[Closed system anaesthesia with continuous inspiratory oxygen measurement (author's transl)].

Relatively simple and inexpensive electrochemical oxygen-sensors have led to clinical evaluation of oxygen and nitrous oxide in completely closed circuits. Thus, a timely solution relating to possibilities of theatre-pollution and the economy this method allows, was obtained. "Fading" is a characteristic of electrochemical sensors; the principal factor involved seems to be the condensation of water vapor on the sensor, attenuating its sensitivity with the passage of time. However, a new model, that of Dräger, showed uniformly less than 1% fading after several hours of closed system anaesthesia, which is clinically negligible. Other failures were unmistakable and immediately recognizable. The techniques for neuroleptanalgesia and halothane anaesthesia with standard anaesthetic machines are described. The dosage of halothane with Vapor vaporizer, the reliability of absorption of CO2, the conditions which may be associated with accumulation of nitrogen up to 10 Vol.-%, as well as the relative merits of different ventilatores were explored. Studies performed with aid of oxygen sensors during clinical closed system anaesthetics are shown in relation to N2O-uptake and N2-elimination. In comparison with conventional methods the understanding of anaesthetic-uptake, the learning process and personal interest are enhanced, the patient's safety being ensured at the same time. The method of using a closed circuit here described was used in fifteen hundred patients ranging from 5-97 years without complications and is now routine at our clinic. Other advantages of the technique for the patient are retention of adequate humidification and heat of inspired gas and an almost complete dissociation of alveolar ventilation and uptake of anaesthetic.