Anesthesia

Question 1

Define general anesthesia.

Answer 1

CNS depressant characterized by its ability to cause loss of consciousness, loss of sensation and adequate muscle relaxation.

Question 2

What are the stages of GA?

Answer 2

4 stages:

1. Stage of analgesia or induction
2. Stage of excitement and delirium with dilated reactive pupil
3. Stage of surgical anesthesia with normal pupil
4. Stage of medullary paralysis with dilated nonreactive pupil.

Question 3

How does N2O and ketamine induce GA?

Answer 3

By decreasing NMDA receptors of glutamate.

Question 4

How is chloroform different from other anesthetics?

Answer 4

It stops respiration with circulation while most anesthetics stop respiration before circulation.

Question 5

What does the onset of a GA depend on?

Answer 5

Solubility in blood or blood/gas partition coefficient. The less soluble, the more rapid its induction and recovery. Examples: N2O has low solubility hence its rapid onset. While methoxyflurane has high solubility hence its delayed onset.

Question 6

Mention 2 benefits of halothane.

Answer 6

It has bronchodilator action so useful in bronchial asthma, it causes controlled hypotension so provides a bloodless field of work.

Question 7

What are the disadvantages of halothane?

Answer 7

Weak muscle relaxant and weak analgesic
Cardiotoxic
Hepatotoxic
Causes malignant hyperthermia 
Uterine relaxant.

Question 8

Mention an advantage of N2O in labor.

Answer 8

Good analgesic in labor.

Question 9

What’s diffusion hypoxia? What causes it? And how to overcome it?

Answer 9

It occurs during recovery from N2O due to diffusion of N2O which is poorly soluble in blood which decreases O2 conc. In alveoli causing hypoxia.
N2O causes it.
It can be overcome by giving oxygen during recovery.

Question 10

What are the disadvantages of N2O?

Answer 10

Weak anesthetic
Weak skeletal muscle relaxant
Diffusion hypoxia 
Megaloblastic anemia
Teratogenicity

Question 11

What’s the difference between methoxyflurane and other fluranes.

Answer 11

Methoxyflurane is cardiotoxic and nephrotoxic while other fluranes are less or not cardiotoxic.

Question 12

What’s the relation between oil/gas partition coefficient and MAC?

Answer 12

The higher the o/g partition coefficient the lower the MAC, which means the more potent the anesthetic is.

Question 13

Methohexital is preferred sometimes.

Answer 13

Because it has little effect on blood pressure.

Question 14

Thiopental should never be mixed with succinylcholine. Yes or No?

Answer 14

Yes because it’s highly alkaline and succinylcholine is acidic.

Question 15

What causes dissociative anesthesia?

Answer 15

Ketamine.

Question 16

What increases all pressures and is contraindicated in glaucoma?

Answer 16

Ketamine.

Question 17

What causes emergence phenomenon?

Answer 17

Ketamine.

Question 18

Which anesthetic has antiemetic effect?

Answer 18

Propofol

Question 19

Which anesthetic is given only to patients with coronary or CVS disease?

Answer 19

Etomidate.

Question 20

What anesthetic causes adrencortical suppression?

Answer 20

Etomidate.

Question 21

What anesthetic has selective alpha2 agonist effect?

Answer 21

Dexmedetomidine.

Question 22

What’s used instead of atropine and gallamine in thyrotoxic patients?

Answer 22

Hyoscine instead of atropine

Curare instead of gallamine.

Question 23

Which LA useful only by injection?

Answer 23

Procaine

Question 24

How are esters metabolized? And what’s the exception?

Answer 24

By plasma pseudocholine esterase. Except cocaine which is metabolized by HME.

Question 25

What’s the sequence in which nerve fibers are affected by LA?

Answer 25

Sensory, cold, touch, pressure then motor.

And unmyelinated before myelinated.

Question 26

Inflammation decreases the action of LA. Why?

Answer 26

Because it causes acidosis which decreases the action of LA.

Question 27

Calcium antagonizes the action of LA while Potassium enhances it. Yes or No?

Answer 27

Yes.

Question 28

What anesthetic causes methemoglobinemia?

Answer 28

Prilocaine.

Question 29

PABA ester anesthetics shouldn’t be given with sulfonamides. Why?

Answer 29

Because they’re metabolized into PABA which antagonizes the effect of sulfonamides.

Question 30

Noradernaline shouldn’t be given to patients with hypertension but can be given with anesthetic to thyrotoxic patients. Yes or No?

Answer 30

Yes