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454 Cards in this Set
- Front
- Back
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Is the trigeminal nerve a sensory or motor nerve? |
both
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Which branches are sensory only?
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opthalmic & maxillary
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Which branch has both sensory and motor function?
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mandibular
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Where do the divisions of cranial nerve V exit the skull?
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Opthalmic-superior orbital fissure
Maxillary- foramen rotundum Mandibular-foramen ovale |
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The opthalmic nerve divides into three branches... name them...
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nasociliary
frontal lacrimal |
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The maxillary division (V2) gives off branches in four regions... name the regions...
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Branch within the cranium (innervates dura mater)
Branch in the pterygopalatine fossa (zygomatic, pterygopalatine nerves, and PSA) Branches in the infraorbital canal (MSA & ASA) Branches on the face (sensory to face) |
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PSA innervates which tooth
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Molars, except the MB root of the 1st molar
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MSA innervates which teeth?
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Pre-molars & the MB root of the 1st molars
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ASA innervates which teeth?
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canines through central incisors
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Dental Nerves
Interdental Branches Interradicular Branches |
Enter apical foramen
Innervate gingiva Innervate PDL |
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Mandibular Division (V3)
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Largest, sensory & motor
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Motor portion of Mandibular Division innervates what?
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muscles of mastication:
Masseter Temporalis Medial Pterygoid Lateral Pterygoid |
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Anterior Division of V3 is aka the?
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Buccal Nerve
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Posterior Divisions of V3 include...
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auriculortermporal, lingual nerve, IA, mylohyoid nerve,
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Lingual nerve innervates what?
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anterior 2/3 of tongue
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Mylohyoid enters which canal through which foramen?
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mandibular canal through mandibular foramen (to reach the mylohyoid muscle)
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IA nerve enters which canal through which foramen?
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mand. canal, mand. foramen
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which branch of V3 exits the mental foramen?
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mental nerve
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The incisive nerve stays in the mand. canal and forms a nerve plexus which innervates?
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incisors, canines, and 1st pre-molars
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V1 branches |
frontal lacrimal nasociliary |
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V2 branches |
1. Within the cranium *middle menengial nerve 2. Within the pterygopalatine fossa *zygomatic, zygomaticotermporal,zygomaticofacial *PSA *pterygopalatine nerves, orbit, naso/greater/lesser palatine, & pharynx 3. Within infraorbital canal *MSA, ASA 4. Within face *eyebrows, nose, lips, etc |
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V3 branches |
1. Undivided Nerve 2. Anterior Division *Buccal (aka long buccal, & buccinator) nerve--gives off branches to muscles of mastication 3. Posterior Division *auriculortemporal *lingual *inferior alveolar--mental & incisive *mylohyoid |
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Which nerve innervates the buccinator?
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Facial nerve (remember that the buccal or anterior branch of the mandibular is only the main muscles of mastication, & V3 is mylohyoid muscle, ant. belly of digastric, & tensors (typmani & veli palatini))
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Which is more pourous, max. or mand?
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maxilla--it's cancellous spongy bone & is paper thin in some areas
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Which is larges and strongest bone in face?
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Mandible--cortical bone & dense
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3 main components of LA armamentarium?
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syringe, needle, cartridge
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Most common Syringes in Dentistry?
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Breech-loading/metallic/cartridge-type/aspirating
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Other syringes besidesBreech-loading/metallic/cartridge-type/aspirating?
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breech-loading/metallic/cartridge type either aspirating, self aspirating, or non aspirating.
there are also plastic ones, pressure syringes for PDL injections, Jet injectors (needleless), Disposable, "safety" syringes, & Computer controlled LA delivery systems |
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Breech loading means?
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Cartridge is inserted from the side
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Plastic syringe adv. and disadv.
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light, artidge visible, rust resistant, long lasting, lower cost, eliminates "metallic" look
DIS: may be too big, poss. of infection w improper care, plastic deteriorates w autoclave |
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Metallic Breech loading adv. and disadv.
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Adv: visible cartr. one hand aspir., autoclavable, rust resistant, long lasting
DIS: heavier than plastic, may be too big or small for operators, poss of infection w improper care |
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Self Aspirating syringes aspirate as well as the harpoon-aspirating syringe?
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TRUE
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Major factor influencing ability to aspirate?
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gauge of needle
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Pressure syringe for?
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PDL & ILI (intraligamentary) injections
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Jet Injector for?
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primarilly topical anesthetic
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Care & Handling of Syringe
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wash and rinse, autoclave, clean harpoon with brush, & every 5 autoclaves parts should be lubricated
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Problems
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Leakage: from putting in new cartridge and not getting needle in center of diaphram
Broken Cartridge: from bent harpoon, & worn syringe (positive pressure causes it to break) Bent Harpoons: causes off center puncture of plunger-occausionally results in cartr. breakage Disengagement of plunger during aspiration: harpoor should be cleaned, sharpened, or replaced |
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Needles today are
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stainless steel and disposable
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Bevel
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point or tip of needle (long, med, short)
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Shaft
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long tube of metal from tip of needle through the hub and penetrating diaphram
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Two components of needle
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diameter of lumen (gauge)
length of shaft |
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Hub |
plastic or metal piece which attaches needle to syringe |
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Gauge
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diameter of lumen
smaller number = larger diameter 25, 27, 30 most common |
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Larger needles (e.g. 25 gauge) have advantages over smaller needles... they are...
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less deflection, easier aspiration
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25 gauge
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preferred for all injections with high risk of positive aspiration
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27 & 30 gauge should be used
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when penetration depth is not very deep and risk of positive aspiration is not great
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Care of needles
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never use on more than one pt
change needle after 3-4 pentrations cover with protector when not in use always be aware of uncovered needle |
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Problems with needles
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Pain on insertion: use topical
Breakage: from bending typically Pain on withdrawal: fishhook barb needle Injury to pt. or operator: |
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The Cartridge aka carpule (which is registered trade name)
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1.8 ml solutions (could actually hold 2 ml)
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Percent concentration can be converted to...?
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mg/mL (ie 2% lidocaine has 20mg/mL of solution... Thus in a cartridge with 1.8 mL there are 36mg of LA)
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a vasopressor increases safety, duration, & depth of LA action. pH will be more acidic with a vasopressor... If you have a vasopressor you will need an...?
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antioxidant or preservative (commonly sodium bisulfite
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why is sodium chloride in anesthetic solution?
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to make it more biocompatible with the body. Isotonic w body.
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Distilled water provides what to solution?
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volume
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Name the ingredients of the anesthetic solution?
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LA drug
Vasopressor/constrictor Preservative for Vasopressor Sodium Chloride Distilled Water |
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Care of Cartridges
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stored at room temp in original container
not be permitted to soak in sterilizing solutions (can leak in & contaminate) warmers not needed no sunlight |
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Problems with Cartridges
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Bubble in cartridge: nitrogen bubble, anything larger than BB indicates freezing during shipment & should be returned
Extruded Stopper: when liquid expands. It's no longer sterile Burning on Injection: could be *normal response to pH of drug *cartridge contains disinfectant (from soaking) *overheated cartr. *Use of vasopressor Corroded Cap: from soaking Rust on Cap: should not be used. there is a leak in one cartr. in container Leakage during injection: improper injection prep. Broken Cartr: upon shipping |
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Topical antiseptic Topical Anesthetic Applicator Sticks Gauze Hemostat Cotton Pliers are all examples of? |
Additional armamentartium |
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Topical Antiseptic's function is to?
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decreause bacteria at injection site
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Topical Anesthetic
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strongly recommended
Benzocaine most common Lidocaine also used Ointments and sprays *Use gauze to dry, apply topical, 1 minute |
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Hemostat/Cotton Pliers
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Should be available at all times
For removal of broken needle or recap when cap falls to floor |
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3 major types of injections are?
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Local infiltration
Field block Nerve block |
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Local infiltration
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smaller area flooded with LA
terminal nerve endings Depends on diffusion/bone (max. more effective) treatment in same area as injections (ie interprox. papilla) |
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Field block
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near larger nerve branches
above apex of tooth supraperiosteal (incorrectly called infiltration) |
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Nerve block
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deposited close to main nerve trunk
anesthetizes larger area |
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Maxillary injection techniques include
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supraperiosteal
PDL intraseptal intracrestal itraosseous PSA MSA ASA Max. nerve block Greater palatine Nasopalatine AMSA |
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Supraperiosteal points of interest
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anesthetizes large terminal branches of dental plexus
not as effective w inflammation high success easy to do usually atraumatic .6 mL of solution |
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PSA points of interest
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nerve block
MB root of 1st molar not always anesthetized as it could be innervated by MSA nerve hematoma risk (use short needle) Molars & buccal periodontium anesthetized relatively painless high success rate technique harder Landmarks: mucobuccal fold, maxillary tuberosity, zygomatic process of max. |
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Right PSA sit at ?
Left PSA sit at? |
8 o'clock
10 o'clock |
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How long to wait after injections?
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3-5 minutes
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if you go too deep on a PSA it increases risk of what?
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hematoma
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Hematoma in a PSA is due to insertion of needle into what plexus of veins?
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pterygoid plexus
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True or False: The PSA can provide some mandibular anesthesia?
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True... The trunk of V3 is close to the PSA nerves
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The three step phrase associated with Malamed's PSA?
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inward, upward, backward
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What are the average needle lengths of short & long needles?
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20mm & 32mm
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How far should the needle advance for a PSA?
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16mm
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Malamed always says to aspirate 2 times. What does he say to do between aspirations?
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turn the syring barrel (needle bevel) one fourth turn and then reaspirate
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MSA points of interest?
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high success
includes MB root of 1st molar above max. 2nd premolar .9 to 1.2 mL of solution (half to 2/3) will fail if not at apex hematoma may develop (RARE) |
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For right MSA sit at?
Left MSA, sit at? |
10 o'clock
8 or 9 o'clock |
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ASA aka infraorbital block points of interest?
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lack of experience with this
fear of injury to eye can't get adequate hemostasis w ASA difficult defining landmarks height of muccoB fold over 1st premolar ave. penetration 16mm operator can feel solution going in as finger is over foramen keep finger over site for at least 1-2 min. to increase diffusion hematoma may develop (RARE) |
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Palatal Anesthesia
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traumatic for many
use pressure at site before & during deposit SLOWLY recommended 27 gauge believe it can be painless |
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Holding a Qtip or mirror handle at site of injection to produce blanching is known as
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pressure anesthesia
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T or F:
Greater palatine, nasopalatine, and palatal infiltrations injections provide pulpal anesthesia to the teeth near the injection site. |
False--but the AMSA and PASA provide extensive areas of pulpal and palatal
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Greater Palatine Nerve Block
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for palatal soft tissues distal to canine
.45-.6mL of solution subging. restorations, perio, oral surgery no hemostasis & potent. traumatic 27 gauge recommended slightly anterior to foramen come from opposite side of mouth lay bevel on site of penetration and deposit a drop before penetration don't enter canal--no reason to |
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Nasopalatine Nerve Block
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highly traumatic potentially most traumatic
anesthetizes canine to canine Two techniques (1) lateral edge of incisive papilla (2) series of 3 injections starting from facial papilla 27 gauge recommended use pressure anesthesia, place bevel at injection site and deposit drop, deposit as you go .45 ml |
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For the 3 injection technique what sites and in what order are the injections administered?
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.3 ml to the labial frenum
.3 ml to labial aspect of papilla between max. central incisors .3 ml to lateral to incisive papilla (if needed. Often the first two will provide adequate anesthesia) |
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Local infiltration of the palate
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anesthetizes soft tissue in area adjacent to injection
for hemostasis or sub ging procedures on one tooth potentially traumatic 27 gauge rcommended .2-.3 ml of solution |
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The AMSA
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goes in palatal around premolar area
anesthetizes central through premolars of one quad best with a CCLAD system |
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P-ASA
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goes in incisive foramen
provides pulpal anesthesia from canine to canine! |
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Maxillary nerve block
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is not a PSA
anesthetizes all but buccal ging of molars in one quad! |
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For the 3 injection technique what sites and in what order are the injections administered?
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.3 ml to the labial frenum
.3 ml to labial aspect of papilla between max. central incisors .3 ml to lateral to incisive papilla (if needed. Often the first two will provide adequate anesthesia) |
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Local infiltration of the palate
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anesthetizes soft tissue in area adjacent to injection
for hemostasis or sub ging procedures on one tooth potentially traumatic 27 gauge rcommended .2-.3 ml of solution |
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The AMSA
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goes in palatal around premolar area
anesthetizes central through premolars of one quad best with a CCLAD system |
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P-ASA
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goes in incisive foramen
provides pulpal anesthesia from canine to canine! |
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Maxillary nerve block
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is not a PSA
anesthetizes all but buccal ging of molars in one quad! |
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High Tuberosity Approach to the maxillary nerve block
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basically a PSA, but deeper
hematoma high risk overinsertion is possible |
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Greater Palatine Canal Approach to the maxillary nerve block
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insert through greater palatine foramen
advance needle 30 mm never force needle against resistance deposit 1.8 ml |
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The semi-lunar/gasserian ganglion is housed where?
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Meckels Cavity
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Success rate for mandibular IA is higher or lower that most other nerve blocks?
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lower
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Why lower success for IA?
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1. anatomical variation
2. greater depth of soft tissue penetration necessary |
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Which is a true mand. nerve block? And why?
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Gow-Gates--provides anesthesia to virtually all the sensory branches of V3
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Which is injected higher? IA or Gow Gates?
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Gow Gates
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What is the closed mouth technique called?
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Vazirani-Akinosi
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What is the Vazirani-Akinosi used for?
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when limited access is allowed (closed mouth due to trismus, TMJD, etc)
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If you give an IA, what areas are anesthetized?
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all pulpul for one mand. quad, and all soft tissue except for the buccal of the molars
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TorF: It is encouraged to give bilateral IA injections.
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FALSE-that can be super uncomfortable
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What nerves are anesthetized with an IA
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Inferior Alveolar
Lingual Mental Incisive |
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What intraoral injection has the highest rate of aspiration?
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IA 10-15% positive aspiration
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IA points of interest
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25 gauge needle
target IA nerve before it enters foramen imaginary line from coronoid notch to pterygomandibular raphe insert 20-25mm (2/3-3/4 needle) you should have bony contact at 20-25mm |
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What is the biggest reason for a failed IA?
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you injected too low anatomically..
next would be you are too far toward midline |
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What nerve is the prime suspect for accessory innervation of mandibular teeth?
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mylohyoid nerve
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If the mylohyoid nerve needs to be anesthetized...
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go to the lingual apex of the tooth behind the tooth that is the problem and insert 3-5mm and inject .6ml
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If the centrals or laterals are not anesthetized...
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infiltrate supraperiostally into the muccobuccal fold below the apex of the tooth (27 gauge reccommended)
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Trismus is...
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prolonged tentanic spasm of jaw muscles by which opening of mand. is restricted
Gives slight soreness when opening the mandible |
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Trismus is caused by |
injection trauma to muscles or blood vessels in the infratemporal fossa. |
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Injection into muscles leads to ...
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progressive necrosis of the muscle fibers
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other causes of trismus
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hemmorhage
low-grade infection BUT most common is injection into infratemporal fossa muscles or blood vessels |
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Buccal Nerve Block
Long Buccal points of interest |
anesthetizes buccal tissue of molars
it's easy and successful 25 gauge usually done right after IANB long needle since you're going way back in the mouth (not way into tissues) bevel toward bone taut tissue =atruamatic .3 ml |
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If solution runs into patients mouth during long buccal injection what should you do?
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STOP
penetrate deeper Re-aspirate Continue injection |
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Where does a hematoma from a Long buccal/ buccal nerve block occur?
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at injection site
blood may pool in vestibule |
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TRUE Mandibular Nerve Block-Gow-Gates Technique
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25 Long
anesthetizes all of V3 higher success than IANB aim for side of condylar neck just below ML cusp of max 2nd molar penetrate 25mm 1.8ml keep pt. open for 1 min. after for diffusion of LA |
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What nerves are anesthtized by the Gow Gates Block?
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inferior alveolar
mental incisive mylohyoid lingual auriculotemporal buccal |
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Which has a shorter time of onset? the IANB or Gow-Gates?
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IANB
Gow-Gates takes longer (about 5 min) |
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For the Gow-Gates, what imaginary line are you looking for?
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from itratragic notch(below tragus) to corner of mouth
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With the IANB and Gow-Gates, should you contact bone?
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YES- Do not deposit until bone is contacted!
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Vazirani-Akinosi (closed mouth), aka tuberosity technique
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situations w limited opening
difficult to visualize no bony contact ONLY closed mouth techn. 25 guage Long BEVEL AWAY FROM RAMUS BONE (so toward midline) 25mm in 1.8ml |
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Extra-oral mand. blocks can be given through the... |
sigmoid notch or inferiorly from the chin |
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Vaz,-Aki. anesthtizes...
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IA
incisve mental lingual mylohyoid (looks same as IANB in picture) |
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Tingling of lip indicates anesthesia of...
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mental nerve
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Tingling of tongue indicates anesthesia of...
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Lingual nerve
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Complications of Vaz.-Aki.? |
less than 10% change of hematoma rare trismus facial nerve paralysis (caused by overinsertion and injection into parotid gland) |
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Mental Nerve Block points of interest...
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terminal branch of IA
very little need anesthtizes buccal soft tissue from premolars to midline hematoma risk 25 gauge short needle between apices of 1st & 2nd premolars (usually 2nd) locate mental foramen taut tissue=atruamatic .6ml |
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Incisive Nerve Block points of interest...
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terminal branch of IA anteriors
pulpal and buccal soft tissue of premolars to midline NO lingual (more comfy) 25 gauge short just anterior to mental foramen .6ml should slightly balloon maintain pressure over site to push solution into mental foramen hematoma risk at injection site |
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With the incisive nerve block using pressure to guide solution into the mental foramen helps to achive...
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pulpal anesthesia (because it innervates the incisive nerve)
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Rate the IA, GG, and VA in order or aspiration rate from highest to lowest
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IA, VA, GG
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When are intraosseous injections used?
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to supplement failed or partially successful injections
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What is intraosseous anesthesia?
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deposition of LA into cancellous bone that supports the teeth
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What are the three intraosseous techniques?
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PDL, Inraseptal, and the traditional Intraosseous
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PDL points of interest...
aka intraligamentary (ILI) and peridental (original) |
good to sub for failed blocks
with use of supraperiosteal injections in maxilla, PDL is not used as much Good for kids because there is little to no soft tissue anesthesia Causes slight damage to tissues in region of injection ONLY Safe to periodontium There is no need for speical PDL injectors Not good for primary teeth when perm. tooth bud is present 27 gauge short bevel toward the root .2ml keep needle against tooth, go slowly, give only .2ml, and don't inject to to highly inflammed tissues |
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Desire properties of LA
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non irritating
no nerve damage low toxicity effective topically & systemically onset short duration long (enough) potent for complete anest. free from producing allergy stable in solution is sterile or able to be sterilized |
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The concept behind local anesthetic is simple... They prevent both the ______ and _________ of a nerve impulse
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Generation
Conduction |
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Sensory nuerons (afferent) have three major portions--(traditional nueron). They are...
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cell body
axon dendritic zone |
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Dendrites...
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respond to stimulation provoking impulse
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the axon...
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distribute/carry impulses to their appropriate sites
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the cell body...
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provides the vital metabolic support for the entire neuron
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Motor neurons (efferent) (away from the brain) are different than sensory neurons in that... |
the cell body lies between the axon and the dendrites! Thus, motor neuron cell bodies are also part of the impulse transmission |
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AXON characteristics and functions
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cytoplasm (axoplasm)
has a nerve membrane (myelin sometimes) |
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ALL BIOLOGICAL MEMBRANES ARE ORGANIZED TO BLOCK THE DIFFUSION OF WATER SOLUBLE MOLECULES
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TRUE
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nodes of ranvier |
gap between adjoining schwann cells |
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Action potential
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depolarizations from a brief increase in Na permiability
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resting membrane potential
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-70mV
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Depolarization
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(slow & rapid) increase in Na+ permiability thus Na+ rushes in
+40mV |
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Repolarization
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Not permiable to Na+ anymore.
Results in outflux of K+ gradually becomes more negative inside until original resting potential is reached -70mV |
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Absolute refractory Period
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nerve is unable to repond to another stimulus, no matter how strong
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Relative refractory period
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an impulse can be initiated, but only by a stronger than normal stimulus
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When transmembrane potential is decreased by 15mV what is reached?
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threshold potential/firing threshold is reached
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unmyelinated nerves are faster or slower than myelinated nerves
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Slower
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How do LA's interfere with the excitation process?
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Alter resting potential
Alter threshold potential Decrease rate of depolarization Prolong rate of repolarization |
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primary effects of LA occur during which phase of the action potential?
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depolarization
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where do LA's exert their pharmacological actions?
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nerve membrane
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Acetylchoine Theory
NOT TRUE |
said that acetylcholine is involved in nerve conduction as well as being a neurotransmitter at synapse
NO EVIDENCE |
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Calcium Displacement Theory
NOT TRUE |
said that nerve block was produced by displacement of calcium
*concentration of Ca+ ions bathing nerve doesn't affect potency |
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Surface Charge Repulsion Theory
NOT TRUE |
LA acts by binding to membrane and changing threshold potential
EVIDENCE: threshold is unaltered by LA |
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the two theories given credence today are the...
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Membrane Expansion Theory
Specific Receptor Theory |
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Membrane Expanstion Theory
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membrane swells preventing permeability to Na+ ions... Thus, no excitation
Possible explanation for benzocaine (potent topical) |
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Specific Receptor Theory
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MOST POPULAR:
LA binds to specific Rc on Na+ channel. Thus Na+ permeabilty is decreased or eliminated and nerve conduction is interrupted |
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4 sites within the Na+ channel where drugs can alter nerve conduction
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1. within channel (tertiary amine LA)
2. outer surface (tetrodotoxin, saxitoxin) 3-4. either activation or inactivation gates (scorpion venom) |
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Within the channel
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tertiary amine LA
bupivocaine articaine etidocaine lidocaine prilocaine mepivacaine |
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Class A Local Anesthetic
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agents acting on outer surface,
i.e. "biotoxins" (tetrodotoxin & saxitoxin) |
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Class C Local Anesthetic
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Physico-chemical mechanism
exist ONLY in uncharged form (RN) Membrane expansion i.e. benzocaine |
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Class B Local Anesthetic
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activation/inactivation gates on internal surface
i.e.scorpion venom & ammonium analogues of lidocaine |
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Class D Local Anesthetic
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combination of receptor and receptor-independent mechanisms
most clinically useful anesthetic exist in both charged and uncharged forms 90% of blocking cause by cationic form of drug (10% produced by base form) BELMAP |
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Primary action of LA
|
to decrease permeability of channels to Na+...
When safety factor falls below unity, conduction fails and nerve block occurs |
|
|
Sequence of action of LA
|
1. displacement of Ca+ which permits
2. LA to bind with receptor site 3. blockade of Na+ channel 4. decrease in Na+ conductance 5. depression of rate of depolarization 6. failure to achieve threshold 7. lack of propagated action potentials 8. Conduction blockade |
|
|
Nerve block produced by local anesthetic is called...
|
nondepolarizing nerve block
|
|
|
Marjority of LA are tertiary amines and only a few are
|
secondary amines
|
|
|
Amphipathic means
|
possessing both lipophilic and hydrophilic parts
|
|
|
LA is classified as either amino esters or amino amides according to...
|
their chemical linkage/mediate chain
|
|
|
Esters
|
are readily hydrolyzed in aqueous solution
|
|
|
Amides
|
are resistant to hydrolysis
|
|
|
Local Anesthetics are...
|
basic compounds
poorly soluble in water unstable on contact with air dispensed as salts |
|
|
What is the most common salt that LA is dispensed as?
|
hydorchloride (dissolved in either sterile water or saline)
|
|
|
pH greatly influences nerve blocking action. Acidification of tissue does what to LA effectiveness?
|
decreases effectiveness
|
|
|
pH of normal tissue
|
7.4
|
|
|
pH of inflammed tissue
|
5 to 6
|
|
|
pH of solution without epi
|
5.5
|
|
|
pH of solution with epi
|
3.3
|
|
|
lower pH can produce two things.. they are...
|
burning on injection
slightly slower onset of anesthesia |
|
|
increasing pH (more alkaline) of LA solution can
(but it is unstable so ill suited for clinical use) |
speed onset of action
increase effectiveness be more comfortable |
|
|
Sodium Bicarbonate or CO2 added to LA immediately before injection provides two things... they are...
|
greater comfort
more rapid onset |
|
|
interior of nerve pH remains stable and is affected very little by change in external environment, however...
|
ability of LA to block impulses is altered by changes in extracellular pH
|
|
|
hydrochloride or LA salt is both __________ & _________. It exists as ___________ molecules and ___________ molecules.
|
water soluble
stable uncharged poitively charged molecules |
|
|
uncharged molecules exist as
|
RN
(free base form) |
|
|
positively charged LA molecules exist as
|
RNH+
(cation form) |
|
|
in high concentration of H+ ions (acidic/low pH) most of the solution exists in which form?
|
Cationic/RNH+
|
|
|
in lower H+ ion concentration (alkaline/high pH) most of the solution exists in which form?
|
Free Base form/RN
|
|
|
pKa is?
|
dissociation constant
measure of molecules affinity for hydrogen ions. |
|
|
When pKa has the same value as pH what does that mean?
|
50% of the drug exists in RNH+ form and 50% exists in RN form.
logxbase/acid=pH=pKa |
|
|
Which form can diffuse through the nerve sheath?
|
RN (free base form)
|
|
|
Which form is responsible for blocking Na+ channels?
|
RNH+ (cationic form)
|
|
|
At normal tissue pH, and pKa of 7.7 (lidocaine) what percentages exist in RN and what in RHN+ forms?
|
75% RNH+
25% RN |
|
|
High pKa = ______ diffusibility
Low pKa=_______diffusibility |
low (slow onset)
high (quick onset) |
|
|
low pKa=more molecules in base form (RN)
|
high pKa=fewer molecules in RN form
|
|
|
The rate of onset of anesthetic is related to the...
|
pKa of the LA
|
|
|
low pKa=faster onset
high pka=slower onset |
go to pages 19-19 to review
|
|
|
low pH of inflammed tissue=
|
low amount of RN form (slow onset & not much to blockade)
icreased toxicity |
|
|
why are LA containing a vasopressor acidified?
|
to retard oxidation of the vasoconstrictor
which increases period of effectiveness |
|
|
epi can be added to LA right before administration without adding antioxidants, but if the solution isn't used right away, what happens?
|
it turns reddish brown from oxidation
|
|
|
what is the most common antioxidant/preservative?
|
sodium bisulfite (this acidifies the solution)
|
|
|
Why does it take longer for LA with vasoconstrictors/epi to act/set in?
|
the preservative acidifies the solution causing extra time for the body to buffer the acid before the clinical action can start
|
|
|
What can EMLA do that most anesthetics cannot
|
penetrate intact skin (even though it's SLOW)
|
|
|
Can TA diffuse through broken skin and mucous membranes?
|
yes
|
|
|
shelf life lf LA decreases and drug pH ______?
|
increases
|
|
|
Increasing pH provides more RN form, increasing potency, however, in this form, the drug is what?
|
more rapidly oxidized
|
|
|
T or F:
Topical anesthetic is less concentrated than injection. |
False.. It is more concentrated (5-10% lidocaine compared to 2% lidocaine)
|
|
|
Benzocaine is...
|
not ionized in solution
poorly water soluble not likely to cause systemic reactions |
|
|
endoneurium
|
covering that protects and separates individual nerve fibers
|
|
|
perineurium
|
binds fibers together into fasciculi
the thicker the perineurium the slower the rate of LA diffusion |
|
|
perilemma
|
innermost layer of perineurium
main barrier to diffusion into a nerve |
|
|
epineurium
|
loose network of areolar CT
LA can readily diffuse because of it's loose consistency blood vessels and lymphatics transverse the epineur. |
|
|
epineural sheath/nerve sheath
|
surrounds the nerve
not a barrier to LA |
|
|
Which parts of a peripheral nerve are the biggest anatomical barriers to diffusion of LA?
|
perineurium and perilemma
(preineurium greates barrier to "penetration") |
|
|
Diffusion
|
unhindered migration of molecules or ions through fluid under the influence of the concentration gradient
|
|
|
Penetration
|
when drug passes through tissue that tends to restrict free molecular moverment
|
|
|
greater concentration=
|
faster diffusion
more rapid onset |
|
|
mantle bundles
|
fasciculi near the surface of nerve
|
|
|
core bundles
|
closer to the center of the nerve
contacted after delay contacted by lower concentration |
|
|
As LA dissolves it is _______ by tissue fluid
|
diluted
|
|
|
What two things are needed for COMPLETE conduction blockade of all nerve fibers in a peripheral nerve?
|
adequate volume
adequate concentration |
|
|
is there ever a time that 100% of nerve fibers are blocked?
|
NO
|
|
|
mantle fibers tend to innervate more proximal regions... for the IA, what would that be?
|
molars
|
|
|
core fibers tend to innervate more distal points of nerve distribution... for the IA, what would that include?
|
incisors and canines
|
|
|
Besides the nerve, where does anesthetic solution diffuse to?
|
absorbed by nonneural tissue (muscle/fat,etc)
diluted by interstitial fluid removed by capillaries and lymph Ester-type anesthetics are hydrolyzed |
|
|
induction time
|
period from deposition to complete conduction blockade
|
|
|
what factors affecting induction time are under the operators control?
|
Concentration of LA
pH of LA |
|
|
What factors affecting induction time are NOT under the operators control?
|
diffusion constant
anatomical barriers |
|
|
increased lipid solubility permits
|
increased potency
penetration of nerve membrane more easily allows more effective conduction blockade at lower concentration |
|
|
what is the degree of protein binding responsible for?
|
the duration of action of LA
|
|
|
Vasoactivity affects both?
|
potency
duration |
|
|
Vasodilation _______ duration of LA.
Vasoconstriction _______ duration of LA. |
shortens/decreases
lengthens/increases |
|
|
mantle fibers lose LA earlier than ________
|
core cundles
|
|
|
Recovery is usually slower than induction because...
|
LA is bound to Rc in Na+ channel and is released more slowly than absorbed
|
|
|
Tachyphylaxis
|
increased tolerance to a drug administered repeatedly.
*more likely to develop if nerve function is allowed to return before reinjection |
|
|
Causes of tachyphylaxis
|
edema
hemorrhage clot formation transudation *these four isolate the nerve from contact with LA hypernatremia *raises Na+ gradient counteracting decrease in Na+ conduction brought on by LA decreased pH * brought on by first injection (fewer molecules in RN form on reinjection) |
|
|
Order of topical absorption from quickest to slowest
|
trachea
pharynx esophogus & bladder injured skin |
|
|
Factors Affecting LA action:
1. pKa= 2. lipid solubility= 3. protein binding= 4. non-nervous tissue diffusability= 5. vasodilator activity= |
1.=onset
2.=potency 3.=duration 4.=onset 5.=potency & duration |
|
|
recovery from a nerve block (coming off) is slower than onset because...?
|
the LA is bound to the nerve membrane
|
|
|
T or F:
LA has some vasodilatory effects |
True: but it varies and some may produce vasoconstriction
|
|
|
Esters or Amides are more potent vasodilators?
|
Esters
|
|
|
Procaine (Novacaine) is probably the most potent __________.
|
vasodilator
|
|
|
What is the only LA that consistently produces vasoconstriction?
|
Cocaine...
(inititally it produces dilation, but that is followed by an intense & prolonged vasoconstriction) |
|
|
Vasodilation produces
|
increased absorption into blood
decreased duration & depth (quality) increased plasma levels and overdose potential |
|
|
after oral (swallow) administration of LA, the gi tract hardly (if at all) absorbs the LA with the exception of one LA... which is it?
|
Cocaine
|
|
|
Most LA (esp. Lidocaine) undergo a significant _______ ____ _____ _____ (in the liver) after oral administration
|
hepatic first-pass effect
|
|
|
EMLA stands for what and has the ability to do what?
|
Eutetic Mixture of Local Anesthetics
provide surface anesthesia of intact skin |
|
|
What type of administration provides the most rapid elevation of blood levels?
|
IV admin.
*also used to manage ventricular dysrythmias |
|
|
High LA blood levels can induce...?
|
toxic reactions
|
|
|
Highly perfused (vascular) organs initially have higher blood levels of anesthetic... which organs are highly vascular |
Brain, head, liver, kidneys, lungs, & spleen |
|
|
What area contains the highest percentage of LA in the body?
|
skeletal muscle (because it makes up the largest mass in the body)
|
|
|
What affects the plasma conectration/blood levels when it comes to LA?
|
rate absorbed into CVS
rate distributed from blood to tissues rate of elimination |
|
|
rate at which LA is removed from blood is called the...
|
elimination half-life
|
|
|
elimination half-life is...
|
time necessary for 50% reduction in blood level
|
|
|
LA crosses the...
|
placenta and blood-brain barrier
|
|
|
ester's are hydrolyzed in the...
|
plasma
by pseudocholinesterase |
|
|
Procaine (Novacaine) is broken down into
|
PABA (excreted unchanged in urine)
& dietheylamine alcohol (further biotransformationb before excretion) |
|
|
allergic reactions (to esters) are related to ______ and not the parent compound.
|
PABA (paraaminobenzoic acid)
|
|
|
1 in 2800 people have an atypical form of pseudocholinesterase which causes...
|
inability to hydrolyze ester LAs and other chemically related drugs (succinylcholine)
|
|
|
Succinylcholine=
|
muscle relaxant
produces respiratory arrest for 2-3 min |
|
|
psuedocholinesterase hydrolyzes
|
succinylcholine
|
|
|
people with atypical psuedocholinesterase can't hydrolyze |
succinylcholine at normal rate causing prolonged apnea. |
|
|
atypical pseudocholinesterase
|
heriditary trait
a confirmed or strongly suspected histroy of atypical pseudo. is a relative contraindication to use of esters |
|
|
absolute contraindication implies that
|
under NO circumstance should the drug be administered to the patient (potentially toxic or lethal)
|
|
|
relative contraindication implies that
|
drug may be used after carefully weighing risk and benefit if better alternative isn't available
*smallest clinically effective dose should be used and there is an increase of adverse reaction |
|
|
Amide LA's are biotransformed in the...
|
liver
|
|
|
prilocaine (Citanest) is metabolized mostly in the liver, but some occurs in the
|
lungs
|
|
|
liver function & _______ _______ significantly influence rate of biotransformation of amide LA.
|
hepatic perfusion
|
|
|
ASA I
|
No systemic disease
*Can have conscious sedation without PCP consult |
|
|
ASA II
|
Single systemic disease (mild & well controlled)
*Can have conscious sedation PCP consult for disease assessment |
|
|
ASA III
|
Multiple systemic diseases or moderately controlled syst. diseases
*Medical consult, review labs & meds |
|
|
ASA IV
|
poorly controlled systemic diseases
*Refer to anesthesiologist for sedation |
|
|
ASA IV to V represents a(n) _______ contraindication to _______ LA's
|
relative
amide |
|
|
what substance induces formation of methemoblobin ?
|
orthotoluidine
|
|
|
orthodtoluidine is a metabolite of which LA?
|
prilocaine
|
|
|
methemoglobinemia=
|
excess accumulation of methemoglobin in the blood
|
|
|
what is the primary excretory organ for LA and it's metabolites?
|
kidney
|
|
|
which appears more in urine?
amides or esters? |
amides (because ester is mostly metabolized in the plasma)
|
|
|
significant renal impairment ______ the potential for toxicity.
|
increases
(because more accum. in the blood) --esp. cocaine |
|
|
signif. renal disease is a _______ contraindication to LA
|
relative
|
|
|
LA block actions potentials. Is this reversable or irreversible?
|
reversable
|
|
|
Most action of LA is related to _______. The higher the level, the greater the clinical action.
|
blood/plasma levels
|
|
|
centbucridine (a quinoline derivative) is 5-8 times as potnent as lido .. It is special because it does not affect the _____ or ______ adversely except in very high doses.
|
CNS or CVS
|
|
|
LA crosses the ______ & the ________
|
blood brain barrier
placenta |
|
|
what does LA do to the CNS?
|
depress
|
|
|
What manifests higher, toxic overdose levels of LA in the CNS?
|
tonic-clonic- convulsion
|
|
|
Some LA have anticonvulsant properties ... which are they?
|
procaine, lidocaine, prilocaine, mepivacaine, and even cocaine
|
|
|
.5-4 ug/ml = 4.5-7 ug/ml = Greater than 7ug/ml = |
anticonvulsant preseizure signs & symptoms tonic-clonic seizure |
|
|
what are pre convulsive signs and symptoms?
|
slurred speech
shivering twitching & tremor lightheadedness dizziness visual disturbance auditory disturbance drowsiness disorientation |
|
|
at 2-3mg/kg, lidocaine has been especially effective in interrupting ______.
|
status epilepticus
|
|
|
LA raise the seizure threshold by ?
|
decreasing excitability of neurons
|
|
|
CNS more sensitive to LA than
|
other systems
|
|
|
above 4.5 signs and symptoms are...
|
excitatory
|
|
|
lidocaine and procain produces initial mild sedation or drowsiness.. what is the result of this?
|
US Air Force & Navy pilots are grounded for 24 hours after receiving LA
|
|
|
What are warning signs of possible toxic blood anesthetic levels
|
excitation or sedation 5-10 minutes arter administration of LA
|
|
|
duration of tonic-clonic reaction from high LA blood levels depends on...
|
blood level & arterial pCO2 level.
|
|
|
When CO2 levels in blood are increased, blood level of LA necessary for seizures ________.
|
decreased
(you don't need as much LA in blood to cause seizure if CO2 is high) |
|
|
during seizure _____ is not signif. impaired reulting in decrease of LA blood level and termination of seizure, usually in less than ________.
|
Cardiovasuclar system
1 minute |
|
|
what acts to prolong convulsive episode of LA overdose?
|
increased blood flow to brain
increased cerebral metabolism |
|
|
dose of LA necessary to cause seizures decreases in _______ or ______.
|
hypercarbia (CO2)
acidosis |
|
|
If anesthetic continues to rise after tonic-clonic phase, seizures will stop, and ______ will occur.
|
respiratory depression
|
|
|
The two parts of CNS that stay in balance according to Malamed are...
|
inhibitory impulse
facilitatory impulse |
|
|
the preconvulsant stage of LA blood levels are produced because ...
|
depression of inhibitory neurons
*(the reason symptoms are excitatory is because depression of inhibitory impulse leaves the facilitatory(excitatory) free and uninhibited) |
|
|
at convulsive blood levels, tonic-clonic symptoms occur because...
|
the inhibitory impulse is completely depressed allowing unopposed function of facilitatory neurons
|
|
|
eventually, increases in LA lead to depression of both the faciltatory and inhibitory pathways ... we call that... |
generalized CNS depression |
|
|
LA intravenously ______ the pain threshold and produces _____.
|
increased
a degree of analgesia |
|
|
cocaine used for
|
mood elevation
(euphoric, fatigue-lessening actions) |
|
|
LA have direct action on myocardium, however the CVS is more ______ to the effects of LA than the CNS
|
resistant
|
|
|
LA _____ force of heart contraction and ______ the conduction rate
|
decrease
decrease |
|
|
what is a theraputic use of LA on the CVS?
and which of the LA's are most useful in humans? |
treating hyperexcitable
procaine & lidocaine 1.8 to 6 ug/ml |
|
|
Lidocaine for cardio therapy
|
dysrythmias
tachycardia life support management of premature ventricular contraction's |
|
|
LA blood levels greater than theraputic level = |
further decrease in contraction & output which lead to circulatory collapse |
|
|
Cocaine is the only LA that does what?
|
vasoconstricts
*Ropivacaine causes cutaneous vasoconstric. |
|
|
what does LA do to blood vessels?
|
dilates
|
|
|
what is the PRIMARY effect of LA on blood pressure?
|
hypOtension
|
|
|
which is more of a vasodilator... procaine or lidocaine?
|
Procaine
|
|
|
LA effects on CVS:
nonoverdose levels |
at the very beginning there is a slight increase or no change in blood pressure
|
|
|
LA effects on CVS:
approaching overdose, yet still below |
HYPOtension
relaxed smooth muscle |
|
|
LA effects on CVS:
overdose levels |
profound hypotension
depressed cardiac muscle |
|
|
LA effects on CVS:
lethal levels |
cardiovascular collapse
|
|
|
Which LA;s could precipitate a fatal ventricular fibrillation?
|
bupivacaine
*lesser degree: etidocaine & ropivacaine |
|
|
Which tissues seems to be more sensitive to LA than other tissues?
|
skeletal muscle
|
|
|
T or F:
intramuscular & intraoral injection of amides can produce skeletal muscle alterations. |
TRUE
|
|
|
longer-acting drugs cause ____ skeletal muscle damage than shorter-acting drugs.
|
MORE
|
|
|
is muscle damage reversible?
if so how long does it take to heal? |
YES
within 2 weeks |
|
|
LA effect on Resp.
nonoverdose levels |
relax bronchial muscle
|
|
|
LA effect of Resp.
overdose levels |
may produce respiratory arrest due to CNS depression
|
|
|
In general, respiratory function is ______ by LA until near-overdose levels are reached.
|
unaffected
|
|
|
LA combined with CNS depressants can produce adverse reactions.. what are they?
|
1. esters and the relaxant succinylchoine require pseudocholinesterase or hydrolysis (& only one will get it) this can result in prolonged apnea if succinylcholine is not hydrolyzed.
2. barbituarates can increase the rate of metabolism of LA |
|
|
malignant hyperthermia |
disorder where genetic variant alters response to certain drugs |
|
|
manifestations of malignant hyperthermia (MH) =
|
tachycardia, tachypnea, unstable BP, cyanosis, metabolic & resp. acidosis, fever, muscle rigidity and death
|
|
|
can amides trigger MH?
|
there is no documented evidence
|
|
|
when blood vessels dilate, what happens to LA?
|
increased absorption
higher blood/plasma levels decreased depth & duration increased bleeding at tx site |
|
|
Vasoconstrictors cause what when it comes to LA?
|
decrease blood flow to admin. site
decreased absorption decreased blood/plasma levels decreased toxicity increased duration decreased bleeding |
|
|
vasoconstrictors resemble which nervous system?
|
sympathetic
|
|
|
what are the adrenergic or sympathomimetic mediators?
|
epinephrine and norepinephrine
|
|
|
sympathomimetic drugs are classified by
|
presence or absence of a catechol nucleus
|
|
|
with only the hydroxyl (OH) =
|
catechol
|
|
|
withthe hydroxyl + amine group =
|
catecholamine
*epi, norepi are naturally occuring catecholamines *isoproterenol & levnordefrin are synthetic catecholamines |
|
|
direct-acting
|
exert action directly on adrenergic Rc
|
|
|
indirect-acting
|
release norepi from adrenergic nerve terminals
|
|
|
the two types of adrenergic Rc are
|
alpha
beta |
|
|
alpha Rc response
|
smooth muscle contraction in blood vessels
alpha1=excitatory alpha2=ihibitory |
|
|
beta Rc response
beta1 beta2 |
smooth muscle relaxation
beta1=heart beta2=lung |
|
|
resting plasma epi levels are _______ after one carp of 1:100,000 epi
|
doubled
|
|
|
norepi does not act on B2 Rc and has a side effect ratio....
|
9 x higher than epi
|
|
|
True or False:
Use of epi & norepi mixed is to be absolutely avoided! |
TRUE
|
|
|
Levarterenol=
Levnodefrin= Phenylephrine= |
no longer available in US
cant be imported no longer available in US |
|
|
Concentration of VC
1:100,000= 1:200,000= 1:50,000= |
.01 mg/ml
.005 mg/ml .02 mg/ml |
|
|
MRD vasoconstrictor healthy=
MRD vasoconstrictor cardiac= |
.2mg/ml epi
.04 mg/ml epi |
|
|
Epinephrine or adrenalin
what is added preservative? shelf life? acts on which Rc? |
sodium bisulfite
18 months both alpha and beta *with beta predominance |
|
|
Even though all the heart responses are increased, there is an overall decrease in..?
|
cardiac efficiency
|
|
|
Epinephrine
|
dilates coronary arteries
bronchiodilates elevates blood sugar levels after 4 cartridges produces mydriasis |
|
|
manifestations of epi overdose
|
CNS stimulation:
fear & anxiety tension resltessness headache tremor weakness dizziness etc etc etc |
|
|
1:100,000 is the what those in North America should use for pain control, but where available_______ should be used
|
1:200,000 or 1:300,000
|
|
|
1:100,000 is preferred over 1:50,000 for hemostasis unless really needed
|
true
|
|
|
Levonordefrin
|
Neo-Cobefrin
acts on alpha Rc with some beta *same as epi, but to lesser degree |
|
|
Factors in selecting a VC
|
length of procedure
need for hemostasis medical status of patient |
|
|
4 conditions to weigh when considering using VC
|
1. high blood pressure 200/115
2. cardiovascular disease-MI in last 6 mo., angina, arrythmia 3. hyperthyroidism-pts w symptoms may not respond to epi 4. MAO & tricyclic anti-depressants & phenothyazines-can receive normal but not large doses |
|
|
Felypressin recommended for ASA III and IV CVD risk patients because...
|
it has minimum CV stimulation and is non-dysrhythmogenic
|
|
|
Levnordefrin & Norepinephrine are absolute contraindications with...
|
Tricyclic antidepressants
|
|
|
what makes a solution c epi more acidic?
|
sodium (meta) bisulfite --the preservative
|
|
|
acidic LA solutions contain more ____ and thus diffusion of LA into axoplasm is _____ resulting in ______ onset of anestheisa.
|
RNH+
slower delayed |
|
|
Duration of Action:
1.Bupivicaine 2. Articaine 3.Lidocaine 4. Prilocaine 5.Mepivacaine |
1.long
2. intermediate 3. plain it's short, c epi it's intermediate 4. plain it's short, c epi it's intermediate 5. plain it's short, c eip it's intermediate |
|
|
factors that affect depth and duration:
|
individual response to drug
accuracy of deposition vascularity & pH of tissue anatomical variation type of injection (infiltration/nerve block) |
|
|
variation in individual response is represented by?
|
a bell curve
(majority of patients in middle, with extremes on either end) *normal responders *hyper-responders-anesthesia lasts beyond expected time *hypo-responders |
|
|
nerve block=
|
longer duration of both pulpal and soft tissue anesthesian that the supraperiosteal
*esp prilocaine 4% (longer NB & shorter infiltration |
|
|
doses of LA in
|
mg/kg or mg/lb
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ABSOLUTE CONTRAINDICATIONS=
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documented LA allergy=no LA of that chemical class
Bisulfite allergy=no vasoconstrictor anesthetic |
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RELATIVE CONTRAINDICATIONS=
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atypical pseudocholinesterase=no esters
methemoglobinemia=no prilocaine liver disfunction=no amides renal disfunction=no amides or esters CVD=no vasoconstrictors in high dose (like racemic epi ging. cords) hyperthyroid=no vasoconst. in high dose (like racemic epi. ging. cords) |
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to increase safety one should always use the...
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smallest clinically effective dose
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two groups at increased risk from overly high LA levels
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small child
debilitated elderly *MRD should always be decreased for medically compromised, debilitated, or elderly |
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Procaine HCl
*Novocaine |
class: ester
metabolized: plasma *greatest vasodilation of all current LA *increased bleeding *injected Intraarterial *high pKa, slow onset |
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Propoxycaine HCl
*mixed |
class: ester
metabolized: plasma & liver *rapid onset *was combined c procaine for more rapid onset *high toxicity |
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Lidocaine HCl
*Xylocaine *Alphacaine *Lignospan *Octocaine |
class: amide
metabolized: liver rapid onset, pKa 7.9 *allergies to amides extremely rare *gold standard of LA *lidocaine plain is rare *available as topical |
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MRD in ...
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mg/kg or mg/lb
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is 1:100,000 as effective for hemostasis as 1:50,000?
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NO
for pain control it is great, but hemostasis is greater in a 1:50,000 concentration |
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Mepivacaine HCl
*Polocaine *Carbocaine *Scandonest *Isocaine *Arestocaine |
class: amide
metabolized: liver *mild vasodilation (so more duration than other plain LA) *rapid onset with 7.6 pKa |
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Prilocaine HCl
*Citanest *Citanest Forte |
class: amide
metabolized: liver & lungs (CO2 major biproduct of prilocaine metabolism) *methemoglobinemia (reversed with methylene blue IV) *rapid metabolism (thus less toxic) *pKa 7.9, onset slower than lido *part of EMLA (lido-prilo) *longer acting with NB & shorter with infiltration *prilo plain NB can get same anesthesia as lido or mepiva |
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RELATIVE CONTRAINDICATIONS TO PRILOCAINE
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methemoglobinemia
hemoglobinopathies (sickle cell) cardiac/resp. failure pts taking acetaminophen or phenacetin |
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Articaine HCl
*Septocaine *Septanest *Astracaine *Ultracaine |
class: amide
metabolized: both plasma & liver pKa 7.8, rapid onset *possess a thiopene ring *claims: faster onset, increased success, increased parasthesia, diffuses through tissues better, infiltrate mandible (these haven't been proven) *used to have paraben--now paraben free |
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Bupivacaine HCl
*Marcaine |
class: amide
metabolized: liver pKa 8.1 little longer onset *used for lengthy anesthesia & post-op pain (not drug of choice for little ones :)) |
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Regimen that works for Post-op Pain
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1. Give 1-2 doses of oral NSAID
2. Use suitable LA for procedure 3. Give bupivacaine right before pt leaves office 4. have pt continue to take NSAID every "x" hours prn |
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Etidocaine HCl
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class: amide
pKa 7.7, onset like lido *long acting like bupivacaine |
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Topical LA |
greater concentration than injected LA vascular absorption is rapid (no vasoconstrictor) |
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Lidocaine
Benzocaine Tetracaine Cocaine Dyclonine are all.. |
useful as topical LA
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Benzocaine
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class: ester
used: topical, not injection poorly soluble in water and CVS remains at site longer *available as aerosol, gel, patch, ointment, solution |
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Cocaine hydrochloride
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class: ester
exclusively for topical rapid acting, lasts long metabolized: liver (even though it's an ester) schedule II drug *abuse potential-not recommended in dentistry |
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Dyclonin HCl
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good for pts with allergy to other LA
potent like cocaine slow onset (up to 10 minutes) low toxicity because of poor H2O solubility |
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EMLA
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eutectic mixture of LA
cream: 2.5 lido 2.5 prilo *designed to penetrate intact skin tube or disc for application NOT FOR methemoblobinemia pts, allergic to amide pts. * |
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Lidocaine Topical
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two forms
lido base-use on ulcerated, abraded, or lacerated tissue & lido hydrochloride-penetrates better, but toxicity is higher |
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Tetracaine HCl
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long duration ester
water soluble more potent than cocaine (5-8x) |
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Selection of LA based on
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length of procedure
need for post-op pain need for hemostasis any contraindications |
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Don't give long lasting LA to..
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younger children
mentally disabled who might injure themselves (biting lips, tongue, cheeks) --infiltration recommended |
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How many drugs are recommended for each dental office by Malamed?
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at least 2
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what is the rebound effect?
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after epi levels decline, vasodilation occurs can lead to post op bleeding
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halogenated general anesthesia refers to
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inhalation anesthesia
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general anesthesia _____ myocardium
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sensitizes
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anesthesiologists should use minimal dosages of
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epinephrine
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determine MRD of vasoconstrictor for healthy pt. w lidocaine 1:100,000 epi?
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take recommended amt for healthy pt=.2 & divide by amt vasoconstrictor in 1:100:000 =.01
SO .2/.01=20mg Now take 20 mg & divide by ml in a cartridge=1.8 SO 20/1.8=11.1 THUS you can give 11.1 carpules with epi before you reach the MRD for epi *For cardiac pt. just substitute the .2 for .04 which is the recommeded amount for a cardiac pt. |
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MRD based on weight in mg/lb
Articaine Bupivicaine Lidocaine Mepivacaine Prilocaine |
Look in book at both manufacturers and Malamed's MRD's
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what are the 2 most common psychogenic reactions to injection?
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vasodepressor syncope
hyperventilation |
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Antibiotic Prohylaxis Recommended in
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HIGH RISK:
prosthetic valves & grafts previous endocarditis complex congential heart disease pulmonary shunts/conduits MODERATE RISK: other congenital malformities valvular dysfunction hypertrophic cardiomyopathy mitral valve prolapse w regurgitation |
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Antibiotic Prophylaxis Recommended for (dental procedures)
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extractions
perio procedures implants endo work subging. anything ortho bands (not brackets) intraligamentary injections cleaning where bleeding is anticipated |
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how much Amoxicillan for Pre-med
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2 grams 1 hr prior
kids=50 mg |
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What is the pre med for those who can't take oral medicine?
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Ampicillin
2grams IV or IM within 30 minutes of procedure |
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If pt. needing pre-med is allergic to penicillin what do you give them?
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Clindamycin 600 mg 1 hour before
OR Cephalexin 2 g 1 hr before OR Azithromycin 500 mg 1 hr before *Clindamycin can also be given IV for those unable to take oral meds and allergic to penicillin... give 600mg 30 minutes prior |
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ASA V
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pt not expected to live 24 hrs w or wout operation
*hospitalized & dental care limited to palliative only |
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ASA VI
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clinically dead waiting for harvesting of organs
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Two drugs mainly seen in MH?
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succinycholine (77%)
halothane (60%) *MH mostly happens in general anesthesia and less in local |
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What is the earliest symptom of MH?
& What is the key for managing MH in the dental office? |
tachycardia
*prevention! *dantrolene sodium and the use of "safe" drugs=successful dental experience |
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succinylcholine produces apnea for a brief time with ventilation returning when...
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succinylcholine is hydrolyzed by plasma cholinesterase
*when atypical psc is present, apnea is prolonged |
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when an ester is not hydrolyzed by psuedocholinesterase, what happens?
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overdose levels of LA are more apt to be noted
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methemoglobin is
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the ferric form of hemoglobin which is more firmly attached to the RCB and can't be released into the tissues
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what enzyme is missing in a pt with methemoglobinemia?
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methemoglobin reductase (erythrocyte nucleotide diaphorase)
*when present, it converts iron from ferric form back to ferrous form which can be released into tissues |
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Otoluidine (a Prilocaine metabolite) has the ability to do what?
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oxidize ferrous iron into the ferric form increasing methemoglobin levels
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what are pathonuemonic signs of methemoglobinemia? |
cyanosis that doesn't respond to O2 & brown arterial blood |
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If a pt is numb for hours longer, is that okay?
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yes
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if pt is numb for days, weeks, or months then?...
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there is invcreased potential for development of problems
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Paresthesia is one of the most frequent causes of ...
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malpractice litigation
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paresthesia is defined as
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persistant anesthesia (well beyond expected duration)
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insertion of needle into foramen ________ liklihood of nerve injury
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increases
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Causes of parethesia
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trauma
hermorrhage LA solution itself most often reported after use of 4% concentration (either articaine or prilocaine) |
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hyperesthesia
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increased sensitivity to noxious stimuli
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dysesthesia
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pain sensation to usually nonnoxious stimuli
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most paresthesias resolve within ___ weeks without tx
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8
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how often should the dr examine a patient with paresthesia?
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every two months for as long as it persisits
*if sill there after 1 yr, consult oral surgeon or neruologist (can consult earlier if pt. or dr. wishes) |
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What occurs when anesthesia is presented into the deep lobe of the parotid gland?
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facial nerve paralysis
*usually lasts the same time as soft tissue anesthesia for that drug would and will resolve without residual effect |
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what are problems with facial nerve paralysis?
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cosmetic
inability to close one eye (blinking) |
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Trismus
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tetanic spasm of jaw
normal opening of mouth restricted |
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what causes trismus?
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trauma to muscles or blood vessels in the infratemporal fossa
LA which alcohol or cold sterile has diffused hemorrhage low grade infection multiple needle penetrations |
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what for tx of trismus?
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heat therapy
warm saline rinse analgesic muscle relaxant physiotherapy (open & close & lateral excursions) chewing gum |
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What to manage self inflicted soft tissue injury?
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anagesics
antiobiotis (if infection occurs) saline rinse (decr. swelling) vaseline or lubricant (min. irritation) |
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Hematoma
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effusion of blood into extravascular spaces from nicking a blood vessel during injection
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how to manage hematoma?
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direct pressure over area of deposition
note in chart! advise pt about soreness and poss. trismus you can ice it it will take time to go away |
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ideal rate of injection=
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1 ml/minute
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what is the most common cause of post injection infection?
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needle contaimation
*other possible causes=improper handling of equipment and tissue prep. |
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why might edema be present after injection?
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trauma
injection allergy hemorrhage herediatary angioedema |
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sloughing of tissue might be caused by?
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topical (normal reaction or from prolonged period)
sensitivity to LA |
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toxic reaction is synonomous with
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overdose
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difference between allergy and overdose
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allergy is exaggerated response of immune system (symptoms the same in every allergy)
overdose is exaggerated response of clinical action of drug (symptoms depend on the drug you took) |
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according to the author, what is the most important factor in preventing overdose reactions?
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the rate of deposition
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eleveated blood levels of LA may result from ...
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slow bitransformation
slow elimination from body too large total dose rapid absorption into blood stream inadvertant IV administration occurs |
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CVS overdose levels
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1.8-5=antidysrhythmic
5-10=myocardial depression 10+=cardiac arrest |
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CNS overdose levels
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.5-4=anticonvulsant
4.5-7=pre-seizure 7.5-10=tonic clonic seizures 10+=generalized CNS depression |
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Basic Emergency Management
P, ABC's, D |
Position:
supine feet elevated=unconscious pt. comfort=conscious Airway: assess & maintain Breathing: asses and ventilate if necessary Circulation: assess and provide compression if needed Definitive Care: Dx Mngment: emergency drugs/assistance 911 |
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Recommeded mg/lb
Articaine Bupivacaine Lidocaine Mepivacaine Prilocaine |
3.2 -- 500
.6 -- 90 2 -- 300 2 -- 300 2.7 -- 400 |
