A pressure based adaptive controller for closed circuit anesthesia

To make the closed-circuit system more general, a pressure-based adaptive controller for closed-circuit anesthesia (CCA) has been developed. The pressure-volume characteristics of the bladder or the bellows is used as the basis for the pressure based control of a CCA system. The controller was tested during six animal experiments on dogs and was stable in both the spontaneous and mechanical models of ventilation. The system developed is more acceptable to the practicing anesthetist accustomed to the direct feel of the anesthetic bladder acting upon the patient, both in case of assisted and manual control of ventilation. The development of this anesthesia delivery system eliminates the problem of solving complex multi-compartment mathematical equations in order to predict the flow of oxygen, anesthetic agent, and nitrous oxide necessary for maintaining the desired level of alveolar oxygen concentration, end-tidal anesthetic concentration, and the pressure inside the bladder or the bellows