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)