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