Local Anesthesia

Question 1

Classification of local anesthetic

Answer 1

Aminoesters and aminoamides

Question 2

Local anesthetic wherein the intermediate chain forms an ester link between the aromatic and amine groups

Answer 2

Aminoesters

Question 3

Local anesthetic with an amide link between the aromatic and amide groups

Answer 3

Aminoamides

Question 4

Metabolism of local anesthetic

Answer 4

Esters undergo hydrolysis by pseudocholinesterases found pricipally in plasma.

Amides undergo enzymatic biotransformation primarily in the liver

Question 5

Least likely to produce sustained elevation in blood levels because of very rapid hydrolysis in the blood

Answer 5

Chloroprocaine

Question 6

Restores equilibrium in the nerve membrane after completion of the action potential

Answer 6

Na-K pump

Question 7

Caused by inflow of Na ions from the extracellular to intracellular space

Answer 7

Depolarization

Question 8

Caused by outflow of K ions from the intracellular toextracellular space

Answer 8

Repolarization

Question 9

Degree of systemic vascular absorption of local anesthetic

Answer 9

Intercostal nerve block>caudal>epidural>brachial plexus>scuatic-femoral>subcutaneous

Question 10

Local anesthetic associated with risk of methemoglobinemia

Answer 10

Prilocaine and benzocaine

Question 11

Protocol for intralipid administration

Answer 11

Initially administer intralipid 20% at a dose of 1.5ml/kg over 1 minute

Follow immediately with an infusion at a rate of 0.25ml/kg/min

Continue chest compressins (lipid must circulate)

Repeat bolus every 3-5 minutes up to 3ml/kg total dosage until circulation is restored

Continue infusion until hemodynamic stability is restored

Increase the rate to 0.5 ml/kg/min if blood pressure declines

A maximum total dose of 8 ml/kg is recommended