CNS Flashcards
What is the cutoff for elevated ICP
> 15
normal 5-10
elevated 15
severe > 40
CPP = MAP - ICP
CPP is constant over what MAP range?
MAP 50 - 150
CBF constant
cerebral ischemia pressures
normal = CBF 40-60cc/100g/min neuro symptoms = 20- 30 isoelectric eeg = 16 - 20 Na/K pump failure, cytotoxic edema = 10 - 12 irreversible brain damage < 10
what is cushing’s triad?
HTN
bradycardia
irregular respirations
What IV anesthestic increases CMR?
ketamine increases cerebral metabolic rate
everything else decrease CMR and CBF
what inhaled anesthetics increases CBF the most?
halothane / head
enflurane
the others don’t do it as bad
iso = des = sevo
effect of inhalational anesthetics on brain
increase CBF
decrease CMR
MAC 1 then CBF = CMR
PACO2 vs CBF curve?
linear between PaCO2 30 - 60
CBF gray matter vs white
Gray matter has increases CBF than white
hypothermia effect of CBF
CBF decreases 5-7% per deg C drop
What can you do during cardio-bypass or valve replacement
embolic risk to brain during CBP or valve change
- hypothermia –> decreases CBF
- burst suppression = isoelectric activity brain during hypoperfusion
- normal Hct 32%
- when warming maintain CPP
- arterial filters
- glucose control
spinal cord vertebral bodies
cervical 7 thoracic 12 lumbar 5 sacrum 5 coccyx 4
spinal cord nerves
cervical 8 thoracic 12 lumbar 5 sacrum 5 coccyx 1
order of nerve blockade
sympathetic/PS: C, B fibers
A-delta,
A-beta
A-alpha
What is brown sequard?
damage to half spinal cord –> paralysis and loss of proprioception to IPSILATERAL side
What is brown sequard?
damage to half spinal cord
paralysis and loss of proprioception to IPSILATERAL side
contralateral loss pain and temperature
anterior vs posterior spinal cord blood supply
1 anterior spinal artery –> ventral 2/3 spinal cord
2 posterior –> dorsal 1/3
anterior cord syndrome
loss ipsilateral motor (ventral corticospinal)
loss contralateral pain/temp (lateral spinothalamic)
largest radicular artery = artery of adamkiewicz
don’t have good collaterals from T1-T4 and first lumbar segments –> prone to ischemia during cross-clamping or vascular occlusions
what is autonomic hyperreflexia
injury at or above T6
flushing above
vasoconstriction below
Brain waves
Alpha = Awake Beta = Busy thinking Theta = GETA Delta = Deep sleeping
what contributes to increased latency?
hypothermia / hyperthermia hypotension anemia (Hct < 15%) hypoxia hypercapnea
exceptions to decreasing amplitude/ increased latency
NO2 = latency stable, decreased amplitude,
etomidate = increased latency + amplitude
ketamine = increased amplitude
opioid = no change
muscle relaxant = no change
what’s the first line therapy for organophosphate toxicity/exposure?
Pralidoxime
organophosphates = irreversible inhibition of ACh-esterase –> tons of ACh in NMJ
PNS arises from what nerves?
CN 3, 7, 9, 10 + sacral segments
What are the risk factors for Postoperative cognitive dysfunction (POCD)?
- advanced age
- lower education
- h/o CVA w/o residual impairment
bainbridge reflex
right atrial wall senses stretch –> increasing HR
see in pregnant women
herning-breuer reflex
over-inflation of lungs –> reflex prevents further inspiration
neurogenic shock
loss of sympathetic function –> cannot oppose vagal stimulation –> bradycardia
pts w/ acute spine injuries
what are important factors in level of spinal dose?
dosage
baricity
positioning
where does great radicular artery originate from?
T9-T12
blood supply to anterior spinal cord –> motor function
different names for same vessel: artery of Adamkewitz, arteria radicularis magna, great radicular artery
if anterior spinal cord syndrome –> loss of motor, pain, temperature
rank nerve fibers by sensitivity to local anesthetics
most sensitive B > A > C least
when doing an epidural, what factors increase spread?
volume
positive airway pressure
lateral/T-berg position
increased age
