Local anesthetics 4

Question 1

LAST is more common with ______________ than with ____________

Answer 1

peripheral nerve blocks than with epidural anesthesia

Question 2

The risk of LAST is increased in the setting of

Answer 2

hypoxia, hypercarbia, acidosis, and hyperkalemia

Question 3

___________ is the only local anesthetic with vasoconstrictive properties

Answer 3

Cocaine

Question 4

_______________ is the primary risk of cocaine toxicity

Answer 4

Excessive SNS stimulation

Question 5

Cocaine toxicity is best treated with

Answer 5

a vasodilator or a mixed alpha and beta antagonist such as labetalol

Question 6

Cardiovascular toxicity causes

Answer 6

conduction block
depresses the myocardium
and reduces systemic vascular resistance

Question 7

CNS complications such as seizures occur _________ CV complications with LAST.

Answer 7

before

Question 8

_____________ is the exception because cardiac complications (myocardial depression, AV block, cardiac arrest) often occurs before a seizure.

Answer 8

Bupivacaine

Question 9

Analgesia occurs at a plasma concentration of ________ mcg/mL of lidocaine

Answer 9

analgesia

Question 10

At a plasma concentration of _________ mcg/mL of lidocaine, tinnitus, skeletal muscle twitching, numbness of lips and tongue, restlessness, vertigo, blurred vision, hypotension, and myocardial depression.

Answer 10

5-10 mcg/mL

Question 11

At a plasma concentration of ______________ of lidocaine seizures and loss of consciousness may occur.

Answer 11

10-15 mcg/mL

Question 12

At a plasma concentration of __________ of lidocaine coma and respiratory arrest can occur.

Answer 12

15-25 mcg/mL

Question 13

At a plasma concentration of ___________ of lidocaine cardiovascular arrest can occur.

Answer 13

> 25 mcg/mL

Question 14

How does hypercarbia increase the potential for LAST?

Answer 14

hypercarbia increases cerebral blood flow and increases drug delivery to the brain
decreases protein binding and increases the free fraction available to enter the brain

Question 15

How does hyperkalemia increase the risk for LAST?

Answer 15

raises resting membrane potential, making neurons more likely to depolarize

Question 16

How does metabolic acidosis increase the risk for LAST?

Answer 16

decreases the convulsion threshold and favors ion trapping inside the brain

Question 17

Factors that decrease the risk of LAST include

Answer 17

hypokalemia, hypocarbia, and CNS depressants

Question 18

What two features determine the extent of cardiotoxicity?

Answer 18

affinity for the voltage- gated sodium channel in the active and inactive states
rate of dissociation from the receptor during diastole

Question 19

The risk of bupivacaine toxicity is increased with

Answer 19

pregnancy
beta-blockers
calcium channel blockers
digitalis

Question 20

Rank the difficulty of cardiac resuscitation with local anesthetics:

Answer 20

bupivacaine> levobupivacaine> ropivacaine> lidocaine

Question 21

Cocaine should be avoided with

Answer 21

MAOIs
TCAs
sympathomimetic drugs

Question 22

Beta blockade in the setting of cocaine overdose is a questionable practice that allows for

Answer 22

unopposed alpha-1 stimulation. High SVR (alpha 1 stimulation caused by cocaine) and reduced inotropy (beta-1 antagonism) set the stage for congestive heart failure and CV collapse

Question 23

What is the best tx for cocaine toxicity?

Answer 23

a vasodilator such as nitroglycerine is best but if given a list of beta-blockers than labetalol (or another mixed alpha and beta antagonist) is a reasonable choice

Question 24

The maximum allowable dose for cocaine is

Answer 24

200 mg

Question 25

The dose range for cocaine is

Answer 25

1.5-3.0 mg/kg

Question 26

One minute following an interscalene block, a 62 kg patient has a seizure. How much 20% lipid emulsion should you administer?

Answer 26

93 mL

Question 27

What are the steps to treating LAST?

Answer 27

1. manage the airway 2. treat seizures with a benzodiazepine 3. ACLS w/ modifications 4. administer 20% lipid emulsion therapy 5. avoid beta-blockers and calcium channel blockers 6. If the patient is unresponsive to modified ACLS and lipid emulsion therapy, prepare for cardiopulmonary bypass

Question 28

What should you not give for seizures in the LAST patient?

Answer 28

propofol

Question 29

What is the agent of choice for ventricular dysrhytmias for the patient with LAST?

Answer 29

amiodarone

Question 30

What drugs should be avoided with LAST?

Answer 30

vasopressin lidocaine procainamide epinephrine

Question 31

Why should epinephrine be avoided with LAST?

Answer 31

epinephrine reduces the efficacy of lipid emulsion therapy if you must give it, then limit the dose to <1 mcg/kg

Question 32

For 20% lipid emulsion therapy what is the bolus and infusion dose for a patient over 70 kg:

Answer 32

bolus = 100 mL over 2-3 minutes infusion = 250 mL over 15-20 minutes if the patient remains unstable--> repeat bolus and/or double the infusion

Question 33

For 20% lipid emulsion therapy what is the bolus and infusion dose for a patient under 70 kg:

Answer 33

bolus: 1.5 mL/kg of lean body weight over 2-3 minutes infusion: 0.25 mL/kg/min. if the patient remains unstable--> repeat bolus and/or double the infusion

Question 34

LAST can be reduced by

Answer 34

using a test dose and incremental dosing with periodic aspiration

Question 35

______ & ____________ will worsen the symptoms of LAST

Answer 35

hypoxia and acidosis

Question 36

If benzodiazepines are ineffective to treat a LAST seizure,

Answer 36

a small dose of succinylcholine or a non-depolarizer should be given to stop muscle contraction this minimizes O2 consumption, hypoxemia, and acidosis although it will not stop seizure activity in the brain

Question 37

Why is propofol avoided for seizures in LAST?

Answer 37

larger doses of propofol augment myocardial depression

Question 38

If epinephrine is used in last, the recommended dose is

Answer 38

below 1 mcg/kg

Question 39

The maximum recommended dose of lipid emulsion is

Answer 39

12 mg/kg

Question 40

The infusion of lipid emulsion should be continued for

Answer 40

a minimum of 15 minutes after the patient regains CV stability

Question 41

Is lipid emulsion safe in pregnancy?

Answer 41

yes

Question 42

What is a theoretical complication secondary to hyperlipidemia and hyperamylasemia after lipid emulsion therapy?

Answer 42

pancreatitis

Question 43

The proposed MOA of lipid emulsion therapy includes?

Answer 43

lipid sink- sequesters LA and reduces the plasma concentration of LA metabolic effect- enhanced myocardial fatty acid metabolism inotropic effect- increased Ca+ influx and intracellular Ca+ concentration membrane effect- impairs LA binding to Na+ channels

Question 44

What is the MAXIMUM recommended dose for lidocaine during tumescent anesthesia? a. 5 mg/kg b. 7 mg/kg c. 55 mg/kg d. 75 mg/kg

Answer 44

C. 55 mg/kg

Question 45

Tumescent anesthesia provides

Answer 45

comfort during liposuction

Question 46

The plasma concentration of lidocaine peaks at __________ and is completely eliminated by _____________

Answer 46

12 hours; 36 hours

Question 47

GA for liposuction is recommended if > ____________ of tumescent is planned

Answer 47

2-3 L

Question 48

_______ & __________ may occur as a result of intravascular volume expansion when using tumescent lidocaine.

Answer 48

fluid overload pulmonary edema