Inhaled Anesthetics

Question 1

In relation to volatile anesthetics what does MAC mean? How is it useful?

Answer 1

MAC is the minimum Alveolar concentration (end expiratory). It is useful to determine the alveolar concentration needed for 50% of the population not to motor response to a surgical stimulus.

Question 2

MAC 1.3 is

Answer 2

99% of will not respond

Question 3

Factors that INCREASED Inhaled anesthetic requirements

Answer 3

Chronic ETOH
Infant (highest MAC at 6 mo.)
Red hair
Hypernatremia
Hyperthermia

Question 4

Factors that INCREASED Inhaled anesthetic requirements

Answer 4

Chronic ETOH
Infant (highest MAC at 6 mo.)
Red hair
Hypernatremia
Hyperthermia

Question 5

Volatile anesthetics and NDNMB

Answer 5

produce dose-dependent relaxation of skeletal muscles and enhance SCh and non-depolarizing neuromuscular drugs (especially desflurane)

Question 6

Nitrous oxide causes cerebral_________and CBF is _____

Answer 6

vasodilation and increases CBF in the absence of volatile anesthetics.

Question 7

Volatiles agents and MH

Answer 7

avoided in the MH-susceptible patient.

Question 8

VA and ICP

Answer 8

measures of brain relaxation suggest that 50% NO plus 0.5 MAC of iso/des provide better relaxation [Miller]

Question 9

VA and brain relaxation what do you use

Answer 9

measures of brain relaxation suggest that 50% NO plus 0.5 MAC of iso/des provide better relaxation [Miller]

Question 10

For Neuro surgery

Answer 10

1.0 MAC of isoflurane or desflurane decreases CBF during craniotomy for supratentorial tumors

Question 11

How do you attenuate the decrease in MAC seen with VA?

Answer 11

Add Nitrous (Increases MAP)

Question 12

Inhaled anesthetics and HR?

Answer 12

Inhaled anesthetics also cause increases in heart rate, although at different doses –

Question 13

Which Volatile anesthetics does not increase HR? Until what?

Answer 13

sevoflurane is unique in that it does not appreciably increase HR until 1.5 MAC is achieved.

Question 14

VA affect CO ?

Answer 14

neither sevoflurane, desflurane, or isoflurane appreciably affect cardiac output in healthy volunteers

Question 15

VA affect CO ?

Answer 15

neither sevoflurane, desflurane, or isoflurane appreciably affect cardiac output in healthy volunteers.
sevoflurane exhibits the most profound drop, from 100 L/min to 80 L/min as MAC goes from 0.0 to 1.0, however this increases back to 90 L/min as MAC approaches 2.0.

Question 16

VA proposed mechanism of ACTION

Answer 16

Enhanced Inhibitory and inhibit excitatory action in the brain

Question 17

What is the 2nd gas effect?

Answer 17

A large intake of one gas enhances the intake of another gas.

Question 18

What is the concentration effect?

Answer 18

Increasing PI in order to accelerate input is known as the concentration effect, although this may only be achievable in the presence of nitrous oxide

Question 19

Isoflurane Brain equllibration time

Answer 19

10-15 mins

Question 20

Isoflurane Brain equllibration time

Answer 20

10-15 mins

Question 21

Sevoflurane Brain equllibration time

Answer 21

6 mins

Question 22

Desflurane Brain equllibration time

Answer 22

6 mins

Question 23

Nitrous Brain equllibration time

Answer 23

6 mins

Question 24

What is the most important factor affecting the decrease in sevoflurane, desflurane, and isoflurane? Tnd essentially independent of case duration

Answer 24

Ventilation

Question 25

What is the time needed for a 50% decrease in sevoflurane, desflurane, or isoflurane? Is it dependent upon case duration?

Answer 25

< 5 minutes; Independent of case duration

Question 26

Should be avoided in patient with prolonged QT syndrome

Answer 26

Sevoflurane

Question 27

What is malignant hyperthermia, how does it present, how is it managed?

Answer 27

Malignant hyperthermia is a dysregulation of calcium transport through the ryanodine receptor

Question 28

What is malignant hyperthermia, how does it present, how is it managed?

Answer 28

Malignant hyperthermia is a dysregulation of calcium transport through the ryanodine receptor. (RYR1), which regulate the passage of calcium from the sarcoplasmic reticulum into the intracellular space [12,13].

Question 29

What is malignant hyperthermia, how does it present, how is it managed?

Answer 29

Malignant hyperthermia is a dysregulation of calcium transport through the ryanodine receptor. (RYR1), which regulate the passage of calcium from the sarcoplasmic reticulum into the intracellular space [12,13].
The most reliable initial clinical sign heralding the development of acute MH is an unexplained increase in end tidal CO2, masseter muscle rigidity , Hyperthermia
Management: Call for help, Notify surgeon,optimize oxygenation and ventilation, Avoid CCB
Dandrolene 2.5 mg/kg IV
For older formulations of dantrolene (Dantrium, Renovo, generic dantrolene sodium), dilute each 20 mg vial with 60 mL sterile water. For a 70 kg patient, 175 mg (9 vials) will be required.

Question 30

What is malignant hyperthermia, how does it present, how is it managed?

Answer 30

PATHO:Malignant hyperthermia is a dysregulation of calcium transport through the ryanodine receptor. (RYR1), which regulate the passage of calcium from the sarcoplasmic reticulum into the intracellular space [12,13].
SIGN: The most reliable initial clinical sign heralding the development of acute MH is an unexplained increase in end tidal CO2, masseter muscle rigidity , Hyperthermia
MANAGEMENT: Call for help, Notify surgeon,optimize oxygenation and ventilation, Avoid CCB
TREATMENT: Dandrolene 2.5 mg/kg IV
For older formulations of dantrolene (Dantrium, Renovo, generic dantrolene sodium), dilute each 20 mg vial with 60 mL sterile water. For a 70 kg patient, 175 mg (9 vials) will be required.

Question 31

VA Associated with the greatest risk of hepatic injury is _____and safe ones are?

Answer 31

Halothane ( no longer use in the US) The newer anesthetics, isoflurane and desflurane, undergo less metabolism to trifluoroacetyl chloride (TFA),