Inhaled anesthetics

Question 1

Gaseous anesthetic

Answer 1

Nitrous Oxide (N2O)

Question 2

Volatile anesthetics

Answer 2

Enflurane
Isoflurane
Halothane

Question 3

Volatile anesthetics pharmacodynamics

Answer 3

-volatile anesthetics are liquid at room temperature
(e.g. enflurane, isoflurane, halothane)
(“Air tank in water”)

-volatile anesthetics are fluorinated
(e.g. enflurane, isoflurane,halothane)
(“Balloon flower”)

-highly soluble inhaled anesthetic (e.g. halothane)
(“Moving freely in ball pit”)

more soluble inhaled anesthetics (e.g. halothane) have a slower onset of action
(“Passed out later”)

-more soluble inhaled anesthetics (e.g. halothane) have a longer duration of action (“Long tapering flag”)

• Partition>>>: higher blood:gas partition coefficient
  (e. g. halothane) → higher solubility → **slower onset of action
• ———————————————————————————**

Less steep arterial tension curve (e.g. halothane) → higher blood:gas partition coefficient→higher solubility → slower onset of action

Question 4

Nitrous Oxide Pharmacodynamics

Answer 4

less soluble inhaled anesthetic
(“Impeded by ball pit”)
(e.g. N2O)

less soluble inhaled anesthetics (e.g. N2O) have a faster onset of action
(“Passed out earlier”)

less soluble inhaled anesthetics (e.g. N2O) have a faster recovery
(“Immediate rescue” )

Steeper arterial tension curve (e.g. N2O)→ lower blood:gas partition coefficient→ lower solubility → faster onset of action

Question 5

Volatile Anesthetics side effects

Answer 5

-inhaled anesthetics can cause respiratory depression (leading to decreased minute ventilation and hypercapni a)
(“Deflating lung balloons”)

-myocardial depression →hypotension
(“deflating heart balloon”)

-fluorinated anesthetics increase cerebral blood flow (decrease cerebral vascular resistance)(“Red brain wig”)

halothane can be hepatotoxic
(e.g. massive hepatic necrosis) (“Cracked liver”)

enflurance can be nephrotoxic (“Smacked in the flank”)

enflurance can induce seizures (“Shaking”)

-malignant hyperthermia
(skeletal muscle hypersensitivity to volatile anesthetics) (“Magnificent birthday”)

Question 6

MAC

Answer 6

minimum alveolar concentration (MAC)

MAC corresponds to the dose of anesthetic that causes 50% of patients to become unresponsive to painful stimuli
(“1 out of 2 unresponsive”)

1/MAC corresponds to the potency of an inhaled anesthetic ​(“Inverted bowl of potent mac and cheese”)

Question 7

malignant hyperthermia

Answer 7

-succinylcholine (depolarizing muscle relaxant) can also causes malignant hyperthermia

malignant hyperthermia is related to a defect in ryanodine receptors (RyR) in the sarcoplasmic reticulum

-excess heat production and consumption of ATP induces rhabdomyolysis

Question 8

what is the treatment of malignant hyperthermia

Answer 8

Dantrolene
———————————————————————————–
Blocking Ryan: dantrolene blocks ryanodine receptors

-treats malignant hyperthermia