In a right-to-left intracardiac shunt, which inhalation anesthetic would have the greatest impact on the rate of induction?

In a right-to-left intracardiac shunt, which inhalation anesthetic would have the greatest impact on the rate of induction?

• A. Halothane
• B. Desflurane
• C. Isoflurane
• D. It would speed up induction for all agents equally

Answer: (B)

Inhaled anesthetic induction depends largely on how quickly the agent moves from alveolar gas into the blood and then to the brain. A right-to-left intracardiac shunt bypasses part of the lungs, so pulmonary uptake is reduced and brain delivery becomes more dependent on the agent’s inherent properties, especially blood-gas solubility. Agents with low blood-gas solubility enter the blood and reach the brain more quickly, so they are less slowed by impaired lung uptake. Desflurane has the lowest blood-gas solubility among the options, so even with a shunt its brain concentration rises fastest, producing the quickest induction. Halothane, with higher solubility, would be more delayed by the shunt; isoflurane falls in between. Therefore desflurane would show the most favorable induction rate in this scenario.

Inhaled anesthetic induction depends largely on how quickly the agent moves from alveolar gas into the blood and then to the brain. A right-to-left intracardiac shunt bypasses part of the lungs, so pulmonary uptake is reduced and brain delivery becomes more dependent on the agent’s inherent properties, especially blood-gas solubility. Agents with low blood-gas solubility enter the blood and reach the brain more quickly, so they are less slowed by impaired lung uptake. Desflurane has the lowest blood-gas solubility among the options, so even with a shunt its brain concentration rises fastest, producing the quickest induction. Halothane, with higher solubility, would be more delayed by the shunt; isoflurane falls in between. Therefore desflurane would show the most favorable induction rate in this scenario.