Local and Regional Anesthesia Lecture PDF

Question 1

General vs local anesthetics

Answer 1

General abolish response to pain by depressing CNS and producing loss of consciousness vs local produce a temporary loss of sensation or feeling in a confined area of the body without loss of consciousness, much less risk and much more rapid recovery

Question 2

Local anesthetics mechanism of action and how does epinephrine impact it?

Answer 2

• block nerve fiber conduction by directly acting on nerve membranes, inhibit sodium ions from crossing membrane by blocking sodium channels
• Reversible with metabolism and with time
• Perception of pain is lost first, followed by cold, warmth, touch, and deep pressure (small fibers), large motor nerves tend to be last nerves to be inhibited (large motor nerves, we don’t want these to be inhibited)
• epi injected with it increases time of effectiveness as it causes vasoconstriction of tissue decreasing blood flow increasing time in which the dispersion occurs (very dilute ratio of epi to anesthetic)

Question 3

Examples of ester local anesthetics (4)

Answer 3

• benzocaine
• cocaine
• procaine
• tetracaine

Question 4

Examples of amide local anesthetics (4) - these work longer than the esters!

Answer 4

• lidocaine
• mepivacaine
• dyclonine
• ethyl chloride

Question 5

Topical anesthetics OTC products and their uses (3)

Answer 5

• benzocaine (sun burn)
• dibucaine (hemorrhoids)
• lidocaine (small cuts)

Question 6

Peripheral nerve block (field block)

Answer 6

Anesthetic injected close to nerve trunk to block transmission along peripheral nerrve interrupted, either minor impacting 1 distinct nerve or major affecting a plexus

Question 7

Central neural blockade and subtypes (3)

Answer 7

• Anesthetic directed within membranes surrounding the spinal cord, used when analgesia needed in a large region, frequently used during surgical and obstetric procedures
• epidural, caudal block, spinal block (btwn arachnoid and pia)

Question 8

Adverse effects of central neural blockade (4)

Answer 8

• hypotension
• autonomic blockade
• headache from CSF leak (relieved in supine position)
• meningitis type effect

Question 9

Cocaine surgical uses (2)

Answer 9

• topically in procedures on eyes and nasal mucosa because of vasoconstrictor action
• local anesthetic with epi

Question 10

The only local anesthetic that causes vasoconstriction is ___, the rest cause vasodilatory effects

Answer 10

cocaine

Question 11

Toxic buildup of systemic local anesthetics signs and symptoms (3)

Answer 11

• hypotension
• tremors
• convulsions

Question 12

Injectable local anesthetics with epinephrine drug interactions (4)

Answer 12

• tricyclic antidepressants
• MAOI
• succinycholine
• diazepam

Question 13

Procaine (novocain) function

Answer 13

Ester type local anesthetic only effective via injection often combined with epi, metabolized very rapidly and rarely systemic toxicity, used less often

Question 14

Lidocaine (xylocaine) funciton

Answer 14

Prototype amide type anesthetic, most widely used, more effective then procaine and often combined with epi, higher risk of systemic toxicity

Question 15

Cocaine function

Answer 15

Ester type anesthetic that has vasoconstriction effects and that also has pronounced sympathetic effect on CNS, only used topically for anesthesia of ears nose and throat, lasts about an hour

Question 16

2 types of general anesthetics

Answer 16

• Inhalation

- Intravenous

Question 17

Analgesia vs anesthesia

Answer 17

Loss of pain sensation vs loss of pain and other sensations sometimes including consciousness

Question 18

Minimum alveolar concentration (MAC)

Answer 18

Measures general anesthetic potency, defined as minimum conc at which alveolar air will produce immobility in 50% of patients exposed to painful stimulus, low MAC indicates high anesthetic potency

Question 19

Blood flow to brain is high, anesthetic levels drop rapidly when drug administration stops, therefore tissues with lower blood flow have slower decline in drug levels resulting in…

Answer 19

….patients waking up from anesthesia before all has left the body

Question 20

General anesthesia adverse effects (4)

Answer 20

• respiratory and cardiac depression
• increased risk of heart arrhythmias
• malignant hyperthermia (rare)
• aspiration of gastric contents

Question 21

Preanesthetic agents and examples (5)

Answer 21

• benzodiazepines (midazolam - versed)
• opioids (relieve pre and post op pain)
• clonidine (reduces anxiety and cause sedation)
• atropine (decrease risk of bradycardia and suppress bronchial secretions)
• neuromuscular blocking agents (succinycholine)

Question 22

Postanesthetic agents and examples (3)

Answer 22

• analgesics (opioids, nsaids)
• antiemetics (odensetron)
• muscarinic agonists (bethanechol)

Question 23

Isoflurane (forane) and enflurane (ethrane), and desflurane (adults only!) function and ADRs (2)

Answer 23

Prototype of volatile inhalation anesthetics, low MAC at 1.15%,
-respiratory depression, hypotension,

Question 24

Nitrous oxide function

Answer 24

Very low anesthetic potency impossible to produce anesthesia alone as MAC is very high, but high analgesic potency so combined with other agents, inhaling 20% can provide analgesic effects similar to morphine
-no serious ADRs

Question 25

Intravenous anesthetics function and examples (2)

Answer 25

• used alone or with other analgesic agents to supplement their effects
• short acting barbiturates (methohexital) - rapid onset in 10-20 seconds
• benzos (diazepam, midazolam)

Question 26

Methohexital ADRs (2)

Answer 26

• CV and respiratory depression

- reflex tachycardia

Question 27

Conscious sedation drug combo

Answer 27

midazolam (versed) and opioid analgesic (morphine, fentanyl)

Question 28

Propofol (diprivan)

Answer 28

Most widely used IV anesthetic, 90% receive, sedative hpynotic for induction and maintenance of general anesthesia, has no analgesic actions, brings rapid onset of 60 seconds, continuous use prolongs effects

Question 29

Propofol (diprivan) ADR’s (4)

Answer 29

• severe respiratory depression
• hypotension
• high risk of bacterial infection (contamination)
• propofol infusion syndrome (metabolic acidosis and rhabdo) very rarely, requires CPK monitoring (skeletal and cardiac muscle injury)

Question 30

Ketamine (ketalar) function

Answer 30

Anesthetic that produces dissociative anesthesia, causes sedation, immobility, analgesia and amnesia, rapid induction and recovery but full recovery may take hours useful in young patients undergoing minor procedures

Question 31

Ketamine (ketalar) ADR’s (2)

Answer 31

• unpleasant psychological reactions during recovery

- high abuse

Question 32

Droperidol plus fentanyl function

Answer 32

Produces neruolept analgesia, characterized by indifference to surroundings and insensitivity to pain, lack of consciousness does not occur, useful for minor procedures