Vascular Anesthesia Pt.2 (Exam II) Flashcards
How much of CO (at rest) goes to the liver?
25%
What major vessels supply oxygenated blood to the liver? What percentage is provided by each?
Hepatic Artery: 30%
Portal Vein: 70%
What type of cells make up 75 - 80% of the liver’s cellular volume?
Hepatocytes
What is the functional unit of the liver?
Hepatic Lobule
What three structures make up the portal triad?
- Portal vein
- Hepatic artery
- Bile Duct
In what zone does aerobic metabolism take place in the hepatic lobules?
- Zone 1 — Periportal (outermost)
What zone of the liver is the major site of aerobic metabolism?
Zone 1
What vascular structure is hepatic zone 3 located next to?
Hepatic Vein
What hepatic zone is the site of glycolysis/glucuronidation?
Zone 3
What hepatic zone is most susceptible to ischemia?
Zone 3
What type of hepatic cells are characterized by their dormancy and only responding to cytokines during inflammatory periods?
Hepatic Stellate Cells
8 - 10 % of liver cells.
How would compensated cirrhosis compare to uncompensated cirrhosis?
Compensated:
- No portal HTN
- No GI Varices
- No Liver dysfunction
Uncompensated:
- Ascites
- Portal HTN
- Varices & hemorrhage
- Hepatic Encephalopathy
How does the body attempt to compensate for portal hypertension? What is the end result?
Release of NO & angiogenic factors → Vasodilation & new vessels → esophageal varices.
Which two veins receive much increase venous flow due to portal hypertension?
- Azygos vein
- Hemiazygos vein
Contribute to esophageal varices.
Where are the azygos & hemiazygos veins located? What areas do they receive venous flow from?
- Located on either side of vertebral column
- Drain & thoracic & abdominal walls
How can esophageal varices bleeds be prevented?
- non-selective β blocker
- Endoscopic band ligation
How is active bleeding of esophageal varices managed?
- Endoscopic banding
- Sclerotherapy
- Octreotide (Somatostatin)
How does Somatostatin treat variceal bleeding?
- Vasoconstriction
- ↓ portal HTN
- Inhibits glucagon release
What does glucagon do to abdominal vessels?
Glucagon = Splachnic dilation
What is a TIPS?
Transjugular Intrahepatic Portosystemic Shunt
What two vessels are connected via TIPS to control portal HTN?
Hepatic Vein & Portal Vein
What are indications for TIPS procedure?
- Secondary prophylaxis of bleeding varices after medical therapy
- Temporary relief of portal HTN while awaiting transplantation
- Treatment of refractory ascites
What are “cons” associated with TIPS procedures?
- Shunt stenosis
- Hepatic encephalopathy
- High cost
- Lack of availability
- Liver waste products (like ammonia) circulate more throughout the body.
What pulmonary volume is decreased in ascites patients?
FRC
What occurs with the following in liver patients:
- Volume of distribution (VD)
- Protein Binding
- Drug Metabolism
- Drug Elimination
- ↑ Volume of distribution (VD)
- ↓ Protein Binding
- ↓ Drug Metabolism
- ↓ Drug Elimination
What is pleuritic chest pain?
Pain when breathing/coughing
What EKG changes are suspicious for pulmonary embolism?
- ST Changes
- A-fib
- ↑HR
- RBBB
What TEE findings are suggestive of Pulmonary embolism?
- Mcconnell’s Sign
- Dilated Right heart
- LV wall abnormalities
What laboratory findings are suspicious for pulmonary embolism?
- D-dimer
- Troponins
What does D-dimer measure?
Fibrin degradation products
What is the gold standard for pulmonary embolism diagnosis?
Pulmonary Angiogram
Spiral CT and VQ studies are used for pulmonary embolism diagnosis. What are the “pros” and “cons” of these two diagnostic methods?
Pros:
- Detects clots in main, lobar, and segmental arteries well
Cons:
- Misses embolism in small vessels.
Increased risk of what occurs the longer an IVC filter is left in place?
Fracture and/or migration
What patient population might benefit most from IVC filters? Why?
Parturients:
- Higher risk of clots
- Warfarin is teratogenic
- IVC dilates during pregnancy
Where does carotid atherosclerosis most often occur?
At the common carotid at the bifurcation into the IC & EC.
What are typical symptoms of carotid disease?
- Asymptomatic Bruit
- TIA symptoms
What are some typical symptoms associated with TIA’s?
- Transient blindness
- Paresthesias
- Speech issues
- Clumsiness
How is carotid atherosclerosis diagnosed?
Duplex Scan
- Doppler flow w/ anatomic imaging
How are TIA’s and strokes differentiated?
TIA’s resolved within 24 - 48 hours.
s/s lasting beyond this = strokes
What two factors would be indications for carotid stenting (as opposed to surgical intervention)?
Stenting indicated if:
- Contralateral laryngeal palsy
- Poor surgical candidate (CHF, advanced COPD, etc.)
A patient is unable to take clopidogrel in addition to their ASA. Is a Carotid stent or CEA a better option?
CEA
Carotid Stenting requires Dual (ASA + Plavix) Antiplatelet therapy
Manipulation of the carotid sinus can result in what?
Baroreceptor reflex
What is the baroreceptor reflex?
Sudden ↓HR and ↓BP due to carotid sinus manipulation
How is baroreceptor reflex treated?
- Cessation of manipulation
- Lidocaine infiltration
- Glycopyrrolate
What regional anesthetic option is available for a CEA?
Cervical Plexus C2-C4 Block
Where does innervation to most neck muscles come from?
Anterior rami of C1 - C4
Differentiate a superficial vs a deep cervical plexus block.
Superficial:
- Sensory block only
- Difficult to assess depth
Deep:
- Sensory & motor
- Can affect phrenic nerve
- Toxic levels of LA
What will be necessary if the phrenic nerve is affected by a deep cervical plexus block?
GETA
Hyperperfusion syndrome can occur after what common vascular surgery?
CEA
What is Hyperperfusion syndrome?
Abrupt increase in blood flow that results in loss of autoregulation
What are the s/s of hyperperfusion syndrome?
- HA (more common)
- Seizure
- Cerebral edema
Hyperperfusion is more common in patients who…
Had contralateral CEA surgery
Differentiate unilateral vs bilateral recurrent laryngeal nerve injury.
Unilateral:
- Coughing
- Hoarseness
Bilateral:
- Life threatening obstruction
