Inhalation agents Flashcards
What is Nitrous Oxide at room temperature?
Gas at room temperature, liquid under pressure.
What is the mechanism of action of Nitrous Oxide?
NMDA receptor antagonist.
What are the cardiovascular effects of Nitrous Oxide?
Stimulates the sympathetic nervous system, masking myocardial depression. Modest increase in RVEDP due to pulmonary vasoconstriction.
What are the respiratory effects of Nitrous Oxide?
Increases respiratory rate, decreases tidal volume with minimal effect on minute ventilation and pCO₂. Significantly depresses hypoxic drive.
What are the cerebral effects of Nitrous Oxide?
Increases cerebral blood flow, cerebral volume, and intracranial pressure. Increases cerebral oxygen consumption. Provides analgesia at sub-MAC concentrations.
What are the neuromuscular effects of Nitrous Oxide?
No significant muscle relaxation; may cause rigidity at high concentrations.
What are the renal and hepatic effects of Nitrous Oxide?
Decreases renal and hepatic blood flow.
What is the metabolism and toxicity of Nitrous Oxide?
Minimal metabolism (<0.01%). Irreversibly oxidizes vitamin B12, inhibiting related enzymes.
What are the drug interactions of Nitrous Oxide?
Reduces required concentration of potent volatile anesthetics. Affects vaporizer-delivered volatile anesthetic concentration.
What are the contraindications for Nitrous Oxide?
Avoid in air-containing cavity conditions (pneumothorax, bowel distention, intracranial air).
What is Isoflurane?
Volatile anesthetic.
What are the cardiovascular effects of Isoflurane?
Dilates coronary arteries, potential myocardial depression in certain patients.
What are the respiratory effects of Isoflurane?
Causes respiratory depression with less pronounced tachypnea, good bronchodilator.
What are the cerebral effects of Isoflurane?
Increases cerebral blood flow and intracranial pressure at concentrations >1 MAC.
What are the neuromuscular effects of Isoflurane?
Provides muscle relaxation.
What are the renal and hepatic effects of Isoflurane?
Decreases renal blood flow. May reduce total hepatic blood flow but maintains hepatic oxygen supply.
What is the metabolism and toxicity of Isoflurane?
Metabolized to trifluoroacetic acid, limited oxidative metabolism minimizes hepatic dysfunction risk.
What are the drug interactions of Isoflurane?
Potentiates nondepolarizing neuromuscular blocking agents (NMBAs).
What are the contraindications for Isoflurane?
No unique contraindications.
What is Desflurane?
Volatile anesthetic.
What are the cardiovascular effects of Desflurane?
Similar to isoflurane, decreases SVR and arterial blood pressure.
What are the respiratory effects of Desflurane?
Airway irritant.
What are the cerebral effects of Desflurane?
Increases cerebral blood flow and intracranial pressure. Cerebral vasculature remains responsive to PaCO₂ changes.
What are the neuromuscular effects of Desflurane?
Dose-dependent decrease in response to peripheral nerve stimulation.
What are the renal and hepatic effects of Desflurane?
No significant nephrotoxicity. Hepatic function tests generally unaffected.
What is the metabolism and toxicity of Desflurane?
Minimal metabolism. Degraded by desiccated CO₂ absorbent into carbon monoxide.
What are the contraindications for Desflurane?
Shares contraindications with other volatile anesthetics. Potentiates NMBAs.
What is Sevoflurane?
Volatile anesthetic.
What are the cardiovascular effects of Sevoflurane?
Mildly depresses myocardial contractility, slight decline in SVR and arterial blood pressure.
What are the respiratory effects of Sevoflurane?
Depresses respiration and reverses bronchospasm, similar to isoflurane.
What are the cerebral effects of Sevoflurane?
Slight increases in cerebral blood flow and intracranial pressure. High concentrations may impair cerebral autoregulation.
What are the neuromuscular effects of Sevoflurane?
Produces adequate muscle relaxation for intubation.
What are the renal and hepatic effects of Sevoflurane?
Slightly decreases renal blood flow, maintains total hepatic blood flow and oxygen delivery.
What is the metabolism and toxicity of Sevoflurane?
Metabolized at a rate lower than halothane but higher than isoflurane/desflurane. Can degrade into nephrotoxic Compound A and hydrogen fluoride.
What are the contraindications for Sevoflurane?
Potentiates NMBAs without sensitizing the heart to catecholamine-induced arrhythmias.
Which inhalation agent is not good for induction?
Desflurane, due to airway irritation.
Which inhalation anesthetic degrades into nephrotoxic byproducts such as Compound A and hydrogen fluoride?
Sevoflurane.
All three inhalation anesthetics (Isoflurane, Sevoflurane, Desflurane) share which cardiovascular effects?
Decrease SVR and arterial blood pressure.
Which agent is less effective at providing muscle relaxation than the others?
Desflurane.
Which inhalation anesthetic is considered the best bronchodilator?
Sevoflurane.
What is the primary method of elimination for all three volatile anesthetics?
Alveolar ventilation.
Which of the following anesthetics undergoes the least metabolism in the body?
Desflurane.
What are the contraindications for all three volatile anesthetics?
Potentiate NMBA, catecholamine-induced arrhythmias, and malignant hyperthermia.
Which inhalation agent is best for kidney patients?
Desflurane.
Sevoflurane is best for:
Asthma, MI, CAD, increased ICP.
Desflurane is best for:
Rapid emergence (outpatient surgery), increased ICP, liver dysfunction, kidney disease.
Isoflurane is best for:
Nothing (avoid in MI, outpatient surgery due to slow emergence, increased ICP).
Avoid Sevoflurane in:
Kidney disease, liver dysfunction.
Avoid Desflurane in:
Asthma.
