Anesthetics

Question 1

Drugs with increased solubility in lipids do what to the potency?

Answer 1

Increased potency = 1/MAC

Question 2

What is the MAC?

Answer 2

minimal alveolar concentration (of inhaled anesthetic) required to prevent 50% of subjects from moving in response to noxious stimulus (i.e. skin incision)

Question 3

N2O

Answer 3

Decreased blood and lipid solubility, and thus fast induction and low potency.

Question 4

Halothane

Answer 4

Halothane has increased lipid and blood solubility and thus high potency and slow induction

Question 5

What are the inhaled anesthetics?

Answer 5

Halothane, enflurane, isoflurane, sevoflurane, methoxyflurane, nitrous oxide

Question 6

mech of inhaled anesthetics

Answer 6

mechanism unknown

Question 7

What is the effect of inhaled anesthetics?

Answer 7

Myocardial depression, respiratory depression, nausea/emesis, increased cerebral blood flow (decreased cerebral metabolic demand)

Question 8

Toxicity of inhaled anesthetics?

Answer 8

Hepatotoxicity (halothane), nephrotoxicity (methoxyflurane), proconvulsant (enflurane), expansion of trapped gsa in a body cavity (nitrous oxide). Can cause malignant hyperthermia - rare, life-threatening hereditary condition in which inhaled anesthetics (except nitrous oxide) and succinylcholine induce fever and severe muscle contractions. Treatment: dantrolene

Question 9

Describe the potency and lipid solubility of IV barbiturates (Thiopental)

Answer 9

high potency, high lipid solubility and therefore rapid entry into brain

Question 10

What is the use of Thiopental?

Answer 10

Induction of anesthesia and short surgical procedures. Effect terminated by rapid redistribution into tissue (i.e. skeletal muscle) and fat. Decrease cerebral blood flow.

Question 11

What is the most commonly used benzodiazepine for endoscopy?

Answer 11

Midazolam; used adjunctively with gasous anesthetics and narcotics.

Question 12

What is the risk of Midazolam?

Answer 12

may cause severe postoperative respiratory depression, decrease BP (treat overdose with flumazenil), and anterograde amnesia

Question 13

What is an Arylcyclohexylamine?

Answer 13

Ketamine

Question 14

What is ketamine?

Answer 14

PCP analog that act as dissociative anesthetic. Block NMDA receptors. Cardiovascular stimulants. Cause disorientation, hallucination, and bad dreams. Increase cerebral blood flow

Question 15

Which opiods are used during anesthesia?

Answer 15

Morphine, fentanyl

Question 16

Propofol

Answer 16

Used for sedation in ICU, rapid anesthesia induction, and short procedures. Less postoperative nausea than thiopental. Potentiates GABA(A)

Question 17

What are the IV anesthetics?

Answer 17

Barbiturates (thiopental), Benzos (midazolam), ketamine, opioids (morphine, fentayl), propofol

Question 18

What are the two classifications of local anesthetics?

Answer 18

Esters and amides

Question 19

What are the Esters?

Answer 19

Procaine, Cocaine, Tetracaine

Question 20

What are the Amides?

Answer 20

lidocaine, mepivacaine, bupivacaine (amides have 2 I’s in name)

Question 21

What is the mech of local anesthetics?

Answer 21

Block Na+ channels by binding to specific receptors on INNER portion of channel. Preferentially bind to activated Na+ channels, so most effective in rapidly firing neurons.

Question 22

How do the tertiary amines bind?

Answer 22

Penetrate membrane in uncharged form, then bind to ion channels as charged form

Question 23

What can be given with the local anesthetics to enhance local action?

Answer 23

vasoconstrictors (usually epinephrine) - decrease bleeding, increase anesthesia by decreasing systemic concentration.

Question 24

In infeted tissue, why must more anesthetic be delivered?

Answer 24

In acidic tissue, alkaline anesthetics are charged and cannot penetrate membrane effectively

Question 25

Order of Nerve blockade?

Answer 25

Small-diameter fibers > large diameter. Myelinated fibers > unmyelinated fibers. Overall, size factor predominates over myelination such that small myelinated fibers > small small unmyelinated > large yelinated fibers > large unmyelinated fibers

Question 26

Order of pain loss?

Answer 26

1) pain 2) temp 3) touch 4) presssure

Question 27

What is the clinical use of local anesthetics?

Answer 27

Minor surgical procedures, spina anesthesia. If allergic to esters, give amides.

Question 28

Toxicity of local anesthetics

Answer 28

CNS excitation, severe cardiovascular toxicity (bupivacaine), hypertension, hypotension, and arrhythmias (cocaine)

Question 29

What are the neuromuscular blocking drugs used for?

Answer 29

muscle paralysis in surgery or mechanical ventilation. Selective for motor (vs. autonomic) nicotinic receptor

Question 30

What are the Depolarizing neuromuscular blocking drugs?

Answer 30

Succinylcholine

Question 31

What is the mech of succinylcholine

Answer 31

strong Ach receptor agonist; produces sustained depolarization and prevents muscle contraction.

Question 32

Describe the reversal of blockade of succinylcholine:

Answer 32

Phase I: (prolonged depolarization) - no antidote. Block potentiated by cholinesterase inhibitors Phase II: (repolarized but blocked; ACh receptors are available, but desensitized) - antidote consits of cholinesterase inhibitors

Question 33

What are the complications of Depolarizing neuromuscular blocking drugs?

Answer 33

Hypercalcemia, Hyperkalemia, and Malignant Hyperthermia

Question 34

What are the nondepolarizing neuromuscular blocking drugs?

Answer 34

Tubocurarine, atracurium, mivacurium, pancuronium, vecuronium, rocuronium

Question 35

What is the mech of the nondepolarizing neuromuscular blockers?

Answer 35

competitive antagonists - compete with ACh for receptors.

Question 36

What is the reversal of blockade for the non depolarizing neuromuscluar blocking drugs?

Answer 36

Neostigmine (must be given with atropine to prevent muscarinic effects such as bradycardia), edrophonium, and other cholinesterase inhibitors.

Question 37

Dantrolene mech

Answer 37

Prevents the release of Ca++ from the SR of skeletal muscle

Question 38

What is the clinical use of Dantrolene?

Answer 38

used to treat malignant hyperthermia and neuroleptic malignant syndrome (a toxicity of antipsychotic drugs).