Systems Review 2: CNS, ENT, Orthopedics, Obstetrics

Question 1

Percentage of Brain, Blood and CSF?

Normal ICP?

Answer 1

Brain 80%
Blood 12%
CSF 8%

Normal ICP: <15 mmHg (Pressure in brain is too much for blood flow from heart)

Question 2

Avg. adult brain weighs _____g

O2 consumption is 20% of total body consumption, or ______ml/g/min

Answer 2

1400g (2% of body weight)

3. 3ml/100g/min
   - 50ml/min total

Question 3

Normal cerebral blood flow?

Answer 3

Normal: 50 ml/100 Gm/min

15% of cardiac output

Question 4

As long as the cerebral pressure stays within ___-___mmHg, then autoregulation maintains pressure in the brain

Answer 4

50-150 mmHg (60-160)

Question 5

A reduction in cerebral perfusion pressure too low can cause ___________.

Answer 5

Cerebral ischemia

Question 6

For every 1 mm Hg decrease in pCO2, CBF decreases by ___________.

Answer 6

1-2 mL/100g/min

Question 7

Elevate head
Hyperventilate
PaCO2 25-30 mmHg probably best
<20 mmHg: too much vasoconstriction with risk of cerebral ischemia
Drain CSF
Osmotic diuretics
Steroids
Barbiturates, Propofol
-Decreases metabolic rate of the brain

Question 8

Nitrous oxide leads to ________ CBF and CMRO2

Answer 8

increased

Question 9

All volatile agents decrease CMRO₂, and increase CBF and ICP, rank them from highest to lowest

Answer 9

Halothane > Desflurane > Isoflurane > Sevoflurane

Question 10

IV anesthetics ___________ CBF and CMRO₂, exception is ketamine

Answer 10

decrease

Question 11

Benzos _________ CMRO₂

Answer 11

reduce

Question 12

N2O may cause tension _____________

Answer 12

pneumocephalus

Question 13

Intraoperative considerations for ENT surgeries

Answer 13

Blood loss can be hidden in oropharynx, stomach - consider using vasoconstrictor (cocaine) or local anesthetic with epinephrine

Slight hypotension

Question 14

Common nasal and sinus pathologies

Answer 14

Polyps, deviated septum or infections

Question 15

Bone Cement (methyl methacrylate) physiological effects

Answer 15

Hypersensitivity/anaphylactic reaction to the acrylic monomer

Reflex bradycardia

Toxic effects of the monomer:

• May produce hypotension when absorbed into the circulatory system
• May enhance the depressant cardiovascular effect of volatile halogenated anesthetic agents

Question 16

Neurapraxia

Answer 16

a temporary loss of motor and sensory function due to blockage of nerve conduction, usually lasting an average of six to eight weeks before full recovery

Question 17

A fat embolism may manifest as

Answer 17

decreased ETCO2, decrease SpO2, increased PAP, ST changes, or Rt. heart strain

Question 18

SSEP

Answer 18

Somatosensory evoked potential (SSEP’s)

Question 19

What prevents venal caval compression?

Answer 19

Left uterine displacement, puts a wedge under their hip to prevent this

Question 20

Side effects of pitocin

Answer 20

excessive contraction of the uterus

maternal nausea and bradycardia

uterine rupture

water intoxication

anaphylaxis