[The closed system. A discredited conception of the past, by innovations the method of choice (author's transl)]

The closed circle system is a secure, modern, totally clean and economic anaesthetic system if there is an O2-control system like the O2-Biomarine, a CO2-control system like the ultrared absorption system at an O2-gas flow of about 250ml per minute and an intermittent N2O supply of 500 ml per minute applied in adult anaesthesia patients. The system has always to remain closed and can always remain closed and it has to be also leakfree. Overfilling of the bag has to be avoided, this can be achieved by totally stopping N2O-supply until the reservation bag or the Biomarine oxygen indicator do not make further N2O supply necessary. In the last four years we have used this closed circle system exclusively more than 17,000 patients. There are some advantages for the patient for example concerning the temperature and humidification of the narcotic gases, the body temperature and so on. Table 3 shows the equivalence and the superiority of the closed circle system in comparison to the semi-closed circle system and the semi open system. --Abbreviations of the description are: good=+, very good=++, excellent=+++, bad=-, very bad=--. From our experience we think that everyone who has learnt to use the closed circle system is no longer able to understand the use of the semi-closed circle system or even of the open and the semi-open system, as far as there are no special indications for them.