Question 1

Differential nerve block occurs because small diameter,unmyelinated neurons that convey _______ are the most sensitive to local anesthetics.&#10;A) pain&#10;B) temperature&#10;C) touch&#10;D) proprioception&#10;E) motor impulses

Accepted Answer

Small diameter, unmyelinated neurons are known as C fibers, and these are responsible for transmitting pain signals. Therefore, local anesthetics are most effective at blocking these fibers and producing a differential nerve block that primarily affects pain sensation.

Question 2

Intravenous regional anesthesia (Bier block)is achieved by&#10;A) injecting a local anesthetic into a peripheral vein located in a selected limb&#10;B) injecting a general anesthetic into a peripheral vein located in a selected limb&#10;C) injecting a local anesthetic into the superior vena cava&#10;D) injecting a local anesthetic into the inferior vena cava

Accepted Answer

Intravenous regional anesthesia (Bier block) is achieved by injecting a local anesthetic into a peripheral vein located in a selected limb. This causes nerve blockage in the affected limb and provides anesthesia for minor surgical procedures such as hand and arm surgeries. Option B is incorrect as injecting a general anesthetic would result in loss of consciousness and not just numbness in the selected limb. Options C and D are also incorrect as injecting the local anesthetic directly into the vena cava could result in systemic toxicity and adverse effects.

Question 3

In order to provide symptomatic relief of minor surface irritation and injury (minor burns,abrasions,and so forth),local anesthetics are typically applied&#10;A) intravenously&#10;B) intrathecally&#10;C) topically&#10;D) by inhalation

Accepted Answer

When providing symptomatic relief of minor surface irritation and injury, local anesthetics are typically applied topically directly to the affected area. Intravenous administration is not necessary for minor surface irritations and could cause unwanted side effects. Intrathecal administration is typically reserved for more severe or chronic pain management. Inhalation is not a common method of local anesthetic delivery.

Question 4

Local anesthetics inhibit action potential propagation along neuronal axons by blocking the opening of ________ channels.&#10;A) potassium&#10;B) sodium&#10;C) chloride&#10;D) calcium&#10;E) magnesium

Accepted Answer

Local anesthetics work by blocking voltage-gated sodium channels, which are responsible for the depolarization and propagation of action potentials along axons. By inhibiting these channels, local anesthetics prevent the transmission of pain signals.

Question 5

Local anesthetics are sometimes used to treat complex regional pain syndrome (CRPS),known also as reflex sympathetic dystrophy syndrome (RSDS),by administering the drug&#10;A) intra-arterially into the affected limb&#10;B) near the sympathetic chain ganglia that innervate the affected limb&#10;C) into the third ventricle of the brain&#10;D) into the fourth ventricle of the brain&#10;E) none of the above; local anesthetics are not used to treat this problem

Accepted Answer

Local anesthetics can be administered near the sympathetic chain ganglia that innervate the affected limb to treat CRPS/RSDS. This blocks sympathetic activity, which is thought to contribute to the pain and other symptoms of the condition. Intra-arterial administration or brain ventricle injection are not commonly used treatments for CRPS.

Question 6

Local anesthetics can be administered via all of the following routes EXCEPT&#10;A) transdermally&#10;B) subcutaneous infiltration&#10;C) direct injection into the epidural space&#10;D) direct injection into the third ventricle of the brain&#10;E) direct injection into the subarachnoid space

Accepted Answer

Direct injection into the third ventricle of the brain is not a common or recommended route for administering local anesthetics. The other routes listed are all commonly used methods for local anesthesia administration.

Question 7

Local anesthetic systemic toxicity (LAST)is typically treated by administering&#10;A) general anesthetics&#10;B) an emulsion of lipid compounds that soak up the lipophilic local anesthetic molecules&#10;C) an amphetamine or other CNS stimulant to reduce CNS excitation caused by the local anesthetic&#10;D) a beta blocker to reverse myocardial depression caused by the local anesthetic&#10;E) other drugs that block sodium channels throughout the body

Accepted Answer

LAST is caused by high concentrations of local anesthetic molecules in the bloodstream, leading to CNS and cardiovascular toxicity. Intralipid emulsion therapy has been shown to effectively treat LAST by creating a sink for the lipophilic local anesthetic molecules, reducing their concentration and reversing the toxic effects. The other choices are not appropriate for treating LAST.

Question 8

Absorption of local anesthetics into the system circulation is dangerous because these drugs can&#10;A) decrease the force of cardiac contraction&#10;B) cause bradycardia&#10;C) inhibit respiratory control centers in the CNS&#10;D) all the above are true&#10;E) none of the above are true

Accepted Answer

Local anesthetics can cause a decrease in the force of cardiac contraction, leading to arrhythmias and even cardiac arrest. Bradycardia (slow heart rate) is also a possible side effect. Inhibition of the respiratory control centers in the CNS can lead to respiratory depression and possibly respiratory arrest. Therefore, all of the above options are true, making D the best choice.

Deck 12: Local Anesthetics