Week 3 General Anesthetics

Question 1

Stage I-Analgesia

Answer 1

subsequent amnesia and inability to feel pain

Question 2

Stage II- Excitement

Answer 2

delirium, combative behavior, elevated BP and resp rate; not common now b/c short-acting anesthetic given before

Question 3

Stage III- surgical anesthesia

Answer 3

reg respiration, skeletal muscle relaxation, decrease in eye reflexes and movements, fixed pupils; loss of motor and autonomic response to pain

Question 4

Stage IV- Medullary paralysis

Answer 4

NOT GOOD; depression of respiratory and vasomotor centers; leads to DEATH

Question 5

Low blood solubility

Answer 5

Leads to faster induction time b/c the drug isnt staying in the blood- also leads to faster elimination

Question 6

Tissue uptake

Answer 6

highly vascularized tissues rapidly reach steady state

Question 7

Adipose tissue

Answer 7

accumulates anesthetics more slowly b/c lower perfusion rate- most anesthetics have high lipid solubility

Question 8

Meyer & Overton Rule

Answer 8

higher lipid solubility the more potent the volatile anesthetic

Question 9

Potency

Answer 9

amt of drug required to produce its effect

Question 10

Efficacy

Answer 10

max strength of the effect of the drug @ saturating concentrations (like Vmax?)

Question 11

Minimum Alveolar Concentrations (MAC)

Answer 11

potency of anesthetics; alveolar concentrations that renders 50% of subjects to strong noxious stimulation’ 1 MAC: Nitrous oxide=100%(not possible), Isoflurane=1.4%(much more potent than NO)

Question 12

Drug elimination

Answer 12

lower blood/gas partitioning coefficient & tissue solubility- faster the elimination; clearance by lungs major route of elimination

Question 13

Analgesia

Answer 13

dorsal horn

Question 14

Sedation

Answer 14

frontal cortex

Question 15

Hypnosis

Answer 15

Thalamus

Question 16

Immobility

Answer 16

Ventral horn neurons (motor neurons)

Question 17

MOA- Inhaled anesthetics-volatiles

Answer 17

ion channels are important targets; potentiate GABAa, glycine receptors, K+ channels; inhibit glutamatergic ionotropic receptors and neuronal nAChRs- stop movement

Question 18

MOA- Nitrous Oxide

Answer 18

blocks NMDA-R like ketamine; powerful analgesic

Question 19

Organ system effects- volatiles

Answer 19

CV- decrease BP; Resp- mucous accumulates, decreased response to hypoxia- must be on ventilator; GI-nausea vomitting; CNS- dec metabolic rate, inc. cerebral blood flow & intracranial pressure; Liver/kidneys- dec blood flow; Uterus- dec contractions

Question 20

Organ system effects- N20

Answer 20

CV- no change; Resp- diffusional hypoxia, can diffuse into pneumothorax; GI- nausea/vomiting; CNS- inc cerebral blood flow & intracranial pressure; Liver/kidneys- dec blood flow

Question 21

Volatile anesthetics- malignant hyperthermia

Answer 21

mutation in Ryanodine receptor- activated by inhaled anesthetic; leads to uncontrolled release of Ca2+ from sarc retic; succinylcholine can also cause it; Tx- dantrolene (blocks Ca2+ release @ ryanodine receptor), cooling, oxygen, correction of acid-base disturbances

Question 22

Premedication (balanced anesthesia)

Answer 22

Midazolam (I.V. benzodiazepine)

Question 23

Induction (balanced anesthesia)

Answer 23

Fentanyl (IV opioid), Propofol (IV anesthetic), Curare-like neuromuscular blocker (Pancuronium or Succinyl CoA); tracheal intubation

Question 24

Maintenance (balanced anesthesia)

Answer 24

Inhalational Anesthetics (combo)- Sevoflurane (not strong analgesic) + Nitrous Oxide (very good analgesic w/ less side effects)

Question 25

Premedication (Total intravenous anesthesia-TIVA)

Answer 25

MIdazolam (I.V. benzodiazepine); Give TIVA if malignant hyperthermia has occured before

Question 26

Induction (Total intravenous anesthesia-TIVA)

Answer 26

Remifentanil (instead of fentanyl; shorter acting), Propofol

Question 27

NMJ blockade (Total intravenous anesthesia-TIVA)

Answer 27

Rocuronium; tracheal intubation after this

Question 28

Maintenance (Total intravenous anesthesia-TIVA)

Answer 28

Remifentanil, Propofol (more to keep asleep?)

Question 29

Benzodiazepines (Midazolam)

Answer 29

use prior to induction of anesthesia- reduce anxiety, induce amnesia & sedation; used for sedation for non general anesthesia; used in perioperative period; 15-60 min before anesthesia to produce amnesia; given IV; rapid onset & shorter duration of action

Question 30

Opioids (Fentanyl)

Answer 30

induction & maintenance in TIVA; epidural anesthesia together w/ local anesthetics; ICU-conscious and deep sedation; potent respiratory depression; chest wall & laryngeal rigidity-impaired ventilation; dec HR & BP

Question 31

Barbiturate anesthetics (Thiopental)

Answer 31

lipophilic rapidly entres & depresses CNS (<1min); short acting b/c it diffuses out of brain rapidly; used during induction of anesthesia & deep sedation; NOT good analgesic; dec cerebral metabolism & blood flow; dec cardiac output & BP; potent respiratory depression

Question 32

Propofol

Answer 32

most common for induction & maintenance or day surgery; potentiates GABAa receptors; onset rapid as other barbiturates-recovery more rapid; rare postop vomiting; potent resp depression; dec periperheral resistance; dec intracranial pressure; not a good analgesic

Question 33

Good analgesics

Answer 33

Nitrous oxide, Ketamine, Fentanyl

Question 34

Ketamine

Answer 34

PCP analog; blocks NMDA receptors; GOOD analgesic; catatonia, amnesia, analgesia w/out loss of consciousness; short procedures; ONLY IV anesthetic that increases HR & cardiac output; minimal effect on respiration; inc intracranial pressure; postop hallucinations

Question 35

Etomidate

Answer 35

potentiates GABAa receptors; minimal CV depression; used for someone experiencing shock; causes: vomitting, pain on injection, myoclonus; use as anesthetic induction for pts @ risk of hypotension (elderly)

Question 36

Dexmetodine

Answer 36

short term sedation of intubated & ventilated ICU pt or during regional anesthesia; alpha adrenergic receptor agonist (tizanidine); analgesia b/c activation of receptors in spinal cord; hypnosis produced’

Question 37

Increase cranial pressure

Answer 37

Volatiles (sevoflurane, desflurane, isoflurane), Nitrous oxide, Fentanyl (in head trauma pts), Ketamine

Question 38

Decrease cranial pressure

Answer 38

Thiopental, Propofol, Etomidate,