New inhaled anesthetics

Desflurane and sevoflurane provide one clear advantage over other currently available potent inhaled anesthetics. Their lower solubilities permit a more precise control over the delivery of anesthesia and a more rapid recovery from anesthesia. Most of their other properties reflect similar properties of their predecessors--with a few exceptions. Indeed, at concentrations of 1 MAC or less, the pharmacologic properties of these two agents differ little if at all. However, in contrast to desflurane, at concentrations exceeding 1 MAC sevoflurane has little or no respiratory irritant properties and may be used to rapidly induce anesthesia. Neither anesthetic seems to materially affect heart rate at concentrations lower than MAC, but at higher concentrations desflurane, but not sevoflurane, may increase heart rate. Desflurane strongly resists biodegradation and degradation by soda lime, whereas sevoflurane is vulnerable to degradation and the degradation by soda lime or Baralyme produces a toxic product. Thus, neither of these new anesthetics can be said to be ideal, but each may be a step in that direction.