Volatile anesthetic agents remain the foundation of inhalational anesthesia. Each agent has a distinct pharmacokinetic profile determined primarily by its blood-gas partition coefficient, which governs speed of onset and offset. Selecting the appropriate agent depends on the clinical scenario, patient factors, and procedural requirements. Understanding MAC, organ system effects, and the comparative pharmacology of each agent enables optimal agent selection.
Sevoflurane: MAC 2.0%, blood-gas partition coefficient 0.65; smooth induction, minimal airway irritation
Desflurane: MAC 6.0%, blood-gas partition coefficient 0.42; fastest emergence but causes airway irritation at >6%
Isoflurane: MAC 1.15%, blood-gas partition coefficient 1.46; coronary steal concern largely theoretical
All volatile agents produce dose-dependent decreases in SVR, MAP, and myocardial contractility
Minimum alveolar concentration (MAC) decreases ~6% per decade of age after 40
For outpatient procedures where rapid emergence is a priority, desflurane or sevoflurane are preferred over isoflurane due to their lower blood-gas solubility. However, desflurane should not be used for mask induction due to airway irritation and sympathetic stimulation above 1 MAC.
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