Vascular PP2a Flashcards
anatomy of arteries for lower extremity
pathway from the aorta down
aorta - iliacs - femoral - popliteal - tibial and peroneal
when your pt has PAD, what other dzs do they probably have
why are they needed bypass sxg (symptoms).
what are they patients at high risk for
what is often a first sign
CAD, CVD
intermittment claudication, cold leg ischemia, intermittent pain
at high risk for CV events
first sign is often intermittent claudication
what is the difference between direct reconstruction and extra anatomic reconstruction
direct: aorta - fem, fem - pop, fem - tib. these procedures have higher mortality but better long term patency
extra anatomic: fem -fem, ax - fem. these have less mortality but but worse patency long term. sicker patients often get these procedures
what are some risk factors for PAD
smoker, dm, HTN, HLD, diabetes, chronic inflammation, renal insufficiency, hypercoaguable, male, nonwhite
what is the cheapest way to test for PAD
ankle brachial index. <.9 is abnormal
if the patient has CAD, step to see if they are ready for surgery
- urgency 2. ACS 3. MACE 4. METS >4 5. Stress test 6. are these tests s going to change whether we do surgery or not
what are some indicators for acute ischemia pathology (3)
timing on surgery
types of procedures
thombus or emboli
cold leg ischemia, loss of pulses
best to get surgery within 4-6 hours
angiography, stent, bypass
chronic ischemia indication
why is this occuring
when is surgery indicated
gangrene, pain at rest, intermittent claudication, ulcers
patho: progressive narrowing of the vessesl
SBi < .9, severe pain, disabling claudication, critical limb ischemia
how do we run the ankle brachial index
ankle SBP/arm SBP
normal is 1.0 - 1.4. <.9 is abnormal
take 2 readings and average
fem-pop procedure
discuss
tolerated better than Aox, bc dont need to clamp aorta
expose areas that will be receiving the graph, clamp fem. can use saphenous as graft
fever hemodynamic hcanges when not clamping aorta. give heparin
confirm flow
why are aorta femoral bypasses tolerated better than aneuysm disease
bc they have time to build up collaterals which will help devert blood flow during clamping
aneurysm repairs typically wont have collaterals built up yet
extra anatomic bypass: fem-fem or ax-fem
which patients get this surgery
patency of graft after 5 years
do you need to clamp AOX with ax-fem?
when is the most stimulating part, how can we help
where is place the A line: which side and proximal or distal
reserved for the higher risk patients
patecy is less at 5 eyars compared to direct repair
ax-fem dont need to cross clamp aorta
tunneling is most stimualting so paralyze
a line is placed opposite side of ax-fem and proximal to clamp
anesthetic management during lower extrm vascular surgery
premeds ti ake
invasive lines
labs to follow
what is an emergency surgery, what (5) things we need to consider
BB, statin, aspiring(way the risks for bleeding)
A line yes, +- CVP or PA depending on PHTN and RV failure
bmp, cbc, coags, TEG
fasciotomy, myoglobenimua, hyperK, ekg ischmic changes, coag status
Regional of GA with lower extrem vascular surgery
when its contrainidication
aid with CVD
aid with graft healing
type of regional placement
pt refuses or when coagulopathic
no differences show w CV when chossing GA or regional
RA is superior for decerased bleeding and increase in blood flow to surgical area, promoting healing to graft site
lumar epidural
what are reasons (4) that GA is worse for graft healing than regional
- Regional provides greater blood flow to the site
- fibrinolytics are decreased GA
- GA is more hypercoagulable
- epi and noepi are released higher w GA
when managing the graft intraop what are some considerations
T10 block with regional
try not use pressors to perfuse the newly placed graft
maintain blood flow and blood pressure to the anastamotic site.
keep warm
frequent pulse checks with doppler
Bypass: postop considerations (5)
prevent anemia
prevent hypotension and give adequate fluids to perfuse the site
high risk MI, check for ST elevation changes
control HR and afterload reduction
discuss the anatomy of the lower extremity and the spine
T12 suprarenal
L1 infrarenal, SMA
L3: IMA inferior mesenteric artery
L5: Iliac
t8-t12 is artery of adomkowit
are most aneuysms repairs suprarenal or infrrenal
85% are infrarenal
for arterial aneurysms, where do most occur thoracic or abdominal
where are most thoracic aneuysms
how are AAA classififed
abdominal, 9x more than thoracic
thoracic 40% ascending 35% descending
supra, 85%infra, juxta
what is the patho of aneursysm
what is most important predictor of rupture and mortality
what is the law of laplace
the connective tissue of the medial layer weakens. from inflammation and immune responses
a weakened wall
law of laplace = wall stress = (pressure x x2radius)/ wall thickness
size of the aneurysm
size of aneurysms and when they need to be fixed
AAA
descending AA
AAA >5.5cm
DAA > 6.5cm
patho of aortic dissection
acute vs chronic
where do most AAA occur
symptoms (3)
DAA death, why?
tear in the intimal layer creating a false lumen
acute <14 days
chronic > 14 days
most occur in the asending region
cardiac tampondae, aortic regur, MI
death from acute DAA because not feeding organs: spleen, liver, bowels, stomach
changes you will see during clamping, things to worry about OVERVIEW
duration, location of clamping. suprarenal above L1 hypertension, decrease of blood flow to spinal cord, bowels, kidneys, spleen. will see hemodyanmic and metabolic changes
if below L1, spleen and visceral organs can take 800cc blood, better tolerated and wont see hypertension. visceral organs get blood flow
what are (5) important things to talk about the aortic clamping
- Location
- Duration
- volume status
- does patient have collarterals
- CAD, temp, anesthetics agents used
hemodynamic changes with clamping aorta
supra and infrarenral
infra: 10% increase MAP
supra: 50% increase MAP, no big changes to HR
supra: will see increase in preload, increase in CVP, increase in CO, may see LV wall abnormalities from the increase in blood flow
infra: splianic organs can take 800 CC of blood, less changes in preload and MAP
how to aid in hemodynamic changes with aortic clamping
want to keep supply and demand in balance. Esmolol can help keeping HR 60-65
afterload reduction (5): nicardipine 200mg, increase VG, milrinone 50mcg/kg, nitroprusside, .5mcg/kg before clamping, shunt
preload reduction (2): NTG 50mcg, thoracic epidural
make sure we are maintaining cardiac output
what metabolic changes are seen with Aortic cross clamping (5)
decrease o2 consumption
decrease o2 extraction
decrease C02 production
increase SVO2
with no changes will see respiratory alkylosis
changes when unclamping depend on what (4) things
duration, level of clamping, coume status, was bypass used
hemodynamic changes occur when unclamping
decrease (4) increase (1)
SVR will drop 80%, decrease in preload, decrease in CVP, decrease in CO
there is an increase PAP from inflammatory mediators causing an increase in PVR
what are the metabolic changes that occur with unclamping
increase in o2 consumption
increase in 02 extraction
increase in co2 production
decrease in mixed venous oxygenation
what are some therapeutic intervention during unclamping
BP meds: (5)
interventions
what if lots of bleeding
help with blood pressure
preload with fluids before unclamping
phenylepherine and levophed ready
can give 500mg CaCl
10mcg epi
release the clamp slowly
clamp needs to be reapplied
AAA anesthestic management
where is place the A line, CVP
when to use a PA cath
how much blood
what else for bleeding
help with spinal cord perfusion
BP meds
A LINE and CVP need to placed proximal to clamp to work
PA cath if EF less than 30% RV failure or PHTN
4-6 units
colloids, cell save ready
have a thoracic epidural or lumbar drain placed
esmolol, NTG, nicardipine, norepi, epi, CaCl
when repairing a AAA, what will determine if the patient goes to the ICU
clamp time longer than 30 min
large blood loss and
pulmonary edema from inflammatory mediator release
AAA induction goals
regional
emergence
will the patient go to the ICU?
smooth, no voughing or bucking, prevent hypotension
can do a thoracic or lumbar block
normal hemocyanamics smooth, keep warm
icuL if clamp time great than 30min, large blood loss, pulm edema
what are some potential complications that can occur during aortic surgery
which organs
bleeding, hypotension, decreased perfusion to kidney, bowels, spine leading to paraplegia, infection, pulmonary issues, MI from supply demand issues
aortic cross clamping and renal function
where does flow preferentially go to, where is most vuneranble
how to prevent renal damage
what is the best predictor of postop renal success
what is not a good indictor of renal postop success
injury depends on clamp time and location of clamp
flow goes to cortical structures and juxtamedullary layers
renal medulla is the most vunerable
no spefic way to prevent damage,
HYDRATION
best predictor: what was their preop renal status
urine volume is not a good indicator
what are some contributing factors to renal dysfunction postop
atherosclerosis, emoboli, hypotension, clamp time, clamp location, needing pressors, 5 units of PRBCs, trauma to renal arteries, nephrotoxic drugs, rhabdomylosis
what are some ways we can help prevent renal dysfunction
keep hydrated, no hypotension, dont give blood if you dont need to, can cool kidneys down to 4 celcius
