general anesthesia

Question 1

mechanism of action of general anesthesia

Answer 1

1- potentiate GABA receptors (inhibitory brain receptors)
2- Inhibiting NMDA receptors (excitatory glutamate receptors)

Question 2

what happens when u potentiate GABA (A) receptors

Answer 2

increase CL influx -> hyperpolarization -> inhibition of CNS

Question 3

what happens when u potentiate GABA (B) receptors

Answer 3

decrease Ca influx -> inhibition of CNS

Question 4

stages of anesthesia

Answer 4

stage 1: stage of analgesia
stage 2: stage of delirium or excitement
stage 3: stage of surgical anesthesia
stage 4: stage of medullary paralysis

Question 5

stage 1

Answer 5

due to inhibition of sensory transmission -> between the spinal cord and thalamus -> less pain awareness & no loss of consciousness

Question 6

stage 2

Answer 6

irregular respiratory rate, increase in blood pressure, rapid pulse and mydriasis
Decrease delirium by benzodiazepine

Question 7

stage 3

Answer 7

regular respiratory and heart rate, normal BP, loss of eye reflexes & muscle relaxation, surgery starts here

Question 8

stage 4

Answer 8

toxic aesthetics -> respiratory failure & circulatory collapse -> death

Question 9

Properties of good GA

Answer 9

safe nontoxic to liver n kidney
non explosive n non inflammable
inert (no drug interactions)
rapid n pleasant induction
does not decrease respiratory or cardiovascular centers
has muscle relaxant effecr

Question 10

night before operation

Answer 10

anxiolytic or sedative to alleviate stress anxiety fear from operation and get good sleep DIAZEPAM

Question 11

one hour before operation

Answer 11

decrease salivation & protect from bradycardia ATROPINE IM

Question 12

after induction

Answer 12

short acting neuromuscular blocker to facilitate intubation SUCCINYLCHOLINE

Question 13

POST OP

Answer 13

MORPHINE IM for pain
antihistaminic + antiemetic drugs

Question 14

process of GA

Answer 14

1- induction = IV ANESTHESIA
2- maintenance= INHALED ANESTHESIA
3- recovery

Question 15

classification of GA

Answer 15

1- inhaled anesthesia: gases (nitrous oxide) & halogenated hydrocarbons (halothane, isoflurane, sevoflurane)
2- intravenous agents: barbiturates (thiopental), BZ (midazolam), opioids (fentanyl), others (ketamine, propofol)

Question 16

Halothane advantages

Answer 16

INHALED
bronchodilator effect =for asthma patients

Question 17

Halothane disadvantages

Answer 17

1- bradycardia due to vagal stimulation or arrhythmia due to heart sensitization of heart to circulating catecholamines
2- no muscle relaxant effect (curare must be used with it)
3- uterus relaxation & decrease response to oxytocin = not for delivery
4- hepatotoxic= not for liver diseases or repeated surgeries

Question 18

enflurane & isoflurane

Answer 18

INHALED
same as halothane but strong skeletal muscle relaxant effect & less sensitization of heart = fewer arrhytmias
not for kidney failure patients

Question 19

methoxyflurane

Answer 19

MOST POTENT (cz of its high solubility in lipids)
INHALED
in labor (doesnt relax uterus)
can be nephrotoxic

Question 20

nitrous oxide

Answer 20

INHALED
safest
fast pleasant induction with laughing and euphoria
no action on cvs or uterus
no sensitization of heart
used in dentistry & labour

Question 21

MAC

Answer 21

minimal alveolar concentration
as mac decreases of GA -> more potent
halothane 0.77
n2o=101

Question 22

Ultra short acting barbiturates

Answer 22

IV
THIOPENTAL
very rapid induction (rapid onset of action = high lipid solubility)
short acting = rapid redistribution from brain

Question 23

barbiturates disadvantages

Answer 23

1- they can pass placenta (fetotoxic) -> not for delivery
2- hypothermia, postop shivering (cz of inhibition of heat regulatory center)
3- cause dose dependent depression of respiration (not for asthma)

Question 24

ketamine

Answer 24

IV
antagonist of glutamic acid -> block excitatory action of NMDA
dissociative anesthesia
no hypotension or bronchoconstriction
minor operations (esp kids)
not for pregnancy (oxytocin effect)
disadvantages: hallucination + vivid dreams -> decreased by diazepam -> contraindicated in psycho patients

Question 25

propofol

Answer 25

IV
induce anesthesia rapidly
maintenance may require N20 inhaled anesthesia & opioids
no impair on renal or hepatic function

Question 26

opioids

Answer 26

IV
MORPHINE & FENTANYL
potent analgesics
used in combinations
morphine + N2O = cardiac surgery
respiratory depressant (reversed by naloxone)

Question 27

neuroleptanalgesia

Answer 27

combination of 2 or more drugs -> decrease side effects & increase activity of both
consciousness + sedation
potent tranquilizer (neuroleptic) + potent narcotic analgesic (droperidol) + fentanyl (innovar)
minor surgery (bronchoscopy + burn dressing)

Question 28

BZS

Answer 28

IV
DIAZEPAM & LORAZEPAM
bind to bz receptors to potentiate GABA = hyperpolarization & cns inhibition
used in: preanesthesia, balanced anesthesia, operations with no required analgesia -> endoscopy