Exam III: Vascular Anesthesia Flashcards
Atherosclerosis is the primary process leading to…
CAD, stroke, extremity ischemia, and aneurysms
presumed progression of atherosclerosis
fatty streaks to fibrous plaques to complicated lesions
atherosclerosis - common formation in:
coronary arteries, carotid bifurcation, infrarenal abdominal aorta, iliac arteries, superficial femoral artery
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
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
arteriosclerosis (pathologic)
_____abdominal aorta
_____abdominal aorta
_____ _____ aorta
infrarenal abdominal aorta
thoracoabdominal aorta
descending thoracic aorta
____ ____ ____ - degeneration of the aortic media (ascending aorta)
cystic medial necrosis
aortic aneurysm mortality rates
- elective repair
- ruptured
- untreated
- elective repair: 1-11%
- ruptured: 75%
- untreated: 5-year 81%, 10-year 100%
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
Aneurysms greater than __ to __ cm in diameter require surgery.
4 to 5
AAA grow approximately ___ ____.
4 mm/year
Law of Laplace
As the radius of the vessel increases, the wall tension increases. The bigger the aneurysm, the higher risk of rupture.
Law of Laplace
formula
T = P x r
25-41% of aneurysms larger than 5 cm rupture spontaneously within __ ____.
5 years
DeBakey type I – originates in the ____ ____ aorta and usually involves the ascending aorta, arch and can go to abdominal aorta
proximal ascending
DeBakey type II - confined to the ____ ____
ascending aorta
DeBakey type III - (a) - confined to the _____ ____ aorta
descending thoracic
DeBakey type III - (b) - may extend into the _____ aorta and ____ arteries
abdominal
iliac
Stanford classification:
Type A: the ascending aorta is involved, ____ or _____ the _____ or the descending aorta.
with or without the arch
Stanford classification:
Type B: the descending thoracic aorta is involved, with or without ____ or _____ extension.
proximal or distal
Aneurysms occur most commonly:
Ascending thoracic aorta close to the ____ _____
Descending thoracic aorta just distal to the ____ ______ _____.
aortic valve
left subclavian artery
Myocardial infarction, respiratory failure, renal failure, and stroke are the major causes of _____ and _____
morbidity and mortality.
Co-existing diseases should be evaluated, optimized, and recorded _______. (See Box 28.4 Nagelhout)
preanesthesia
CAD – _____ ______ are responsible for 40-70% of all fatalities occurring after AAA repair.
50% of patients for AAA reconstruction have CAD
Myocardial infarctions
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
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.
