Vascular Anesthesia Flashcards
What is the most common cause of PVD?
Atherosclerosis
Plaque/Cholesterol deposits between what 2 layers of the artery
Media (middle) and Intima (inner)
What i s Peripheral Vascular Occlusive Disease (PVD)?
Degenerative and INFLAMMATORY process involving formation of atherosclerotic plaques that obstruct the vessel lumen resulting in reduction of distal blood flow
Atherosclerosis primarily affects which vessel type?
Arteries
Major Risk Factors for PVD (development of atherosclerotic lesions)
- SMOKING **
- HTN
- DM
- Obesity
- Insulin resistance
- Age
- Family Hx / Genetic Predisposition
- Sedentary Lifestyle
8 . Male Gender - Elevated CRP
- Elevated Lipoprotein
- HLD
- Hypertriglyceridemia
- Homocysteine (high LDL, low HDL)
Symptoms of PVD
Claudication, Skin ulcerations, gangrene, impotence, warm to touch
Why are patients with PVD usually not symptomatic right away?
They develop collateral blood flow. This suffices until O2 demand is more than collateral vessels are able to meet - this leads to ischemia (pt becomes symptomatic)
Surgical options for PVD
- transluminal angioplasty - endarterectomy
- thrombectomy
- endovascular stenting,
- arterial bypass
When you encounter a patient with PVD, what should your assumption be?
assume the patient has atherosclerotic plaques EVERYWHERE - Coronary, Cerebral and Renal!)
More than 1/2 of mortality r/t PVD is result of _____
Adverse Cardiac events
Patients undergoing surgery r/t to complications of PVD should have a thorough preoperative eval by what service? If pathology is discovered, what should be the approach to management?
- Cardiology
- Approach should be aggressive to optimize cardiac function and decrease mortality
Pharmacological management of PVD includes which 3 classes of Meds?
- BBs
- Statins
- Anti-platelet
Beta blockers are recommended for PVD patients at high risk of
Myocardial ischemia and infarction
What preoperative pharmacological intervention reduces mortality tenfold in patients going for elective AAA repair
Adequate pre op beta blockade
When should BBs be started for patients having cardiac AAA repair? What is the goal?
- BBs should be started 7-10 days prior to surgery
-Goal: target heart rate 50-60bpm
For patients having non-cardiac surgery when is the latest BBs should be initiated? What are the risks?
Beta blockade started within 1 day or less prevents non-fatal MI but increases risk of: hypotension, bradycardia, stroke and death
What instructions do you give a patient who is taking BBs and is going to have vascular surgery in a few weeks?
Continue taking BBs up to day of surgery and continued postop
What are the benefits of statins for patients undergoing vascular surgery ?
Statins have cardio-protective effects: they reduce vascular inflammation, decrease
incidence of thrombogenesis, enhance nitric oxide bioavailability, stabilize atherosclerotic plaques, and lower lipid concentrations.
When should vascular surgery patients start taking statins?
30 days prior to surgery and continued through postoperative period
Statins are proven to be especially beneficial for patients undergoing which type of vascular surgery?
Endovascular Aortic aneurysm reapair (EVAR)
What is the verdict on Aspirin and vascular surgery
UNCLEAR - Periop aspirin does not prevent MI, nor does it alter risk of periop CV events–even for those taking Aspirin for prolonged period. Aspirin DOES increase risk of bleeding.
BOTTOM LINE;
Aspirin should not be administered to patients undergoing surgery
unless there is a definitive guideline-based primary or secondary prevention indicated
What instructions should
be given to patients who have been on a long-term aspirin regimen and have aspirin withheld during the periop period ?
It’s important aspirin is restarted AFTER increased risk period for bleeding has passed (8–10 days s/p surgery).
What is the correlation between a patient’s comorbidities and surgical outcomes of vascular surgery?
Preoperatively, the greater the # of comorbidities that exist, the greater the risk of morbidity and mortality during the periop period.
Monitoring for what development should be priority in vascular surgery?
Myocardial ischemia
What are the 3 main methods used to evaluate cardiac function in vascular surgery?
- Electrocardiography
- Pulmonary artery pressure (high risk; low value)
- Transesophageal echocardiography (TEE) - best way to detect ischemia
Because most all patients with PVD have some degree of systemic CV disease, it can be assumed that cerebral And coronary autoregulation _____ for patients w PVD compared to those without.
- Auto-regulation occurs within a higher range (60–140 mm Hg) for patients with PVD. Auto-regulation curve is shifted to the RGHT
- Short, sustained periods of hypotension can result in cardiac or neurologic ischemia
Why is an A-line warranted for patients undergoing vascular surgery
Direct intra-arterial BP monitoring allows for near–real-time determination of BP values; Data ascertained from an A-line (fluid volume status, acute fluctuations in BP caused by surgical intervention, and titration of vasopressor/
vasodilator meds) guides treatment decisions.
How is anesthetic technique determined for vascular surgery?
Depends on the type of surgical procedure and coexisting diseases.
NO single anesthetic technique decreases morbidity and mortality in this population
What are the goals of anesthesia in vascular surgical patients
- Maintaining HD stability
& avoiding dramatic swings in BP in order to:
- Maintain O2 delivery to
vital organs - decreasing possibility of increased myocardial O2 consumption
- decrease potential for hemorrhagic
stroke.
What Anesthesia technique can reduce morbidity and mortality in patients undergoing vascular surgery on LEs?
Regional anesthesia
For patients undergoing Aortic surgery what anesthetic technique has proven benefits
Epidural anesthesia reduces rate of MI, stroke, and respiratory failure in patients undergoing aortic surgery.
What is one consideration for patients receiving neuraxial anesthesia for vascular surgery?
Most vascular surgery patients are on anticoagulants and will receive intraop heparin…
So, neuraxial anesthesia could lead to epidural hematoma formation
Endocrine benefits of using epidural anesthesia in vascular surgery
- Inhibits surgical stress response
- Inhibits release of epi + cortisol
- Inhibits hyperglycemia
- Inhibits lymphopenia + granulocytosis
- Causes nitrogen sparing
- Blocks sympathetic tone
- Inhibits inflammatory mediator release
CV benefits of using epidural anesthesia in vascular surgery
- Decreases myocardial O2 demand + afterload
- Increases endocardial perfusion at ischemic zone
- Increases HD stability
- Decreased blood loss
- Decreases anesthetic med requirements
- Redistributes blood to LEs
Pulmonary benefits of using epidural anesthesia in vascular surgery
*Decreased effect on FVC, FEV1, and PEFR
* Decreases V/Q mismatch
* Improves AV O2 differentiation
* Decreases pulmonary postop complications
* Decreased incidence of thromboembolism
Renal benefits of using epidural anesthesia in vascular surgery
- Increases blood flow in renal cortex
- Decreases renovascular constriction
Geriatric benefits of using epidural anesthesia in vascular surgery
- Inhibits physiologic stress
- Improves postop mental status
Miscellaneous benefits of using epidural anesthesia in vascular surgery
- Allows earlier extubation, ambulation, and discharge
- Improves postoperative pain control
Why is pain control important postoperatively in patients who have had vascular surgery? What are efficacious treatments?
- Pain can greatly enhance SNS stimulation. Acute pain increases inflammatory mediators (CK, CRP, IL-6, TNF) which can lead to regional blood flow alterations, organ dysfunction, and cell death
- Postop admin of narcotics provides comfort + contributes to CV stability. Epidural opioids and local anesthetics help to reduce pain in these patients
What postop complication are vascular surgery patients at risk for developing? What can be done to prevent it?
- Venous thromboembolism (VTE)
- All methods intended to prevent DVTs should be employed during periop period.
What is LMWH used for in patients undergoing vascular surgery?
What is important to know about this regimen?
LMW heparin is frequently used to bridge time between withholding oral anticoagulants and surgery.
It is important to restart oral anticoagulant medications postoperatively
after the risk of bleeding is decreased to minimize DVT and VTE.
Increased postoperative hematocrit concentration is associated with increased 30 day mortality from what 2 post-op complications
DVT and PE
What is the best indicator of post op renal function?
pre op renal fucntion
What interventions during vascular surgery increase risk of AKI?
Cross-clamping and use of Dye
The Common carotids bifurcate into which 2 arteries?
internal and external carotid arteries
(at the level of the thyroid cartilage, home of carotid sinus)
Where do 50-80% of patients with ischemic stroke demonstrate evidence of disease?
at the carotid bifurcation
Internal carotid has ____ and goes _____
External carotid has ______ and goes ______
Carotid Sheath Contains:
Internal Carotid:
- NO branches
- Straight to the brain
External Carotid:
- branches
- goes to face
Carotid Sheath:
- Internal carotid artery,
- internal jugular vein
- Vagus nerve
- CN 9,11,12
Which 2 EKG leads detect ischemia?
Lead II and V5
Admin of epidural opioids can lead to:
post op MI, hypotension, respiratory depression
Detection of AAAs has improved d/t:
Increased screening of asymptomatic aneurysms
by noninvasive diagnostic modalities such as:
CT, MRI + US
AAAs are most common in what gender? What race? At what age?
White Males ages 50-80
What characteristics are true about women with AAAs
Women are being treated at older ages and aneurysms are usually smaller in dimeter
General Risk Factors for AAAs
- Smoking
- Older age
- Gender - male
- Family hx
- CAD
- HLD
- COPD
- Height (per 7 cm interval)
- HTN
- PVD
- Caucasian
Which Independent risk factors are thought to be causes rather than markers for development of an AAA?
Which risk factor is most highly correlated with AAA?
- Age, gender, and smoking.
- Smoking is the risk factor that is most highly
correlated with AAA.
AAAs with diameters up to _____ cm are at low risk for rupture. Risk dramatically increases when diameter of AAA reaches ______ cm.
4 cm = low rupture risk
> /= 5 cm - risk of rupture dramatically increases.
Criteria for Surgery for AAAs:
- Ruptured AAA
- Patients with AAA who are symptomatic
- AAAs w diameter of 5.5 cm or more
- 4-5 cm AAA w > 0.5 cm enlargement in <6 months
- 5 cm AAA or greater in a patient with a reasonable life expectancy.
Symptom indicative of AAA discovered on routine exam
Pulsatile abdominal mass
Minimally invasive method useful for initial diagnoses of the presence of AAA, but not highly accurate in determining the extent of the AAA
or if rupture has occurred
Ultrasound
Which method of AAA evaluation allows for a more
precise view of the aneurysm morphology, including aneurysm size, vessel wall integrity, and adjacent anatomic definition such as iliac ateries
CTA
This method has become the imaging test of choice for AAA because of its high quality resolution, rapid image acquisition, and wide availability
CTA
Why is information gained from CTA is valuable to the surgeon and interventional radiologist ?
Guides determination of initial surgical intervention (e.g., open or EVAR) and the extent of the distal and
proximal aneurysm if an endovascular stent graft is to be implanted.
Which is more indicative of increased surgical risk, chronologic or physiologic age?
Physiologic age is more indicative of
increased surgical risk
Contraindications to elective AAA repair include:
- Intractable angina pectoris
- Recent MI
- Severe pulmonary dysfunction
- Chronic renal insufficiency.
Which 3 of the following characteristics put a patient at high risk for AAA Repair:
a. Age older than 70 years
b. Gender Male
c. Cardiac Hx of Angina pectoris
d. Ventricular ectopy
a, c, and d.
Male gender places a patient at risk for developing AAA, Females are at higher risk for surgical complications during repair
Other high risk criteria includes:
Cardiac Hx
- Hx of MI
- Myocardial disease
- Q waves on ECG
- ST/T wave changes on ECG
- HTN with LVH
- Congestive heart failure
Endocrine - Diabetes
Neurologic - Stroke
Renal - Chronic or acute renal failure
Pulmonary
- COPD
- Emphysema
- Dyspnea
- Previous pulmonary surgery
AAAs expand by approximately ________
4 mm/yr.
Vessel radius is proportional to ___________
and inversely proportional to __________
wall tension/shear stress and intra-luminal pressure
wall thickness
It can be assumed that:
the. larger the aneurysm:
a. the lower the likelihood of spontaneous rupture
b. the higher the likelihood of spontaneous rupture
c. the likelihood of spontaneous rupture is not affected
d. aneurysm rupture depends on wall thickness
a. the higher the likelihood of spontaneous rupture
this is d/t the law of laplace
T = P (r)
Wall tension = Pressure (radius)
You evaluate an 84 y/o male patient w a 5 mm aneurysm that has grown 0.25 cm in the last 6 months. The patient wants to know if they should schedule surgery. You tell them:
a. Yes, call immediately to schedule
b. Yes, call whenever it’s convenient
c. No, the aneurysm is stable and likely will not continue to grow. No intervention is necessary at this time
d. Surgery is not indicated at this time but the AAA needs to be closely monitored for growth or signs of rupture.
d. Surgery is not indicated at this time but the AAA needs to be closely monitored for growth or signs of rupture.
Aneurysms measuring< 4 - 5 cm should not be considered benign, and monitoring of the condition is indicated.
An aneurysm has the potential to rupture regardless of its size. As the diameter of the aneurysm
increases in size, the risk of rupture increases.
AAAs most frequently develop in the ______. Approximately 40% of AAAs also involve the __________
infrarenal aorta
iliac arteries
What is the most common reason for poor outcomes in non-cardiac surgery for patients with vascular disease
Perioperative MI
The most important preop interventions for a patient scheduled for vascular surgery include:
a. initiation of β-Blockers and statins
b. Prophylactic coronary revascularization
c. Preoperative cardiac testing
d. Preoperative fluid loading and restoration of intravascular volume
a & d
a. initiation of β-Blockers and statins
- Optimization of myocardial oxygen supply and demand and
modification of cardiac risk factors are the major goals of
preoperative risk reduction.
d. Preoperative fluid loading and restoration of intravascular volume
- perhaps the most important techniques used to enhance
cardiac function during abdominal aortic aneurysmectomies
- Prophylactic coronary revascularization does not reduce the incidence of perioperative cardiac events and Preoperative cardiac testing is recommended only if interpretation of the results will change anesthetic management
Massive hemorrhage is an ever-present threat in vascuolar surgery so the CRNA knows to ensure ;
- Reliable venous access (must be secured for volume replacement)
- Large-bore IV and central lines can be used to infuse fluids or blood.
- Availability of blood and blood products should be ensured.
- Provisions for rapid transfusion and intraoperative blood salvage
Prior to the surgery the CRNA knows that it will be helpful to review the hospital’s:
a. Fire policy, since fire risk in vascular surgery is quite high
b. Radiation limit, since radiation exposure in vascular surgery is high
c. Massive transfusion protocol, since hemorrhage is a risk in vascular surgery
d. Dress code since the Eagles play tomorrow and the CRNA wants to where their jersey in the OR
c. Massive transfusion protocol, since hemorrhage is a risk in vascular surgery
Which is the primary intra-operative method for monitoring CV status during AAA repair.
a. Pulmonary catheter
b. A-line
c. TEE
d. CVP
c. TEE
- TEE provides a sensitive method for assessing ventricular wall motion abnormalities.
- Wall motion abnormalities also occur much sooner than electrocardiographic changes during periods of reduced coronary blood flow.
the TEE detects
changes/abnormalities in ventricular wall motion
When ____ is used to guide intra-operative hemodynamic management, patients with left ventricular diastolic dysfunction have a decreased incidence of developing congestive heart failure and A-fib
TEE
The most common abnormalities detected by intra-operative TEE include
- hypovolemia
- low ejection fraction
- RV failure
- segmental wall motion abnormalities,
- pulmonary embolus
_________ poses the greatest risk of mortality after abdominal aortic reconstruction.
Myocardial ischemia
The most dramatic physiologic change occurs with:
a. The application of an aortic cross-clamp
b. removal of the cross clamp
c. suturing
d. DLing
a. The application of an aortic cross-clamp
Which five are correct expected hemodynamic changes associated with cross clamping:
a. HTN above cross clamp
b. Hypotension below cross-clamp.
c. Decreased lvls of catecholamines, aldosterone, cortisol, prostaglandins
d. Absence of blood flow distal to cross-clamp in pelvis and LEs
e. Decrease in afterload
f. Decreased myocardial O2 demand.
g. Increased MAP
h. Increased SVR
i. CO may increase or remain unchanged.
j. Decreased pulmonary artery occlusion pressure (PAOP)
a. HTN above the cross clamp,
b. hypotension below the cross-clamp.
d. Absence of blood flow distal to the cross-clamp in the pelvis and lower extremities.
g. increased MAP
h. increased SVR
—————————-
Wron Answers:
c. plasma levels of catecholamines , aldosterone,
cortisol, prostaglandins, and other stress hormones are INCREASED
AND are associated with a SNS response.
e, f. AFTERLOAD is increased this causes the left ventricular myocardial wall tension to increase, which in turn increases myocardial O2 demand.
i. CO may DECREASE or remain unchanged.
J. Pulmonary artery occlusion pressure (PAOP) may INCREASE or remain unchanged
How is preload affected during cross clamping?
Preload does not necessarily increase with infrarenal clamping.
Depending on splanchnic vascular tone, blood volume can be shifted into the splanchnic circulation, and preload will not increase
clamping causes _____ and ____ in distal structures
Furthermore, anaerobic metabolism leads to the accumulation of serum lactate. The release of arachidonic acid derivatives may
be a contributing factor leading to cardiac instability and myocardial
depression during aortic cross-clamping. Thromboxane A2 synthesis,
which is accelerated by the application of an aortic cross-clamp, may
be responsible for the decrease in myocardial contractility and cardiac output that occurs.
hypoxia and ischemia
In response to tissue ischemia caused by cross clamping, the hypoxic tissue forms:
metabolites such as cytokines, prostaglandins, nitric oxide, and arachidonic acid which are then released into circulation
What metabolic process which occurs in hypoxic and ischemic tissues during cross clamping causes build up of lactate?
anaerobic metabolism
What leads to cardiac instability and myocardial depression during aortic cross-clamping.
The release of arachidonic acid derivatives
What process is accelerated by the application of an aortic cross-clamp, and may be responsible for the decrease in myocardial contractility and cardiac output that occurs?
Thromboxane A2 synthesis
Surgical maneuver used for exposing the aorta
Mesenteric traction
cluster of symptoms which occur in response to mesenteric traction and are known as Mesenteric traction syndrome
- Hypotension
- Decreased SVR
- Tachycardia
- Increased CO
- Facial flushing
2 severe complications related to decreased perfusion to organs distal to cross clamp include:
Renal insufficiency and ARF
AKI may occur in as many as 18% of patients undergoing aortic aneurysm repair. Preoperative evaluation of renal function is the best method
of assessing and anticipating which patients may develop postoperative
renal dysfunction. Preexisting renal impairment is common after elective infrarenal EVAR, and preoperative renal function appears to be the
main factor associated with AKI. A complete evaluation of renal function is required during the preoperative period, and patients with a low
glomerular $ltration rate should be managed with more aggressive renal
protection interventions.
Which 2 methods of cross clamping more often results in renal insufficiency?
a. Infarenal
b. Suprareanl
c. Juxtarenal
b, c
Suprarenal and juxtarenal cross-clamping are associated with a higher incidence of altered renal dynamics and can decrease renal blood flow by as much as 80%.
Infrarenal cross clamping causes _____% reduction in renal blood flow
a. 10%
b. 20%
c. 30%
d. 40%
d. Infrarenal aortic cross-clamping is associated with a 40% decrease in renal blood flow.
SUPRARENAL cross-clamp times longer than _______ increase the
risk of postoperative renal failure.
A. 15 min
b. 30 min
c. 2 hrs
d. 6 hrs
b. 30 min
Even though renal blood flow is restored after unclamping, prolonged effects associated with ischemic reperfusion injury (IRI) occur.
Injury caused to the renal tubular epithelium causes a __________ This effect may lead to acute renal failure, which is fatal in 50% to 90% of patients who have undergone aneurysmectomy.
decrease in GFR
Clamp position ____ the renal arteries is predictive of ______ in patients treated with Open surgical repair.
a. below, AKI
b. above, AKI
c. below, anuria
d. above. anuria
b. above, AKI
When Clamp position is below renal arteries for elective infrarenal EVAR, it is common for _____ to occur also
AKI
What is the main factor associated with AKI?
preoperative renal function
Which 2 decrease the incidence of AKI during aortic cross clamping?
a. crystalloid solutions
b. colloid solutions
c. hyperchloremic solutions
d. glucose containing solutions
a, c
- balanced crystalloid solutions and hyperchloremic solutions
All of the following reduce the incidence of AKI during aortic cross clamping. Which is the most important:
a. Minimizing pre op use of nephrotoxic meds (NSAIDS, aminoglycosides)
b. Aggressive hemodynamic stabilization
c. Minimization of aortic clamp time
d. Intra-operative renal perfusion with cold solution
e. Use of ANP to promotes renal vascular dilation
b, c
- Aggressive hemodynamic stabilization and Minimization of aortic clamp time
Longitudinal blood flow to the spinal cord includes ____ posterior and _____ posterolateral artery (s) which supplying blood to the DORSAL/SENSORY portion of the spinal cord and accounts for ____ of spinal cord blood. Additionally, ____ anterior spinal artery(s) supplies blood to the ANTERIOR/MOTOR portion of spinal cord and accounts for _______ of spinal cord blood.
2, 2, 20%, 80%
Transverse blood flow originating from the aorta is via ________ . Interruption of blood flow to the this artery ( the absence of collateral blood flow) has bee identified as a factor that can cause paraplegia in patients having AAA repair.
the greater radicular artery (artery of Adamkiewicz).
What explains why the presence of paraplegia with aortic cross-clamping is unpredictable?
The variation in location of origin of Adamkiewicz artery.
The great radicular artery most often originates between spinal segments _____, but it can originate as low as ___ in a small segment of
T8 and T12
L2
The incidence of neurologic complications increases as the aortic
cross-clamp is positioned ________ to the heart.
higher or more proximal
Why is SSEP monitoring limited in its ability to detect spinal cord ischemia?
a. It only reflects dorsal (sensory) spinal cord function, and does not
provide information regarding the integrity of the anterior (motor)
spinal cord.
b. It only reflects anterior (motor) spinal cord function, and does not
provide information regarding the integrity of the posterior (sensory)
spinal cord.
c. It only reflects anterior (sensory) spinal cord function, and does not
provide information regarding the integrity of the dorsal (motor)
spinal cord.
d. It only reflects dorsal (motor) spinal cord function, and does not
provide information regarding the integrity of the anterior (sensory)
spinal cord.
a. It only reflects dorsal (sensory) spinal cord function, and does not
provide information regarding the integrity of the anterior (motor)
spinal cord.
Motor-evoked potential (MEP) monitoring is capable of
determining anterior cord function so why isn’t this used?
This monitoring modality relies on intact neuromuscular functioning for analysis, which limits its use in abdominal aortic aneurysmectomies, because neuromuscular blocking drugs are routinely used.
Spinal cord protection strategies include:
a. Distal aortic perfusion
b. CSF drainage
d. Mild hypothermia
e. TOF
a, b, c
Distal aortic perfusion
CSF drainage
Mild hypothermia
Which 2 complications are assoc w manipulation of the inferior mesenteric artery?
Ischemia of the colon
Increased intra abdominal pressure
The _________ , which supplies the primary blood supply to the left colon is often sacrificed during surgery, and blood flow to the descending and sigmoid colon depends on the presence and adequacy of the ________.
The inferior mesenteric artery
Collateral vessels
When cross clamp is released…
EVERYTHING DECREASES ( EXCEPT PULMONARY ARTERY PRESSURE WHICH INCREASES)
SVR decreases –> blood is sequestered into previously dilated veins, decreasing venous returN –> Reactive hyperemia –> transient vasodilation 2/2 to the presence of tissue hypoxia; results in decreased preload and afterload.
The hemodynamic instability that may ensue after the release of an aortic cross-clamp is called:
Declamping shock syndrome.
The magnitude of the response to unclamping is largely dependent on:
The site and duration of cross-clamp application, as well as the gradual release of the clamp
To providing circulatory stability before unclamping, its imperative that ________.
circulating blood volume is restored
The magnitude and direction of change in CO in response to releasing the clamp is largely dependent on:
intravascular volume
What is a method to lessen the severity of hypotension that comes with unclamping?
Partial release of the aortic cross-clamp over time often results in less severe hypotension
The standard surgical approach for elective abdominal aortic reconstruction is ?
transperitoneal incision
Advantages of transperitoneal incision include:
- exposure of infrarenal and iliac vessels
- ability to inspect intra-abdominal organs
- rapid closure
Unfavorable consequences associated with the transperitoneal approach include
- Increased Fluid losses
- Prolonged ileus
- Postoperative incisional pain
- Pulmonary complications
The _____ is alternative to the standard transperitoneal approach is:
retroperitoneal
Advantages of retroperitoneal include:
-
Excellent exposure (especially for juxtarenal and suprarenal aneurysms and in obese patients),
- Decreased fluid losses,
- Less incisional pain
- Fewer postoperative pulmonary and intestinal complications. I
- Does not elicit mesenteric traction syndrome.
Disadvantages of the retroperitoneal approach include
Unfamiliarity of surgeons with this technique,
poor right distal renal artery exposure,
Inability to inspect the integrity of the abdominal contents
Which surgical approach does not elicit mesenteric traction syndrome?
retroperitoneal
After cross-clamping, the aneurysm is incised, and a synthetic graft is sewn ______ and _______ to the aneurysm. The aorta _____ is then re-sewn over the synthetic graft
distally and proximally
adventitia (Outer layer)
What is the cause of most blood loss during AAA repair?
Back-bleeding from the lumbar and inferior mesenteric arteries after the vessels have been clamped and the aneurysm is opened
Anticoagulation with the use of heparin also contributes to blood loss. Excessive bleeding, however, can occur at any point
during surgery, and blood replacement is often necessary during open
abdominal aortic resections.
An independent risk factor for poor outcome after cardiac surgery.
an increased number of banked red blood cell units infused .
autologous blood is preferred
_____ is the single most significant risk factor influencing long-term survivalability
CAD
____ are responsible for 40% to 70% of all fatalities that occur after aneurysm reconstruction.
MI
What is the best anesthetic technique for AAA repair?
There is no superior technique
Anesthetic selection should be based on the following objectives: providing optimum analgesia and amnesia, facilitating relaxation, maintaining hemodynamic stability, preserving renal blood floow, and minimizing morbidity and mortality
All inhalation anesthetics may depress the myocardium in a dose dependent fashion and cause hemodynamic instability. Therefore high concentrations of inhalation agents should not be used in patients with
moderate to severely decreased ejection fraction.
lower concentrations are acceptable~
high doses of pain meds (neuraxial opioids) don’t blunt SNS response so dose narcotics judiciously
Benefits of volatile agents include :
Ability to alter/blunt autonomic responses
Reversibility
Rapid emergence
Earlier extubation
Neurologic protection
Cardioprotection
What class of drugs should be used for post op pain control in patients with ischemic heart disease and ventricular dysfunction due to providing cardiovascular stability provided?
opioid (neuraxial)
The use of thoracic epidural analgesia (TEA) in patients having
coronary artery bypass surgery decreases the incidence of :
postoperative supraventricular arrhythmias and respiratory complications.
General anesthesia with TEA does not increase the risk of mortality, MI, or neurological complications compared to GA alone.
After Open aneurysm repair postoperative epidural analgesia reduces postoperative pain and pulmonary complications in patients with _______ as compared to general anesthesia alone
COPD
n summary, all the aforementioned anesthetic techniques can be
used safely and can demonstrate positive outcomes. Even more important than anesthetic selection is the clinical management of each
patient. Observation, accurate interpretation, and immediate intervention to minimize dramatic hemodynamic variability during the anesthetic process reduces morbidity and mortality to a much greater extent
than selection of a superior anesthetic technique.P
The 2 major risks associated with neuraxial anesthesia are
- Subarachnoid or epidural hemorrhage (resulting in hematoma after heparinization)
- Hypotension, which may be difficult to treat, especially during an
episode of acute blood loss.
What fluid type should be used for replacing basal and third-space losses ? What is the approximate rate of replacement?
Crystalloids @ 10 mL/kg per hr
Blood losses during abdominal aorta reconstruction can initially can be replaced with crystalloids at a ratio of:
3:1.
- A combination of crystalloid and colloid administration is also acceptable
Fluid replacement during abdominal aorta reconstruction should be sufficient to maintain normal cardiac filling pressures and cardiac output, and a urine output of at least:
1 mL/kg per hr
Mesenteric traction is associated with stimulation of which reflex? What are the 2 main S&S of activation of this reflex?
celiac
Bradycardia and hypotension
WAHT are the 3 most common complications observed postoperatively in patients recovering from abdominal
aortic reconstruction?
Cardiac, respiratory, and renal failure
POST OP Considerations for patients recovering from abdominal
aortic reconstruction?
- Continue invasive hemodynamic monitoring for 24hrs in ICU
- Treat acute blood pressure extremes, arrhythmias (atrial fibrillation)
- Assess for postoperative myocardial infarction
- Provide ventilatory management with weaning and extubation
- Assess for abdominal compartment syndrome
- Evaluate hgb, HCT, coagulation, and adequacy of volume repl.
- Assess BUN/creatinine and urine output
- Institute deep vein thrombosis prophylaxis per protocol
Juxtarenal aneurysms are located at the level of the renal arteries, but they spare
the renal artery orafice.
the magnitude of hemodynamic alterations _____ as the aorta is clamped more proximally.
increases
Paraplegia is possible when the blood supply to the spinal cord is
interrupted by aortic cross-clamping at or above the level of the _____, as is the case during supra or juxtarenal clamping
diaphragm
Ways to prevent paraplegia:
Increase spinal cord perfusion pressure by
- increasing MAP or
- decreasing CSF pressure by placing a catheter in the subarachnoid space to drain CSF
- Total body hypothermia
- multimodal neurological monitoring, including SSEPs and MEPs, can be used to decrease the incidence of paraplegia.
Neurologic deficits can become evident weeks after surgery.
What are the most common symptoms of ruptured AAAs `
triad of
- severe abdominal discomfort or back pain,
- altered level of consciousness caused by hypotension
- pulsatile abdominal mass
Other common symptoms include syncope, groin or flank pain, hematuria, and groin hernia.
Which risk factor are associated with mortality after AAA rutpture?
- Women
- Increased age
- Non-white race
- Insurance status (higher for those who self-pay or are on Medicaid in the United States)
- Comorbid conditions
- Congestive heart failure
- Renal failure
- Valvular heart disease
Which 2 factors are associated with the poorest prognosis in AAA rupture and warrant immediate transfer to the OR for surgical exploration.
Hypotension and a history of cardiac disease
Patients receiving large amounts of banked blood are at risk for which electrolyte imbalance?
What are S&S of hypocalcemia ?
Hypocalcemia =
Large amounts of citrate used as a preservative in banked blood bind calcium ions and result in relative hypocalcemia. Calcium is a positive inotrope, which is necessary for myocardial contractility.
Decreased myocardial contractility––as evidenced by
hypotension, increased left ventricular end-diastolic pressure, and
increased CVP––can be caused by hypocalcemia.
Increased bleeding can also be caused by intraoperative hypocalcemia.
Treatment of hypocalcemia includes:
calcium chloride can be administered, as guided by ionized calcium levels.
You have acitivated the MTP, your patient now is hypotensive, has increased LVEDP increased CVP - there is blood oozing from IV site. You suspect
hypocalcemia
What is the most common reason for coagulopathy to develop after massive intravenous fluid and blood administration.
The use of _______ has been shown to decrease the total transfusion requirement and the incidence of coagulopathies
- Dilutional thrombocytopenia
- FFP
During repair of ruptured AAA, ventilation may be difficult
due to surgical displacement of the diaphragm ______ . This will
decrease lung expansion and FRC and increase peak pressures.
Because positive pressure ventilation ______ venous return, hypotension can occur.
Minimizing ________ and administering higher concentrations of oxygen will help maximize venous return and maintain oxygen saturation. Manual initiation of a positive pressure breath will improve alveolar recruitment and distention.
Cephalad
decreases
PIPs
Aneurysms of the thoracic aorta may be classified with respect to
type, shape, and location.
Typically, aneurysms involving all three layers of
the arterial wall—tunica adventitia, tunica media, and tunica intima—
are considered to be _____
true aneurysms
Aneurysms that solely involve the adventitia are termed ______ aneurysms.
False
The result of a spontaneous tear within the intima that permits the flow of blood through a false passage along the longitudinal axis of the aorta
Aortic dissection
2 major classifcation schemes for aortic dissections, based on the
location.
DeBakey and Stanford classifications
Thoracoabdominal aortic aneurysms (TAAA) are classified using:
The _________ is the most emergent
the Crawford classification
Acute dissection of Descending Aorta, which occurs. in Stanford ____ and Debakey ____, can be treated more conservatively than the other types
= more conservative – treat HR/pain/BP
Stanford B
Debakey 3
Debakey ___ and ___ & Standford ___ are surgical emergencies because they inolve acute dissection ascending aorat
Debakey 1 and 2
Standford A
Stanford A involves:
Stanford B involves ______
Type A involves the ascending aorta and may extend into the aortic arch.
Type B starts at the proximal descending aorta and extends distally.
________ is the most common cause of aneurysmal pathology.
Atherosclerotic lesions occur most often in the _____ and ________
Atherosclerosis
descending
distal thoracic aorta
symptomatology of thoracic aneurysms is often related to the _____ and its compression of adjacent structures.
site of the lesion
Pain, stridor, and cough are indicative of
compression of thoracic structures from aneurysm
The patient is experiencing change in the quality of their voice, and hoarseness after thoracic AAA repair. This is from:
Impingement by the aneurysm on the left recurrent laryngeal nerve. (RLN). The left recurrent laryngeal nerve is most susceptible due to its close proximity to the aortic arch. Bilateral recurrent laryngeal nerve compression or damage can result in respiratory compromise. The Left recurrent larynx nerve bifurcates from the vagus nerve at the level of the aortic arch.
Symptoms related to aortic insufficiency may be observed in aneurysms of:
the ascending aorta
What incidental finding on conventional chest radiography is found in an asymptomatic patient indicating an aneurysm of ascending aorta?
An upper mediastinal mass
Resection of the ascending aorta and graft replacement necessitate the use of:
complete cardiopulmonary bypass or partial cardiopulmonary bypass (atrial-femoral:left atrial cannulation to a centrifugal pump, and reinfusion to a femoral artery cannula).
If extracorporeal circulation is not indicated,
heparin _________ is required prior to aortic cross-clamping.
50–100 units/kg
For complete cardiac byp
For complete cardiac bypass, total systemic heparinization with is necessary
400 units/kg
Surgical resection of lesions in the _______ compromise cerebral perfusion
transverse arch
Arterial line and pulse oximetry monitoring should occur on the ___
side for TAAA repair because impingement of the left subclavian artery, which provides blood flow to the left hand, is possible
RIGHT
The procedure for a TAAA is a _______________ and require:
- placement of a _____ ETT
- To improve the surgical operating conditions and avoid left lung contusion, ______________ is necessary.
- The patient is positioned in the _________ position,
Left-sided thoracotomy
double lumen
deflation of the left lung
left lateral decubitus
A lower thoracic incision made during a TAAA is associated with a _______ incidence of postoperative pulmonary dysfunction
decreased
What is the most common factor that contributes to the progression of the lesion to aortic dissection?
HTN
What. is the most serious complication of aortic dissection?
is aneurysm rupture
aneurysm rupture
manipulation of the _____ aorta may be associated with aortic
dissection.
ascending
The symptoms of aortic dissection are the result of:
interruption of blood supply to vital organs
Anesthesia for aneurysms of the ascending and transverse aorta
require:
cardiopulmonary bypass
Routine use of pulse oximetry may be limited if the left subclavian artery is manipulated; therefore, the right ____, _____ or ______
should be used for monitoring oxygen saturation.
A _____________ is inserted to access CSF pressure. ‘
SSEPs and/or MEPs are often used to monitor and detect neurologic dysfunction.
hand, the ear, or the nasal passages
a lumbar intrathecal catheter
Spinal cord perfusion pressure can be estimated by
calculating the arterial blood pressure minus the CSF pressure
During aortic clamping, CSF pressure _______ whereas arterial pressure _______ distal to the clamp. The spinal cord perfusion pressure can therefore be manipulated by altering ABP and draining CSF through the intrathecal catheter
increases, Decreases
The most influential interventions used to protect the spinal cord during thoracic aortic cross-clamping include:
1) routine CSF drainage (CSF pressure < 10 mm Hg),
2) endorphin receptor blockade (naloxone infusion)
3) moderate intraoperative hypothermia (< 35°C),
4) avoiding hypotension (MAP >90 mm Hg)
5) optimizing cardiac function.
Early Complications following TAAAR
- Respiratory failure (most common complication)
- Hemorrhage
- Myocardial infarction
- Congestive heart failure
- Early paraplegia
- Embolization/thrombosis
- Distal artery occlusion
- Bowel ischemia
- Sexual dysfunction
- Infection
- Renal failure
- Cerebrovascular accident
Late Complications following TAAAR
- Delayed paraplegia
- Graft thrombosis
- Fistula formation
- False aneurysm
- Graft infection
_______ is the treatment of choice for the majority of patients with an AAA.
the patient population who may benefit most from EVAR are ________ patients
EVAR
high risk
Reinterventions occur more frequently after EVAR than after
OSR, the primary reason for a secondary corrective procedure is due
to ______
interventions used to correct these complications include
endoleak
implantation of a second endograft or open repair.
Term that is used to describe the inability of the EVSG to isolate blood flow into the aneurysm sac.
it is the most likely causes of EVSG-related late aneurysm rupture
.
Endoleak
A significant risk factor for late open conversion from EVAR to open during a AA repair
3 Types. of endoleaks , type ____ is the most common
-Endoleak
-Type II is most common
-Type II endoleaks are caused by collateral retrograde perfusion and are associated with long-term complications.
-Type I and type III endoleaks are caused by device-related problems and most often occur soon after EVSG implantation.
Th 2 main reasons why EVAR has a low incidence of spinal cord ischemia and paraplegia
1) no thoracic aortic cross-clamping
2) no prolonged periods of extreme hypotension
Perioperative hypotension (MAP < ______ mm Hg) was a significant predictor of spinal cord ischemia in patients undergoing EVAR for TAA
70
Medical centers that consider EVAR for ruptured AAA repair must
have
- Immediate CT imaging capabilities,
- trained endovascular teams,
- adequate endovascular supplies
- A specially arranged surgical suite
The 2 most significant intraoperative advantages with EVAR as compared to OSR are the:
1) absence of aortic cross-clamping
2) absence of an incision that extends from the xiphoid process to the pubis.
OTHER ADVANTAGES:
decreased incidence of embolic events, decreased blood loss,
a reduced stress response, decreased incidence of renal dysfunction, and decreased postoperative discomfort.
The graft restricts blood flow to the portion of the aorta where the aneurysm exists. !is procedure is also performed for patients who have TAAs or TAAAs. Cannulation of both femoral arteries is performed.
Which type of Endoleak is most common ?
Type 2 branch leaks – think an arterial branch leaking (reverse flow) back into the aneurysm
Type 1: attachment site leaks
Type 3: graft defect (fabric tear)
Type 4: graft wall porosity/suture holes
TAA considered acute vs chronic after?
2 weeks
Anesthetic techniques that can be used for EVAR include: ______
which is the besT?
general anesthesia, neuraxial blockade, or local anesthesia with sedation
local or neuraxial better than GA
Complications associated with EAR
Graft and Deployment Complications
* Failed deployment
* Microembolization
* Migration/occlusion of major branch arteries (i.e., renal,
mesenteric)
* Aortic perforation/aneurysm rupture
* Aortic dissection
* Hematoma formation
* Endoleak
* Stenosis/kink/thrombosis
* Graft tear
* Damage to access arteries (femoral → iliac)
* Infection
Radiologic Implications
* Radiation exposure
* Allergy to contrast dye
* Renal insufficiency from contrast dye
Systemic Complications
* Neurologic (CVA, paraplegia)
* Cardiac morbidity/mortality
* Pulmonary insufficiency
* Renal insufficiency
* Postimplantation syndrome
Complications associated with EAR
1,
6, 12, and 18 months postoperatively, and then annually.165 Additionally, abdominal x-rays should be obtained on a regular basis. Lifelong
radiographic evaluation and surveillance is necessary to monitor aneurysm size, graft migration, and endoleak. Intensive follow-up care, the
need for reinterventions, and the cost of the endograft make EVAR
more expensive than open repair.166
