Accuracy of the Universal Portable Anesthesia Complete Drawover Vaporizer When Using the Anesthesia Simulator
UNIFORMED SERVICES UNIV OF THE HEALTH SCIENCES BETHESDA MD BETHESDA United States
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Drawover anesthesia is not a new concept, it dates to the earliest use of volatile anesthetic agents. William T.G. Morton used ether and a drawover vaporizer on October 16, 1846in the first public demonstration of volatile agent anesthesia. Ether was widely used as a volatile anesthetic in the military from 1846 until the end of World War II. Drawover vaporizers were used on a limited basis during the Viet Nam War. As a result of success with drawover anesthesia experienced by British Armed Forces during the Falkland War the United States military gained a renewed interest in this device. Currently the Ohmeda Universal Portable Anesthesia Complete UPAC drawover device is used by the United States military. Patient simulation is a relatively new tool in teaching anesthesia students. Teaching drawover anesthesia using the patient simulator may have potential advantages. In this study the accuracy of anesthetic delivery by the UPAC as measured by the RASCAL was assessed. The anesthesia patient simulator provided an accurate source of negative inspiratory force to operate the UPAC. The study found that the UPAC delivers accurate and consistent concentrations of isoflurane when used with the anesthesia simulator. However at tidal volumes of 900ml after prolonged use expired concentrations of isoflurane exceeded inspired. This may be a result of absorption of isoflurane into the rubber and plastic components of the anesthesia simulator. It may also have been the result of large tidal volumes and increased amounts of isoflurane drawn into the mechanical lung of the simulator resulting in a concentration effect due to ventilatory limitations of the simulator.