
what do you cannulate for retrograde cardioplegia and side effects of this
coronary sinus, can have similar effects as cannulation of aorta and RA (drop BP/arrhythmias)
what to pre medicate the patient with before cannulization
midazolam and fentanyl
frequently encountered problems pre bypass include (5)
arrhythmias (may be from cannulation or may be first sign of MI)
HTN (esp during aortic cannulation)
HoTN (can give volume via aortic line/pump)
heart failure
bleeding (sternotomy lacerates RV or aorta)
transitioning to CPB: steps
pay attention, surgeon will say to go on bypass
perfusionist opens venous clamp>blood drains passively into venous reservoir, immediately begins to cool patient
arterial trace goes flat but ECG still presnt
pull back PAC 2-3cm
look at head for swelling
check pupils and BIS
stop ventilator once heart is empty
HIT platelet count, what to test for before procedure, what you can use in place of heparin
100,000
look for antibodies before procedure
can use bivalrudin
what does ACT have to be before going on bypass
> 400
where are cannulas placed
aorta first (taken out last, can give fluid through this “arterial bypass line”)
right atrium
cardioplegia catheter (anterograde or retrograde)
ven in left ventricle
before cannulation, what should you do and what will you expect?
must drop BP to SBP <90 (to decrease risk of dissection. can give NTG or nipride to achieve this)
medicate patient with midazolam and fentanyl
BP might drop and/or arrhythmias can occur while placing venous cannula
frequently encountered problems pre bypass
arrhythmias (usually r/t cardiac manipulation and cannulation. can be first sign of ischemia, monitor ST segment)
HTN: esp during aortic cannulation
HoTN: volume can be given through aortic line via pump
heart failure
bleeding: sternotomy lacerates RV or aorta
too cold before bypass: fibrillation and swelling of left ventricle
hemodilution and pump prime: how much fluid is primed in CPB machine for adults
1500-2500mL of balanced electrolyte solution
what can you add to the prime solution and what are the benefits
albumin, heparin, mannitol, NaHCO3- to increase osmolality, reduce edema, promote diuresis
what occurs when patient is on pump and therefore what is acceptable
hemodilution and decrease in oxygen carrying capacity. therefore, HCT ~20% typically acceptable
hemodilution is associated with (3)
decreased viscosity
decreased SVR
promotes BF to tissues
how is cardioplegia induced (2 factors)
- cool to 4 degrees celsius
2. K containing solution (depolarizes heart)
what happens to the heart at 25-30 degrees celsius
vfib
elements of cardioplegic solution
KCl 26mEq Glucose 43.9gm/L mannitol 12.5gm/L sodium bicarbonate 2.67mEq/L solumedrol 1gm/L normosol-R "vehicle" pH 7.6 osmolality 480mOsm/kg H2O
issues related to CPB
HoTN related to decreased SVR
renal ischemia from hypo perfusion and/or hemodilution
CVA from thrombus in CPB system (clot or foreign object)
air emboli introduced into CPB system
thrombocytopenia
increased inflammatory response
(CPB issues may not happen to everyone but team needs to be hyper vigilant to detect and intervene early)
cardiac surgery inflammatory response
place holder
cardiac surgery inflammatory response
place holder
biggest culprit to cerebral compromise and how to avert it
emboli (hypothermia, blood gas management, adequate BP, cerebral oximetry)
coronary anastamosis
place holde
re warming begins
prior to aortic cross clamp removal or
begins with last distal anastomosis in angioplasty or
begins when all valve sutures are in and knots are being tied down
preparation for coming off of bypass includes a core temperature above
35c (eventual target is 37)
preparation for coming off of bypass includes correcting
K first!
then ABG
then HCT
what to do before cross clamp is removed (lungs)
inflate (de airing maneuvers) ?
what is the sequence of events after cross clamp is removed to facilitate coming off of bypass
defibrillation
heart rate: paced or SR at sufficient rate (80-90BPM)
rhythm: av paced or v paced (need adequate rate around 90, will turn pacing down later in ICU)
venous return line intervention by perfusionist to facilitate coming off of bypass
clamped slowly
perfusionist will begin to turn down flows and allow RA to fill.
look for PA and aline pressures to increases
when are you officially off of bypass?
when pump comes off and venous cannula is clamped
after coming off bypass, watch CO via
watching TEE for LV failure, monitor PA and arterial line pressures
post bypass, what to monitor for increased O2 demand or decreased O2 delivery
SvO2
what to do for a patient freshly off of bypass intraoperatively if they are shivering
give muscle relaxant
what to do for the patient freshly off of CPB intraoperatively: airway consideration
turn on the vent hoe
when cross clamp is coming off, what can paradoxically occur
myocardial damage can occur and limit the extent of recovery
complications of aortic cross clamp may include (3)
hemorrhage (at cannulation site), dislodgment of atheromas (clots) and aortic dissection
how many joules to defibrillate a patient during cardiac surgery (open chest, direct contact)
10-30 joules
what to look at when coming off bypass to monitor contractility
look at TEE (volume, wall motion, valve function)
how is it filling?
is it vigorously beating?
needs adequate contractility to come off CPB
coming off bypass: systemic and PA pressure
what is the systemic pressure in relation to PA pressure
coming off bypass: protamine dosing
give slowly
1mg/100U of protamine given
when chest is closed, what can occur
tamponade scenario. then you will have to re open
post CPB challenges (6)
recall and neurocognitive changes bleeding organ hypo perfusion non pulsatile BF, embolie, thrombi systemic inflammation response residual hypothermia
post CBP challenges: bleeding. what contributes to this challenge?
loss of clotting factors fibrinolysis thrombocytopenia surgical blood loss transfusion rreaction vessel trauma metabolic byproducts
reperfusion interventions
spend time “paying back” by re perfusing the empty heart at adequate perfusion pressure (typically takes 20-30m)
allows heart time to recovery by washing out metabolic by products
correct metabolic abmormalities
if it was an exceptionally long cross clamp time, consider
IABP
protamine is composed of
multiple low molecular weight proteins derived from salmon sperm
MOA of protamine
neutralize and reverse effects of heparin. unable to therefore form a complex with ATIII
why do we give protamine slowly
can cause pHTN and right HF
half life of protamine
30-60 minutes, shorter than herpain
what type of allergic reactions can protamine be responsible for
type 1 and II (histamine releasing)
what kind of line can you give protamine through
give slowly via peripheral vein
does protamine have anti coagulant effevts
yes but they are not seen unless you give 2-3x the reversal dose
what do you need during transport of this patient to the ICU
Bambu bag, oxygen tank
monitors: EKG, arterial line, ECG
emergency drugs
keep surgical table sterile until out of room
after moving to bed, recheck breath sounds
transport assistance is needed in the form of a surgeon, anesthesiologist, or another CRNA
in the ICU, remember to:
attach to ventilator and re check breath sounds. make sure patient is being ventilated.
what can you expect during cannulation of the coronary sinus for retrograde cardioplegia
the same side effects as cannulation of the aorta (arterial) and RA (venous). decreased BP, arrhythmias can occur.
while transitioning to CPB post cannulation, what medications would you anticipate administering or stopping
NMB to stop shivering
versed to provide amnesia
stop fluids
what should your mixed venous saturation be on bypass?
70-80%
what does it mean if your mixed venous saturation drops while on bypass
metabolic rate could be increasing, consider muscle relaxant
where should your MAP be on pump?
65-70
if increasing, talk to perfusionist who controls pressors/dilators
where can your MAP be while on pump for a valve repair?
MAP 50-60 is fine because valves aren’t grafts and therefore this isn’t an oxygenation problem to the heart
if you had a big change in pump flow on your monitor (LPM), what would you consider
a cannula malfunction
if you had a CVP higher than 0-5mmHg while on pump, what would you consider
a kink in the lines
what is the usual pump flow L/min and ml/kg on bypass that the perfusionist maintains
2.5-3L/min
50-60mL/kg
what would you anticipate happening to your arterial line flow tracing when CPB is just starting or at partial or weaning process
your arterial line trace will diminish
what would you anticipate happening to your arterial line trace at full CPB flow?
arterial line waveform will be gone
if the head is swelling during transition to CPB,
venous catheter could be improperly placed
