CHAPTER 36: Local and Regional Anesthesia

Question 1

The local anesthetic most commonly used in the ED

Answer 1

Lidocaine

Question 2

Local anesthetic class that are hydrolyzed by cholinesterase enzymes in plasma

Answer 2

Esters

Question 3

Local anesthetic class that are metabolized by hepatic microsomal enzymes

Answer 3

Amides

Question 4

Are the three primary factors in selecting a local anesthetic

Answer 4

Duration of anesthesia
Onset of action
potential for Systemic toxicity

Question 5

Where the ONSET of action of a local anesthetic is dependent

Answer 5

pKa

the pH at which 50% of the drug is ionized and 50% of the drug is nonionized

Question 6

Where the DURATION of action of the local anesthetics is dependent

Answer 6

Receptor affinity

Question 7

Local anesthetics that appear to have a lower risk of systemic toxicity than bupivacaine; significantly less cardiotoxic

Answer 7

Levobupivacaine & Ropivacaine

Question 8

Tx: systemic toxicity from local anesthetics

Answer 8

IV 20% lipid emulsion

Dose: 1.5 mL/kg infused over 1 minute
Repeat Dose Max: 10 mL/kg over the initial 30 minutes

Question 9

Local anesthetics that can cause oxidation of the FERROUS iron in normal hemoglobin to the FERRIC form creating methemoglobin

Answer 9

Prilocaine & Benzocaine

Cyanosis if dose >1.5 grams/dL

Question 10

Local anesthetics with highest lipid solubility & protein binding
Table 36-2 p. 237

Answer 10

AMIDES: Bupivacaine & Levobupivacaine (Ropivacaine= high protein binding only)
ESTERS: Tetracaine (amethocaine)

Question 11

Additive to local anesthetic that:
Increases the duration
Control wound bleeding
Slows the systemic absorption

Answer 11

Epinephrine

Question 12

Additive to local anesthetic & alternative to Epinephrine
An α-adrenergic agonist drug alternative to epinephrine used in combination with a local anesthetic to prolong the duration of anesthesia (by >50%)

Answer 12

Clonidine

Dose: 0.5 mcg/kg
Max: 150 mcg

Question 13

Additive to local anesthetic that reduces the pain of injection and slightly shortens the onset of action by raising tissue pH

Answer 13

Sodium Bicarbonate
Add 1 mL of NaHCO3 8.4% (1 mEq/mL) to 9 mL 1% LIDOCAINE
Add 1 mL of NaHCO3 8.4% (1 mEq/mL) to 29 mL 0.25% BUPIVACAINE

Question 14

Nontraditional agents can be used for wound repair via local injection

Answer 14

Diphenhydramine & Benzyl alcohol with Epinephrine

Question 15

The first topical anesthetic formulated to penetrate intact skin

Answer 15

Eutectic Mixture of Local Anesthetics [EMLA®]

Lidocaine 2.5% + Prilocaine 2.5%

Question 16

Mixture that acts as a topical anesthetic when used on open dermis

Answer 16

Lidocaine, epinephrine, tetracaine [LET]

Lidocaine 4% + Epinephrine 0.1% + Tetracaine 0.5%

Question 17

Is a technique that infiltrates local anesthetic agents adjacent to peripheral nerves

Answer 17

Regional anesthesia (“nerve blocks”)

Question 18

Normal two-point discrimination is —?— mm at the fingertips

Answer 18

<6 mm

Question 19

Required time to achieve optimal analgesia for LIDOCAINE in peripheral nerve blocks

Answer 19

10 to 20 minutes

Question 20

Required time to achieve optimal analgesia for BUPIVACAINE in peripheral nerve blocks

Answer 20

15 to 30 minutes