[Closed circuit anesthesia: its foundation and application].

Abstract

The basic theory of closed circuit anesthesia (CCA) was founded by Dr. H Lowe in 1970's. The introductory textbook he and his colleague wrote was published in 1981, which, surprisingly, has not been revised since then. Furthermore, there are no other monographs on this subject, reflecting a decline in the interest of many anesthesiologists in CCA. However, CCA has been drawing more and more attention recently because of the introduction of new and expensive inhalational anesthetics and growing concern over environmental pollution. In this review, we aimed at explaining the basis on which how Dr. Lowe derived his original theory of CCA called square root method, and what limitations this theory has in applying CCA to our clinical practice. Then, we proposed a practical modification of Lowe's approach, introducing a statistical method called "Bayesian updating" to predict a changing variables during anesthesia. We conclude this review by discussing future perspective of CCA, taking Xenon as an example of an ideal anesthetic agent that may be introduced into our clinical practice in the near future.