Stewart 3-25-08 Anesth

Front 1

Local Anesthetics Mode of Action:
Block generation of action potential by reversibly inhibiting ____ influx

Back 1

Na+

Preferentially block activated Na+ channels

Front 2

Locals are weak bases (pKa=8-9)
(mainly ionized at physiologic pH and act). Why are they bases?

Back 2

they penetrate the cell membrane in the non-ionized form

Front 3

what kind of nerves have high sensitivity to locals?

Back 3

Thin, non-myelinated nerve fibers (sensory roots)  Pain, touch, temperature

Front 4

what kind of nerves have medium sensitivity to locals?

Back 4

Thin --> medium, myelinated nerve fibers (sympathetic nerves) : vasomotor, visceromotor function

Front 5

what kind of nerves have low sensitivity to locals?

Back 5

Thick, myelinated nerve fibers (somatic nervous system): motor function

Front 6

What is the Order (timing) of nerve function block of the following:

touch, cold, motor, warmth, pain, cold, deep pressure

Back 6

1. pain
2. cold
3. warmth
4. touch
5. deep pressure
6. motor
Recovery in reverse order

Front 7

How do you know an amide from an ester by only knowing the drug name ? (without looking at the structure)

Back 7

Amides all have 2 “I”s in them. Esters have one.

Front 8

Which amide drug blocks only motor?

Back 8

Etidocaine only blocks motor.

Front 9

Esters are broken down in the blood by___________

Back 9

plasma esterases

Front 10

Amides are metabolized by the______ and excreted by the kidney

Back 10

liver

Front 11

pKa correlates with what property of local anesthetic

Back 11

speed of onset

Front 12

Adding WHAT makes local anesthetic less ionized and it crosses the membrane faster! Faster action.

Back 12

bicarb

Front 13

Example of a condition that lowers pH and may have a negative impact on the onset and the quality of the local anesthesia.

Back 13

tissue acidosis produced by infection

Front 14

Lipid solubility correlates with what characteristic of the local anesthetic

Back 14

potency

Front 15

Plasma protein binding correlates with their affinity for protein with sodium channels and predicts what about a local anesthetic

Back 15

the duration they will sustain neural blockade

Front 16

The big thing. What are Signs and symptoms of Bupivicaine toxicity ?

Back 16

metallic taste in mouth. Then seizures, coma, and cardiac arrest.

Front 17

Local anesthetics depress the CNS in a ____-dependent manner

Back 17

dose

Front 18

Low serum concentrations are used clinically for suppressing cardiac dysrhythmias, but higher concentrations induce________ activity.

Back 18

seizure

Front 19

WHAT are the principal life-threatening consequence of local anesthetic overdose?

Back 19

Convulsive seizures

Front 20

Max dose of lidocaine

Back 20

4.5 mg/kg without Epi,
7 mg/kg with Epi

Front 21

Max dose of bupivicaine

Back 21

3 mg/kg with or w/o epi

Front 22

0.25% bupiv = ___mg/cc

Back 22

2.5mg/cc

Front 23

1% xylocaine = __mg/cc

Back 23

10mg/cc

Front 24

How many milligrams of bupiv can you give a 60 kg pt?

Back 24

60kg * 3mg/kg = 180mg

Front 25

How many ccs of .5% bupiv can you give a 60 kg pt?

Back 25

180mg / 5mg/cc = 36 cc

Front 26

Preservative _____ is used with ester compounds and may cause allergic reaction.

Back 26

PABA

Front 27

Most adverse reactions to locals are caused by_______.

Back 27

toxicity

Front 28

Tachycardia and palpitations may be from________ in some solutions of local anesthetic

Back 28

epinephrine

Front 29

Less than _% of all adverse reactions due to locals are caused by allergic mechanisms.

Back 29

1

Front 30

The ester local anesthetics produce a metabolite related to ____
____ can cause allergic reactions in some patients.
Amides and some esters have a preservative (methylparaben) that resembles ____ and can cause allergic reactions.

Back 30

para-aminobenzoic acid (PABA).

Front 31

Mechanism of cocaine

Back 31

reversibly binds to and inactivates sodium channels. This inhibits excitation of nerve endings. Cocaine blocks the reuptake of dopamine, serotonin, and NE.

Front 32

How long does lidocaine last?

Back 32

30-60 min

Front 33

How long does bupivicaine last?

Back 33

120-240 min

Front 34

Cocaine is metabolized by hydrolysis by _______

Back 34

plasma pseudocholinesterases.
Also oxidative metabolism in the liver
And 5% excreted unchanged

Front 35

toxic dose of cocaine

Back 35

2-3 mg/kg

Front 36

Treatment of Cocaine Toxicity

Back 36

ABCs
Cooling blankets
No known antidote
What drugs may be useful?
Propanolol
Nitrates
Calcium-channel blockers
Benzodiazepines

Front 37

short-acting ester

Back 37

chloroprocaine (Used in epidurals and spinals)

Front 38

(long-acting) ester

Back 38

Tetracaine

Front 39

2 other long acting amides

Back 39

Ropivacaine (long-acting)
Levobupivacaine (long-acting)

Front 40

Toxic dosage of lidocaine

Back 40

4.5 mg/kg
With epi 7 mg/kg

Front 41

Transient neurologic symptoms
of lidocaine

Back 41

Like cauda equina syndrome
Syndrome of pain and/or dysesthesia
Appear 12-24 hours after surgery
Most often resolves in 3-7 days
Pain can be severe (even worse than surgery)

Front 42

Most commonly used local used for epidurals. OK for spinals

Back 42

Bupivacaine

Front 43

caution with bupivicaine

Back 43

Highly cardiac toxic

Front 44

the concentration of the vapour in the lungs that is needed to prevent movement (motor response) in 50% of subjects in response to surgical (pain) stimulus

Back 44

MAC
Minimum alveolar concentration
(should be "median")

Front 45

If MAC is 1.0, then ___ MAC would block response in 95% of subjects.

Back 45

If MAC is 1.0, then 1.3 MAC would block response in 95% of subjects.

Front 46

MAC of halothane

Back 46

0.76

(the lower the more potent)

Front 47

Hair color that increases MAC

Back 47

Red

Front 48

1L of O2 and 1L of N2O does what to MAC?

Back 48

That is 50% N2O, therefore MAC is 50% less

Front 49

Halothane (MAC = 0.74).... what is MAC w/ 60% N20?

Back 49

0.74 - 60%(0.74) = 0.29

Front 50

N2O can increase air spaces in the body. Give examples

Back 50

Pneumothorax
VAE
Bowel distension
Tympanic membrane pressure

Front 51

what could the abbreviation MAC be mistaken for?

Back 51

monitored anesthesia care

Front 52

What is the blood-gas partition coefficient? Why do we care?

Back 52

An ideal anaesthetic would act extremely quickly (be highly insoluble in blood: have a low blood gas partition coefficient), BGPC is proportional to a gas's solubility

Front 53

Example of drug with low blood-gas partition coefficient and works quickly

Back 53

desflurane

Front 54

3 most important Factors Affecting the Speed of Action of Inhaled Anesthetics

Back 54

Alveolar anesthetic partial pressure
Anesthetic solubility
Cardiac output
(Decreased cardiac output accelerates the rate of increase of FA/FI; Fi = inspired fraction)

Front 55

What is the significance of halothane having the largest degree of metabolism?

Back 55

halothane is liver toxic.

Front 56

What Drugs trigger MH and are Not Safe? 

Back 56

Desflurane
Halothane
Isoflurane
Sevoflurane
Xenon (Rarely Used) 
Succinylcholine

Front 57

How would you diagnose malignant hyperthermia susceptible pt?

Back 57

Caffeine Halothane Contracture Test is the gold standard,
Molecular Genetic Testing for Malignant Hyperthermia (RYR1 mutation)

Front 58

Pseudocholinesterase deficiency is an inherited enzyme abnormality that results in abnormally slow metabolic degradation of exogenous choline ester drugs such as ____________.

Back 58

succinylcholine

Front 59

This condition is recognized most often when respiratory paralysis unexpectedly persists for a prolonged period of time following administration of standard doses of succinylcholine

Back 59

Pseudocholinesterase Deficiency

Front 60

Pseudocholinesterase Deficiency is Confirmed by a laboratory assay demonstrating decreased plasma cholinesterase enzyme activity -->________ number

Back 60

Dibucaine

Front 61

milk of amnesia. It burns. Give with lido. Short acting for induction. No analgesia. Hypotensive

Back 61

Propofol

Front 62

used for intubation. Sedative. Less resp depression than propofol. Causes adrenal suppression (*). Cardiovascularly stable

Back 62

Etomidate

Front 63

hallucinogenic. Used with kids. Cariovascularly stable. Causes release of NE. If stressed pt, can cause cardiac instability b/c no more NE

Back 63

Ketamine

Front 64

can’t give in porphyria.

Back 64

Barbiturates

Front 65

alpha 2 agonist (like clonidine)
No respiratory depression
New

Back 65

Dexmedetomidine

Front 66

IV Agents for sedation

Back 66

Propofol
Etomidate
Ketamine
Barbiturates
Dexmedetomidine

Front 67

histamine release, N/V, longer acting than fentanyl

Back 67

Morphine

Front 68

Muscle relaxant:
increases heart rate, (similar to atropine)

Back 68

Pancuronium

Front 69

Muscle relaxant:
histamine releasing

Back 69

Atracurium

Front 70

Muscle relaxant:
less histamine release

Back 70

Cis-atracurium

Front 71

If pt is hypotensive, don't use what sedative?

Back 71

propofol and thiopental

Front 72

Pt is coming in for bowel resection due to obstruction secondary to large mass. Don't give what gas?

Back 72

N2O b/c it increases bowel gas volume

Front 73

Low BP --> would avoid propofol and thiopental – could consider_____

Back 73

etomidate or ketamine

Front 74

Pt is anxious -->_________ might be warranted

Back 74

benzodiazepine

Front 75

we will need something for pain  allergic to morphine -->________

Back 75

fentanyl

Front 76

Family hx of “reaction to anesthesia” --> could be MH or _____________________ deficiency --> avoid volatile agents and succinylcholine

Back 76

Family hx of “reaction to anesthesia” --> could be MH or pseudocholinesterase deficiency --> avoid volatile agents and succinylcholine

Front 77

anesthetic plan for pt with extensive past medical history and numerous meds (from packet)

Back 77

have the surgeon use local anesthesia.
We could use a little fentanyl maybe. Must titrate in slowly.