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