Oral Maxillofacial Trauma & Local Anesthetics - Quiz 5 Flashcards
Which Facial Fracture is Triangular/Pyramidal in shape and affects the Nose and Palate?
Lefort II
Which type of Facial Fracture affects the entire face and completely separates the Midfacial Skeleton from the Cranial Base?
Lefort III
Which type of Facial Fracture affects just the Palate?
Lefort I
What is a concern while Intubating if a Lefort II or III is suspected?
Possible Intracranial Placement of ETT
Label the 7 Parts of the Mandible.
What are the Anesthetic Considerations regarding Facial Fractures?
Pretreat Edema w/ Steroids
Difficult/Bloody Airway
Awake Extubation
MUST have Wire Cutter/Scissors
What med can be given to help with Nasal Intubation?
Phenylephrine
A Left Enantiomer is denoted with an ___ for _______ and a Right Enantiomer is denoted with an __ for _______
A Left Enantiomer is denoted with an “s” for SINISTER and a Right Enantiomer is denoted with an “r” for RECTUS
Which Local Anesthetics are Pure Isomers?
Ropivacaine (s)
&
Levobupivacaine (s)
What are the advantages of using Local Anesthetics that are S Enantiomers?
S Enantiomers are LESS Neuro & Cardio-toxic
How do Local Anesthetics work?
Stops Na+ Ions from going through Sodium Channels
Slows Depolarization
Local Anesthetics do not alter _____ or _____ potentials
Local Anesthetics does not alter RESTING MEMBRANE or THRESHOLD potentials
How do Local Anesthetics affect nerves with more activity and firing?
Faster Blockade d/t more frequently activated-open state
Local Anesthetics have a much lower affinity for ________ than they do Sodium Channels
Local Anesthetics have a much lower affinity for POTASSIUM ION CHANNELS than they do Sodium Channels
What Increases the Minimum Local Anesthetic Concentration (Cm) to produce a conduction block?
Larger Nerve Diameter
What factors Decrease Minimum Local Anesthetic Concentration?
Higher Frequency Nerves
&
Higher pH
How does the Minimum Local Anesthetic Concentration compare between Motor & Sensory Nerves?
Minimum concentration is 2X more for Motor than Sensory Nerves - easier to block Sensory Nerves
How do Epidurals & Spinals affect Local Anesthetic Minimum Concentration?
No effect on Minimum Concentration, but requires less amount d/t direct nerve access
Local anesthetics must block at least ______ Nodes of Ranvier, preferably ____ Nodes
Local anesthetics must block at least TWO Nodes of Ranvier, preferably THREE Nodes
What is the Order of Blockade for Nerve Fibers
- B Fibers
- C & A-Delta Fibers
- A-Gamma Fibers
- A-Beta Fibers
- A-Alpha Fibers
What does the blocking of B Fibers affect?
Preganglionic Sympathetic Efferents
What does the blocking of C & A-Delta Fibers affect?
Pain
Temperature
Touch
Postganglionic Sympathetic Neurons
What are the function of A-Gamma fibers?
Efferent to Muscle Spindles
Muscle Tone
What is the function of A-Beta Fibers?
Afferent from Skin & Joints
Tactile
Propioception
Touch Pressure
What is the Function of A-Alpha Fibers?
Efferent to Muscles
Motor
&
Propioception
What is the Order of Blockade for Nerve Functions?
ATP - TP - MVP
Autonomic, Temperature, Pain
Touch & Pressure
Motor, Vibration, Proprioception
What happens if B, C, and small/medium A Fibers are blocked, but NOT Large A Fibers?
Sympathectomy
Loss of Temp & Pain Sensation
Preserved Motor & Proprioception
What form is required to cross the Lipid Bilayer regarding pK?
Unionized, therefore Local Anesthetics closer to Physiologic pH have FASTER onset
Which particular Local Anesthetic does NOT ionize based on pH and has an Unknown mechanism?
Benzocaine - Weak Acid - pKA 3.5
A ________ pH Lessens sting of Local Infiltration
A HIGHER pH Lessens sting of Local Infiltration
How is Local Anesthetics Distrubuted throughout the body?
Lungs 1st
High Perfused Tissues 2nd
<span>(Heart, Brain, Kidneys)</span>
Low Perfused Tissue 3rd
(Muscle & Fat)
Which type of Local Anesthetics are more widely distributed throughout the body?
Amides
Which Local Anesthetic has a higher chance to Crossing Placenta: Lidocaine, Bupivacaine, or Ropivacaine?
Lidocaine since it’s NOT as protein-bound
What happens when Local Anesthetics cross the placenta?
Local becomes more Ionized & cant get back out = Fetal Local Toxicity from Ion Trapping
The Potency of Local Anesthetics is related to ________, while the Onset is more related to ______
The Potency of Local Anesthetics is related to LIPID SOLUBILITY, while the Onset is more related to IONIZATION
How does Protein-Binding of Local Anesthetics affect Duration of Action?
More Protein-Binding = Stronger Attachment & Longer Duration
Which Amide is the fastest to be Metabolized?
Prilocaine
Which Amides are the slowest to be Metabolized?
Etidocaine
Bupivacaine
Ropivacaine
How are Amides metabolized versus Esters?
Amides = Hepatic Clearance
Esters = Plasma Cholinesterase
Which Ester is the fastest to be metabolized?
Chloroprocaine
Which Ester is the slowest to be metabolized?
Tetracaine
What Ester metabolite can cause allergic reactions?
Paraaminobenzoic Acid (PABA)
Which local injection site has little to no cholinesterase?
CSF - must wait for systemic absorption for hydrolysis
What can Inhibit the activity of Plasma Cholinesterase?
Liver Disease
Increased BUN
Parturients
Chemotherapy
What is the function of Epinephrine with Local Anesthetics?
Test Dose
Limits Systemic Absorption
Prolongs Lidocaine by 1/3
No effect on Onset
Which two Local Anesthetics have ZERO Vasodilator Activity?
Cocaine & Ropivacaine
How does Clonidine affect Local Anesthetics?
Enhance Neuraxial Anesthesia & Increase Duration
The Effects of Mixing Local Anesthetics are _______ and NOT _______
The Effects of Mixing Local Anesthetics are ADDITIVE and NOT SYNERGISTIC
What is the Max Dose of Lidocaine?
300 mg
What is the Max dose of Ropivacaine?
200 mg
What is the Max dose of Bupivacaine?
175 mg
What are symptoms of Systemic Local Anesthetic Toxicity w/ Plasma Lidocaine levels of 5-10 mcg/mL?
Circumoral Numbness
Tinnitus
Twitching
Hypotension
Myocardial Depression
What are symptoms of Systemic Local Anesthetic Toxicity w/ Plasma Lidocaine levels of 10-15 mcg/mL?
Seizures & Loss of Consciousness
What are symptoms of Systemic Local Anesthetic Toxicity w/ Plasma Lidocaine levels of 15 - 25 mcg/mL?
Apnea & Coma
What are symptoms of Systemic Local Anesthetic Toxicity w/ Plasma Lidocaine levels > 25 mcg/mL?
CV Collapse
What are the systemic levels related to blood flow of tissue from fastest to slowest for Local Anesthetics?
In Time I Can Please Everyone But Suzi and Sally
IV
Tracheal
Intercostal
Caudal
Paracervical
Epidural
Brachial Plexus
Subarachnoid
Subq
What is the risk involved with Intrathecal Lidocaine?
Transient Neuro Symptoms (Back, Butt & Thigh Pain)
Cauda Equina Syndrome
Anterior Spinal Artery Syndrome
What is Cauda Equina Syndrome?
Neurotoxicity r/t Lidocaine
Lumbosacral Plexus Injury
Bowel & Bladder Dysfunction
Paraplegia
What happens with Anterior Spinal Artery Syndrome?
Lower Extremity Paresis
&
Sensory Deficit
It takes 3x more in Plasma Local Anesthetic Concentration to see Cardiotoxicty versus CNS, except when using which Local Anesthetic?
Bupivacaine 8-10 mcg/mL - will see CV symptoms before CNS
What happens with Cardiotoxicity r/t to Local Anesthetics?
Profound Hypotension
&
Myocardial Depression
What should be done first for treating Local Anesthetic Toxicity?
Manage Airway & Supress Seizures
Regarding Local Anesthetic Toxicity, which meds should be avoided when managing Arrhythmias?
Vasopressin
B-Blockers
CC-Blockers
Reduce Epi to < 1mcg/kg
What can be given for CV Collapse related to Local Anesthetics?
20% Lipid Emulsion
Which Local Anesthetics is Methemoglobinemia associated with?
Prilocaine > 8mg/kg
Lidocaine
Benzocaine
Cetacaine
