Exam III: Vascular Anesthesia Flashcards by Linsley Lloyd

Atherosclerosis is the primary process leading to…

CAD, stroke, extremity ischemia, and aneurysms

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presumed progression of atherosclerosis

fatty streaks to fibrous plaques to complicated lesions

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atherosclerosis - common formation in:

coronary arteries, carotid bifurcation, infrarenal abdominal aorta, iliac arteries, superficial femoral artery

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Although atherosclerosis is a slow, gradual process, the reason for the ultimate injury is:
_____ ____ reducing blood flow
_____ of plaque-associated platelet thrombi or debris
Complete _____ of ______ by advanced plaques.

Plaque enlargement
Embolism
occlusion of arteries

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risk factors for atherosclerosis

hyperlipidemia
smoking (8x)
diabetes
HTN (60%)
family history
male
advanced age
insulin resistance
physical inactivity
elevated c-reactive protein
elevated lipoprotein

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arteriosclerosis (pathologic)
_____abdominal aorta
_____abdominal aorta
_____ _____ aorta

infrarenal abdominal aorta
thoracoabdominal aorta
descending thoracic aorta

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____ ____ ____ - degeneration of the aortic media (ascending aorta)

cystic medial necrosis

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aortic aneurysm mortality rates
- elective repair
- ruptured
- untreated

elective repair: 1-11%
ruptured: 75%
untreated: 5-year 81%, 10-year 100%

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Due to the relatively low mortality rate with elective AAA repair, surgery is recommended for any one with greater than ____ cm in diameter aneurysm.

5.0 cm

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Aneurysms greater than __ to __ cm in diameter require surgery.

4 to 5

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AAA grow approximately ___ ____.

4 mm/year

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Law of Laplace

As the radius of the vessel increases, the wall tension increases. The bigger the aneurysm, the higher risk of rupture.

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Law of Laplace
formula

T = P x r

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25-41% of aneurysms larger than 5 cm rupture spontaneously within __ ____.

5 years

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DeBakey type I – originates in the ____ ____ aorta and usually involves the ascending aorta, arch and can go to abdominal aorta

proximal ascending

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DeBakey type II - confined to the ____ ____

ascending aorta

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DeBakey type III - (a) - confined to the _____ ____ aorta

descending thoracic

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DeBakey type III - (b) - may extend into the _____ aorta and ____ arteries

abdominal
iliac

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Stanford classification:
Type A: the ascending aorta is involved, ____ or _____ the _____ or the descending aorta.

with or without the arch

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Stanford classification:
Type B: the descending thoracic aorta is involved, with or without ____ or _____ extension.

proximal or distal

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Aneurysms occur most commonly:
Ascending thoracic aorta close to the ____ _____
Descending thoracic aorta just distal to the ____ ______ _____.

aortic valve
left subclavian artery

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Myocardial infarction, respiratory failure, renal failure, and stroke are the major causes of _____ and _____

morbidity and mortality.

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Co-existing diseases should be evaluated, optimized, and recorded _______. (See Box 28.4 Nagelhout)

preanesthesia

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CAD – _____ ______ are responsible for 40-70% of all fatalities occurring after AAA repair.
50% of patients for AAA reconstruction have CAD

Myocardial infarctions

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The greater number of _______ that exist, the greater the risk of morbidity and mortality during the perioperative period.

comorbidities

____ ____ ____ is common during the perioperative period; this is associated with a high risk for cardiovascular-specific mortality comparable to that seen with chronic kidney disease.

Acute kidney injury (AKI)

Aortic Cross- Clamping Hemodynamic effects depend on the ____ of the clamp, the patient’s pre-op ____ ____, and the patient’s intravascular _____.

site cardiac reserve volume

Aortic Cross- Clamping With X-clamping, hypertension occurs _____ the X-clamp and hypotension occurs _____.

above below

Aortic Cross- Clamping systems involved

Hemodynamic Myocardial Pulmonary Renal Spinal cord Hormonal / Metabolic

Aortic Cross- Clamping Hemodynamic/cardiac Effects of X-clamp afterload? MAP and SVR? HR? CO? LVEDP?

Afterload increases – myocardial wall tension increases. Mean arterial pressure and SVR increase. Heart rate unchanged Cardiac output may decrease or remain unchanged. LVEDP may increase or show no change.

Aortic Cross- Clamping Patients with poor cardiac reserve may have decreased ____ ____ and _____ _____. They will have an increase in LVEDP.

ventricular function and myocardial ischemia

LVEDP, CVP and PCWP may ______ due to vasoconstriction of venous vasculature distal to the x-clamp – increasing preload

increase

The effects of the X-clamp are altered depending on the _____ of the occlusion.

location

The longer the duration of the X-clamping, the greater the increase in ____ and decrease of ____

SVR CO

Pulmonary damage related to: ______ pulmonary vascular resistance (more at unclamping) Increased capillary membrane _______ Development of ______ _____

Increased permeability pulmonary edema

potential causes of pulm damage:

hypervolemia prostaglandins, oxygen free radicals, activation of RAAS, complement cascade

prostaglandins cause ________

bronchoconstriction

Renal Effects of X-clamp Renal blood flow is _____ 40% and renal vascular resistance ______ 75% when the X-clamp was placed infrarenally.

decreased increased

Renal Effects of X-clamp ______ & ______ cross-clamping can decrease renal blood flow by as much as 80%.

Suprarenal and juxtarenal

Renal Effects of X-clamp Renal failure post aortic surgery is usually acute tubular necrosis r/t ____-____ injury.

ischemic-reperfusion

_____ occurs in as many as 18% of patients undergoing aortic aneurysm repair.

AKI

____ _____ damage is associated with aortic X-clamping.

Spinal cord

Specifically, the ____ of _____ is occluded with no collateral flow to the anterior portion which is motor.

artery of Adamkiewicz

The more proximal the X-clamp, the greater the risk for ______.

paraplegia

Somatosensory Evoked Potential – SSEP – does not provide information about the _____ spinal cord.

Anterior Spinal Syndrome the higher the cross clamping the greater the chance of ____ ____ ____

spinal cord ischemia Elective infrarenal 0.2%, Ruptures of the descending aorta 40%

Anterior Spinal Syndrome Main blood supply to anterior cord is from the artery of Adamkiewicz; origin ____ ____-____

unknown (T5-L2)

Anterior Spinal Syndrome spinal cord perfusion =

MAP - CSF pressure

Anterior Spinal Syndrome drainage of CSF has allowed the ____ ____ of ischemia, limited x-clamp time of 30 mins

best avoidance

Anterior Spinal Syndrome artery of adamkiewicz nearly always comes from ____ side

left

anterior spinal preventative measures

Shunt from the left atrium to the common femoral artery Maintenance of hypertension during X-clamp (post-op*) Methylprednisolone Moderate hypothermia (30-32 degrees C) Avoiding hyperglycemia Mannitol – lowers CSF pressure by decreasing production Drainage of CSF

anterior spine syndrome Nipride decreases pressure proximal to the clamp, BUT also _____ to the _____. This may contribute to the increased risk of spinal cord ischemia.

distal to the clamp

anterior spinal syndrome classic s&s: loss of what and preservation of what

Loss of motor function and pinprick sensation Preservation of vibration and proprioception (posterior)

*Maintain ____tension (systolic > ______) through the second postoperative day decreased the incidence of paraplegia during thoracic aortic reconstruction anterior spinal syndrome

normo 120 mm Hg

Metabolic/Hormonal Effects of X-clamping Tissues distal to the clamp are hypoxic causing metabolites such as _____ to accumulate.

lactate (metabolic acidosis)

Metabolic/Hormonal Effects of X-clamping Decreased _____ consumption due to the portion of tissues not being perfused.

oxygen

Metabolic/Hormonal Effects of X-clamping Decreased total body oxygen extraction; Increased ____ ____ ____ saturation

mixed venous oxygen

Metabolic/Hormonal Effects of X-clamping Increased levels of ______ circulating during X-clamp time (decreased renal blood flow)

catecholamines

Metabolic/Hormonal Effects of X-clamping Respiratory _____ (decreased ____ production)

alkalosis CO2

Intraoperative Interventions during AoX-clamping reduce afterload:

- nipride - inhalation agents - milrinone - shunt: aorta to femoral bypass

Intraoperative Interventions during AoX-clamping reduce preload:

- NTG - atrial to femoral bypass

Intraoperative Interventions during AoX-clamping renal protection:

- fluid - renal cold perfusion - pharmacologic

Intraoperative Interventions during AoX-clamping _____thermia, decrease ______ ventilation, ______

hypo minute ventilation NaBicarb

Release of Aortic X-clamp Metabolites such as lactate are circulated which cause _____, increased _____, hypotension.

vasodilation ETCO2

Release of Aortic X-clamp afterload and SVR _____

decrease

Release of Aortic X-clamp MAP

decreases

Release of Aortic X-clamp preload

decreases

Release of Aortic X-clamp CO _____ or no change or _____

increases decreases

Release of Aortic X-clamp wedge

decreases

Release of Aortic X-clamp EtCO2 _____ and pH ______

increases decreases (metabolic acidosis)

Release of Aortic X-clamp temperature

decreases

Unclamping Hypotension Blood shifting to _____ – in reperfused tissue

periphery

Unclamping Hypotension Hypoxia-related _____ in vessels below the level of the X-clamp

vasodilation

Unclamping Hypotension Release of _____ & ______ ______metabolites in the reperfused tissues Increased lactate, prostaglandins, activated complement, metabolic acidosis Increased myocardial depressant factors

vasoactive and myocardial depressant

To minimize the effects of the X-clamp release Intravascular _____ must be maintained or restored.

volume

To minimize the effects of the X-clamp release Replace ____ loss

blood

To minimize the effects of the X-clamp release To prevent hypotension and decreased cardiac output with release of X-clamp, the PCWP should be raised ___ to ___ ____ above pre-clamp values just prior to release.

3 to 4 mm Hg

To minimize the effects of the X-clamp release The lower the sight of clamping, the ____ ____ the changes.

less drastic

To minimize the effects of the X-clamp release The clamp can be released _____

gradually.