Final Thoughts Flashcards
What is organ least likely to withstand hypoxia?
Brain
What are MEP?
Motor evoked potentials
What are SSEP?
Somatosensory evoked potentials
What does EEG stand for?
Electroencephalography
What does EEG measure?
Brain ischemia
Seizure activity
Brain metabolic activity
What does MEP measure?
Motor nerve ischemia / Spinal cord ischemia
Spinal cord injury / Motor nerve injury
What does SSEP measure?
Stroke
Spinal cord injury / Sensory nerve injury
Sensory nerve ischemia / Spinal cord ischemia
When using ECoG (electrocorticogram), what is the symbol given for midline ?
z
Where are the even numbers on ECoG?
RIght side
Where are odd numbers on ECoG?
Left side
What waves are indicative of sleep?
Spindle waves
Are the waves in synchrony when you are asleep or awake?
Asleep
What frequency range is sleep?
What are those waves called?
0-7 Hz
4-7 Hz = Theta ( Light anesthesia)
0-4 Hz = Delta (Deep anesthesia)
What frequency range is quiet wakefulness?
What are those waves called?
8-12 Hz Alpha waves (resting or eyes closed)
What kind of technique does the BIS monitor use?
Averaging
What waves are indicated by a >12 Hz and what do they indicate?
Beta waves
Indicates sedation / Stage 2 excitation
What is normal cerebral blood flow?
50mL / (100 g x min)
When does EEG become abnormal?
CBF of 20-25 mL / (100 g x min)
T or F: Deep anesthesia and ischemia produce the same EEG patterns?
TRUE
How much does normal brain weigh?
1500 g or 3 lbs
Which 2 IV drugs and what 1 class of drugs can cause burst suppression on EEG?
Etomidate
Propofol
Barbiturates
When patient gets sleepier, what happens to f and what happens to amplitude?
f gets lower
Amplitude gets larger
List intracranial contents:
Brain parenchyma : 1200-1600 mL
ECF : 100 - 150 mL
Blood: 100 - 150 mL
CSF: 100 - 150 mL
What factors causes acidosis and vasodilation on cerebral vessels ultimately increasing ICP?
Increased PaCO2
Decreased Bicarb
Increased metabolic activity ( lactic , pyruvic)
What factors causes alkalosis and vasoconstriction on cerebral vessels ultimately decreasing ICP?
Decreased PaCO2
Increased Bicarb
Cerebral O2 consumption is what ?
20% of total body O2 consumption
~ 3.5 mL / 100 g / min
or ~ 50 mL / min
How much of CO is CBF?
15% of CO
What is TCD and how many MHz does the probes use?
Transcranial doppler
2- MHz probes
What kind of waveform does TCD look like?
Arterial
What does TCD look at?
Looks at middle cerebral artery perfusion
What is cerebral blood flow autoregulation range?
50 - 150 mmHg
How to calculate perfusion pressure?
PP = MAP - ICP
or MAP - CVP (if CVP is higher than ICP)
What drugs for most part increase ICP?
- Succinycholine
- Ketamine
- Nitroprusside
- Hydralazine
- Nitroglycerin
- Nicardipine ++
What drugs decrease ICP?
- Etomidate
- Mannitol
- Furosemide
- Barbiturates
- Propofol
- Benzo’s
What do the inhaled anesthetics do to ICP?
All increase (iso increases it the least)
What is only IV drug to increase CBF?
Ketamine
On the glasco coma scale, what do the numbers indicate?
- Small #’s mean more obtunded
- - Large #’s mean the better they are
What is the best most sensitive way to detect venous air embolism?
Transesophageal echocardiography
Precordial doppler
What is the standard way for ICP measuring and CSF drainage?
Ventriculostomy
What does a intracranial hemorrhage present with?
- Hypervolemic
- Hypertension
- Hemodilution
What is a homunculus?
A diminutive human being without any deformity of physiology
T or F: the motor area of the brain is slightly more frontal than the sensory area?
TRUE
Can you NMB block when doing SSEP?
Yes, NMB does not affect
What is the SSEP pathway?
What is MEP pathway?
Dorsal (posterior horns) = sensory
Ventral (anterior) horns = motor
T or F: the larger the amplitude on the evoked potential waveform, the closer (nearness) to the electrical stimulus the electrode is
TRUE
What does latency equal?
TIME
