Inhalation Agents

Question 1

Inhalation Agents MOA (3)

Answer 1

Volatile anesthetics primarily affect the function of ion channel and neurotransmitter receptor proteins in the membranes of nerve cells, which are lipid environments.

CNS ; GABAa stimulation produces supraspinal inhibition of transmission.

The Spinal Cord mediates immobility via inhibition of glycine channels.

Question 2

Inhalation Agent Effects (4)

Answer 2

Unconsciousness : cerebral cortex, thalamus

Amnesia : amygdala , hippocampus

Analgesia: spinothalamic tract

Immobility : spinal cord receptors

Question 3

Vapor Anesthetic Effects on Cardiac (4)

Answer 3

decrease BP, CO, SVR

+/- heart rate

Question 4

Vapor Anesthetic Effects on Respiratory (2)

Answer 4

increase rate, decrease TV

Question 5

Vapor Anesthetic Effects on Cerebral (2)

Answer 5

increase blood flow , decrease CMRO2

Question 6

Vapor Anesthetic Effects on Muscular

Answer 6

Neuromuscular relaxation

Question 7

Vapor Anesthetic Effects on Renal (2)

Answer 7

decrease blood flow and filtration rate

Question 8

Vapor Anesthetic Effects on Hepatic

Answer 8

decrease blood flow

Question 9

Vapor Anesthetic Effects on Metabolism (2)

Answer 9

slight decrease if normothermic

all are MH triggers

Question 10

Isoflurane Class

Answer 10

Halogenated methyl ethyl ether

Question 11

Isoflurane Vapor Pressure (pressure exerted by molecules from a volatile liquid that escape the liquid phase and become vapor, higher number= more molecules in vapor phase)

Answer 11

VP 239 mm Hg at 20 degrees C

Question 12

Isoflurane MAC (relative potency)

Answer 12

MAC 1.17 in oxygen

Question 13

Isoflurane B/G Coefficient (speed of onset, lower # = faster)

Answer 13

B/G = 1.4

Question 14

Isoflurane Oil/Gas Coefficient (usually inversely related to MAC)

Answer 14

Oil /gas = 0.99

Question 15

Isoflurane Considerations (3)

Answer 15

Not degraded
Non flammable
Irritating to airways

Question 16

Desflurane Class

Answer 16

Fluorinated methyl ethyl ether

Question 17

Desflurane Vapor Pressure (pressure exerted by molecules from a volatile liquid that escape the liquid phase and become vapor, higher number= more molecules in vapor phase)

Answer 17

VP 673 mmHg at 20 degrees

Question 18

Desflurane Boiling Point (temperature at which the vapor pressure equals atmospheric pressure)

Answer 18

BP 23.5 degrees C

Question 19

Desflurane B/G Coefficient (speed of onset, lower # = faster)

Answer 19

B/G = 0.42

Question 20

Desflurane Oil/Gas Coefficient (usually inversely related to MAC)

Answer 20

Oil/Gas = 18.7

Question 21

Desflurane MAC (relative potency)

Answer 21

MAC 4-6%

Question 22

Desflurane Considerations (6)

Answer 22

Needs special heated vaporizer d/t low boiling point (Tec-6)

When heated under pressure it exists as vapor

Low tissue solubility

Irritating to airways

Cardiac: tachycardia more common

CO formation in desiccated absorber

Question 23

Sevoflurane Class

Answer 23

Flourinated isopropyl ether

Question 24

Sevoflurane Vapor Pressure (pressure exerted by molecules from a volatile liquid that escape the liquid phase and become vapor, higher number= more molecules in vapor phase)

Answer 24

VP = 162 mm Hg

Question 25

Sevoflurane B/G Coefficient (speed of onset, lower # = faster)

Answer 25

B/G=0.59-0.6

Question 26

Sevoflurane Oil/Gas Coefficient (usually inversely related to MAC)

Answer 26

Oil/Gas= 50

Question 27

Sevoflurane MAC (relative potency)

Answer 27

MAC 2 in oxygen

Question 28

Sevoflurane Considerations (4)

Answer 28

Degrades in Baralyme absorber -Compound A ( sub clinical) Not irritating to the airways -Best for inhalation induction** Moderate fat solubility Combustion risk in desiccated absorber

Question 29

Nitrous Oxide Class

Answer 29

Inorganic, supports combustion

Question 30

Nitrous Oxide Vapor Pressure (pressure exerted by molecules from a volatile liquid that escape the liquid phase and become vapor, higher number= more molecules in vapor phase)

Answer 30

VP 39,000mm Hg

Question 31

Nitrous Oxide B/G Coefficient (speed of onset, lower # = faster)

Answer 31

B/G 0.47

Question 32

Nitrous Oxide Oil/Gas Coefficient (usually inversely related to MAC)

Answer 32

Oil/Gas = 1.4

Question 33

Nitrous Oxide Boiling Point (temperature at which the vapor pressure equals atmospheric pressure)

Answer 33

Boils at 88 degrees C.

Question 34

Nitrous Oxide MAC (relative potency)

Answer 34

MAC 104

Question 35

Nitrous Oxide Considerations

Answer 35

Stored as liquid under pressure Pleasant smell Danger of hypoxia with high concentration or low atm. pressure Because it is 30-34 x more soluble the nitrogen it can cause closed air spaces (bowel, ET cuff, air embolism) to expand as it replaces the N2 in the air.

Question 36

Nitrous Oxide Critical Temperature

Answer 36

Critical temperature= 36.5 degrees C.

Question 37

Nitrous Oxide Summary

Answer 37

Incomplete anesthetic Rapid Onset and Recovery

Question 38

Desflurane Summary

Answer 38

Low Volatility Poor Induction Agent (very pungent and irritating to airway) Rapid Recovery

Question 39

Sevoflurane Summary

Answer 39

Rapid onset and recovery Unstable in soda lime

Question 40

Isoflurane Summary

Answer 40

Medium rate of onset and recovery