Anesthesia Technologist Practice Exam

Which of the following agents may use a variable bypass vaporizer for delivery?

1. Halothane, enflurane, isoflurane, and sevoflurane

2. Desflurane, isoflurane, and nitrous oxide

3. Methohexital, thiopental, and propofol

4. Halothane, nitrous oxide, and desflurane

The correct answer is: Halothane, enflurane, isoflurane, and sevoflurane

The use of a variable bypass vaporizer is designed for inhalation anesthetics that require precise control over the concentration delivered to the patient. This technique allows anesthesiologists to mix fresh gas flow with vaporized anesthetic agents in a way that adjusts the output concentration depending on the needs of the patient. Halothane, enflurane, isoflurane, and sevoflurane are all halogenated volatile anesthetics that can effectively utilize a variable bypass vaporizer. These agents have specific physical properties, such as vapor pressure and boiling point, which make them suitable for this method of delivery. Variable bypass vaporizers can adjust the amount of the agent vaporized based on the flow rate of carrier gases, thereby allowing for more accurate dosing and better control during anesthesia management. In contrast, agents like desflurane, while also a volatile anesthetic, are typically delivered using a specific vaporizer designed for their unique properties. Nitrous oxide is a gas at room temperature and is not delivered via a variable bypass vaporizer but rather through a different mechanism that doesn't involve vaporization. Agents such as methohexital, thiopental, and propofol are not volatile anesthetics but rather intravenous anesthetics, which