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67 Cards in this Set

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AAA involves what layers of the aorta?
All 3 layers-however medial layer is thinner as you descend down thru the body making it prone to weakening
Where does the Abdominal Aorta begin and end?
Aortic hiatus in the diaphragm-T12 and ends common iliac bifurcation @ L4
What are the main branches off the anterior aorta?
Celiac, SMA, IMA
What are the branches off the posterior aorta?
Inferior phrenic, Lumbar arteries
What are the branches off the lateral aorta?
Suprarenal, Renal, Gonadal
What are the main branches off the celiac artery?
Common Hepatic, Left gastric, Splenic
What is the #1 reason for AAA?
Atherosclerotic Disease
Where is the most common site for AAA?
The aortoiliac bifurcation
What is the risk for AAA if familial?
25%
Medical tx for AAA?
Those less than 5cm (Nml-1-3cm; >50% diameter of vessel is aneurysm)
β-blocker tx
Serial ultrasounds q 6-12 mths
Avg growth rate-0.2-0.5cm/yr (any > then consider sx)
Mortality for a ruptured AAA is?
15-90%
What are the most common approaches for a AAA?
Transperitoneal - midline
Retroperitoneal -R lateral decub - Left exposure
Which one has the least amt of EBL?
Retroperitoneal
Which surgical approach has less post op ileus?
Retroperitoneal
Which surgical approach is more painful?
Transperitoneal
What are the 3 types of aneurysms?
Fusiform
Berry/Sacular
Dissecting
What is the dosing of heparin?
100 units/kg-given IV
X-clamping distally is done first for what reason?
To prevent migration of any emboli
What are the common grafts made from?
Dacron/Gortex/Polytetrafluorethylene- these require less dissection during sx, shorter OR times
The main body system for concern during AAA repair is what?
The CV system because of the increase in afterload
What is normal size of the aorta?
1.5-3 cm
What is a big predictor of postoperative recovery?
Creatinine >3
What factors require CABG prior to AAA repair?
LM disease\
EF<35%
TVD
How should the pts deficit be approached?
Euvolemia is optimal in this sx. Replace ½ of the deficit early but not entirely. Needed for optimal CO and renal function however when x-clamp is placed hypervolemic state may impair CO
What are factors that may lead you to place a PA catheter in your pt?
Creatinine> 3
Suprarenal clamping
Hemodynamic parameters should remain where for this sx?
20% of baseline as rule of thumb
HR-tachycardia causes Decreased filling and Increased MVO2-keep lower parameters
What agents should be readily available for this sx?
SNP/NEO/Fenoldapam
NTG
Ca++channel/β-blockers
Dopa/Dobt/
Heparin/Protamine
********Have a prepared plan ready
Heparin may be safely given when neuraxial anesthesia is used after what time frame?
>1hr
What is Enoxaparin?
LMWH
What is considered a high dose?
1mg/kg bid
When can neuraxial anesthesia be used safely when LMWH is used?
10-12 hrs after last dose or >24hrs if high dose was given
When may the catheter be safely removed when LMWH is used?
2hrs prior to next dose or 10-12 hrs after last dose given
What may be the best induction agent available for AAA cases?
Etomidate
What should fluid status be at the time of x clamping?
Euvolemic or mild hypovolemia
What is Mesenteric Traction Syndrome?
A metabolite of prostacyclin and thromboxane B2 that causes:
Flushing
decrease SVR/MAP
Tachycardia
Pronounced increase CI
***Will not be seen with the retroperitoneal approach
How is MTS tx’d?
Cycoloxygenase inhibitors however may be contraindicated in sx so tell surgeon to release traction-use phenylephrine and/or β blockers, not fluids
What metabolite of prostacyclin and thromboxane B2 affects MTS?
6-Ketoprostaglandin F1
What is the affect of x-clamping the aorta?
Myocardial stress increases due to increased afterload-the amount of stress is r/t the height of the clamp. Hypervolemia at the time of x-clamping will accentuate the afterload and stress. This is why it is good to have a PA/CVP in place
What should be done prior to x-clamping?
Assess renal function-U/O and myocardial function
What actions may be taken prior to x-clamping for the kidneys?
Mannitol/Lasix/Fenoldopam
Blood flow will decrease as much as 40%
What is Fenoldapam?
DA1 agonist that produces renal artery dilation
What should be done immediately after x clamping?
Check myocardial function/EKG
Evidence of ischemia or LV failure post clamp should include what interventions?
Inform surgeon Full or partial removal of clamp Vasoactive drugs
What effects should be anticipated post removal of clamp?
HOTN
Metabolite washout/Vasoactive agents-causes Pulm HTN
increase ETCO2
Hypovolemia
Initial increase in CO then decrease in CO
Important documentation of this surgery includes?
Keeping the x clamp time
Prior to removal x clamp one should consider?
Decrease SNP and/or lightening the anesthesia
Where should Hct be kept?
Around 30
Where should PCWP be?
12-18-careful not to overdilate the myocardium.
HOTN > 4 minutes after x clamp release may be due to what problems?
Excessive anesthesia
Vasodilators still on
Myocardial dysfunction
Bleeding
What is the #1 morbidity in the post op period r/t?
Myocardial dysfunction
Spinal cord perfusion comes from what areas?
Superior: Upper thoracic/Cervical
Subclavian/Vertebral
Mid Thoracic-T2-T8
Intercostals
Thoracolumbar: T8-Conus (L1-2)
Artery of Adamkiewicz
75% T8-12
15% L1-2
What is the latest solution to traditional AAA repair?
Endovascular grafting
Selection of patients may include what characteristics for endovascular grafting?
Infrarenal aneurysms-cant do for suprarenal or long aneurysms
Abnormal mesenteric circulation
Tortuous or angled iliac or aorta
Decreased BP may be desired in the endovascular graft for what reasons?
To prevent forward flow of the graft
The reason for higher circulating levels of epi in the open procedure vs. the closed procedure is?
The NE response is activated much more
Goals of the anesthetic management of ruptured AAA include?
Immediate attempt to control proximal aorta –may require cutting prior to induction
Blood loss control
Attain BP
Preserve myocardial function
Induction/cut
How should induction occur with a ruptured AAA?
Awake-Etomidate and MR
Unconscious- MR and Scopolamine
Management of ruptured AAA?
***Primary concern is to gain control of bleeding
Monitors after induction
MR/Vasoactive drugs
Type specific non-crossed blood or O-
NO Heparin
List the branches of the aorta from superior to inferior:
Inferior phrenic- posterolateral
Celiac trunk - anterior T12
SMA - anterior L1
Suprarenal - lateral, paired L1
Renal - lateral, paired L2
Gonadal - lateral, paired L2
IMA - anterior L3
Lumbar - posterolateral
"I Can Smell Supper Real Good I'm Lucky"
Criteria for high risk in AAA repair include:
a) serum creatinine level > 3 mmg/dl
b) PaO2 50-85 mmHg
c) Age > 85 yrs
d) LVEF<30%
e) Male gender
a,c,d
PaO2 should be < 40 mmHg, gender isn't a criteria for high risk repair
Classify the following hemodynamic changes to aortic cross clamping/declamping as: increase,decrease or no change:
1.MAP with aortic clamping
2. CO with declamping
3. SVR with declamping
4. Pulmonary artery occlusion pressure with declamping
5. CO with clamping
6. Afterload with clamping
1. Increase
2. no change or increase
3. decrease
4. decrease
5. no change or decrease
6. increase
Place the following branches from the abdominal aorta in order from diaphragm to iliac bifurcation:
a) inferior phrenic arteries
b) renal arteries
c) inferior mesenteric artery
d) celiac trunk
e) superior mesenteric artery
a,d,e,b,c
Which of the following actions are appropriate when preparing for the cross clamp to come off in a AAA repair?
a) start Nipride infusion
b) add PEEP
c) restore circulating blood volume
d) have bicarb readily available
e) increase IA
c,d
SNP, PEEP and increasing agent are not appropriate actions to take when the cross clamp is coming off as these actions would decrease SVR and venous return. Declamping causes hypotension and decreased CO.
Renal failure post op can be linked to:
a) cross clamp time> 45 min
b) infrarenal cross-clamp
c) suprarenal cross-clamp
d) complete cross clamp removal vs. staged removal
c
there is an 80% decrease in RBF with a 13% occurrence of post -op failure with suprarenal clamping
Pt status just prior to pre-clamp should include:
a) hypervolemia to euvolemia to maintain adequate perfusion and blood pressure.
b) Use of mannitol and low dose Epi for optimal renal protection
c) dosage of Heparin at 200 units/kg IV
d) vasodilator dose of Nitroglycerin at 0.25 mcg/kg/min
d
Some of the initial hemodynamic changes of cross clamping can be attenuated by vasodilators given immediately before clamp placement -Nipride 0.3-0.7 mcg/kg IV over 10 min/NTG at 0.25 mcg/kg/min
There are many physiologic changes with the clamping of the aorta. Choose the best answer to manage these changes:
a) Afterload reduction (diastolic wall tension) with Nipride
b) Preload reduction (systolic wall tension) with Nipride
c) Renal protection with mannitol, fluid restriction, Lasix
d) Afterload reduction (systolic wall tension) with inhalation agents
d
Afterload reduction is a decrease in systolic wall tension and includes interventions such as Nipride, IA, amrinone, shunts and aorta-to-femoral bypass.
Physiologic changes and therapeutic management with aortic unclamping include:
a) decreased myocardial contractility, decreased pulmonary artery pressure that can be managed by decrease in IA, increase in fluid admin
b) decreased venous return, decreased cardiac output, increased myocardial contractility, managed by a decrease in vasodilators, increase in vasoconstrictors, increase in fluid admin.
c) decreased venous return, ecreased cardiac output, increased pulmonary artery pressure, managed by a decrease in inhalational anesthetics, decrease in vasodilators
c
Hemodynamic changes: decreased myocardial contractility/ arterial BP/ CVP/ venous return/ CO, increased PAP
Metabolic changes: increased total body O2 consumption/lactate/prostaglandins, activated complement and myocardial depressant factors, decreased mixed venous O2 sat/temp, metabolic acidosis
Therapeutic interventions:
decrease IA/ vasodilators, increase fluid admin/vasoconstrictors, reapply cross clamp for severe hypotension, consider mannitol and sodium bicarb