Vascular Basic Overview & Aortic Cross Clamping Flashcards
What are the 3 layers of an artery?
-Tunica Intima: Smooth endothelial layer. Endothelium that lines the lumen of all vessels
-Tunica Media: Muscular middle portion. Smooth muscle cells and elastic fibers
-Tunica Adventitia: Outer layer; connective. Collagen fibers.
How does vascular disease occur?
Arterial supply of oxygen and nutrients to the tissues is compromised:
-Ischemia
-Necrosis
What is the most common cause of occlusive disease in the arteries of the lower extremities?
Atherosclerosis is the most common cause of occlusive disease in the arteries of the lower extremities.
-Occlusive disease can also be due to Embolism, aneurysm, thrombosis, or trauma
Describe the etiology of peripheral vascular disease
Hypertension, hemodynamic stresses (HF, etc), toxins in cigarette smoke, and/or increased LDL cholesterol all damage the endothelium (inner, sensitive layer of vasculature).
-End up with collagen synthesis and the formation of foam cells.
-Leads to the creation of atherosclerosis.
How does Atherosclerosis occur?
Normal homeostatic functions of the endothelium are altered.
Inflammatory response:
-Damage of the endothelium
-Chronic inflammation
Injury/damage of some kind leads to macrophages entering the Media (middle), leading to development of foam cells and plaque.
Chronic inflammation implicated in disease process:
-C-reactive protein = substance released by body’s tissues in response to inflammation
What are the stages of Atherosclerosis?
1) Healthy
2) Fatty streak (lipids & foam cell in the MIDDLE Layer)
3) Fibrofatty plaque
4) Complicated plaques (thrombus or calcification can occur, leading to occlusion)
Thrombus can lead to acute ischemia.
All of these things can lead to a weakening of the arterial wall, causing aneurysm formation.
Where can atherosclerosis occur?
In basically any artery.
-Femoral, tibial, etc.
-Coronary, cerebral, or renal arteries
Mortality r/t PVD is usually due to adverse cardiac events (MI)
What are risk factors for development of Atherosclerosis?
-Smoking
-HTN
-Insulin resistance
-DM
-Ischemic Heart Disease
-Altered serum lipids
-Obesity
-Family history (genetic predisposition)
-Sedentary lifestyle
-Advancing age
-Co-Existing CAD
Non-modifiable:
-Genetics
-Gender (Male > Female)
-Menopause
What are S/Sx of Peripheral Vascular Disease (PVD)?
-5 ‘Ps’: Pain, pulselessness, paralysis, paresthesia, pallor
-Skin ulcerations
-Gangrene
-Intermittent claudication (Calf pain, usually due to Superficial femoral artery occlusion)
-Subcutaneous atrophy
-Hair loss
-Cool, dusky extremities
-Sexual dysfunction
How do you diagnose PVD?
1) Doppler ultrasound:
-Finds stenotic lesions w/in arteries
2) Duplex ultrasound scan:
-Finds plaque and abnormal blood flow (measures FLOW)
3) Transcutaneous oximetry:
-Transcutaneous oxygen tension decreases in ischemic limbs (will see less O2 sat on ischemic limbs)
What are the treatment goals for PVD?
-Restoration of normal perfusion to the affected limb or organ
-Improved functional status
-Prevent death and disability
What is involved in medical treatment for PVD?
1) Cessation of smoking
2) Dyslipidemia Tx: Statins and Diet
3) Anti-Platelet Therapy: to prevent them from forming a thrombus when plaque is present
4) Control of DM
5) Correct or improve poor pump function (Tx HF if they have it to stop endothelial damage from low blood flow)
6) Exercise training programs
7) Anti-hypertensive therapy
8) Anti-oxidants
What are the surgical treatments for PVD?
1) Revascularization: (uses a graft to bypass atherosclerosis plaque)
-Endovascular procedures (Percutaneous angioplasty or stent placement)
-Thrombectomy
-Embolectomy
-Surgical reconstruction
-Bypass (ex: Fem-Pop bypass)
2) Amputation (Worst case scenario if unable to revascularize and tissue is gangrenous)
What is Percutaneous Transluminal Angioplasty (PTA)?
-The most common treatment for PVD
-Endovascular procedure
-A catheter with a balloon is placed in the occluded area.
-Balloon is inflated to open up the blood vessel by smushing away the foam cells, fatty deposits, etc.
-Restores blood flow
-Stent is often placed.
Describe anesthetic management of an Endovascular procedure for PVD.
-Role of Percutaneous Technique (Fluoro and contrast are used). Not as stimulating (femoral stick)
-Regional is beneficial due to significant comorbidities in these patients. High risk for MI or stroke if atherosclerosis is also in coronary or cerebral vessels.
-General is used for larger cases or if going into the abdomen for aortic work
-Need plenty of IV access (lots of fluid/blood replacement)
-Arterial line (comorbidities)
-Will give heparin to prevent thrombosis of catheter and reverse with protamine
-Emergence -> PACU
Describe an Open Surgical thrombectomy/embolectomy
May have to do Open instead of endovascular if the disease is very severe.
-Incision is made
-Heparin is given
-Artery is isolated and arteriotomy is performed.
-Clamp artery, remove debris
-Balloon is used to ensure clog is cleared
-Once blood shoots out, obstruction is cleared.
Where can you perform bypass procedures?
Can do a bypass pretty much anywhere.
-Lower extremities: Aorta-bifemoral, Aorto-iliac, Fem-popliteal, etc.
-Upper extremities: Axillo-bifemoral bypass
Named by proximal to distal
-Most proximal thing you’ll ever bypass to is the Aorta. Larger surgeries.
What is an Aorto-Bifemoral Bypass?
Bypassing from the aorta to bilateral femoral arteries.
-A larger surgery. Have to open abdomen
-Both a vascular and an abdominal case
-Evaporative losses more of an issue. Requires arterial line
-Cross clamp will be applied
-ICU post-op
Describe the pre-op evaluation of a patient with PVD.
-History
-Physical exam
-EKG
-CXR
-Labs
-Exercise tolerance
-Invasive testing
Why do patients with PVD always need a Cardiac Consult pre-op?
Myocardial dysfunction is the single most important cause of morbidity following vascular surgery!!!!!
-Whether they know it or not, they have underlying CAD
-Myocardial dysfunction occurs intra-op and post-op.
What are the different options for Anesthesia for the patient with PVD?
-GA
-Epidural or RA (good for smaller or peripheral cases)
-GA + RA: Good for larger cases that you have to paralyze. Can do thoracic epidural for post-op pain control.
What are advantages to Epidural Anesthesia for PVD?
-Excellent surgical exposure
-Excellent muscle relaxation
-Potential for decrease in myocardial ischemia (by avoiding GA)
-Great post-op pain control
-Decreased blood loss
-Vaso-dilated extremity
What are disadvantages associated with Epidural Anesthesia for PVD?
-Use of heparin and risk of epidural hematoma
-Inability to evaluate patient’s sensory and motor function post-op
-Hypotension
-As the block “wears off”, the patient may not receive adequate pain control, which may trigger myocardial ischemia
What are advantages to using GA for a patient with PVD?
-Removes any controversy over using regional anesthesia in a patient with drug induced anticoagulation.
-Control of the airway, and the patient, for what may be a long case.
When would you need invasive monitoring for a patient with PVD?
-The patient’s pre-op condition and evaluation will determine the extent of invasive monitoring
-The location of the surgery, and the need to place an aortic cross clamp, will further determine the extent of invasive monitoring (Anytime you’re doing stuff to the aorta will need a central line and invasive monitoring)
-Always do arterial line due to frequency of labs being drawn
What is an aneurysm?
Intimal damage secondary to disease, congenital defect, or physical damage that causes weakening of the media of the arterial wall.
-Arterial wall expands, forming a sac
-Organs and tissue distal to the aneurysm are compromised due to clotting and decreased blood flow.
