Which volatile agent will have the quickest onset without considering potency?

Desflurane is noted for its rapid onset of action primarily due to its low blood-gas solubility coefficient. This means that desflurane equilibrates quickly between the alveoli of the lungs and the bloodstream, allowing for a faster delivery of the anesthetic agent to the brain and other tissues. Its low solubility enables a more rapid rise in alveolar concentration, which is critical for achieving the desired anesthetic effects quickly.

In practice, this rapid onset is significant for procedures that require swift induction, making desflurane a preferable choice in many surgical scenarios where time is of the essence. The other agents listed, such as enflurane, sevoflurane, and isoflurane, have higher blood-gas solubility coefficients, which leads to a slower onset compared to desflurane, reflecting their slower equilibration dynamics in the body.