Midterm Flashcards
Peripheral Nerve Fiber Classification
Which subtype of Type A fibers is efferent; muscle tone?
A(gamma)
How do you prevent Needle Breakage?
- use 25 g or 27 g needles
- Use long - 32mm needle for IA block
What are the 2 Needle lengths used in Dentistry?
- Long - 32 mm
- Short - 20 mm
Peripheral Nerve Fiber Classification
Which subtype of Type A fibers is afferent; proprioception, touch, pressure?
Type A(beta)
What effect does Sodium bisulfite have on the LA?
- decrease solution pH = more acidic = delayed onset
What is the relative refractory period due to?
hyperpolarization before RMP is established
Peripheral Nerve Fiber Classification
Which subtype of Type A fibers is, the largest; fastest; efferent; muscle movement?
A(alpha)
What are the 2 causes of Facial Paralysis?
- LA deposited in parotid gland
- bone not contacted during mandibular block
What LA is not used for hemostasis?
Mepivacaine
What is the MRD per appointment for Mepivacaine?
Adult = 400mg Child = 300mg
What type of LA should you select if you need hemostasis?
- Epi ONLY (no levonordefrin)
- 1:50,000 best
- 1:100,000 is better than 1:200,000
What is the Tx of Paresthesia?
- 3 wks to 3 months, possible 1 yr
Acceptable RR for an Adult?
12-20
What are the 3 causes of Edema?
- Trauma
- Contaminated Anesthetic
- Allergic rxn to LA/sodium bisulfite
What is the absolute refractory period due to?
inactivation of Na+ channels during repolarization
What is the onset time of Bupivacaine?
5-10 mins
What are the symptoms of Allergic Reactions?
- Delayed Hypersensitivity = rash; itching
- Immediate Hypersensitivity = anaphylaxis
What length of needle is ALWAYS required for a Mandibular Block?
Long - 32mm
What concentration of Cetacaine is used?
- 14% Benzocaine
- 2% Butamben
- 2% Tetracaine
What is the mechanism of action of Topical Anesthetics?
- dec Na+ ion permeability = dec depolarization = blocks nerve impulse
Relative Contraindications of LAs (6)
- H2-receptor blockers
- Beta Blockers
- CNS Depressants
- Pregnancy
- Significant Liver Ds
- Renal Dysfunction
How do you prevent a Hematoma?
- Use 27g short - 20mm needle for PSA
What effect does a Vasoconstrictor in LA have on Duration = Potency?
dec BF = inc Duration = inc Potency
Acceptable HR for a Child?
75-100
What is the MRD per appointment for Bupivacaine?
Adult = 90mg Child = 90mg
What is the onset time for Lidocaine?
2-3 mins
What Amide LA’s are metabolized in the Liver ONLY (inc toxicity in liver ds)?
- Lidocaine
- Mepivacaine
- Bupivacaine
What 3 factors affect the duraction of LA = Potency?
- Protein binding of specific LA
- Vascularity of injection site
- Vasoconstrictor in LA
Peripheral Nerve Fiber Classification
- Largest fibers = fastest impulse conduction
- Myelinated
- Afferent or Efferent
Type A Fibers
What is the weakest part of the needle?
Hub + Needle Adaptor (1 piece)
What size of nerve fibers are MORE sensitive to LAs?
Small diameter
Which Amide is the most potent vasodilator?
Bupivacaine
What is the effect of inc protein binding of molecules on LA?
inc duration
What are the symptoms of Syncope?
- Sweating; nausea, pallor
- inc HR and inc RR
What is the duration of topical lidocaine?
15-45 min
What vasoconstrictor should be used if the pt is taking tricyclic anti-depressants?
- 0.04mg Epi
- No Levo
Peripheral Nerve Fiber Classification
Which subtype of Type A fibers is afferent; PAIN; temperature?
A(delta)
What is the duration of action of 4% Prilocaine 1:200,000 epi?
60-90 mins
What LA is a good choice for readministration, CV ds, and Liver ds pts?
Articaine
What is a good choice if a vasoconstrictor is contraindicated?
Mepivacaine
What Amide LA’s are metabolized in Liver + Lungs (shorter 1/2 life due to lungs)?
Prilocaine
What causes the rapid onset of Nitrous Sedation?
low solubility in blood
What Pregnancy Category is Mepivacaine, and is it safe for lactation?
- Category C
- Lactation Safe
What is the duration of Cetacaine?
30-60 min
How do LA’s stabilize the membrane?
Decreases the rate of depolarization; membrane remains polarized
What is another name for Benzocaine?
Hurricaine
What is the most common cause of a Hematoma?
- Entering the venous Pterygoid Plexus when giving a PSA block
Remember to use a short 20mm, 27g needle @ 45 angles to long axis of tooth and to alveolar bone
Is Cetacaine and Ester or Amide?
Ester
Which LA is the best choice for long tx and post-op pain control?
Bupivacaine
What is the MRD per appointment for Prilocaine?
Adult = 400mg Child = 400 mg
What size of nerve fibers require MORE volume of LAs?
Large diameter
What Topical Anesthetic is a good choice for thoose allergic to esters?
Lidocaine
What is the active form of the drug that canNOT cross the membrane?
- RNH+ = cations (acid)
Amide LA’s are combined with an acid to form what?
HCl Salt = water soluble = stable injectable solution
What is the Tx of Trismus?
- 2-3 days
- moist heat (20 min on/ 20 min off)
What are the symptoms of Epi Overdose?
- Fight or Flight response - lasts 5-10 mins
What is the primary factor associated with the Induction (diffusion of molecules across membrane) of LA’s?
- Initial concentration
- inc conc = inc diffusion = rapid onset
How does an inc pKa = inc cations = dec base affect the diffusion across the membrane?
Slower onset = slow diffusions
What LA’s are Long-Acting (90min or > pulpal anesthesia)?
- 0.5% Bupivacaine 1:200,000
What is the Tx for Allergic Rxns?
- Delayed = antihistamine, and document
-
Immediate life-threatening Anaphylaxis
- Stabilize pt
- Activate EMS
- Document
What level of LA’s shows initial CNS Stimulation (inc HR, RR, and BP, muscle twitching, tremors)?
Moderate Overdose of LA’s
What is the Tx for Epi Overdose?
- Healthy Pts = reassure
- CV Pts = prepare for medical emergency
What is the duration of action of Prilocaine without epi (4% Prilocaine Plain)?
40-60 mins
What is the tx for Hematoma?
- Apply ice/pressure immediately
- inform pt of swelling/discoloration 7-14 days