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45 Cards in this Set
- Front
- Back
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Hepatic blood supply
-% of cardiac output |
-25%
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Hepatic artery
-blood flow |
-25% liver flow
-1/2 oxygen |
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Portal vein
-blood flow |
-75% liver flow
-1/2 oxygen |
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Liver
-function |
-protein synthesis
-glucose homeostasis -Bile (bilirubin, fat metabolism) -Immune (kuppfer cells) -Drug metabolism |
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Protein synthesis by the liver is important for
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-albumin
-coagulation factors (Vitamin K related) |
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Albumin
-function |
-oncotic pressure
-drug protein binding |
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Effect of albumin on propofol
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-90% of dosed propofol bound to albumin, but free 10% causes anesthesia
-if low albumin, will get anesthesia with less dosed propofol |
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Albumin
-indicator of |
-increased risk
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Albumin
-drugs that are highly protein bound |
-opioids
-benzodiazepines -barbituates |
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How should highly protein bound drugs be dosed?
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-dose to effect
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Effect of low albumin on oncotic pressure
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-dec. oncotic pressure ---> fluid leaks out of vasculature ---> peripheral edema
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Albumin
-size |
-70,000 daltons
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Albumin
-production is regulated by: |
-peri-hepatic interstitial osmoreceptors working with hormonal control
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Surgery effect on albumin levels
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-tends to shift albumin to interstitium, which can be devastating in hepatically impaired patients
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Hepatic insufficiency
-effect on coagulation |
Leads to inability to coagulate
-decreased production -increased use (anti-thrombin) |
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Hepatic insufficiency
-effect on glucose levels |
liver normally produces glucose
-may need to supplement dextrose if hypoglycemic |
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Exaggerated drug effects of liver dogs/cats due to
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-hypoproteinemia
-decreased metabolism -increased sensitivity -altered blood flow |
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Pathways of drug metabolism
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-oxidation
-reduction -hydrolysis -conjugation |
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Effect of decreased liver metabolism on drugs
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-drug effects may be altered or prolonged
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Reasons for increased drug sensitivity in liver cats/dogs
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Unknown
Possibly: -altered blood-brain barrier -altered CNS receptor kinetics -circulating amines ***DOSE TO EFFECT |
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Altered liver blood flow through liver can be due to:
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-portal hypertension
-shunting -systemic hypotension -surgical manipulation |
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Liver Cat/Dog
-pre-op testing |
-bile acids
-profile (ALB, CHOL, GLUC, BILI, BUN) -PT, PTT, Platelets, BMBT -assess volume status because dehydration can falsely elevate albumin and PCV |
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BMBT
-how long in a normal patient |
-should clot within a few minutes
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Childs-Hugh Classification
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-bili
-alb -PT -Ascites -Encephalopathy |
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Anesthesia for a liver animal
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Cautious dosing
-premed benzodiazepine/opioid (probably won't need full dose) -induce propofol or inhalent (don't want to give a drug that may last a long time) -maintain inhalant Monitor -CVP, direct ABP, urine production |
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Kidney
-normal function |
Maintain constant extracellular environment
-water balance -electrolytes -hydrogen and nitrogen excretion -acid-base balance Target for various hormones Secretion of erythropoietin, renin, etc. |
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Renal blood supply
-% of cardiac output |
-25%
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GFR
-% of renal plasma flow |
-20%
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Ratio of urine produced to filtrate
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1 mL urine / 100 mL filtrate
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Amount of urine produced per hr
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-0.5-1.0 mL/kg/hr
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Effect of renal arterial pressure on:
-renal blood flow -GFR -urine flow rate |
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Effects of perfusion pressure and how the effect urinary output
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-hypotension: reduced glomerular hydrostatic pressure---> reduced filtration
-increased sympathetic tone: constriction of renal artery ----> flow decrease -renin release: decrease renal blood flow -hemorrhage, dehydration, hypovolemia |
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Nephrotoxicity
-typically caused by |
-anesthetics that are unavailable
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Anesthetics that could cause nephrotoxicity
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-sevoflurane
-compound a *but generally not a problem in semi-closed circuits |
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Renal patient
-typical presentations |
-Post renal issue (obstruction)
-chronic renal disease (presented for other issues) -rare to see acute renal failure come through anesthetic service |
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Renal patient
-pre-op testing |
-BUN, CR, Creatinine clearance (GFR tests)
-USG, urine osmolarity (renal tubular function tests) -Electrolytes -albumin (PLN) -hematocrit (no EPO production) |
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Hyperkalemia
-treatment |
-dextrose +/- insulin
-hyperventilation -bicarbonate (rare, don't want to be chasing pH) -electrolytes? |
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Band-aid for hyperkalemia
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Calcium
-adjusts the resting membrane threshold |
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Renal patient
-stabilization of obstruction |
-hydration status (volume replacement)
-treat hyperkalemia, hyponatremia, hypochloremia, acidosis, uremia -peritoneal fluid? |
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Renal patient
-stabilization of chronic renal disease |
-hydration status (volume replacement)
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Renal patient
-goals of anesthesia |
-maintain hydration and blood volume
-maintain renal blood flow and GFR -avoid hypotension -avoid renal vasoconstriction -avoid hypovolemia |
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Renal patient
-why is it important to treat hypovolemia early |
-don't want to get into a range where you can't autoregulate blood flow
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Renal patient
-support |
-fluids (colloids, crystalloids)
-increase cardiac output??? (dobutamine, dopamine, ephedrine) -Increase resistance???? (phenylephrine, vasopressin) |
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Renal patient
-monitoring |
-ECG (K+ concern ---> bradycardia)
-Blood pressure |
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Renal patient
-drug selection for anesthesia |
-acepromazine?
-alpha-2 not a good idea (vasoconstriction) -opioids (benign) -ketamine (exclusively removed by the kidneys of cats) vs. propofol (short lived but profound hypotension) -avoid halothane and methoxyflurane |
