Abstract: An anesthesia system wherein the respiratory system is fitted with interchangeable patient circuit modules that allows a generic fitting in the machine to have affixed, hereto, a module that has ports suitable for connection to various patient breathing circuits. As such, the anesthesia machine can have the patient circuit modules easily changed and thus be adaptable for use with patient breathing circuits such as the circle system, the open/nonrebreathing circuit and the Bain or Mapleson D circuits. A detector system is provided that identifies that particular patient module installed in the anesthesia machine to alert the main CPU and to thus provide the correct flow sensing schemes and flows to the patient breathing circuit then being used.

Abstract: A system that enables the accurate monitoring of tidal volume of a patient when using a Bain, Mapleson D or similar type of patient breathing circuit in an anesthesia system. The system allows the use of flow sensors positioned at the machine or distal end of the patient breathing circuit and not at the less desirable patient or proximal end of the patient breathing circuit. Thus, the flow sensors can be positioned out of the way of the patient and will provide a measurement of the tidal volume of the patient. A CPU is used to take into account, the additional fresh gas provided to the patient breathing circuit during the expiration cycle to correct the flow monitored in the main breathing tube that supplies the gas to the patient from a ventilator or breathing bag.

Abstract: An improved system for the determining the collapse of a bellows within a canister as part of a ventilator system for delivering breaths to a patient via a patient circuit. The system measures the pressure in the bellows canister external of the bellows and measures the pressure within the interior of the bellow. A processor compares the pressures and determines when the pressure within the canister exceeds a predetermined offset in excess of the pressure within the interior of the bellows to conclude that the bellows is in a collapsed condition. In the preferred embodiment, the processor also uses, as input data, the flow delivered by the ventilator to the bellows canister to determine that offset value. When a bellows empty condition is determined, various actions can be taken, among them to signal an alarm and also to change various functions of the ventilator to prevent further difficulties in the overall system.