CHAPTER 26 CRAP Flashcards
What is #1 cause of AAA (90% of patients?)
atheroscelerosis
aneurysmal vessel dimensions correspond to which LAW?
LaPlace
law of Laplace equation (& what do each stand for?)
T = P x r T = wall tension P = transmural pressure r = vessel radius
As _____ of vessel increases, ____ _____ increases (LAPLACE STUFF)
RADIUS, WALL TENSION
IN GENERAL, aneurysms >____cms require surgery.
4-5cm
Preoperatively, what is the most important techniques to enhance cardiac function during AAA repair?
preop fluid loading & restoration of intravascular volumes
what is better PA catheter monitoring or central venous monitoring?
neither, randomized controlled studies show no difference
Aortic cross clamping causes release of ____ ___ derivatives and the synthesis of _____ __ .
Arachidonic acid derivatives, thromboxane A2 synthesis
traction of mesentery has been associated w/ high concentrations of _-____________ __ which can cause ______ (multiple factors).
6-ketoPROSTAGLANDIN F1, Decreases in blood pressure and SVR, tachycardia, increased cardiac output, and facial flushing are common responses to mesenteric traction. (nagelhout)
Aortic cross clamp end organ concerns? 50-90% of patients having aneurysmectomies have ___ ___ ____.
renal insufficiency, acute renal failure
interruption of blood flow to what artery causes paraplegia? (two names) Originates where on spinal column
greater radicular artery AKA, artery of Adamkiewicz… b/t T8 and L2
Name 2 types of (neuro)monitoring used for spinal cord ischemia?
SSEP, MEP
SSEP is ?
SomatoSensory Evoked Potentials and reflects DORSAL (sensory) spinal cord function (NOT MOTOR).
MEP
Motor Evoked Potentials and reflects ANTERIOR (ventral) cord function
Colonic bloodflow is determined by which artery?
inferior mesenteric artery
AORTIC CROSS CLAMP releases serum ______, causing ______ and ______ _____. This is manifested by _______ in SVR.
serum LACTATE, vasodilation and vasomotor paralysis. DECREASED SVR
AA reconstruction APPROACH? Advantages? Disadvantages?
TRANSPERITONEAL INCISION. Advantages: exposure of infrarenal and iliac vessels, visible intraabdominal organs, rapid closure… Disadvantages: fluid losses, prolonged ileus, post-op incisional pain & pulmonary complications.
50% of patients who req. AA reconstruction have ___ (dx) and it is the biggest risk factor for long-term survivability.
CAD
_______ _______ testing is perhaps one of the most reliable methods for evaluating the extent of myocardial dysfunction associated with CAD and for predicting coronary events after vascular surgery.
Dipyridamole thallium
Dipyridamole thallium is key b/c it does not rely on _______ to detect areas of myocardial hypoperfusion.
EXERCISE
What anesthetic technique is ideal for AAA reconstruction? Why?
The McDizzle technique… A balanced technique using a combination of high-dose narcotics with nitrous oxide can be used as the anesthetic for major vascular surgery. Why? B/C of the CV stability provided by opioids and B/C IAA depress myocardium and cause hemodynamic instabilty.
Best induction agent for patients w/ poor cardiac function/limited cardiac reserve?
etomidate
In CAD patients, increases in PAOP and decreases in CO are treated w/ NG. Why?
decreases PRELOAD and decreases myocardial O2 DEMAND
The more proximal the cross clamp is place on aorta, the _________ the severity of hemodynamic responses.
GREATER
what do you expect when cross clamp is released? Prevented by doing what just before release?
declamping shock syndrome (severe hypotension and reduction in CO)… preventing via VOLUME LOADING to raise CVP 3-5mmHg or raising PAOP 3-4mmHg. Give HCO3 w/ acidosis.
What does Mannitol do for renal function vs. CPB priming agent?
Renal: preserves renal function via osmotic effect (incapable of being reabsorbed from the renal tubule, resulting in decreased water and Na+ reabsorption/excretion thus lowering ECF)
CPB: the solution prevents the swelling of endothelial cells in the kidney, which may have otherwise reduced blood flow to this area and resulted in cell damage (also preserving renal blood flow)
Renal cooling is suggested for ischemic periods >____minutes. What is it?
flushing kidneys w/ iced electrolyte perfusate (contains heparin and glucose)
3 layers of arterial wall?
tunica adventia, tunica media, tunica intima
dissection vs. aneurysm
dissection = intima tear only w/ blood flowing along aorta's longitudinal axis aneurysm = all 3 layers of arterial wall
which type of lesions (aneurysm) is more likely to rupture and thus require surgical intervention? A or B
A, B is managed medically w/ arterial dilators and beta blockers
why would a complete neurologic assessment be important prior to thoracic aorta surgery?
paraplegia d/t poor arterial flow… hoarseness secondary to RLN damage (wraps around aorta remember)
For any kind of aorta surgery, what special arterial monitoring is preferred?
R radial arterial b/c L SC bloodflow may be compromised during surgery… femoral arterial lines allow monitoring of lower extremity perfusion (in conjunction w/ R radial)
spinal cord injury risk increases ____ minutes after aortic cross clamping
45
one method that is proven to prevent spinal cord ischemia is
CSF drainage
formula for spinal cord perfusion pressure
arterial pressure minus CSF pressure
renal protection agents like mannitol and LASIX should be given __ minutes prior to clamping?
20-30
one-lung ventilation is specific to which aortic surgical procedure
thoracic
EVAR stands for? Procedure? Benefits?
endovascular aortic aneursym repair… EVAR involves deployment of an endovascular stent graft within the aortic lumen. The graft restricts blood flow to the portion or the aorta where the aneurysm exists… potential explanations for the absence of spinal cord complications are (1) no thoracic aortic cross-clamping and (2) no prolonged periods of extreme hypotension
EVAR anesthetic considerations
GA and be prepared to convert to an open procedure
