Do the newer volatile agents offer advantages over older agents such as enflurane and isoflurane?
Two volatile anesthetic agents, desflurane and sevoflurane, both ethers, have been extensively tested. Desflurane is a clear nonflammable liquid that is extremely insoluble and requires a specially designed, heated vaporizer for administration. Unfortunately, the gas has a strong odor and is a powerful airway irritant. It can produce coughing, breath-holding, and laryngospasm; therefore its use as an inhalation induc-tion agent is precluded. Its major advantage is low blood and tissue solubility, which allows for a fast emergence when compared with currently available volatile agents. Low solubility properties also allow rapid titration of anesthetic depth.
Although desflurane and isoflurane have similar muscle relaxing properties, higher levels of desflurane can be administered without concern about a delayed emergence. Studies to date have revealed that the times to ambulation and discharge with desflurane are similar to those seen with propofol, although patients anesthetized with desflu-rane appear to be less sedated in the early postoperative period. However, nausea and vomiting were less frequent with propofol.
Sevoflurane is nonpungent and odorless, and coughing and breath-holding are absent on rapid inhalation induc-tion. Its solubility in blood approaches that of nitrous oxide. Fires have been reported when sevoflurane is used in the presence of desiccated soda lime. Both sevoflurane and desflurane can provide sufficient muscle relaxation to allow tracheal intubation. Both can trigger malignant hyperthermia.