General Anesthesia 1: applied kinetics

Question 1

clearance formula

Answer 1

clearance = elimination const x Vd(ss)

Question 2

elimination half life formula

Answer 2

t1/2= 0.693/elimination const

Question 3

loading dose formula

Answer 3

D = conc. in plasma at steady state x Vd

Question 4

const rate infusion formula

Answer 4

CRI = conc in plasma at ss x elim. const x Vd

Question 5

methods of elimination for general anesthetics

Answer 5

 Biotransformation
* Inactivation
* Metabolites (active or inactive)
* Liver and many other organs
 Clearance
* Kidney and many other organs

Question 6

END-TIDAL INHALATIONAL ANESTHETIC CONCENTRATION reflects:

Answer 6

• Reflects the alveolar concentration
• Reflects the brain concentration

Question 7

ALVEOLAR CONCENTRATION depends on

Answer 7

1. Inspired concentration
2. Alveolar ventilation
3. Solubility of inhalational anesthetic
4. Cardiac Output
5. Tissue capacity and blood flow to it

Question 8

how does inspired conc affect alveolar conc?

Answer 8

Higher % results in faster achievement of desired %.

Question 9

how does alveolar ventilation affect alveolar conc

Answer 9

 Better ventilation results in faster increase in FA
 Ventilation depends on depth as well as rate
 Wasted ventilation occurs if shallow (dead space rebreathing)

Question 10

how does inhalant solubility affect alveolar conc

Answer 10

 The tension or pressure exerted to get into the blood
 High solubility => more in blood and less in alveoli initially
 This delays transfer to the brain because the drug has to saturate the blood before it moves through a pressure gradient into the brain

Question 11

BLOOD/GAS PARTITION COEFFICIENT what is it what does it mean

Answer 11

Number of parts of gas in blood vs alveolus. High number means gas is very soluble in blood

Question 12

High solubility inhalant=

Answer 12

prolonged induction and recovery

Question 13

how does cardiac output affect anesthetic effects?

Answer 13

1. FA
2. Brain blood flow
    Normally 8 % of cardiac output goes to brain in healthy animals
    Rapid equilibration when blood saturation (partial) occurs
    Very high % of cardiac output goes to brain in animal in shock (low cardiac output)

Sick animals induce faster than healthy!

Question 14

Brain concentration will not rise significantly until

Answer 14

alveolar concentration starts to rise.

Question 15

Anesthetic quantity in blood is dependent on both

Answer 15

solubility and alveolar concentration.

Question 16

Most of the inhalant in the body is eliminated via ? solubility affects this how, allowing what?

Answer 16

via ventilation (Lung)

More soluble inhalants are in the body longer allowing time for a more significant degree of metabolism by the liver

Question 17

RECOVERY DEPENDS ON …

Answer 17

. Movement from brain back to blood
1. Movement from blood back to alveolus
2. anesthetic removed from alveolus back to anesthetic system and scavenging