Inhaled Anesthetics - Nitrous Oxide

Question 1

What is the Minimum Alveolar Concentration (MAC) of Nitrous Oxide?

A) 0.8%
B) 2.5%
C) 50%
D) 104%
E) 1.0%

Answer 1

D) 104%

MAC (dose): 104% (won’t solely induce pt, used as 2nd gas effect)

Question 2

Blood:Gas Partition Coefficient of Nitrous Oxide, and what does it indicate about its onset?

A) 0.46, indicating a rapid onset
B) 1.2, indicating a slow onset
C) 0.8, indicating an intermediate onset
D) 2.5, indicating a very slow onset
E) 0.2, indicating a very rapid onset

Answer 2

A) 0.46, indicating a rapid onset

Question 3

What is the Vapor Pressure of Nitrous Oxide and what does this value indicate?

A) 745 psi, indicating it is stored as a liquid at room temperature
B) 380 torr, indicating it is a solid at room temperature
C) 745 torr, indicating it is a gas at room temperature
D) 38,770 psi, indicating it is highly volatile and can easily evaporate
E) 745 psi, indicating it is a gas that is easily vaporized

Answer 3

A) 745 psi, indicating it is stored as a liquid at room temperature

Vapor Pressure: 38,770 torr (745 psi)

Question 4

What factors primarily influence the half-life of Nitrous Oxide? (Select 2)

A) Cardiac output (CO)
B) Ventilation (Vm)
C) Plasma protein binding
D) Liver metabolism
E) Renal excretion

Answer 4

A) Cardiac output (CO)
B) Ventilation (Vm)

Question 5

What is the primary mechanism of action of Nitrous Oxide in the context of anesthesia? (Select 2)

A) Inhibition of NMDA receptors at the dorsal horn of the spinal cord
B) Potentiation of GABAA receptors
C) Inhibition of serotonin reuptake
D) Potentiation of K+ channels, leading to hyperpolarization
E) Activation of adrenergic receptors

Answer 5

A) Inhibition of NMDA receptors at the dorsal horn of the spinal cord

D) Potentiation of K+ channels, leading to hyperpolarization

-MAIN–Inhibition of NMDA-R at dorsal horn of spinal cord)
-K+ Channel Potentiation (Increases K permeability = hyperpolarized) (doesn’t stimulate GABAA)

Question 6

Which of the following are the primary elimination pathways for Nitrous Oxide? (Select 3)

A) Alveoli
B) Hepatic biotransformation
C) Renal excretion
D) Percutaneous loss
E) Gastrointestinal excretion

Answer 6

A) Alveoli
B) Hepatic biotransformation
D) Percutaneous loss

Question 8

Which of the following conditions should be avoided when administering Nitrous Oxide? (Select 3)

A) Bullae seen on chest X-ray
B) Pregnancy with suspected B12 deficiency
C) Inner ear surgery
D) Uncomplicated appendicitis
E) Chronic kidney disease

Answer 8

A) Bullae seen on chest X-ray
B) Pregnancy with suspected B12 deficiency
C) Inner ear surgery

Question 9

Action:
SVR +
HR +
CVP +
SV no change

Question 10

Which is Nitrous Oxide contraindicated in?

A) Nero case: Nitrous Oxide is neuroprotective and reduces cerebral metabolic rate of oxygen (CMRO2)
B) Neuro case: Nitrous Oxide increases cerebral metabolic rate of oxygen (CMRO2) and cerebral blood flow (CBF)
C) Neuro case: Nitrous Oxide has no effect on cerebral metabolic rate of oxygen (CMRO2)
D) Neuro case: Nitrous Oxide decreases cerebral blood flow (CBF)

Answer 10

B) Nitrous Oxide increases cerebral metabolic rate of oxygen (CMRO2) and cerebral blood flow (CBF)

Question 10

Which of the following are contraindications for the use of Nitrous Oxide? (Select 4)

A) Bowel surgery
B) Pneumothorax
C) Intraocular surgery following retinal repair
D) Inner ear surgery
E) Routine dental procedures

Answer 10

A) Bowel surgery
B) Pneumothorax
C) Intraocular surgery following retinal repair
D) Inner ear surgery

Question 11

Why is Nitrous Oxide contraindicated in patients with pulmonary hypertension?

A) It can cause further myocardial depression and increase pulmonary vessel resistance

B) It decreases pulmonary vessel resistance and improves myocardial function

C) It has no effect on myocardial function or pulmonary vessel resistance

D) It reduces the risk of pulmonary hypertension complications

E) It increases systemic vascular resistance without affecting pulmonary vasculature

Answer 11

A) It can cause further myocardial depression and increase pulmonary vessel resistance

Question 13

Which of the following are common side effects of Nitrous Oxide? (Select 3)

A) Postoperative nausea and vomiting (PONV)
B) Malignant hyperthermia (MH)
C) Postoperative shivering
D) Hyperglycemia
E) Respiratory depression

Answer 13

A) Postoperative nausea and vomiting (PONV)
B) Malignant hyperthermia (MH)
C) Postoperative shivering as general