The Desflurane Tec 6 has a 'low agent' alarm and a 'no output' alarm, in addition to the ability to detect when it has been tipped (and therefore shouldn't be used). The other common agent, Sevoflurane, is delivered via a vaporizer that has none of these things. I am personally aware of two cases where no volatile anesthetic was delivered despite the vaporizer being 'open'. Two cases that would have been uneventful if desflurane and a Tec 6 vaporizer had been used. I'm going to ask the Society for Technology in Anesthesia listserv if there is any reason the Sevoflurane vaporizer couldn't have these features.