Anesthesia for Vascular Surgery Flashcards
common coexisting diseases with vascular patients include (6)
DM, HTN, renal impairment, pulmonary disease (r/t smoking), systemic atherosclerosis, CAD
leading cause of perioperative mortality at the time of vascular surgery?
CAD
pathology of atherosclerosis
generalized, progressive, chronic inflammatory DO of the arterial tree with development of fibrous intimal plaque associated endothelial dysfunction
what does atherosclerosis lead to when BF is compromised? (3)
MI, CVA, gangrene of LE’s.
atherosclerosis progression: stage 1, fatty streak
starts in childhood! enthothelium is damaged due to hemodynamic shear stress, oxidized LDL destruction, chronic inflammatory responses, infection, and hypercoagulability resulting in thrombosis. lipoproteins enter arterial intimal layer via endothelium. they become trapped. macrophages come, inflammation promoted. foam cells are formed
atherosclerosis progression: stage 2, fibrous plaque
composed of oxidized lipid accumulation, inflammatory cells, proliferated smooth muscle cells, connective tissue fibers, calcium deposits. blood flow reduction-ischemia to vital organs and extremities, thrombus risk
atherosclerosis progression: stage 3, advanced lesion
plaque with expanded lipid rich necrotic core, calcium accumulation, endothelial dysfunction. physical disruption of plaques protective cap (rupture or ulceration) exposes blood to highly thrombogenic material promoting acute thrombus formation and vasospasm. complete occlusion possible (MI, stroke, limb ischemia, etc)
atherosclerosis morbidity: three types
- enlarged plaque reduces limen of blood vessel. supply versus demand problem. can result in delayed periop MI (limb ischemia, stable angina)
- plaque rupture/ulceration/embolization, and thrombus formation. acute occlusion, can result in early periop MI (unstable angina, MI, TIA, CVA)
- Atrophy of media with arterial wall weakening (aneurysm dilation)
most common sites for atherosclerotic lesions
occurs at bifurcations
coronary artery and aortoiliac peripheral artery
2014 ACC and AHA preoperative evaluation guidelines include
clinical history (risk factors, exercise tolerance)
supplemental evaluation
perioperative therapy
surgical procedure itself (low risk, intermediate risk, high risk)
medical management and home meds: aspirin
inhibits platelets. increases bleeding and decreases GFR. continue for vascular procedures most of the time
medical management and home meds: plavix
inhibits platelets, potential increase in bleeding, do not continue on DOS
medical management and home meds: statins
effects liver function, continue on DOS
medical management and home meds: ACEI’s
induction hypotension, coughing, d/c 24h before surgery
medical management and home meds: diuretics
hypovolemia, electrolyte imbalance possible. continue DOS
medical management and home meds: CCB’s
HoTN is concern, continue on DOS
medical management and home meds: hypoglycemic drugs (and SE of one of them)
hypoglycemia, lactic acidosis with metformin. do not continue on DOS
medical management and home meds: BB’s.
bronchospasm, decrease in BP and decrease in HR. if you want to start them on a BB, start them 3-4d preop
post stenting and antiplatelet therapy
dual therapy will be required post stenting. usually ASA and plavix
when to stop anti platelet therapy for new bare metal stent
do not want to stop anti platelet therapy <1 month out from stent placement. usually on anti platelet therapy for 1-3 months
when to stop anti platelet therapy for drug eluding stent
do not want to stop anti platelet therapy <6 months out from surgery
critical period for coronary stenting
6 weeks to endothelialize
when performing a procedure on a previous coronary stent patient, what to do with preop ASA and plavix
continue ASA, hold plavix x7-8days
perioperative MI’s during vascular surgery are related to either
culprit lesions (vulnerable plaques with high likelihood of thrombotic complications, often located in coronary vessels WITHOUT critical stenosis or demand ischemia. this is likely the predominant cause and we can prevent this
tools and tests for cardiac function assessment for vascular surgery patients include
- advanced cardiac testing to determine the need for coronary intervention prior to vascular surgery OR to determine if aggressive intraop/postop managment
- exercise/ pharmacologic stress test
- echo
- assessment of ischemia, previous MI, valvular dysfunction, and heart failure
- duplex imaging of carotid arteries or angiography (esp if sx of TIA’s)
most important pulmonary complications to assess for/risk of before vascular surgery include
atelectasis, PNA, ARF, exacerbation of underlying chronic disease
pulmonary tests to consider include
PFT’s, ABG’s, CXR’s
things to consider for patients with pulmonary dysfunction undergoing vascular surgery
incentive spirometry, steroids, regional, abx, CPAP
what strongly predicts long term mortality in patients with symptomatic LE arterial occlusive disease irrespective of disease severity, CV risk, and concomitant tx
chronic renal disease
preop tests to consider for renal function assessment
serum creatinine, creatinine clearance
things to consider for patients with renal dysfunction undergoing vascular surgery
contrast dye use, BB’s, statins, volume status, perfusion pressures
definition of LE PAD
insufficiency in LE’s presenting with acute or chronic limb ischemia with occlusions distal to the inguinal ligament
patients who need LE revascularization, often on what kind of meds?
ASA, ticagrelor (P2Y12 inhibitors), rivaroxaban (Xa inhibitor). clopidogrel
anti platelet and anticoagulant will likely both be on their regiment
peripheral revascularization indications
acute ischemia (emboli, thrombus, pseudoaneurysm postop from femoral arterial line) chronic ischemia (atherosclerotic plaque progressively narrowing vessel- claudication with eventual thrombosis of vessel)
irreversible ischemic damage from acute ischemia occurs in how many hours
4-6 hours
treatment for acute ischemic event
urgent thormbolytic therapy and/or angioplasty
arteriography
surgical intervention
treatment for chronic ischemia: when is surgery indicated?
severe disabling claudication, critical limb ischemia (limb salvage)
peripheral occlusions: traditional surgical approach for revascularization
unobstructed BF source (donor) artery is exposed. typical the common femoral, superficial, or deep femoral
target distal artery (recipient) is exposed at or below the knee. typically dorsals pedis or posterior tibial arteries
if saphenous vein used, vein is dissected all branches ligated, divided and excised (reversed, permits blood flow in direction of valves)
after donor and recipient arteries exposed, tunnel is created and graft is passed.
graft may be saphenous vein of prosthesis
heparin IV given (and not reversed)
anastomosis constructed
arteriogram to confirm adequate flow
anesthetic managment of peripheral revascularization patient
preop BB’s and/or other chronic medication
intraop arterial line
continuous EKG monitoring and ST analysis (leads 2,5)
monitor intravascular volume by foley (+/- CVP or PA cath)
minimal blood loss and third spacing
anesthetic management of peripheral revascularization patient for emergency surgery
carefully watch K levels myoglobinemia fasciotomy may be required coagulation status EKG ischemia, etc
anesthetic management of peripheral revascularization surgery: regional versus general
assess for coagulopathy or anticoagulation therapy
spinal may be best to avoid hematoma
regional superior to GA r/t to decrease in graft reocclusion
postop epidural versus PCA still a convo but PCA
anesthetic management: cardiopulmonary complications and regional versus GA
no difference
regional versus general: coagulation and BF
regional: promotes BF d/t sympathectomy
GA: hypercogulation more possible d/t decreased fibrinolysis
postop: epidural versus opioids or PCA
postop epidural versus PCA still a convo but PCA seen more often
epi, norepi, cortisol RA v GA
epi, norepi, cortisol release increased after GA compared to RA
vasopressors and peripheral revascularization surgery
avoid vasopressors
how to perform a GETA for peripheral revascularization surgery
opioids, inhlationals, N2O, NMB’s. deepen anesthetic during tunneling phase. ex) 3-5mcg/kg fentanyl. avoid hemodynamic extremes. BB’s often necessary
how to perform regional anesthetic for peripheral revascularization surgery
L1-L4 dermatomes, T10 level adequate. epidural dosing usually 9-12mL including test dose. remember that elderly patients require decreased dosing
postop anesthetic managment of patient after peripheral revascularization
control pain and anxiety (to decrease the risk of MI)
avoid anemia (HGB 9 or higher preferred)
control HR/BP
frequent checks of peripheral pulses
continuous EKG monitoring and ST analysis
lower extremity endovascular treatment can be done as what type of anesthetic
GA, neuraxial, or MAC
percutaneous often MAC, open access (ex femoral stenosis) consider GA
principal cause of carotid endarterectomy
atherosclerosis
where does atherosclerosis often occur
common carotid, internal and external carotid arteries
signs and symptoms of atherosclerosis occluding the carotids
fatal or debilitating CVA, TIA, amaurosis fogax aka transient monocular blindness, asymptomatic bruit
leading risk factors of CVA (4)
DM, smoking, HTN, obesity
indications for CEA (carotid endarterectomy)
patients with high grade carotid stenosis (70-99% occlusion) or that is symptomatic
how to treat asymptomatic carotid stenosis
medical therapy (ASA), percutaneous angioplasty. usually
preop assessment for CEA: medical management. how to optimize?
beta blockers, statins, anti platelet therapy.
HTN control, restore intravascular volume, reset cerebral auto regulation, DM control
what is recommended before CABG?
carotid revascularization in patients with symptomatic carotid disease and bilateral severe asymptomatic carotid stenosis.
anesthesia for CEA and lines
awake v GETA
aline always
PIVx2, arms usually tucked
do you continue ASA for a CEA?
yes
CEA and GA case setup includes (labs, lines, equipment, infusions, meds)
T&S
aline, act machine, fluid warmer, lower body forced air warming blanket
neo and remi infusions in line
clevidipine (1-2mg/h) and NTG (5-25mcg IV) infusions available
BB’s and ephedrine avail
heparin and protemine
esmolol during induction possible
CEA and GA monitoring includes
routine with V5 lead and ST segment analysis plus aline
consider cerebral oximeter (foresight) esp if surgeons are not placing a shunt during cross clamp
occasionally surgeons want to measure “stump” pressures, so have an extra pressure tubing to connect to aline adapter
can you use neo during CEA
yes because not a microvascular procedure
where should the arterial blood pressure be maintained during a CEA
high-normal (~20%) for duration of procedure and especially during carotid clamping to increase collateral flow
(note pre induction MAP)
what happens during surgical manipulation of the carotid sinus and how to treat it pharmacologically
baroreceptor reflex (decrease HR and BP) infiltration of carotid bifurcation with 1% lidocaine usually prevents further episodes.
where are the baroreceptors located
aortic arch and internal carotids
what happens if neurologic deficits are assessed during emergence from CEA
angiography, reoperation, or both
emergence considerations for CEA
marked HTN and tachycardia can increase risk for ischemia and MI so tx aggressively and consider precedex/BB/something to smooth emergence
regional anesthesia for CEA or “awake carotid” block
blocks C2 to C4 determatomes by use of superficial, intermediate, deep, or combined cervical plexus block
benefits of awake carotid (regional anesthetic)
allows for continuous neurologic assessment for awake patient
reduces need for shunts
greater hemodynamic stability
reduced costs (avoid cerebral oximetry, dont need because theyre awake, and operative time is reduced)
requires patient cooperation
describe a superficial cervical plexus block
locate the midpoint of the posterior border of the sternocleidomastoid muscle
injection along the posterior border of the medial surface of the muscle
may block accessory nerve causing trapezius muscle paralysis
cerebral auto regulation: normal reactivity to hypocapnea
decrease in cerebral blood flow/vasoconstriction
cerebral auto regulation: normal reactivity to hypercapnea
increase in cerebral blood flow/vasodilation
what increases the risk for cerebral ischemia after carotid artery clamping
impaired CO2 reactivity (consider people with pulmonary diseases like COPD)
describe the carotid artery stump pressure
ICA stump pressure represents back pressure resulting from collateral flow through circle of willis via contralateral carotid artery and vertebrobasilar system
may be performed every time or never performed
what is the idea stump pressure
50 or greater
<45mmHg is cause for concern
describe near infrared spectrophotometry
noninvasive technique that allows continuous monitoring of regional cerebral O2 saturation through the scalp and skull
based on oxygenated and deoxygenated HGB, however it measures O2 saturation of HGB of entire tissue bed and therefore approximates venous blood O2 saturation
CEA postoperative complications
thromboembolic and hemorrhage intracerebral events
HTN r/t denervation of carotid sinus baroreceptors
HoTN r/t baroreceptor hypersensitivity
cerebral hyper-perfusion syndrome
cranial and cervical nerve dysfunction
carotid body denervation
wound hematoma
“loss of auto regulation once carotid is fixed”
describe cerebral hyper perfusion syndrome (CEA postoperative complication)
abrupt increase in BF with loss of auto regulation manifested as HA, seizure, focal neurologic signs, brain edema, and possibly ICH
describe types of cranial and cervical nerve dysfunction in relation to CEA postoperative complications
RLN, SLN, hypoglossal, mandibular
bilateral RLN injury and resultant bilateral vocal cord paralysis can result in life threatening upper AW obstruction
describe carotid body denervation side effects in relation to CEA complications
impaired ventilatory response to mild hypoxemia, central chemoreceptors impaired, worsened with opioid administration
steps to percutaneous transluminal angioplasty and stenting r/t endovascular carotid artery stenting
femoral access, aortic arch angiogram, selective cannulaiton of common carotid artery origin and angiogram, guide wire advancement into external carotid, sheath placement and advancement into CCA, placement of ambolic protection device, balloon angioplasty of lesion, advancement of stent delivery catheter across dilated lesion, deployment of self expanding stent, balloon dilation of stent, completion angiogram, access site management
do patients who received percutaneous transluminal angioplasty and stenting need antiplatelet therapy
yes theyre on dual antiplatelet therapy
