General Anesthetics

Question 1

Nitrous Oxide

Answer 1

C: --
M: NMDA receptor antagonist
T: Mask induction in children
SE: Post-operative nausea and vomiting; inactivates vitamin B (leading to abnormal embryonic development, abortion); accumulates in closed, air-containing spaces (bowel, middle ear, pneumothoraces, air emboli) because N2O insoluble in blood
MISC: No muscle relaxation

Question 2

Isoflurane (Forane)

Answer 2

C: Volatile anesthetic
M: Most potent
T: Gold standard for maintenance of anesthesia
SE: Pungent; dose dependent CNS depression, increase in cerebral blood flow and intracranial pressure; dose dependent decrease in systemic BP, decrease in respiratory function; relaxes skeletal muscle; increase in HR; malignant hyperthermia
MISC: –

Question 3

Desflurane (Suprane)

Answer 3

C: Volatile anesthetic
M: Least soluble, least potent (allows for rapid emergence from anesthesia)
T: –
SE: Most pungent (airway irritation symptoms); dose dependent CNS depression, increase in cerebral blood flow and intracranial pressure; dose dependent decrease in systemic BP, decrease in respiratory function; relaxes skeletal muscle; increase in HR; malignant hyperthermia
MISC: –

Question 4

Sevoflurane (Ultane)

Answer 4

C: Volatile anesthetic
M: Less soluble, less potent (but not irritating)
T: Mask induction in children and adults
SE: Can form CO if not combined with CO2 correctly; dose dependent CNS depression, increase in cerebral blood flow and intracranial pressure; dose dependent decrease in systemic BP, decrease in respiratory function; relaxes skeletal muscle; malignant hyperthermia
MISC: –

Question 5

Methohexital (Brevital)

Answer 5

C: Barbiturates
M: GABAa receptor binding; produce hypnosis and sedation,
T: Induce general anesthesia
SE: –
MISC: Redistribute from brain to muscle and fat, metabolized by liver; dosed based on lean body mass

Question 6

Propofol (Diprivan)

Answer 6

C: Alkylphenol (a fatty acid)
M: GABAa receptor agonist, antagonist of NMDA-glutamate receptor; some a2 receptor activity; rapid onset and offset
T: Anti-emetic at low doses; induction and maintenance of general anesthesia; sedation in ICU, procedural sedation
SE: Propofol infusion syndrome: being given for several days leads to metabolic acidosis, rhabdomyolysis, renal failure, lowering of BP, bradycardia, and death (likely due to fatty acid oxidation)** Painful injection site; supports bacterial growth
MISC: Administered IV in a lipid emulsion (cause of pain); be aware of allergies (egg and soy in emulsion); no malignant hyperthermia

Question 7

Etomidate (Amidate)

Answer 7

C: Carboxylated imidazole
M: GABAa receptor agonist (only D-isomer)
T: Hypnosis; no analgesic activity
SE: Pain on administration (due to solvent, propylene glycol); involuntary myoclonic movements due to subcortical disinhibition (not a seizure); post-operative nausea and vomiting; single dose inhibits cortisol synthesis
MISC: Minimal cardiorespiratory depression (good agent in patients with minimal cardiac reserve)

Question 8

Ketamine (Ketalar)

Answer 8

C: Phencyclidine
M: NMDA receptor antagonist, kappa opiate agonist; leads to dose-dependent unconsciousness, amnesia, analgesia
T: Sedative/anesthetic for pediatric/developmentally delayed patients; induction in patients with reactive airway disease, hypovolemia (trauma patients), cardiac disease; with propofol for IV procedural sedation; adjuvant during and after surgery to reduce opiod use; part of multimodal pain therapy regimen; depression treatment
SE: Stimulates sympathetic nervous system outflow; increases cerebral blood flow, ICP; emergence delerium; nystagmus, lacrimation, salivation, and dissociative anesthesia
MISC: Racemic mixture (S more potent); metabolized by P450 (norketamine, a third to a fifth as effective); great bronchodilator; contraindicated in CAD, patients with intracranial lesions

Question 9

Dexmedetomidine (Precedex)

Answer 9

C: a2 adrenergic agonist
M: Binds a2a and a2b in locus coeruleus and spinal cord (produces sedation, sympatholysis, and analgesia)
T: Awake intubations, awake craniotomies; adjunct to general anesthesia in patients susceptible to narcotic-induced post-op respiratory depression; withdrawal/detoxification
SE: Limited respiratory depression (wide safety margin)
MISC: Since GABA not hit, sedation is easier to wake from and is similar to non-REM sleep; FDA approved only for ventilation of ICU patients for under 24 hours

Question 10

Succinylcholine (Anectine)

Answer 10

C: Depolarizing NMB
M: Divalent ACh molecule; attaches to all ACh receptors, overstimulating them (first seen as disorganized muscular contractions (fasiculations), then paralysis)
T: Skeletal muscle relaxant (intubation)
SE: Malignant hyperthermia; cardiac dysrhythmias, hyperkalemia, increased intraocular pressure, increased intracranial pressure** Increased intragastric pressure, myalgias, masseter spasm
MISC: Hydrolyzed by pseudocholinesterase (in plasma); blockade cannot be reversed; only NMB with rapid onset and ultra-short duration of action

Question 11

Pancuronium (Pavulon)

Answer 11

C: Amino steroid non-depolarizing NMB
M: Competitive blockade of ACh (no depolarization); vagolytic
T: Skeletal muscle relaxant; avoid in patients with renal insufficiency
SE: Increase in HR
MISC: Only long acting non-depolarizing agent; supplied as liquid; 80% excreted unchanged in liver (low metabolism in liver); reverse with AChEI

Question 12

Vecuronium (Norcuron)

Answer 12

C: Amino steroid non-depolarizing NMB
M: Competitive blockade of ACh (no depolarization)
T: Skeletal muscle relaxant
SE: No cardiovascular effects
MISC: Intermediate acting; supplied as a powder (reconstitute); hepatic metabolism, hepatic and renal excretion; reverse with AChEI

Question 13

Rocuronium (Zemuron)

Answer 13

C: Amino steroid non-depolarizing NMB
M: Competitive blockade of ACh (no depolarization)
T: Skeletal muscle relaxant (can substitute succinylcholine in rapid sequence intubation)
SE: No cardiovascular effects
MISC: Intermediate acting; supplied as a liquid; hepatic metabolism, hepatic and renal excretion; can speed onset with higher dose; reverse with AChEI

Question 14

Sugammadex (Bridion)

Answer 14

C: Selective relaxant binding agent
M: Complexes with rocuronium, rendering it inactive; no effect on AChesterase
T: Immediate reversal of rocuronium
SE: Decrease in blood presure, nausea and vomiting, dry mouth
MISC: Not yet FDA approved

Question 15

Atracurium (Tracrium)

Answer 15

C: Isoquinoline non-depolarizing NMB
M: Competitive blockade of ACh (no depolarization)
T: Skeletal muscle relaxant; use in patients with liver or renal dysfunction
SE: Histamine release (especially if given as rapid IV bolus), with resultant hypotension and tachycardia
MISC: Undergoes spontaneous, non-enzymatic degradation (Hofman elimination); intermediate acting; reverse with AChEI

Question 16

Cis-atracurium (Nimbex)

Answer 16

C: Isoquinoline non-depolarizing NMB
M: Competitive blockade of ACh (no depolarization)
T: Skeletal muscle relaxant; use in patients with liver or renal dysfunction
SE: Unlike atracurium, no histamine release or downstream effects
MISC: Undergoes spontaneous, non-enzymatic degradation (Hofman elimination); intermediate acting; reverse with AChEI

Question 17

Edrophonium (Enlon)

Answer 17

C: AChE-I
M: --
T: Reversal of NMB
SE: --
MISC: Short-acting, fast onset

Question 18

Neostigmine (Prostigmin)

Answer 18

C: AChE-I
M: --
T: Reversal of NMB (most commonly used)
SE: --
MISC: More complete antagonism than edrophonium

Question 19

Pyridostigmine (Mestinon)

Answer 19

C: AChE-I
M: --
T: Reversal of NMB
SE: --
MISC: Longer duration of action than neostigmine, edrophonium

Question 20

Glycopyrrolate (Robinul)

Answer 20

C: Anti-muscarinic
M: --
T: Reversal of neuromuscular blockade's muscaranic effects
SE: DUMBELLS
MISC: Could also use atropine