Inhalation agents

Question 1

What is Nitrous Oxide at room temperature?

Answer 1

Gas at room temperature, liquid under pressure.

Question 2

What is the mechanism of action of Nitrous Oxide?

Answer 2

NMDA receptor antagonist.

Question 3

What are the cardiovascular effects of Nitrous Oxide?

Answer 3

Stimulates the sympathetic nervous system, masking myocardial depression. Modest increase in RVEDP due to pulmonary vasoconstriction.

Question 4

What are the respiratory effects of Nitrous Oxide?

Answer 4

Increases respiratory rate, decreases tidal volume with minimal effect on minute ventilation and pCO₂. Significantly depresses hypoxic drive.

Question 5

What are the cerebral effects of Nitrous Oxide?

Answer 5

Increases cerebral blood flow, cerebral volume, and intracranial pressure. Increases cerebral oxygen consumption. Provides analgesia at sub-MAC concentrations.

Question 6

What are the neuromuscular effects of Nitrous Oxide?

Answer 6

No significant muscle relaxation; may cause rigidity at high concentrations.

Question 7

What are the renal and hepatic effects of Nitrous Oxide?

Answer 7

Decreases renal and hepatic blood flow.

Question 8

What is the metabolism and toxicity of Nitrous Oxide?

Answer 8

Minimal metabolism (<0.01%). Irreversibly oxidizes vitamin B12, inhibiting related enzymes.

Question 9

What are the drug interactions of Nitrous Oxide?

Answer 9

Reduces required concentration of potent volatile anesthetics. Affects vaporizer-delivered volatile anesthetic concentration.

Question 10

What are the contraindications for Nitrous Oxide?

Answer 10

Avoid in air-containing cavity conditions (pneumothorax, bowel distention, intracranial air).

Question 11

What is Isoflurane?

Answer 11

Volatile anesthetic.

Question 12

What are the cardiovascular effects of Isoflurane?

Answer 12

Dilates coronary arteries, potential myocardial depression in certain patients.

Question 13

What are the respiratory effects of Isoflurane?

Answer 13

Causes respiratory depression with less pronounced tachypnea, good bronchodilator.

Question 14

What are the cerebral effects of Isoflurane?

Answer 14

Increases cerebral blood flow and intracranial pressure at concentrations >1 MAC.

Question 15

What are the neuromuscular effects of Isoflurane?

Answer 15

Provides muscle relaxation.

Question 16

What are the renal and hepatic effects of Isoflurane?

Answer 16

Decreases renal blood flow. May reduce total hepatic blood flow but maintains hepatic oxygen supply.

Question 17

What is the metabolism and toxicity of Isoflurane?

Answer 17

Metabolized to trifluoroacetic acid, limited oxidative metabolism minimizes hepatic dysfunction risk.

Question 18

What are the drug interactions of Isoflurane?

Answer 18

Potentiates nondepolarizing neuromuscular blocking agents (NMBAs).

Question 19

What are the contraindications for Isoflurane?

Answer 19

No unique contraindications.

Question 20

What is Desflurane?

Answer 20

Volatile anesthetic.

Question 21

What are the cardiovascular effects of Desflurane?

Answer 21

Similar to isoflurane, decreases SVR and arterial blood pressure.

Question 22

What are the respiratory effects of Desflurane?

Answer 22

Airway irritant.

Question 23

What are the cerebral effects of Desflurane?

Answer 23

Increases cerebral blood flow and intracranial pressure. Cerebral vasculature remains responsive to PaCO₂ changes.

Question 24

What are the neuromuscular effects of Desflurane?

Answer 24

Dose-dependent decrease in response to peripheral nerve stimulation.

Question 25

What are the renal and hepatic effects of Desflurane?

Answer 25

No significant nephrotoxicity. Hepatic function tests generally unaffected.

Question 26

What is the metabolism and toxicity of Desflurane?

Answer 26

Minimal metabolism. Degraded by desiccated CO₂ absorbent into carbon monoxide.

Question 27

What are the contraindications for Desflurane?

Answer 27

Shares contraindications with other volatile anesthetics. Potentiates NMBAs.

Question 28

What is Sevoflurane?

Answer 28

Volatile anesthetic.

Question 29

What are the cardiovascular effects of Sevoflurane?

Answer 29

Mildly depresses myocardial contractility, slight decline in SVR and arterial blood pressure.

Question 30

What are the respiratory effects of Sevoflurane?

Answer 30

Depresses respiration and reverses bronchospasm, similar to isoflurane.

Question 31

What are the cerebral effects of Sevoflurane?

Answer 31

Slight increases in cerebral blood flow and intracranial pressure. High concentrations may impair cerebral autoregulation.

Question 32

What are the neuromuscular effects of Sevoflurane?

Answer 32

Produces adequate muscle relaxation for intubation.

Question 33

What are the renal and hepatic effects of Sevoflurane?

Answer 33

Slightly decreases renal blood flow, maintains total hepatic blood flow and oxygen delivery.

Question 34

What is the metabolism and toxicity of Sevoflurane?

Answer 34

Metabolized at a rate lower than halothane but higher than isoflurane/desflurane. Can degrade into nephrotoxic Compound A and hydrogen fluoride.

Question 35

What are the contraindications for Sevoflurane?

Answer 35

Potentiates NMBAs without sensitizing the heart to catecholamine-induced arrhythmias.

Question 36

Which inhalation agent is not good for induction?

Answer 36

Desflurane, due to airway irritation.

Question 37

Which inhalation anesthetic degrades into nephrotoxic byproducts such as Compound A and hydrogen fluoride?

Answer 37

Sevoflurane.

Question 38

All three inhalation anesthetics (Isoflurane, Sevoflurane, Desflurane) share which cardiovascular effects?

Answer 38

Decrease SVR and arterial blood pressure.

Question 39

Which agent is less effective at providing muscle relaxation than the others?

Answer 39

Desflurane.

Question 40

Which inhalation anesthetic is considered the best bronchodilator?

Answer 40

Sevoflurane.

Question 41

What is the primary method of elimination for all three volatile anesthetics?

Answer 41

Alveolar ventilation.

Question 42

Which of the following anesthetics undergoes the least metabolism in the body?

Answer 42

Desflurane.

Question 43

What are the contraindications for all three volatile anesthetics?

Answer 43

Potentiate NMBA, catecholamine-induced arrhythmias, and malignant hyperthermia.

Question 44

Which inhalation agent is best for kidney patients?

Answer 44

Desflurane.

Question 45

Sevoflurane is best for:

Answer 45

Asthma, MI, CAD, increased ICP.

Question 46

Desflurane is best for:

Answer 46

Rapid emergence (outpatient surgery), increased ICP, liver dysfunction, kidney disease.

Question 47

Isoflurane is best for:

Answer 47

Nothing (avoid in MI, outpatient surgery due to slow emergence, increased ICP).

Question 48

Avoid Sevoflurane in:

Answer 48

Kidney disease, liver dysfunction.

Question 49

Avoid Desflurane in:

Answer 49

Asthma.