Local Anesthesia Boards Prep

Front 1

With the exception of prilocaine and hexylcaine, what molecular class do the majority of injectable local anesthetics fall under?

Back 1

Tertiary Amines
(Prilocaine and hexylcaine are secondary amines)

Front 2

What part (lipophobic or lipophilic) is the largest of the molecule?

Back 2

Lipophilic

Front 3

True or False: All local anesthetics posses hydrophilic and lipophilic characteristics.

Back 3

True; this is called amphipathic

Front 4

True or False: Local anesthetic parts with a hydrophilic part are not suited for injection but are good topical anesthetics (i.e. Benzocaine)

Back 4

False; Local anesthetics WITHOUT a hydrophilic part are not suited for injection, but make good topical agents

Front 5

What are the two chemical classes that local anesthetics can be according to their linkage?

Back 5

1) Amino Esters
2) Amino Amides

Front 6

True or False: Ester-linked local anesthetics (procaine) are readily hydrolyed in aqueous solution.

Back 6

True

Front 7

True or False: Amide-linked local anesthetis (lidocaine) are relatively resistant to hydrolysis.

Back 7

True

Front 8

Which class, amide or ester local anesthetics, are excreted in a greater percentage in the urine unchanged?

Back 8

Amides

Front 9

List three properties of local anesthetics as prepared in the labratory:

Back 9

1) Weakly Basic
2) Poorly soluble in water
3) Unstable when exposed to air
In this form, they are of little clinical value

Front 10

What do local anesthetics combine with to form salts? Why is this relevant?

Back 10

They combine with acids to form local anesthetic salts which are quite soluble in water and comparatively stable; thus most LA's are dispensed as salts (Hydrochloride, most commonly)

Front 11

What is the pH of normal tissue?

Back 11

7.4

Front 12

What is the pH of inflamed tissue?

Back 12

5 to 6

Front 13

True or false: Manufacturers often acidify local anesthetics that contain epinephrine to prevent oxidation of the vasopressor?

Back 13

True; this pH is usually around 3.3 whereas the pH of solutions w/o epinephrine is 5.5

Front 14

Name two results of injecting into an area of inflammation?

Back 14

1) Burning sensation on injection
2) Reduced efficacy of local anesthesia

Front 15

True or False: Increasing the pH (more basic) of a local anesthetic solution speeds its onset of action, increases effectiveness, and makes the injection more comfortable.

Back 15

True

Front 16

True or False: The ability of a local anesthetic to block nerve impulses is profoundly altered by changes in intracelluar pH.

Back 16

False; it is affected by EXTRACELLULAR pH. The nerve or intracellular pH remains rather stable

Front 17

Fill in the blank: For clinical use, local anesthetics are available as ________.

Back 17

Salts

Front 18

In solution, the local anesthesia salt exists simultaneously in what two forms?

Back 18

1) RN or base (uncharged, lipid-soluble)
2) RNH+ or cation (charged)

Front 19

True or False: The proportion of each ionic form (RN or RNH) in solution varies with the pH of the solution or surrounding tissues?

Back 19

True

Front 20

In the presence of many hydrogen atoms (high concentration = high acidity = low pH), what form does most of the anesthetic solution exist as?

Back 20

Cationic (i.e. RNH+ > RN + H+)

Front 21

As the number of hydrogen ions decrease (i.e. low concentration = low acidity = high pH), the equilibrium shifts which direction?

Back 21

The equation shifts to the right (i.e. RNH+ < RN + H+)

Front 22

What is the pKa a measure of?

Back 22

The pKa is also known as the dissociation constant and is a measure of a molecule's affinity for hydrogen ions (H+)

Front 23

When the pKa of the local anesthetic = the pH of the solution, what percentage exists of both the base and the cation?

Back 23

They are exactly proportional (i.e. 50% of the drug exists as RNH+ and 50% exists as RN)

Front 24

What is the Henderson-Hasselbalch equation?

Back 24

It determines the percentage of drug existing in either form (i.e. base or cation). The formula is as follows:

Log (Base/Acid) = pH-pKa

Front 25

Name the two factors involved in the action of a local anesthetic on the nerve membrane:

Back 25

1) Diffusion of drug through the nerve sheath
2) Binding at the receptor site in the ion channel

Front 26

What form of the drug is responsible for diffusion through the nerve sheath?

Back 26

RN (uncharged, lipid-soluble, base)

Front 27

From the axoplasmic side, what ions enter the sodium channels and bind to the receptor sites and are ultimately responsible from the conduction blockade that results?

Back 27

RNH+

Front 28

Of the two properties, diffusion and binding, which is more important in actual practice when it comes to local anesthetic effectiveness?

Back 28

Diffusability

Front 29

True or False: The rate of onset of anesthetic action is related to the pKa (drug's affinity for H+ molecule) of the local anesthetic.

Back 29

True! High pKa = low RN form to diffuse through the nerve membrane (if pH of surrounding tissue is around 7.4). Low pKa = abundance of RN to diffuse through membrane; however, once inside the axoplasm, only a small number of base molecules regroup back to the cationic form necessary for binding to the receptor site, thus anesthetic action is inadequate

Front 30

In inflamed tissue, why is the succeeding round of RN base molecules not as great in number in crossing the membrane as the initial wave of RN molecules (Sum total is less)?

Back 30

Because of the greatly increased absorption of anesthetic molecules due to increased vascularity

Front 31

True or False: Local anesthetics are clinically effective on both axons and free nerve endings?

Back 31

True

Front 32

What kind of membrane do topical anesthetics easily penetrate?

Back 32

Mucous membranes and (injured skin)

Front 33

To increase clinical effectiveness of topical anesthetics, the pH is often raised. Why?

Back 33

Increasing the pH of the drug provides more base form (RN) for diffusion and dissociation to the active cation form at free nerve endings

Front 34

Individual nerve fibers are also known as ____.

Back 34

Axons

Front 35

What is the function of the endoneurium?

Back 35

To separate indvidual nerve fibers (axons) from each other.

Front 36

The _________ binds nerve fibers together into fasciculi.

Back 36

Perineurium; The thicker, the slower the rate of local anesthetic diffusion across it

Front 37

What is the innermost layer of the perineurium?

Back 37

Perilemma

Front 38

What problem does the perilemma/perineurium pose to local anesthetics?

Back 38

It is the main barrier of diffusion into a nerve

Front 39

True or False: The epineurium has a tight consistency?

Back 39

False; it is loose connective tissue where local anesthetics are able to readily diffuse through

Front 40

What layer do blood vessels and lymphatics traverse through?

Back 40

Epineurium; the vessels absorm the local anesthetic molecules, thus removing them from the site of the injection

Front 41

True or False: The epineural sheath or nerve sheath constitutes a barrier to diffusion of local anethetics.

Back 41

False

Front 42

Define diffusion.

Back 42

The unhindered migration of molecules or ions through a fluid medium under the influence of the CONCENTRATION GRADIENT.

Front 43

True or False: The greater the initial concentration of the local anesthetic, the faster is the diffusion of its molecules and the more rapid its onset of action.

Back 43

True!

Front 44

What are mantle bundles and where are they located?

Back 44

Mantle bundles are fasciculi or bundles of nerve fibers (axons) and they are located near the surface of ther nerve

Front 45

True or False: Mantle bundles are the last ones reached by the local anesthetic and are exposed to a higher concentration of it.

Back 45

The first part of the statement is FALSE, they are reached first; the second part of the statement is TRUE. Mantle bundles are usually blocked completely shortly after the injection

Front 46

Fasciculi found closer to the center of the nerve are called ________ bundles.

Back 46

Core

Front 47

Why is it that core bundles are contacted by a local anesthetic after much delay and a lower anesthetic concentration?

Back 47

Because of the greater distance that the solution must traverse and the greater number of barriers it must cross

Front 48

True or False: Amide anesthetics undergo almost immediate enzymatic hydrolysis once within the tissues.

Back 48

False; ESTER anesthetics do

Front 49

Complete conduction blockade of all nerve fibers in a peripheral nerve requires an adequate _________ and ________ of local anesthetic.

Back 49

1)Volume
2)Concentration

Front 50

Which regions do the mantle and core fibers tend to innervate?

Back 50

1) Mantle: More proximal regions like molar areas with an IA
2) Core: More distal regions of the nerve like the incisors and canines with an IA

Front 51

Define Induction Time.

Back 51

The period from deposition of the anesthetic solution to complete conduction blockade

Front 52

True or False: Although molecular forms of the anesthetic are important in neural blockade, drugs with a lower pKa possess a more rapid onset of action than do those with a higher pKa.

Back 52

True!

Front 53

Name some physiochemical factors of a local anesthetic that influence its clinical characteristics.

Back 53

1. Dissociation Constant (pKa)
2. Lipid Solubility (i.e. lipophilic nerve membrane)
3. Protein Binding (i.e. at receptor sites = longer duration)p.24
4. Vasoactivity
4.

Front 54

When emerging from a LA block, why is it that the molars will "wake up" before the incisors?

Back 54

Because the mantle fibers which innervate the molars lose the local anesthetic much earlier than the core fibers which innervate the incisors

Front 55

Define Tachyphylaxis.

Back 55

An increasing tolerance to a drug that is administered repeatedly. It is much more likely to develop if nerve function is allowed to return before reinjection

Front 56

Name some factors most likely associated with the development of Tachyphylaxis

Back 56

1) Edema (isolate nerve from LA)
2) Localized hemorrhage(isolate nerve from LA)
3) Clot formation (isolate nerve from LA)
4) Transudation (isolate nerve from LA)
5) Hypernatremia (raises sodium ion gradient)
6) Decreased pH of tissues (due to first injection of acidic LA, fewer LA molecules are transformed into the free base to traverse across membrane)

Front 57

Name three factors that are associated with the rate at which an anesthetic is removed from a nerve.

Back 57

1) Protein binding
2) Vascularity of the injection site
3) Presence or absence of a vasoactive substance

Front 58

List the most desirable properties of a local anesthetic.

Back 58

1) Not irritating to tissue at which it is applied
2) Not cause permanent alteration of nerves
*3) LOW SYSTEMIC TOXICITY
4)Effective injected and/or applied locally
5) Time of onset is short
6) Duration is long enough for procedure but short enough so there is no extended recovery
7) Potency sufficient to give complete anesthesia w/o use of harmful concentrations
8) Relatively free from producing allergic reactions
9) Should be stable in solution and readily undergo biotransformation in body
10) Should either be sterile or capable of being sterilized by heat without deterioration

Front 59

List the methods of inducing anesthesia.

Back 59

1) Mechanical trauma
2) Low temperature
3) Anoxia
4) Chemical irritants
5) Neurolytic agents (alcohol, phenol)
6) Chemical agents (local anesthetics)
*We desire TRANSIENT or COMPLETELY REVERSIBLE methods

Front 60

Define Local Anesthesia

Back 60

A loss of sensation in a circumscribed are of the body caused by a DEPRESSION of excitation in nerve endings or an INHIBITION of the conduction process in peripheral nerves...without loss of consciousness (separating factor from general anesthesia)

Front 61

What is another name for a Sensory nerve?

Back 61

Afferent (SAME)

Front 62

Where does the sensory nerve travel?

Back 62

To the CNS

Front 63

Name the three parts of the sensory nerve.

Back 63

1) Dendritic zone
2) Axon
3) Cell body

Front 64

True or False: The cell body of the sensory neuron is located between the axon and the dendrites and plays a role in both 1) nerve transmission and 2) metabolic support

Back 64

False; this is a definition of the motor neuron

Front 65

Where is the senory neuron located?

Back 65

Away from the axon or main pathway of nerve transmission

Front 66

What is the primary function of the sensory neuron?

Back 66

To provide metabolic support for the entire neuron

Front 67

What is another name for a motor neuron or nerve?

Back 67

Efferent (SAME)

Front 68

Which direction does the motor neuron travel?

Back 68

Away from the CNS toward periphery

Front 69

The motor neuron plays a role in both _______ ____________ and _________ ________ for the cell.

Back 69

1) Nerve transmission
2) Metabolic support

Front 70

What does the axoplasm do?

Back 70

Provides metabolic support

Front 71

What does the nerve membrane consist of?

Back 71

1) Bilipid layer of phospholipids
2) Associated proteins (receptor sites), lipids, and carbohydrates

Front 72

What are the Nodes of Ranvier?

Back 72

Portions of the nerve membrane exposed directly to the extracellular medium

Front 73

Name 4 ways in which an impulse can be initiated.

Back 73

1) Chemical
2) Thermal
3) Mechanical
4) Electrical

Front 74

True or False: An impulse loses its energy as it propagates along a nerve fiber.

Back 74

False; it does not lose energy rather it remains constant

Front 75

What is the charge of a nerve at resting potential?

Back 75

-70mV

Front 76

Name the three essential components of the local anesthetic armamentarium.

Back 76

1) Syringe
2) Cartridge
3) Needle

Front 77

What is the ADA's criteria from acceptance of local anesthetic syringes?

Back 77

1) Must be durable and able to withstand repeated sterilization w/o damage (if disposable, packaged in a sterile container)
2) Capable of accpeting a wide variety of cartridges and needles of different manufacturers, and permit repeated use
3) Inexpensive, self-contained, lightweight, and simple to use w/one hand
4) Should provide for effective aspiration and be constructed so that blood may be easily observed in the cartridge

Front 78

What is the most commonly used syringe in dentistry today?

Back 78

Breech-loading, metallic, cartridge-type syringe

Front 79

What is the major factor influencing the ability to aspirate?

Back 79

Gauge of the needle

Front 80

What are some advantages of a pressure syringe?

Back 80

1) Trigger permits measured does administration
2) Enables a relatively weak (muscularly) administrator to overcome the significant tissue resistance that is encountered during a PDL injection

Front 81

Who introduced the hypodermic syringe?

Back 81

Alexander Wood

Front 82

What is the primary use of a jet injector?

Back 82

To obtain topical anesthesia before the insertion of a needle; it may also be used for mucosal anesthesia of the palate

Front 83

True or False: The jet injector is an adequate substitute for the more traditional needle and syringe in obtaining pulpal or regional block anesthesia

Back 83

False

Front 84

When should a disposable syringe be considered for use?

Back 84

Only when a traditional syringe is not available or cannot be used (i.e. severe latex allergy, diphenhydramine is used as a local anesthetic is presumed cases of LA allergy)

Front 85

Is the use of a safety syringe recommended by the author?

Back 85

Yes

Front 86

What does CCLAD stand for?

Back 86

Computer-Controlled Local Anesthetic Delivery Systems

Front 87

In a CCLAD injection, what explains the reduced pain perception noted by most patients during the injection?

Back 87

The controlled rate of fluid administration

Front 88

After administering one cartridge of anesthetic, you switch it out for a new cartridge. It begins to leak as pressure is applied. What could be the problem?

Back 88

The needle did not penetrate the diaphragm in the center (ovoid puncture) allowing leakage of the solution

Front 89

Why does disengagement of the harpoon occur? When is this most likely to happen?

Back 89

Because it is dull or the administrator applies too much pressure during aspiration. Disengagement is most likely to occur when a 30-guage needle is being used because there is significant resistance produced within the needle lumen as aspiration is attempted

Front 90

Who would most benefit from a self-aspirating syringe?

Back 90

Practitioners with small hands

Front 91

List the components of the needle.

Back 91

1) Bevel
2) Shaft
3) Hub
4) Cartridge-penetrating end

Front 92

True or False: A needle whose point is centered on the long axis will deflect less than a beveled-point needle whose point is eccentric.

Back 92

True

Front 93

When selecting a needle for an injection, what two factors should be considered?

Back 93

1) Gauge
2) Length

Front 94

True or False: The smaller the number (or gauge), the greater the diameter of the lumen.

Back 94

True

Front 95

What are some distinct advantages of larger-gauge needles over smaller ones?

Back 95

1) Less deflection...
2) Which causes greater accuracy in insertion which leads to increased success rates (especially in injections where the depth of soft tissue being penetrated is significant)
3) Needle breakage less likely to occur
4) Aspiration of blood is possibly easier and more reliable through a larger lumen
5) No perceptual differences in patient comfort

Front 96

When is the use of larger-gauged needles recommended?

Back 96

For any injection technique used in a highly vascular area or when needle deflection through soft tissue would be a factor (i.e. inferior alveolar, posterior superior alveolar, mental or incisive nerve block)

Front 97

True or False: The 27-gauge is the preferred needle for all injections presenting high risk of positive aspiration.

Back 97

False; the 25-gauge is the preferred needle, the 27 can be used for all other injection techniques provided the aspiration percentage is low and tissue penetration depth is not great

Front 98

What injection is the 30-gauge needle specifically recommended?

Back 98

None, although it may be used in instances of local infiltration as when obtaining hemostasis during periodontal therapy

Front 99

True or False: The greater the angle of the bevel, the lesser the degree of needle deflection.

Back 99

False; the greater the deflection

Front 100

What is BRIT?

Back 100

Birotational insertion technique; A technique in which the operator rotates the handpiece or needle in a back and forth rotational movement while advancing the needle through tissues. Can be used with a CCLAD device

Front 101

What are the average lengths for short and long needles?

Back 101

20mm and 32mm, respectively

Front 102

When is a long needle preferred?

Back 102

For all injection techniques where the penetration of significant thicknesses of soft tissue is required

Front 103

When is a short needle preferred?

Back 103

Short needles may be used for any injection in any patient who does not require the penetration of significant depths of soft tissue

Front 104

Why do we change the needle after 3 to 4 injections?

Back 104

Because it becomes dull and can cause pain and trauma to the tissues.

Front 105

According to Malamed, which needle is the only needle necessary in a dental office?

Back 105

25-gauge long; however, he states that it is practical to have a second needle available(25 or 27-gauge short)for injections in which the soft tissue thickness is less than 20mm and where the risk of positive aspiration is minimal, and in areas where stabilization of a long needle might be difficult (i.e. maxillary anterior teeth and palate)

Front 106

Needles should not be bent if they are to be inserted into the soft tissue to a depth of __ mm.

Back 106

5; There is no injection technique in which the needle enters into the soft tissue that mandates that the needle be bent for an injection to be successful

Front 107

True or False: According to Malamed, no attempts should be made to change the direction of a needle when it is embedded in tissue

Back 107

True

Front 108

Name the 4 parts of the cartridge.

Back 108

1) Cylindrical glass tube
2) Stopper (plunger, bung)
3) Aluminum cap
4) Diaphragm

Front 109

True or False: Cartridges whose plungers are flush with or extruded beyond the glass of the cylinder are fine to use as long as the cartridge is inspected for cracks or leakage.

Back 109

False

Front 110

What group of people might need special consideration when administering a local anesthetic through a glass cartridge? Why?

Back 110

Persons with latex allergy due to the latex rubber diaphragm

Front 111

How can the number of milligrams of an agent be calculated?

Back 111

By multiplying its percent concentration (i.e. 20%=2.0mg/mL) by total volume of cartridge (i.e. 1.8mL in U.S. or 2.2mL in U.K.). Thus, 1.8mL cartridge of a 2% solution contains 36mg of a drug.

Front 112

True or False: The local anesthetic drug is not stable or capable of being autoclaved, heated, or boiled without breaking down.

Back 112

False; it is stable and capable of the above mentioned things. However, the vasopressor drug and/or cartridge seals are more easily destroyed

Front 113

Why is the vasopressor drug included in most anesthetic cartridges?

Back 113

To increase the safety, duration and depth of action of the local anesthetic

Front 114

True or False: The pH of dental cartridges containing vasopressors is lower or more acidic compared to those that do not contain a vasopressor (3.3 to 4.0 versus 5.0 to 6.0. Thus, plain local anesthetics have a slower onset of action and cause more "burning" upon injection.

Back 114

The first statement is true; the second statement is false. Plain local anesthetics have a quicker onset of action (more free base to penetrate membrane) and are more comfortable on injection

Front 115

Cartridges containing vasopressors also contain an antioxidant. What is the name of the antioxidant added?

Back 115

Sodium (meta) bisulfite

Front 116

What does sodium (meta) bisulfite do?

Back 116

Prevents oxidation of vasopressor by reacting first with oxygen that was either trapped in the cartridge or oxygen that has seeped in. This reaction prevents the oxygen from destroying the vasopressor

Front 117

What does sodium bisulfite oxidize to and which form has a lower pH?

Back 117

Sodium bisulfate which has a lower pH thus increased "burning" upon injection if an older cartridge is being used over a newer one

Front 118

Why is sodium chloride added to the cartridge?

Back 118

To make the solution isotonic with the tissues of the body

Front 119

What is the diluent that provides the volume of solution in the cartridge?

Back 119

Distilled water

Front 120

If a doctor gets the "urge" to "sterilize" a cartridge before administering, what should he or she do?

Back 120

Wipe the exterior of the cartridge with an isopropyl(91%) or ethyl (70%) alcohol-dampened wipe. There should be no liquid alcohol present around the cartridges

Front 121

Why are cartridge warmers not necessary?

Back 121

Overheating the LA soluction can lead to patient discomfort and destruction of the heat-sensitive vasopressor

Front 122

What is the "bubble" that is sometimes seen in local anesthetic cartridges?

Back 122

Nitrogen gas

Front 123

When a stopper is visibly extruded, what conclusions can be made? Is this a problem?

Back 123

The cartridge was frozen thus causing the liquids within to expand. This is a problem because it means that the cartridge can no longer be considered sterile and should not be used for injection (Extruded stopper can be seen with and without a bubble. Without, indicative of prolonged storage in chemical disinfectant and diffusion of solution into cartridge)

Front 124

"Burning" sensation upon injection may be the result of what four things.

Back 124

1) Normal response to the pH of the drug
2) Cartridge containing sterilizing solution (i.e. alcohol that has seeped in; more intense burning)
3) Overheated cartridge
4) Cartridge containing a vasopressor

Front 125

If a cartridge has a corroded cap, what can be concluded?

Back 125

It was immersed in a cold sterilizing solution (the metal and disinfecting salts are not compatible)and should not be used

Front 126

What does rust on a cartridge indicate?

Back 126

That at least one cartridge in the tin storage container has broken or leaked. Cartridges should not be used if they contain rust

Front 127

Name one commonly used antiseptic.

Back 127

1) Betadine (povidone-iodine)
2)Merthiolate (thimerosal)

Front 128

Why should antiseptics that contain alcohol be avoided?

Back 128

Because the alcohol is irritating to the tissues

Front 129

What class of local anesthetic is benzocaine?

Back 129

Ester

Front 130

True or False: The likelihood of allergic reactions to esters (topically) is significantly greater than that to amide topical anesthetics.

Back 130

True

Front 131

Why is it that allergic reactions to benzocaine are usually localized?

Back 131

Because benzocaine, although an ester (increased chance of allergy), is not absorbed systemically

Front 132

Of the amides, which one possesses topical anesthetic properties in clinically acceptable concentrations?

Back 132

Lidocaine

Front 133

True or False: The risk of overdose with ester topical anesthetics is greater than that with amide anesthetics.

Back 133

False; it is the opposite

Front 134

What does EMLA stand for and what does it consist of?

Back 134

Eutectic mixure of local anesthetic; Lidocaine and prilocaine. It is designed to provide topical anesthesia to intact skin

Front 135

Why should only small, metered doses of topical anesthetic sprays be used?

Back 135

Because topical anesthetics require greater concentration to penetrate mucous membranes, and because topical anesthetics are rapidly absorbed by the cardiovascular system

Front 136

Nerve conduction depends on two factors. Name them.

Back 136

1) Concentration of electrolytes in axoplasm (or interior of cell) and extraceullular fluids
2) Permeability of nerve membrane to Sodium and Potassium

Front 137

In order for firing threshold to be reached, how many millivolts must the charge decrease by?

Back 137

15 mV

Front 138

True or False: Local anesthesia increases the firing threshold, leading to a need of less Na+ to create an action potential.

Back 138

First part of the statement is true, the second part of the statement is false. More Na+ is needed within the membrane to create an action potential

Front 139

During repolarization, what is required to establish equilibrium of potassium and sodium?

Back 139

ATP energy and their respective pumps

Front 140

Define Action Potential.

Back 140

Transient depolarizations of a membrane that result from a brief increase in permeability of the membrane to sodium and usually a delayed increase in permeability to potassium

Front 141

List the steps to an action potential.

Back 141

1) Stimulus excites nerve (Resting potential of nerve = -70mV
2) Slow depolarization (electrical potential within nerve becomes slightly less negative; remember...it must reach a change of 15 mV before rapid depolaraization. 15 mv is considered "firing threshold")
3) Rapid depolarization (threshold, potential or firing threshold which leads to reversal of electrical potential = +40 mV on interior of nerve)
4) Repolarization

Front 142

True or False: The influx of Na+ and efflux of K+ require ATP energy during an action potential

Back 142

False; this process is passive during the action potential. However, during repolarization, ATP energy is required

Front 143

What does the myelin sheath allow?

Back 143

Faster nerve conduction

Front 144

With the exception of Cocaine, what is the action produced by local anesthetic drugs?

Back 144

Vasodilation

Front 145

Cocaine is the only local anesthetic that produces vasoconstriction. It inhibits the uptake of __________ into tissue binding sites.

Back 145

Catecholamines (especially norepinephrine)

Front 146

When applied topically, local anesthetics are taken up most rapidly by which mucous membrane?

Back 146

Tracheal mucosa (followed by pharyngeal then esophogeal and bladder mucosa)

Front 147

Once absorbed into the blood, local anesthetics are distributed throughout the body to all tissues. What tissue and/or organ contains the greatest percentage of local anesthetic than any other in the body? Why?

Back 147

Skeletal muscle; this is because it constitutes the largest mass of tissue in the body

Front 148

The "blood level" of the anesthetic is influenced by which three factors?

Back 148

1) Rate at which drug is absorbed into the CVS
2) Rate of distribution of the drug (more rapid in health patients)
3) Elimination of the drug through metabolic or excretory pathways

Front 149

What is the main excretory organ for both the amide and ester local anesthetics?

Back 149

Kidneys

Front 150

What is a byproduct of procaine that is linked to allergic reactions?

Back 150

PABA

Front 151

When is the use of ester local anesthetics relatively contraindicated?

Back 151

When the patient has atypical plasma pseudocholinesterase

Front 152

Your client has marked "difficulty" during general anesthesia on her health history. What should you be cautious of?

Back 152

The use of ester local anesthetics due to the probable genetic inheritance of atypical plasma cholinesterase (inability to hydrolyze ester local anesthetics and other chemically related drugs such as Succinylcholine that is used to induce general anesthesia)

Front 153

Where are ester local anesthetics biotransformed (metabolized)?

Back 153

In the plasma by the enzyme plasma cholinesterase

Front 154

What is the main site of metabolism for amide local anesthetics?

Back 154

Liver

Front 155

Prilocaine undergoes primary metabolism in the liber. Where else could it possibly be metabolized?

Back 155

Lungs

Front 156

True or False: Liver funcion and hepatic perfusion significantly influence the rate of biotransformation of an ester local anesthetic.

Back 156

False! Amide local anesthetic

Front 157

What ASA classes are considered relative contraindications to receive amide local anesthetics?

Back 157

ASA IV and V (significant liver dysfunction or heart failure)

Front 158

Which drug is associated with methemaglobinemia?

Back 158

prilocaine

Front 159

Does significant renal disease (ASA IV or V) indicate a relative contraindication for both amide and ester local anesthetics?

Back 159

Yes; this includes patients undergoing renal dialysis, and those with chronic glomerulonephritis or pyelonephritis. Patients with such problems may be unable to eliminate the parent LA compound or its metabolites from the blood resulting in elevated blood levels and increased potential for toxicity

Front 160

What is the pharmacological action of LA's on the CNS?

Back 160

Depression, there is a spectrum of symptoms depending on the blood levels (low vs. high)

Front 161

What is a sign or symptom that is an "exception" to the direct depressant action of the local anesthetic on the CNS?

Back 161

Circumoral and lingual numbness; these are not caused by CNS depression but rather is the direct result of high blood levels of LA reaching the highly vascular area of the mouth

Front 162

You administer an IA on the left side. Ruling out crossover innervation, your client complains of bilateral mandibular numbness. Why should you be concerned?

Back 162

The anesthetic dose administered was too high and has been transported to those tissues by the CVS

Front 163

True or False: If either excitation or sedation appears within 20 to 30 minutes after the intraoral administration of a local anesthetic, it should serve as a warning to the clinician of a rising local anesthetic blood level and the possibility of a more serious reaction.

Back 163

False; within the first 5 to 10 minutes

Front 164

Although not known for sure, where within the CNS is the local anesthetic thought to exert its effect?

Back 164

At the inhibitory cortical synapses or directly on the inhibitory cortical neurons

Front 165

True or False: Local anesthetics have a direct action on the mycardium and peripheral vasculature.

Back 165

True

Front 166

Which of the two systems, CNS or CVS, is more resistant to the effects of local anesthetic drugs?

Back 166

CVS

Front 167

Local anesthetics produce a myocardial ________ that is related to the local anesthetic blood level.

Back 167

Depression

Front 168

True or False: Local anesthestics decrease eletrical excitability, decrease the conduction rate, and decrease the force of contraction of the heart

Back 168

True

Front 169

At what blood level will signs and symptoms of local anesthesic overdose be noted?

Back 169

If the blood level rises past 6 ug/mL

Front 170

What is the primary effect of local anesthesia on blood pressure?

Back 170

Hypotension

Front 171

With the exception of Cocaine and ropivacaine, what effect do local anesthetics have on peripheral vasculature?

Back 171

Vasodilation; through relaxation of the smooth muscle in the walls of the blood vessels (increased blood flow = increased rate of drug absorption = decreased depth and duration of anesthesia and increaed bleeding and increased LA blood levels)

Front 172

True or False: Negative effects on the CVS are not noted until significantly elevated blood levels of LA are reached.

Back 172

True; see page 37 of Malamed

Front 173

What effect do local anesthetics have on the respiratory system?

Back 173

1) Nonoverdose levels-- direct relaxation on bronchial smooth muscle
2) Overdose levels-- may produce respiratory arrest as a result of generalized CNS depression

Front 174

From the following description, name the associated pharmacogenic disorder: Acute clinical manifestations include tachycardia, tachypnea, unstable blood pressure, cyanosis, respiratory and metabolic acidosis, fever, muscle rigidity, and death. Many commonly used anesthetic drugs can trigger the manifestation of this disorder.

Back 174

Malignant Hyperthermia