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PDA II anesthetics
PDA II anesthetics
47
Health Care
Professional
09/24/2008

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Cards

Term

Which stage of general anesthesia would a person be most susceptible to a cardiac arrhythmia?

 

Which stage should be totally avoided?  

 

Which stage is the goal?

Definition

Stage II 

 

Stage IV 

 

Stage III

Term

What is induction?

 

What is maintenance?

Definition

The time required from consciousness to stage III

 

Keeping a pt at stage III

Term

What did the Meyer-Overton theory suggest?

 

Why was this theory no good?

 

What does the more recent hypothesis of general anesthetics say?

Definition

It suggested that the mechanism of action for anesthetics was due to a good correlation b/w a potent anesthetic & lipid solubility. Once inside the cell membrane, the anesthetic then perturbed the cell membrane.

B/c some anesthetics are enantiomers that have the same lipid solubility, but different anesthetic effects.

 

It says anesthetics bind to specific protein receptors on a membrane. Then, it modulates the cells membrane ion channels, thereby causing the cell to hyperpolarize at pre and post synapses.  The anesthetics may then inhibit the excitatory response or enhance the inhibitory response.

Term
Explain the GABAnergic mechanisms for GABAA and GABAB
Definition

When GABA acts on GABAA, Cl rushes inside the cell to hyperpolarize the cell (the cell becomes more negatively charged). The more hyperpolarized it is, the more difficult it is to get a depolarization.

 

When GABA acts on GABAB, it causes second messengers inside the cell to stimulate potassium efflux.  The result is a positive charge outside of the cell, which also results in a hyperpolarization.

Term
Are general anesthetics more selective for GABAA or GABAB?
Definition
GABAA
Term

What happens when glycine stimulates glycine receptors in the CNS?

 

What happens when glutamate stimulates glutamate receptors in the CNS?

 

What drug blocks glutamate receptors?

Definition

There is an inhibitory effect that leads to a hyperpolarization.

 

There is an excitatory effect that leads to a depolarization.

 

Ketamine blocks glutamate receptors which leads to a hyperpolarization.

Term
What is the minimum alveolar concentration?
Definition
1 MAC is the concentration required to prevent movement in 50% of people.
Term

Why is it easy to measure the alveolar and brain concentrations of anesthetic?

Definition

The [alveolar] = [anesthetic] at equilibrium

The [brain] = [alveolar] at equilibrium.

Term

T or F:

The MAC is independent of noxious stimuli

Definition
true
Term

Nitrous oxide N2O

Definition
Has a low potency, good analgesic properties, it's usually used w/ anesthetics, & the recovery time is quick. It also has minimal effects on HR, BP, and respiration.  It's only drawback is that it inhibits methionine synthesis which can lead to a vitamine B12 deficiency if used too long.
Term

Halothane

Definition

Sensitizes heart to catecholamines (could cause arrhythmias).

Can cause malignant hyperthermia when given w/ succinylcholine.

 

Term

Which general anesthetic is commonly used for maintenance, b/c it causes airway irritation?

Definition

desflurane

Term
List the general anesthetics by decreasing potency
Definition
Halothane, Isoflurane, Enflurane, Sevoflurane, Desflurane, & N2O
Term

Which general anesthetic is not capable of taking a person to stage 3?

Definition
N2O
Term

How is thiopental distributed after a single IV injection?

Definition

It first goes to the brain & viscera, then to lean tissues, then to fat. 

Term

Thiopental

Definition

Rapid action and recovery

Decreases bp

Respiratory depression (may occur so maintenance is required)

Histamine release may occur & cause bronchodilation.

 

Term
What are the advantages & disadvantages of Etomidate.
Definition

Advantages:

Rapid onset and recovery

CV stability

No histamine release

 

Disadvantages:

Injection is painful

Involuntary motor movements are possible

Nausea and vomiting

Inhibits corticosteroid production which suppresses the adrenocortical stress response.

 

 

Term
Ketamine
Definition

Moderately rapid onset and recovery

May be administered by oral, rectal, or IM.

Produces a cataleptic state known as dissociative anesthesia (eyes open, involuntary motor movements, analgesia, amnesia, unresponsiveness, & spontaneous respiration).

Inhibits catecholamine reuptake, which increases bp, HR, & CO (cardiac output) & causes bronchodilation.

Increases cerebral blood flow.

Emergence rxns include hallucinations & vivid dreams.

 

Term
Propofol
Definition

Rapid onset and recovery

Hypotension may occur (not a big deal

if recognized and handled in time)

Anti-emetic action is present

Histamine release is possible

 

 

Term

What is the mechanism of action for local anesthetics?

 

How do local anesthetics block Na channels?

Definition

They block nerve conduction by blocking & inactivating Na channels.

 

They have to get inside the nerve cell. To cross the cell membrane, they have to be in the unionized form.  To block the Na channel, they have to convert back to the ionized form once they are in the nerve cell.

Term

What happens to an action potential when Na channels are blocked?

 

Do they change the resting membrane potential?

 

Do they cause a hyperpolarization or depolarization? Explain.

Definition

1) rate of rise of EPSP decreases (b/c Na doesn't rush in as quickly)

2) TP increases (more Na is required for AP)

3) rate of rise of AP decreases

4) Overshoot decreases

 

 No

No, they simply change the characteristics of the AP which deadens the nerve.

 

Term
Which nerves (and their function) are very sensitive to local anesthetics?
Definition

A fibers:

     delta fibers - pain, temperature, and touch 

B fibers: preganglionic efferents

C fibers:

     Sympathetic - postganglionic efferents (motor functions)

     Dorsal root - pain, temperature, touch (sensory functions)

 

 

 

 

Term
Which are more responsive to local anesthetics: large unmyelinated nerves, small unmyelinated nerves, small myelinated nerves,  or large myelinated nerves?
Definition
Small unmyelinated nerves
Term
List, by rank, the functions that are most susceptible to anesthetics to those that are least susceptible
Definition

1) pain

2) touch

3) adrenergic vasoconstriction

4) temperature

5)propioception

6)motor function

Term

Which would act faster: an anesthetic that is a larger molecule or a smaller molecule?

 

Which would act faster: an anesthetic that is more lipid soluble or less lipid soluble?

 

Is a local anesthetic only active in the cationic form or the anionic form?

Definition

A larger molecule will attach to the receptor better.

 

A more lipid soluble anesthetic can cross the nerve cell membrane faster

 

cationic

Term
What causes termination of action of local anesthetics?
Definition

They revert back to the unionized form and diffuse out of the neuron.  Also, regional blood flow can wash the drug away.

 

 

Term
What would happen if you used a vasoconstrictor along w/ a local anesthetic?
Definition
It would delay absorption, prolong the effects, and reduce toxicity.
Term
Which will have a longer duration of action: an anesthetic that is an ester or an anesthetic that is an amide?
Definition
An amide will have a longer duration of action, b/c it has to go through the liver to be metabolized.  An ester will not last as long, b/c it will be metabolized by esterases in the blood and tissues.
Term

What is surface anesthesia?

Definition

Surface anesthesia is a topical anesthesia used for pain, itching, soreness, etc.

 

Term
What is infiltration anesthesia?
Definition
It's an injection into a surgical area w/ no regard for nerves.
Term
What is nerve block anesthesia?
Definition
It's where you inject into an area of nerves to deaden the surgical region, which is not by the injection.  An example is where you inject into the upper arm to deaden the fingers.
Term
What is a spinal anesthesia?
Definition
It's where you inject into the CSF to deaden nerves below the injection site.
Term
What is intravenous regional anesthesia?
Definition
It's where you inject into the circulation in a regional area after the blood has been removed from that area.  This type of anesthesia has to be done quickly, b/c your tissues won't last long w/o oxygen.
Term
What is an epidural injection?
Definition
It's an injection into the epidural to block the spinal nerve roots.  This is commonly used during child-birth.
Term
An adverse rxn to a local anesthetic is usually related to the                  &                              or it may be an                 .
Definition
CNS and CV system or allergic rxn
Term
What was the first local anesthetic?
Definition
Cocaine; many anesthetics are based off of its structure.
Term
Procaine
Definition

Think:  Procaine, PABA, Ester, Injection 

It's an ester

  Has to be given by injection, b/c it is poorly absorbed in the mucous membranes. 

Hydrolysis of procaine produces PABA; this could interfere w/ sulfonamides. 

Term
benzocaine
Definition
topical use only due to a complete lack of water solubility
Term
Chloroprocaine
Definition

Think: Chloroprocaine - short 1/2 life, low toxicity, thrombosis 

Extremely short half life

One of the least toxic anesthetics

Contraindicated for intravenous regional block due to its tendency to cause thrombosis.

Term
Tetracaine
Definition

Longer duration than procaine or chloroprocaine

Used for topical or spinal anesthesia

Term
Lidocaine
Definition

 Think Lidocaine - amide, hypersensitivity, adminstration

It's an amide 

  Less likely than procaine to produce hypersensitivity rxns.

Can be administered via any route except for eyes.

 

Term
Prilocaine
Definition

Think Prilocaine - metabolized faster than lidocaine, methemoglobinemia 

Might be used over lidocaine for its more rapid hepatic metabolism.

Could cause methemoglobinemia in infant if used during labor and delivery.  Methemoglobinemia is where hemoglobin is converted to methemoglobin, which doesn't carry oxygen as well.

Term

T or F

All general anesthetics relax muscle and potentiate NM blockers

Definition

False

nitrous oxide doesn't

Term

Which 4 drugs could be used for status asthmaticus?

Which of the 4 drugs is most commonly used for status asthmaticus?

Definition

HEDS

Halothane, Enflurane, Desflurane, & Sevoflurane

Sevoflurane is most common

Term
Which of the general anesthetics has the slowest induction?
Definition
Enflurane
Term

Which general anesthetic(s) increase cerebral blood flow?

 

Which general anesthetic(s) dilates cerebral blood vessels?

 

Who would these anesthetics be contraindicated in?

Definition

Sevoflurane & desflurane

 

Halothane

 

Someone w/ swelling in the brain, maybe due to a tumor.

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