Pharmacology-General Anesthetics Flashcards Preview

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Flashcards in Pharmacology-General Anesthetics Deck (26)
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1
Q

4 A’s of General Anesthesia

A

Amnesia, Analgesia, Akinesia, Autonomic & sensory reflex blockade

2
Q

What is defined as the concentration of an inhalant required for immobility of 50% of subjects exposed to a noxious stimulus?

A

Minimum alveolar concentration (MAC)

3
Q

Are the MAC values of different drugs additive?

A

Yes

4
Q

What does 1 MAC do? 1.3 MAC? 1.5-2 MAC?

A

50% of patients won’t move at surgical incision. 95% of patients will not move at surgical incision. Blocks 50% of patient autonomic responses.

5
Q

Stage I of anesthesia

A

Analgesia w/o amnesia

6
Q

Stage II of anesthesia

A

Delirious excitement

7
Q

Stage III of anesthesia

A

Surgical anesthesia

8
Q

Stage IV of anesthesia

A

Medullary depression

9
Q

What is the goal in delivering inhaled anesthetics?

A

The partial pressure in the alveolar gas (FA) = partial pressure in inspired gas (FI). When this ratio gets close to 1, you’ve reached steady state because the tissue can no longer take up more gas.

10
Q

What happens to speed of induction as minute ventilation is increased?

A

It also increases

11
Q

What is the blood:gas partition coefficient?

A

The difference in concentration between the inspired gas and blood at steady state.

12
Q

Why do you need very little nitrous oxide to put someone out? Why do you need lots of halothane?

A

It has low solubility. The blood does not absorb any of it, so most of what is delivered through the ventilator goes to the target tissue. Halothane needs lots of gas because it is very soluble.

13
Q

How does decreased cardiac output affect reaching your target blood concentration?

A

It increased the induction rate because most blood is going to your target tissue, the brain.

14
Q

How are most general anesthetic eliminated? How does solubility affect elimination.

A

Lungs. The lower the solubility the better it is eliminated. The liver gets rid of some

15
Q

Why would you never give a patient 2 MAC of volatile anesthetic?

A

You can drop their mean arterial pressure to 50.

16
Q

How does halothane affect SVR and CO?

A

It has a huge CO depression and little effect on SVR.

17
Q

Why are patients at higher risk for arrhythmias when given volatile anesthetics?

A

They sensitize the heart to the effects of NE

18
Q

How do volatile anesthetics affect respiration?

A

Increased RR, decreased ventilatory response to hypoxemia and decreased minute ventilation

19
Q

How to volatile anesthetic affect the brain?

A

Decreased metabolic O2 requirement, increased cerebral blood flow (may increase intracranial pressure)

20
Q

How do volatile anesthetics affect the kidneys and liver?

A

Blood flow to these organs is decreased.

21
Q

Inhalation of what anesthetic can cause malignant hyperthermia? How do you treat a patient with this?

A

Succinyl choline and other anesthetics. It is treated by giving dantrolene (Ca2+ channel blocker)

22
Q

What are the four classes of sedative hypnotics? What are these used for?

A

Barbituates, Etomidate, Propofol, Benzodiazepines (used to induce unconsciousness)

23
Q

What is the idea that the longer you infuse a drug, the longer it will take to eliminate it due to increased uptake by other tissues during infusion?

A

Context sensitive half time

24
Q

What is them most commonly used induction agent?

A

Propofol (works at GABA receptors)

25
Q

Why would you use etomidate over propofol?

A

It has minimal CV effects

26
Q

What induction agent might you use if someone is in shock?

A

Ketamine. It maintains blood pressure and heart rate.