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? |
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Definition
Stage II Stage IV Stage III |
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Term
What is induction? What is maintenance? |
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Definition
The time required from consciousness to stage III Keeping a pt at stage III |
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Term
What did the Meyer-Overton theory suggest? Why was this theory no good? What does the more recent hypothesis of general anesthetics say? |
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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. |
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Term
| Explain the GABAnergic mechanisms for GABAA and GABAB |
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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. |
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Term
| Are general anesthetics more selective for GABAA or GABAB? |
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Definition
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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? |
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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. |
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Term
| What is the minimum alveolar concentration? |
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Definition
| 1 MAC is the concentration required to prevent movement in 50% of people. |
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Term
Why is it easy to measure the alveolar and brain concentrations of anesthetic? |
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Definition
The [alveolar] = [anesthetic] at equilibrium The [brain] = [alveolar] at equilibrium. |
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Term
T or F: The MAC is independent of noxious stimuli |
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Definition
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Term
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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. |
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Term
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Definition
Sensitizes heart to catecholamines (could cause arrhythmias). Can cause malignant hyperthermia when given w/ succinylcholine. |
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Term
Which general anesthetic is commonly used for maintenance, b/c it causes airway irritation? |
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Definition
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Term
| List the general anesthetics by decreasing potency |
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Definition
| Halothane, Isoflurane, Enflurane, Sevoflurane, Desflurane, & N2O |
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Term
Which general anesthetic is not capable of taking a person to stage 3? |
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Definition
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Term
How is thiopental distributed after a single IV injection? |
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Definition
It first goes to the brain & viscera, then to lean tissues, then to fat. |
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Term
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Definition
Rapid action and recovery Decreases bp Respiratory depression (may occur so maintenance is required) Histamine release may occur & cause bronchodilation. |
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Term
| What are the advantages & disadvantages of Etomidate. |
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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. |
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Term
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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. |
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Term
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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 |
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Term
What is the mechanism of action for local anesthetics? How do local anesthetics block Na channels? |
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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. |
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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. |
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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. |
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Term
| Which nerves (and their function) are very sensitive to local anesthetics? |
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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) |
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Term
| Which are more responsive to local anesthetics: large unmyelinated nerves, small unmyelinated nerves, small myelinated nerves, or large myelinated nerves? |
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Definition
| Small unmyelinated nerves |
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Term
| List, by rank, the functions that are most susceptible to anesthetics to those that are least susceptible |
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Definition
1) pain 2) touch 3) adrenergic vasoconstriction 4) temperature 5)propioception 6)motor function |
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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? |
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Definition
A larger molecule will attach to the receptor better. A more lipid soluble anesthetic can cross the nerve cell membrane faster cationic |
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Term
| What causes termination of action of local anesthetics? |
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Definition
They revert back to the unionized form and diffuse out of the neuron. Also, regional blood flow can wash the drug away. |
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Term
| What would happen if you used a vasoconstrictor along w/ a local anesthetic? |
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Definition
| It would delay absorption, prolong the effects, and reduce toxicity. |
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Term
| Which will have a longer duration of action: an anesthetic that is an ester or an anesthetic that is an amide? |
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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. |
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Term
What is surface anesthesia? |
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Definition
Surface anesthesia is a topical anesthesia used for pain, itching, soreness, etc. |
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Term
| What is infiltration anesthesia? |
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Definition
| It's an injection into a surgical area w/ no regard for nerves. |
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Term
| What is nerve block anesthesia? |
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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. |
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Term
| What is a spinal anesthesia? |
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Definition
| It's where you inject into the CSF to deaden nerves below the injection site. |
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Term
| What is intravenous regional anesthesia? |
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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. |
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Term
| What is an epidural injection? |
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Definition
| It's an injection into the epidural to block the spinal nerve roots. This is commonly used during child-birth. |
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Term
| An adverse rxn to a local anesthetic is usually related to the & or it may be an . |
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Definition
| CNS and CV system or allergic rxn |
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Term
| What was the first local anesthetic? |
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Definition
| Cocaine; many anesthetics are based off of its structure. |
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Term
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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. |
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Term
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Definition
| topical use only due to a complete lack of water solubility |
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Term
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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. |
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Term
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Definition
Longer duration than procaine or chloroprocaine Used for topical or spinal anesthesia |
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Term
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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. |
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Term
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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. |
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Term
T or F All general anesthetics relax muscle and potentiate NM blockers |
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Definition
False nitrous oxide doesn't |
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Term
Which 4 drugs could be used for status asthmaticus? Which of the 4 drugs is most commonly used for status asthmaticus? |
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Definition
HEDS Halothane, Enflurane, Desflurane, & Sevoflurane Sevoflurane is most common |
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Term
| Which of the general anesthetics has the slowest induction? |
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Definition
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Term
Which general anesthetic(s) increase cerebral blood flow? Which general anesthetic(s) dilates cerebral blood vessels? Who would these anesthetics be contraindicated in? |
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Definition
Sevoflurane & desflurane Halothane Someone w/ swelling in the brain, maybe due to a tumor. |
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