Loading...
Question 1
Local anesthesia route of admin
• topical • injection
Question 2
What are the two main types of LA
Esters and Amides
Question 3
Which types of local anesthetics are no longer available in dental cartridges due to risk of allergic reactions?
Esters
Question 4
What are the desirable properties of injectable local anesthetics?
• transient and completely reversible • Does not cause permanent nerve damage. • Low systemic toxicity • Short onset • Relatively hypoallergenic
Question 5
What is the purpose of formulating local anesthetics as a hydrochloride salt?
To enhance their stability in solution
Question 6
What is the pKa range for local anesthetics?
7.5-10
Question 7
How does an acidic pH affect the efficacy of local anesthetics?
shifts the equilibrium towards protonation → decreasing efficacy
Question 8
what is the impact of inflammation on LA
• tissue more acidic → incomplete anesthesia • vasodilation → rapid diffusion of LA away from site • infected tissues: increase risk of spreading infection
Question 9
What are nociceptors and thermoreceptors and how do they function in pain transmission?
Nociceptors and thermoreceptors are sensory receptors that detect pain and thermal stimuli, respectively. They activate when stimulated, generating an action potential and transmitting the signal to the somatosensory cortex through the dorsal horn of the spinal cord.
Question 10
How do local anesthetics inhibit the conduction of action potential?
• inhibits conduction of action potential in all afferent nerve fibers •
blocking the sodium channels
Question 11
What is the mechanism of action of local anesthetics?
• prevent pain perception by binding to receptors and blocking sodium channels • stops sodium influx • prevents depolarization or action potential generation
Question 12
What factors influence the onset of local anesthetic (LA) action?
• Size and lipophilicity of LA • Smaller and more lipophilic LA = faster • Dissociation constant (pKa) of LA • Near physiological pH, more non-protonated form
Question 13
What factors influence duration of LA
• Protein binding; more = longer • vasodilator activity; more = diffusion = shorter
Question 14
How does vasodilator activity affect the duration of local anesthetic action?
Increased blood flow will increase diffusion, thus affecting the duration of action.
Question 15
What is the anatomical proximity to the injection site?
The distance from the injection site to the nerve fibers.
Question 16
What is differential functional blockade?
It refers to the varying susceptibility of nerve fibers to block local anesthetics • myelination • nerve diameter • tissue pH • vasoactivity • lipid solubility
Question 17
WHat size axons are more susceptiple to LA
smaller = more susceptible C and A-delta most susceptible
Question 18
What is the function of Type A alpha fibers?
Proprioception, motor
Question 19
Which type of nerve fiber is most susceptible to local anesthetics?
Type C
Question 20
relation of ionization to onset
increase in non-ionization = decrease in onset smaller pKa = shorter onset time
Question 21
What is LAST
Local anesthetic system toxicity
Question 22
What are the initial signs of systemic toxicity in LAST?
The initial signs include agitation, confusion, and dizziness.
Question 23
What are the progression stages of LAST and their corresponding serum concentrations?
• seizures at 10 ug/ml • coma at 15 ug/ml • respiratory failure at 20 ug/ml • cardiovascular collapse at >20 ug/ml
Question 24
What is the most common cause of Local Anesthetic Systemic Toxicity (LAST)?
Accidental intravascular injection during the administration of local anesthetics.
Question 25
What is the importance of aspiration before every injection?
To prevent accidental intravascular injection.
Question 26
co-morbidity that can increase risk of local anesthetic overdose?
Hepatic dysfunction
Question 27
initial management steps for LAST
Airway management, circulatory support, and calling for help.
Question 28
medication administered by EMS to manage convulsions in LAST?
Benzodiazepines
Question 29
What is the lipid rescue treatment for patients exhibiting seizures or signs of CVS toxicity?
20% Lipid emulsion (triglycerides and phospholipid) infusion.
Question 30
Ester metabolization
• metabolized in the plasma by pseudocholinesterase enzyme • yields para-aminobenzoic acid • Metabolites are eliminated via the kidneys
Question 31
Examples of esters
• benzocaine • procaine • chloroprocaine • tetracaine
Question 32
How is benzocaine applied and what is its absorption rate?
• mucous membranes as a topical anesthetic • poorly absorbed into the circulation.
Question 33
Amide Local Anesthetics
• Lidocaine • Mepivacaine • Prilocaine • Bupivacaine • Articaine
Question 34
What is the primary organ for the excretion of metabolites?
Kidneys
Question 35
What is the range of elimination half-life for Amide LAs?
20 minutes to few hours
Question 36
Which Amide LAs can be suitable for patients with renal dysfunction?
Those that undergo liver/plasma metabolism to inactive metabolites prior to excretion
Question 37
What are the components of a dental cartridge (LA Solution)?
• Local anesthetic agent • vasoconstrictor • reducing agent: Sodium metabisulfite • preservatives: Methylparaben. • Fungicide: Thymol. • Vehicle: distilled water, Standard volume is 1.8 ml
Question 38
What is the pH range for LA with vasoconstrictors compared to LA without vasoconstrictors?
• LA with vasoconstrictors: more acidic (3.5) • LA w/out vasoconstrictors: more basic (6.5)
Question 39
What is the purpose of LA buffering in dental procedures?
bringing the solution near the physiological pH by mixing w/ sod.bicarb. • To increase the onset of action • enhance patient comfort, acidity = pain
Question 40
What does vasodilation cause in relation to LA
• causes redistribution of local anesthetic • higher plasma concentration • decreased depth and duration of anesthesia at site • increased bleeding risk at injection site
Question 41
What is the purpose of using vasoconstrictors with local anesthesia?
To reduce bleeding and prolong the effect of local anesthesia.
Question 42
vasoconstriction effects with in regards to LA injection
• decreasing blood flow to the injection site • reducing local anesthesia redistribution • lowering the risk of systemic side effects • decreasing the risk of bleeding • increasing the duration of the anesthetic action
Question 43
What are the effects of epinephrine on the cardiovascular system?
Epinephrine increases cardiac output and blood pressure.
Question 44
common epi drug-drug interactions
tricyclic antidepressants nonselective beta blockers
Question 45
What is the dilution of epinephrine used as a hemostatic reagent?
1:50,000
Question 46
What is the effect of increasing the concentration of epinephrine on the duration of local anesthesia?
Increasing the concentration of epinephrine decreases the duration of local anesthesia.
Question 47
Max dose of epi for a healthy subject?
0.2 mg
Question 48
Max dose of epi for a patient with severe cardiovascular disease (ASA III and IV)?
0.04 mg
Question 49
MRD for epi-sensitive individuals, ASA category III patients?
40 μg per appointment
Question 50
What is the effect of epinephrine on blood glucose levels in diabetic patients who do not use their hypoglycemic medication?
Epinephrine may increase blood glucose levels.
Question 51
What is glycogenolysis?
The breakdown of glycogen into glucose.
Question 52
What is Levonordefrin?
A synthetic vasoconstrictor that mainly acts by α2 receptor stimulation.
Question 53
How does Levonordefrin affect the heart and central nervous system?
It has lower cardiac and CNS stimulation.
Question 54
What is the dilution ratio of Levonordefrin when combined with mepivacaine?
1:20,000
Question 55
Which LAs are risk category B during pregnancy?
Lidocaine and prilocaine
Question 56
Which LAs are risk category C during pregnancy?
Articaine Mepivacaine Bupivacaine
Question 57
What is the mechanism of action of Phentolamine Mesylate (OraVerse)?
It is an alpha-adrenergic antagonist that decreases local anesthetic duration by inducing vasodilation.
Question 58
What are the indications for using a specific medication?
• Reverse local anesthesia and soft tissue numbness • prevent self-inflicted soft-tissue trauma in children/patients w/ cognitive impairment
Question 59
What is tachyphylaxis in the context of local anesthesia (LA)?
• where nerve function returns before re-injection of LA, • leads to pain in the patient
Question 60
How can tachyphylaxis be prevented?
additional injections are administered before the full recovery of nerve function
Question 61
What are GABA receptors and how do they work in the context of general anesthesia?
• GABA: inhibitory neurotransmitters • when stimulated → induce general anesthesia by reducing neural activity
Question 62
What are NMDA receptors and how do they relate to general anesthesia?
• NMDA receptors: excitatory receptors • when blocked → MOA in general anesthetics in inducing anesthesia
Question 63
What are the four goals of general anesthesia?
Hypnosis, Analgesia, Amnesia, Muscle relaxation
Question 64
What is the first stage of general anesthesia?
Induction
IV injection with propofol + neuromuscular blocker
Question 65
What is the second stage of general anesthesia?
Maintenance
Question 66
What is the last stage of general anesthesia
Recovery
redistribution of anesthetics from the site