ETHRANE CONCENTRATION DETERMINATION IN LOW FLOW SYSTEM ANESTHESIA

Using infra-red anesthetic gas analyzer as the monitor during low flow system anesthesia, the inspiratory enthrane concentration has been shown to be rather safe to the patient with an in-circle vaporizer, providing some precautions are strictly followed.Model 103 chinese anesthetic machine was tested. The general impression is: the smaller the gas current passing through vaporizer, the lighter the concentration liberating to the patient. With O₂ flow 1 L/min figures obtained after continuous collective measurements are presented as following:Vaporizer control set Enthrane concentration（%）"1" 0.616 0.132"2" 1. 324 0.220"3" 1.720 0.160Three main safe guards for this kind of anesthesia are: 1) Costant low O₂ flow （less than 500ml/min）, 2) well adjusted vaporizer set control and 3) assisted respiration with unchanged optimum tidal volume. A rapid and potentially dangerous increase in concentration will occur only if signinficant increase in respirtory minute volume or intermittent pressurization of vaporizer content is present.