RE4: Chapter 25: Anesthesia for Vascular Surgery Flashcards
What pharmacological therapy should be instituted in patients at high risk for myocardial ischemia and infarction days to weeks before surgery?
What range should the KR be kept?
B-blockers
HR should be between 50-60 bpm to decrease demand and increase supply
What are major risk factors associated with atherosclerotic lesions???
Hypercholesterolemia Elevated triglycerides levels Cigarette smoking HTN DM Obesity Genetic predisposition Sedentary lifestyle Sex (male > female) Impaired long-term glucose regulation Homocysteine C-reactive protein
What is the primary objective in patients with vascular disease?
Detection of myocardial ischemia
What do patients with HTN and/or angiopathology rely on to perfuse their vital organs?
Increased mean arterial pressures
Why is epidural opioids and local anesthetics in patients recovering from vascular surgery important postoperatively?
Pain can greatly enhance sympathetic nervous system stimulation
What are some risk factors associated with AAA?
Smoking Older age Gender (male > female) Family history CAD High cholesterol COPD Height (per 7cm interval) HTN Peripheral vascular occlusive disease Caucasian
Which risk factor is most highly correlated with AAA and how much does the incidence increase by?
Smoking
Incidence of AAA increases five-fold!
What size AAA is surgical intervention recommended for?
5.5cm or greater in diameter
<4cm have low risk of rupture, but risk dramatically increases for AAAs with a 5cm or greater diameter
What are contraindications to elective repair of AAA?
Intractable angina pectoris
Recent MI
Severe pulmonary dysfunction
Chronic renal insufficiency
What calculation measures the wall tension of an aneurysm?
Law of Laplace
T = P x r
(As the radius increases, the wall tension increases. Therefore, the larger the aneurysm, the more likely the risk of spontaneous rupture.)
What is the average growth per year of an AAA?
4mm/yr
What are the most important techniques used to enhance cardiac function during an AAA repair?
Preoperative fluidity loading and restoration of intravascular volume
What are the hallmark pharmacologic treatments for medical management of an AAA?
Beta blockers, statins, and aspirin
What monitors should be used for AAA?
ECG with lead II for detection of dysrhythmias and V5 for analysis of ischemic ST-segment changes Pulse ox Capnography Esophageal stethoscope Urinary catheter Invasive BP monitoring
What is the primary method of intraoperative cardiac assessment?
TEE
True or False. Wall motion abnormalities occur sooner than ECG changes during periods of reduced coronary blood flow.
TRUE
Where is the most common site for cross-clamping for AAA?
INFRARENAL - because most aneurysms appear below the level of the renal arteries
What happens to the BP above the clamp and below the clamp during the cross clamping of the aorta?
Hypertension ABOVE the cross-clamp
Hypotension BELOW the cross-clamp
What happens to the MAP and SVR with cross-clamping?
Increase
What happens to CO with cross clamping?
Decrease or remain unchanged
PAOP may increase or display no change as well
What may the increased wall stress from increased afterload with cross clamping contribute to?
Decreased global ventricular fxn and myocardial ischemia
What happens metabolically to the tissues distal to the cross-clamp?
Prone to developing hypoxia. In response to hypoxia, metabolites such as lactate accumulate.
What is released that may also contribute to cardiac instability during aortic cross-clamping?
What can be administered to pretreat this?
Arachidonic acid derivatives
Thromboxane A2 synthesis may be responsible for decreasing myocardial contractility and CO
ASA or ibuprofen
What can mesenteric traction cause during AAA?
What metabolite is associated with this?
Mesenteric traction syndrome - decreases in BP and SVR, tachycardia, increased CO, and facial flushing
6-ketoprostaglandin F1