Abstract: Improved apparatus and methods for non-invasively assessing one or more parameters associated with systems such as fluidic circulating systems (e.g., the circulatory system of a living organism). In a first aspect, an improved method of continuously measuring pressure from a compressible vessel is disclosed, wherein a substantially optimal level of compression for the vessel is achieved and maintained using dynamically applied dither perturbations (e.g., modulation) on the various axes associated with the vessel. In a second aspect, an improved apparatus and method are provided for monitoring hemodynamic parameters, such as blood pressure, in a continuous and non-invasive manner while operating under a single unifying scheme. One variant of this scheme using a simulated annealing (SA) type approach to determining and maintaining an optimal operating state.

Abstract: An anesthesia delivery system having a means of determining the functioning of its gas mixer, vaporizer and analyzers, their accuracies and other characteristics by comparing, at high flow conditions, the input of oxygen concentration and agent concentration set by a clinician and delivered by the system, the input from a feedback respiratory analyzer of the inspired O.sub.2 and agent concentrations and the input of a monitor analyzer that determines the O.sub.2 and agent concentrations in the patient circuit. A CPU compares the three sets of input data to make various determinations since, at high flow conditions, all of the three sets of data should be consistent. Thus the CPU can determine from a comparison, whether one set of data is indicative of a faulty device, can provide a bias adjustment if an analyzer is merely off in its readings or carry out other safety and corrective functions based on comparing the three data inputs.

Abstract: A system for automatically refilling the patient breathing circuit of an anesthesia system wherein the system detects the existence of a large leak in the patient breathing system and reduces the flow of the fresh gas to the patient circuit to minimize the amount of gas that is vented to the atmosphere. As the leak is corrected, the system automatically detects that the leak has been alleviated and increases the fresh gas flow to a high flow to refill the patient breathing circuit in a rapid time. Upon refill, the system detects that the circuit and the system has been refilled and automatically reduces the fresh gas flow back to a lower level desired by the clinician to maintain the anesthesia. The fresh gas flow used to refill the patient circuit is the same composition of gases and anesthetic agent as initially set by the clinician.

Abstract: Efficient management of breathing gases and anesthesia is achieved in an anesthesia delivery system which incorporates a flow minimization routine. The breathing circuit is provided with a pop-off valve and a flow sensor for detecting the pop-off flow. The flow rate of fresh gas into the breathing circuit is controlled, preferably via a digital computer, to minimize the amount of gas exhausted from the circuit. A control routine determines the minimal fresh gas flow necessary to maintain appropriate oxygen concentration, anesthetic agent concentration pop-off flow. A minimum value for the fresh gas flow may also be input to the control system. A fresh gas flow boost routine provides quick responses to charges in the user-set oxygen and agent concentrations. A circuit fill routine provides fresh gas to fill the breathing circuit until pop-off flow is sensed.

Abstract: An anesthesia system is disclosed that prolongs the lifetime of an oxygen fuel cell be used to detect the concentration of oxygen in that anesthesia system. The system determines and provides a signal indicating the end of any particular operation using the anesthesia system and that signal is used to cut off all gas supplies with the exception of the fresh air supply which is then allowed to pass through the system to wash the various lines, including the conduit having the oxygen gas fuel cell thus preventing the typically high concentrations of oxygen used in a operation from remaining in the oxygen fuel cell for an unnecessary period of time. Furthermore, the gases in the anesthesia machine are eliminated along with their deleterious effects and replaced by fresh air from the normal supply of fresh air to the system.