38. Intracranial anesthesia

Question 1

define monroe kellie doctrine

Answer 1

cranium in noncompliantblood, CSF, brain create a state of volume equilibriumany increase in one area, decreases anotherlimited compliance in this mechanism and will eventually get overcome if volumes are too high for compensatory mx (pressure will exacerbate)

Question 2

CPP equation

Answer 2

cerebral perfusion pressure (CPP) = MAP- ICPnormal ICP should be 5-12 mm Hg

Question 3

what does cerebral blood flow depend on

Answer 3

cerebral blood flow largely depends on CPPCBF= CPP/cerebral vascular resistance

Question 4

T/Fdexmedetomidine has been shown to be neuroprotective

Answer 4

TRUEalpha 2 agonist

Question 5

T/FTobias et al Acepromazine increased the incidence of seizures in epileptic dogs

Answer 5

FALSENO evidence that acepromazine increased the risk of epileptic episodes in dogs with a history of seizures

Question 6

why is ketamine avoided as an induction agent in neuro patients

Answer 6

has sympathomimetic effects and can elevate CO and MAPwhich increases cerebral perfusion pressure and intracranial pressure

Question 7

cerebral metabolic rate for oxygen

Answer 7

brain accounts for 20% of the total body oxygen requirementincreases during pyrexia, seizure, shivering, fand certain drugs

Question 8

propofol as an induction agent for neuro patients

Answer 8

induction agent of choice–reduces cerebral metabolic rate for oxygen–rapid smooth recovery–decreases CBF and ICP–pressures cerebral autoregulatory mx–may be neuroprotectant via antioxidant properties

Question 9

other cardioprotective induction agent for neuro patients

Answer 9

etomidate–causes minimal drop in systemic BP–preserves CPP –reduces cerebral metabolic rate for oxygen–reduces CBF and ICP

Question 10

T/Fas a rule of thumb, mildly hyperventilate (dec PaCO2) in neuro patients

Answer 10

TRUEmild hyperventilation with goal etCO2 28-32 mm Hg in order to avoid increases in ICP

Question 11

check list to avoid ischemic brain injury under GA (10)

Answer 11

1. ventilation (mild hypocapnia)2. preoxygenate, oxygenate post op3. maintain normotension4. ensure adequate venous drainage from head/elevate head 30 degrees5. rule out pneumothorax 6. maintain NM blockade7. mannitol if needed for suspected incr in ICP8. low MAC for inhalants (sevo is superior–0.5 MAC)9. switch anesthesia technique if no improvement, use CRI (propofol and opioid if needed)10. barbituate CRI in protracted intracranial hypertension suspected post op