Renal, CNS, And Hepatic Disease Flashcards
Renal blood flow is constant within a mean arterial pressure of ???
80180mmHg
-glomerular afferent arteries are dilated or constricted to maintain a constant flow
*autoregulation altered by renal insufficiency/failure
T/F: most anesthetic drugs increase GFR and RBF in a dose dependent fashion
False
DECREASE GFR and RBF
-autoregulaiton is generally maintained at light planes of inhalant anesthesia
In renal disease, what drugs should you avoid?
Anesthetic causing hypotension or requiring renal excretion (eg ketamine in cats)
NSAIDS —> decreased prostaglandin production and cause renal ischemia
How do you manage renally compromised patients pre-op?
Fluid diuretics Monitor electrolyte (potassium commonly high or low)
How do you manage renal compromised patients intra-op?
IV fluid mandatory -> usually high end of surgical rate
MAP maintained above 70-80 mmHg
T/F: feline urethral obstruction patients usually do not require general anesthesia
True
Especially if debilitated
How will you stabilize your feline urethral obstruction patient prior to surgery?
Hyperkalemia
- > Ca gluconate (cardio protective)
- > regular insulin +dextrose
Hypovolemia
-buffered isotonic IV fluids
What are the cardiovascular-sparing drugs that can be used in Feline urethral obstruction patients?
Opioids and benzos
AVOID ketamine
Cerebral blood flow is normally maintained by autoreguation at a MAP of ___________
50-150mmHg
Perfusion must be adequate to prevent hypoxia brain injury but not high causing increased ICP
Cerebral perfusion pressure =________-________
CPP = MAP - ICP
What can disrupt cerebral blood flow ?
Tumors PaCO2 PaO2 Temperature Seizure Anesthetic Blood viscosity
Does the cerebral metabolic requirement for oxygen usually increase or decreased with anesthesia?
Usually decrease
What is the cushing reflex?
Severe increase ICP—> poor cerebral perfusion AND irregular breathing pattern
Leads to sympathetic response: vasoconstriction, increased cardiac output —> hypertension
Carotid baroreceptors sense hypertension —> reflex bradycardia
What sedatives can be used in patients with CNS dysfunction?
Acepromazine -> decrease seizure threshold
Benzodiazepines —> decreased CBF and ICP, Control seizure
Opioids -> minimal effect on CPF and ICP, vomiting can increase ICP
A2 agonists —> minimal CNS effects except for antagonist (atipamezole cause increase ICP), usually not nessesary
What induction agents are used in CNS disease patients?
Propofol and barbiturates -> preferred to decrease ICP and CBF (CRI)
T/F: ketamine can be used in patients with CNS disorders
False
Increases ICP and CBF
Can neuromuscular blockers be used in patients with CNS disorders?
Non-depolarizing can
NOT succinylcholine -increase ICP
Do volatile anesthetics increase or decrease ICP and CBF?
INCREASE
Halothane has the greatest effect and is not recommended
Nitrous oxide not recommended
flip for fun fact..
Modest hyperventilation (pCO2 = 30=35) May eliminate the effects of iso and sevoflurane on CBF and ICP
What happens if you have an accidental intracartoid injection in equine?
Causes violent behavioral reaction and seizures
Treat with thiopental +/- guaifenesin
Supplemental O2 and IV fluid
Continue sedation for 30mins, usually recover uneventfully
What are clinical signs of liver disease and what do you see on biochem?
Depression, anorexia, wight loss
Icterus, ascities, abnormal behavior/mentation, seizure
DECREASED: albumin, BUN, glu, chol,
INCREASED: Tbili , ammonia, bile acids, PT/PTT
What factors in patients with hepatic disease increase anesthetic risk?
Low albumin/portal hypertension —> ascities
Decreased coag factors —> hemorrhage
Decreased gluconeogensis —> hypoglycemia
Increased ammonia and other toxins —> encephalopathy/coma
Hepatic disease has what effect on duration and action of most drugs?
Prolonged action and increased action (slower metabolism in diseased liver)
_________________ may worsen signs of hepatic encephalopathy
Benzodiazepines
