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Volatile agents are specially formulated organic liquids that evaporate readily into vapors, and are given by inhalation for induction and/or maintenance of general anesthesia. Nitrous oxide and xenon are gases at room temperature rather than liquids, so they are not considered volatile agents. The ideal anesthetic vapor or gas should be non-flammable, non-explosive, lipid soluble, should possess low blood gas solubility, have no end organ (heart, liver, kidney) toxicity or side effects, should not be metabolized and should be non-irritant when inhaled by patients.No anesthetic agent currently in use meets all these requirements. The agents in widespread current use are isoflurane, desflurane, sevoflurane, and nitrous oxide. Nitrous oxide is a common adjuvant gas, making it one of the most long-lived drugs still in current use. Because of its low potency, it cannot produce anesthesia on its own but is frequently combined with other agents. Halothane, an agent introduced in the 1950s, has been almost completely replaced in modern anesthesia practice by newer agents because of its shortcomings. Partly because of its side effects, enflurane never gained widespread popularity. In theory, any inhaled anesthetic agent can be used for induction of general anesthesia. However, most of the halogenated anesthetics are irritating to the airway, perhaps leading to coughing, laryngospasm and overall difficult inductions. For this reason, the most frequently-used agent for inhalational induction is sevoflurane. All of the volatile agents can be used alone or in combination with other medications to maintain anesthesia (nitrous oxide is not potent enough to be used as a sole agent).Currently research into the use of xenon as an anesthetic is underway, but the gas is very expensive to produce and requires special equipment for delivery, as well as special monitoring and scavenging of waste gas.Volatile agents are frequently compared in terms of potency, which is inversely proportional to the minimum alveolar concentration. Potency is directly related to lipid solubility. This is known as the Meyer-Overton hypothesis. However, certain pharmacokinetic properties of volatile agents have become another point of comparison. Most important of those properties is known as the blood:gas partition coefficient. This concept refers to the relative solubilty of a given agent in blood. Those agents with a lower blood solubility (i.e. a lower blood:gas partition coefficient, e.g. desflurane) give the anesthesia provider greater rapidity in titrating the depth of anesthesia, and permit a more rapid emergence from the anesthetic state upon discontinuing their administration. In fact, newer volatile agents (e.g. sevoflurane, desflurane) have been popular not due to their potency [minimum alveolar concentration], but due to their versatility for a faster emergence from anesthesia, thanks to their lower blood:gas partition coefficient.
Laryngospasm usually occurs when fluids or mucus enter the throat, sending the larynx into spasm to prevent further accumulation of fluid in the airway and lungs, much like what happens when you drown. Laryngospasm can also occur if the breathing tube stimulates the larynx on the way out. Sometimes, however, laryngospasm is idiopathic--that is, it just happens with no identifiable cause.There are drugs that can be used to reverse laryngospasm, so when they suctioned and performed a jaw thrust and failed to reverse the spasm, they should have considered pushing more propofol or some diazepam. They also could have used a 2% lidocaine spray.