Anesthesia Flashcards
In pt with positive lip signs how successful was man 1st molar block? 1st premolar? Lat incisor?
Molar 53%
1st premolar 60%
Lat incisor 40%
How successful are IAN blocks in teeth with irreversible pulpitis
20-70%
Teeth with inflamed pulps are how many times more likely not to achieve plural anesthesia
8x
Describe Aβ
nerve fibers
The largest are the A- beta, heavily myelinated and responsible for touch and pressure, fastest
Describe Aδ
fibers
Then there are the A-delta fibers, a little smaller in diameter and with a slower conduction velocity. These fibers are responsible for pain, temperature and touch. They are also myelinated.
Describe C fibers
small, unmyelinated C-fibers responsible for the throbbing pain associated with tissue injury, slowest conduction speed
A delta pain description
Temperature sensitive
- Often sharp
Short Duration
C fiber pain description
Temperature sensitive
- Often sharp
Short Duration
Compare nerve fiber sensitivity to lido
Aβ > Aδ > C
Therefore – if your patient has a numb lip (Aβ), then the pulp is not necessarily anesthetized
Two important points about c fibers
C fibers are the hardest to anesthetize
C fibers are the most resistant to necrosis (irreversible pulpitis)
What are some anatomical mechanisms of IAN failure
Needle placement Accessory nerves Size of the nerve Length of nerve exposed Type of sodium channel
What are some inflammatory mechanisms of failure for IAN blocks
Local pH Inflammatory mediators Sprouting Central sensitization Neuropeptides Local blood flow
How many nodes of ranvier need to be blocked for nerve blockade
Initially thought to be 3 now believed to be 4
What are TTX-r sodium channels
New Sodium Channel discovered that is resistant to local anesthetic
Tetrodotoxin resistant sodium channel (TTX-r)
Takes 4 x more anesthetic to block action potential
what form of the anesthetic can diffuse through the membrae
non ionized form
What is the average pH of the extracellular space
7.4
Which form of the anesthetic blocks the channel
ionized
How does PGE2 affect ability to anesthetize
Sensitizes neurons Mense Brain Research 1981
Doubles the activity of TTX-resistant (TTX-r) sodium channels
alter structural properties of nociceptors
-nerves sprout into areas of inflammation
-greater field, spatial summation of stimuli, activation
what is central sensitization
Barrage of afferent impulses
Exaggerated response to gentle peripheral stimuli
Does anxiety play a part in anesthesia
Anxious patients reported greater pain
Prior painful treatment or anxiety about treatment led to an increase in reported pain
Different procedures caused more anxiety
Does a 2nd IAN block increase success if positive lip sign already present
no
What are some advantages of a low gates nerve block
True V3 block Inferior alveolar Buccal Lingual Mylohyoid Low positive aspiration rate (1.8%) Constancy of landmarks
What are some disadvantages of a cow gates
Slower onset
Provider anxiety during learning phase
What are the landmarks for the low gates
Anterior border of ramus
Corner of mouth
Intertragic notch
clinical technique for how gates
Patient supine with mouth wide open
Thumb in anterior border of ramus and finger in meatus of ear
Insertion below the ML cusp of maxillary 2nd molar aim toward finger
Depth of penetration 25mm (contact bone)
Deposit 1.8ml and keep patient open
What are the literature ranges for gow gates success
35-91
not significant improvement
Indication for akinosi block
Infection
Trismus
Trauma
Closed mouth technique
What are landmarks for akinosi block
Occlusal plane of occluding teeth
Mucogingival junction of maxillary molars
Anterior border of ramus
Akinosi technique
Patient gently occludes with muscles relaxed
Reflect soft tissues laterally
Position barrel of syringe
Parallel with maxillary occlusal plane
Needle at the level of the mucogingival junction of max 2nd molar
Direct needle posteriorly and laterally
Bevel of needle away from mandibular ramus so needle deflection is toward ramus
Patient can move mandible to the side of the injection for better access
Advance needle approximately 25mm
Aspirate and deposit entire carpule
Akinosi advantages
Anesthesia obtained with limited opening
2% positive aspiration
disadvantages of akinosi
Absence of a bony landmark
Unexpected side effects
Akinosi success rates
77-85%
does lingual infiltration help
IAN block alone (73%) or with mylohyoid block (83%) – no significant difference in anesthesia success Clark et al OOOOE 1999
Technique addresses only one mechanism of failure
When should you consider a 2nd IAN, Gowgates, or akinosi
when initial block fails to produce a positive lip sign.
How does a PDL injection spread
mesial and distal
Primarily pulp of tooth anesthetized
Pulps of 2 adjacent teeth mesial and distal to point of injection
PDL landmarks
Periodontal ligament space
Line angles of tooth
Crestal bone
PDL clinical technique
27 - 30 gauge short or ultra-short needle
Needle type not critical, but back pressure is (to force solution into bone)
Insert into PDL space
Bevel facing bone
All four line angles of tooth
Inject 0.3 ml with pressure
Advantages of PDL injection
Increases success of IAN anesthesia
Minimal damage to periodontium
No special instruments
Disadvantages of PDL injection
Short duration
Mild discomfort
Adverse effects of PDL injection
HR increase 10-20% Smith & Pashley Oral Surg 1983 Decreases pulpal blood flow Kim et al. J Dent Res 1984 9.6% at 5 minutes 65.3% at 65 minutes
Indications and contraindications for PDL injection
Indications
Failed IAN block
As a primary in hemophilia patient
Contraindications
Restorative
PDL success rates
63-81% on first attempt
83-92% if second injection needed
NOTE: only 3.8% pulpal anesthesia when 3% mepivacaine used as a primary injection
What are two types of intraosseous injection
Stabident
Xtip
For stabident where should the perforation site be
Perforation site – 2 mm below intersection of a line along gingival margin & line bisecting the papilla
Needle perpendicular to cortical plate
How should you drill for the stabident
Light pressure at full speed with pecking motion
2-5 seconds
Injecting with stabident
Align needle into perforation – ‘pen grasp’
Slowly inject over 1-2 minutes 0.9-1.8 cc
Should not have resistance or backflow
What differentiates tip from stabident
2 piece system
internal perforator and external guide sleeve
tip is also longer
Contraindication for intraosseous
root proximity
per disease
local infection
Advantages of intraosseous
Acts quickly
excellent plural anes
fairly easy to use
Dis of intraosseous
difficulty inserting the needle
short duration
15-45 min
IO injection and systemic effects with lido
HR increase 12-32 ppm lasting 4 mins in 46-90% of pts
perceived 60-75% rate increase
NO affect on BP
IO injection and systemic effect with 3% Mepi without epi
none
Adverse effects of IO injection
Perforator breakage
Rarely separates from plastic
Injection discomfort
Low; may increase with irreversible pulpitis
Postoperative problems
None to mild pain
<5% develop exudate +/or localized swelling
Pressure; thicker bone; larger perforators
Resolve over 3-4 weeks on their own
IO injection success
90-95% for 2% lidocaine w/1:100K epi
Uninflamed and inflamed pulps
Fairly similar rates for 3% mepivacaine
Only with an IAN block (45% as primary)
Duration not as long
Two IO injections increased success to 98%
Reisman et al. OOOOE 1997
Long-acting anesthetics not recommended
Heart muscle toxicityIntrapulpal injection
Assumes an endodontic procedure Advise patient – “sharp sensation” Use as last resort 27- or 30-gauge short needle Tight fit
whats the key to success of intrapulpal injection
0.2 – 0.3 cc over 10 seconds Backpressure is KEY to SUCCESS Birchfield & Rosenberg J Endodon 1975 Solution used is not important Vasoconstrictor is not critical
how often is intrapulpal injection needed
5-10% of time in iR pulpitis
