Neuro

Question 0

Which part of brain is most sensitive for lack of O2:

Answer 0

• cerebellum

- hippocampus

Question 1

Brain consumption of O2:

Answer 1

• 3 to 3.8 mlO2/100g/min (50 ml/min, CMR-O2)
• 20% of total body O2 consumption
  - > 60% neuronal electrical activity
  - > 40% cellular integrity

Question 2

What is glucose uptake of the brain?

Answer 2

• 5mg/100g/min
• 90% is metabolized aerobically(CMR-O2 parallels Glc consumption normally, cave Ketons, Lac)

Question 3

What is CBF normally:

Answer 3

• 50 ml/100g/min (750ml/min, 15 - 20% of CI)
  - varies locally: 10 - 300 ml/100g/min
  • > grey matter: 80 ml/100g/min
  • > white matter: 20 ml/100g/min

Question 4

What is relationship between EEG and CBF:

Answer 4

CBF: < 25 => slowing EEG

      < 20   => iso - EEG

      < 10   => irreversible damage

Question 5

Blood-flow speed in middle cerebral artery:

Answer 5

55 cm/s

> 120 => Vasospasm/hyperemic blood flow

Question 6

What is Lindegaard ratio:

Answer 6

• speed of blood flow in middle cerebral artery / external a.carotis int.
• hyperemia
• > 3 => vasospazm

Question 7

Normal pO2 in brain tissue:

Answer 7

• 20 to 50 mmHg

Question 8

How is defined CPP (cerebral perfusion pressure):

Answer 8

• CPP = MAP - ICP (CVP when higher)
• norm: 60 - 80 mmHg
• severe TBI: 50 - 70 mmHg

Question 9

What is relationship between EEG and CPP:

Answer 9

CPP: slowing EEG

         irreversible damage

Question 10

CBF is autoregulated in range:

Answer 10

• MAP 60 - 160mmHg
• based on: - myogenic response
  - metabolic issues (tissue metabolites)

Question 11

Tension of pCO2 versus CBF:

Answer 11

• nearly linear relationship in range of pCO2 20 - 80

(1-2 ml/100g/min/mmHg)

Question 12

Tension of pO2 versus CBF:

Answer 12

• independent down to 50mmHg, then log

Question 13

Temperature versus CBF:

Answer 13

• 5 to 7% /celsius

- > 42 => neuronal cell injury

Question 14

What is ideal Hct for optimal cerebral oxygen delivery:

Answer 14

• 30%

Question 15

What usually disrupt blood-brain barrier:

Answer 15

• severe hypertension
• tumors / trauma
• strokes / sustained seizures
• infection / marked hypoxia / hypercapnia

Question 16

Volume of CSF:

Answer 16

• 150ml

Question 17

Speed of secretion of CSF:

Answer 17

• 21 ml/hr

Question 18

What decreases CSF production:

Answer 18

• diuretics
• corticosteroids
• vasoconstrictors
• isoflurane

Question 19

Cranial vault consist of:

Answer 19

• brain (80%)
• blood (12%)
• CSF (8%)

Question 20

ICP is defined:

Answer 20

• cortex / lateral ventricle CSF pressure
• norm: < 10mmHg
• in lateral position = lumbar CSF pressure

Question 21

When ICP raises the major compensatory mech.starts:

Answer 21

1. initial displacement of CSF from cranial to spinal compartment
2. increase of CSFabsorption
3. decrease in CSF production
4. decrease in total CBV (mainly venous)

Question 22

Potential sites of brain herniation:

Answer 22

• g.cinguli -> falx cerebri
• g.uncinatus -> tentorium cerebelli
• cereb.tonsills -> foramen magnum
• any area through a defect in the skull

Question 23

Effect of anesthetic agents on cerebral physiology:

Answer 23

• CMR goes down (reduced electrical activity)

- ICP and CBF up: Ketamine, Halotan and inhalation anestetic

Question 24

Effect of inhalation and intravenous anestetic on CBF:

Answer 24

• CO2 responsiveness is always preserved
• inhalation anestetic decreases cerebral autoregulation
• intravenous anestetic preserves cerebral autoregulation

Question 25

Effect of barbiturates on CBF:

Answer 25

• increased cerebral vascular rezistance => lower CBF
  => reverse steal phenomenon (increased flow to isch.areas)
• facilitate CSF absorption as well

Question 26

What happens to cerebral vasculature in ischemic areas:

Answer 26

• maximal dilatation as a result of vasomotor paralysis

Question 27

What is effect of opioids on CBF:

Answer 27

• minimal effect on CBF, CMR, ICP (provided pCO2 is stable)

Question 28

Intracranial hypertension is defined:

Answer 28

• ICP > 15 mmHg

- ICP > 30 mmHg => CBF progressively decreases -> vicious circle

Question 29

Types of cerebral edema:

Answer 29

• Vasogenic = disruption of blood-brain barrier
  (trauma, HTN, stroke, inflammation, tumours)
• Cytotoxic = metabolic insult (failure of Na-K ATPasis)
  (ischemia, hypoxia)
• Interstitial = result of obstructive hydrocephalus

Question 30

Cerebral edema - treatment:

Answer 30

• fluid restriction
• loop diuretics (start in 30 min)
• moderate hyperventilation: pCO2 30 - 33 mmHg
• mannitol -> goal: osm 300 - 315 (NOT IN HEMORRAGE)
  - dose: 0.25 - 0.5 g/kg IV

Question 31

Raccoon sign is:

Answer 31

• ecchymosis into periorbital tissues

Question 32

Battle’s sign is:

Answer 32

• ecchymosis behind the ear

Question 33

Head trauma - minimal BP systolic is:

Answer 33

• 80mmHg