Lecture 54: General Anesthetics Flashcards Preview

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Flashcards in Lecture 54: General Anesthetics Deck (25):
1

General anesthesia is used

For procedures that require loss of consciousness; immobility despite painful stimulation

2

What is the surgical plane and one goal of anesthesia

Surgical plane = Level III EEG; goal is to minimize time at levels I & II

3

What four things would an ideal anesthetic do? What do we have to do to achieve these effects?

1. Loss of consciousness, 2. Analgesia, 3. Paralysis, 4. Amensia; no ideal anesthetic, must blend drugs = balanced anesthesia

4

What drugs as used as adjuncts in anesthesia?

Sedative-hypnotics, opioids, NM blockers

5

Advantage of an inhaled anesthetic

Rapidly titrate depth of anesthesia

6

Advantage of intravenous anesthetic

Better tolerated at induction (no mask)

7

Three examples of high potency inhaled anesthetics we need to know (+ one from LC) and the molecule they're derived from

Sevolurane*, isoflurane*, desflurane* (halothane**); ether

8

One example of low potency inhaled anesthetic

N2O*

9

How are inhaled anesthetics thought to work (2)

Enhance inhibitory ligand-gated channels (GABAa, glycine in SC) and inhibit excitatory ligand-gated channels (AMPA, NMDA, nAChR)

10

What is the limit on volatile anesthetic concentration?

Vapor pressure of the liquid

11

Define MAC; how is MAC expressed and how would you describe a certain dose?

Minimum Alveolar Concetration: median value of the minimum effective concentration to suppress movement in standardized incision, expressed a % and dose given as MAC multiples

12

Describe lipid solubility and anesthetic potency. What key drug has the highest oil:gas ratio?

Oil : gas partition coefficient --> greater oil solubility (larger coefficient), lower the MAC; Isoflurane

13

Higher blood solubility means you need more/less molecules to get anesthetic to brain

More

14

Describe blood solubility and rate of equilibrium. What drug has very low solubility?

Lower the solubility, the faster the induction; N2O

15

What is the effect of ventilation on induction rate? Biggest effect on what type of anesthetic?

Increased ventilation speeds induction; those w/ high solubility

16

Anesthesia is maintained at what MAC multiple? What if its used for induction?

1.3 - 1.4x MAC; higher MAC (maybe 3-4x MAC)

17

Name and describe two considerations for NO (one when NO is turned on and one when it's turned off)

1. Turn on: Trapped air space, due to N2O moving into blood faster than N2 leaves; 2. Turn off: Diffusion hypoxia, due to N2O flooding alveoli, terminate with 100% O2

18

Why would you want to deliver NO with other inhaled anesthetics. Name the effect.

Second gas effect: N2O creates alveolar "vacuum" which increases respiration, quickening induction of all inhaled anesthetics

19

All high-potency agents do what to blood pressure, GFR, pCO2?

Decrease; decrease; increase

20

Describe N2O's BP/pCO2 effects

N2O does not decrease BP and is less likely to increase pCO2

21

When used with what, what SE of inhaled anesthetics can occur? Treatment?

Malignant hyperthermia; Dantrolene

22

What is the most widely used induction agent. Receptor? Advantage? SEs?

Propofol*; GABA; rapid onset; decreases BP/respiratory depression

23

Explain why Propofol's half life increases with length of administration

Obeys two-compartment kinetics: the fast phase involves distributing the drug into poorly perfused tissues and the slow phase involves hepatic elimination; injection favors fast phase while infusing favors slow phase

24

Name another common infused anesthetic and its advantage over Propofol

Etomidate*; does not cause cardiopulmonary SEs

25

What is the mechanism of ketamine? What state does it produce? SEs?

Inhibits excitatory glutamate signaling via NMDA receptors; dissociated anesthetic state; sympathetic: increased HR/BP/bronchodilation

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