Inhaled Anesthetics Flashcards
In relation to volatile anesthetics what does MAC mean? How is it useful?
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.
MAC 1.3 is
99% of will not respond
Factors that INCREASED Inhaled anesthetic requirements
Chronic ETOH Infant (highest MAC at 6 mo.) Red hair Hypernatremia Hyperthermia
Factors that INCREASED Inhaled anesthetic requirements
Chronic ETOH Infant (highest MAC at 6 mo.) Red hair Hypernatremia Hyperthermia
Volatile anesthetics and NDNMB
produce dose-dependent relaxation of skeletal muscles and enhance SCh and non-depolarizing neuromuscular drugs (especially desflurane)
Nitrous oxide causes cerebral_________and CBF is _____
vasodilation and increases CBF in the absence of volatile anesthetics.
Volatiles agents and MH
avoided in the MH-susceptible patient.
VA and ICP
measures of brain relaxation suggest that 50% NO plus 0.5 MAC of iso/des provide better relaxation [Miller]
VA and brain relaxation what do you use
measures of brain relaxation suggest that 50% NO plus 0.5 MAC of iso/des provide better relaxation [Miller]
For Neuro surgery
1.0 MAC of isoflurane or desflurane decreases CBF during craniotomy for supratentorial tumors
How do you attenuate the decrease in MAC seen with VA?
Add Nitrous (Increases MAP)
Inhaled anesthetics and HR?
Inhaled anesthetics also cause increases in heart rate, although at different doses –
Which Volatile anesthetics does not increase HR? Until what?
sevoflurane is unique in that it does not appreciably increase HR until 1.5 MAC is achieved.
VA affect CO ?
neither sevoflurane, desflurane, or isoflurane appreciably affect cardiac output in healthy volunteers
VA affect CO ?
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.
VA proposed mechanism of ACTION
Enhanced Inhibitory and inhibit excitatory action in the brain
What is the 2nd gas effect?
A large intake of one gas enhances the intake of another gas.
What is the concentration effect?
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
Isoflurane Brain equllibration time
10-15 mins
Isoflurane Brain equllibration time
10-15 mins
Sevoflurane Brain equllibration time
6 mins
Desflurane Brain equllibration time
6 mins
Nitrous Brain equllibration time
6 mins
What is the most important factor affecting the decrease in sevoflurane, desflurane, and isoflurane? Tnd essentially independent of case duration
Ventilation
What is the time needed for a 50% decrease in sevoflurane, desflurane, or isoflurane? Is it dependent upon case duration?
< 5 minutes; Independent of case duration
Should be avoided in patient with prolonged QT syndrome
Sevoflurane
What is malignant hyperthermia, how does it present, how is it managed?
Malignant hyperthermia is a dysregulation of calcium transport through the ryanodine receptor
What is malignant hyperthermia, how does it present, how is it managed?
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].
What is malignant hyperthermia, how does it present, how is it managed?
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.
What is malignant hyperthermia, how does it present, how is it managed?
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.
VA Associated with the greatest risk of hepatic injury is _____and safe ones are?
Halothane ( no longer use in the US) The newer anesthetics, isoflurane and desflurane, undergo less metabolism to trifluoroacetyl chloride (TFA),
