Pharmacology Of Inhaled Surgical General Anesthetics

Question 1

General anesthesia definition

Answer 1

Loss of consciousness, feeling and protective reflexes

Side effects:

• analgesia
• amnesia
• skeletal muscle relaxations

Question 2

What was the first anesthesia?

Answer 2

Diethyl ether inhalation

- nitrous oxide

Question 3

stages of general anesthesia

Answer 3

1) stage of analgesia
- loss of conscious w/ loss of pain
- amnesia can be developed here
- inhibits cerebral cortex

2) stage of excitement
- patient is delirious/excited
- respiration is irregular
- can vomit and or incontinent
- elevated blood pressure and heart rate
- once the hypothalamus takes over this stage occurs
* this is the stage to avoid, or minimize during anesthesia treatment*

3) stage of surgical anesthesia
- regular respiration and blood pressure occurs
- continues until regular respiration ceases
- subdivided into 4 phases based on eye movements and pupil reflexes
- ventilators must be present
* you have to try to keep patient in this stage*

4) stage of medullary depression
- severe depression of vasomotor and respiratory centers
- kills patient
* DONT get in this stage*

Question 4

Induction vs maintenance in anesthesia

Answer 4

Induction:
- time required to take a patient from consciousness -> stage 3

Maintenance:
- ability to keep patient safely in stage 3

Question 5

Examples of inhaled anesthetics

Answer 5

Nitrous oxide

Flurane agents

MOA:

• inhibt excitatory synapses by blocking NMDA receptors
• enhance inhibitory synapses in CNS by agonist activity to GABAa receptors

Question 6

What determines the rate of induction

Answer 6

Time required for therapeutic Concentration of inhaled anesthetic that gets into the CNS

Question 7

Solubility in anesthesia

Answer 7

Most important factor effecting transfer of general anesthesia from lung -> blood

Question 8

Blood:Gas partition coefficient

Answer 8

Determines the solubility of an inhaled drug

High coefficients indicate the drug is more soluble in blood
- higher solubility in blood = slower onset for action (this is bad)

Question 9

How to combat high blood:gas partition agents

Answer 9

Administer at higher dose intitally and reduce for maintenance

Also can give in conjunction with a low solubility agent (nitrous oxide)

Question 10

What determines the time to recovery from anesthesia?

Answer 10

Rate of elimination of general anesthesia from the brain

measured by the brain: blood coefficient
- lower number = quicker recovery