On-line fault detection and correction in anesthesia delivery system

Anesthesia system for delivering a breathing gas containing a known anesthetic agent concentration to a patient, said anesthesia system comprising:

• a patient circuit for administering the breathing gas and anesthetic agent to the patient, said patient circuit having a wye connector for connection to a patient through which inhaled and exhaled gases pass to and from a patient, a fresh gas supply providing a fresh gas to said patient circuit at a known rate, said fresh gas supply comprising an electronic controlled gas mixer for providing a mixture of gases at a known proportion and an electronic controlled vaporizer for introducing anesthetic agent vapor to the mixture of gases from said electronic controlled gas mixer, a CPU controlling said electronic controlled vaporizer and said electronic controlled mixer, a data input device operable by a user to input to said CPU the concentrations of oxygen and anesthetic agent desired to be administered to a patient through said patient circuit, a first gas monitor for analyzing oxygen and anesthetic agent at or near said wye connector, a second gas monitor detecting the concentration of oxygen and anesthetic agent in the gas circulating within said patient circuit, flow control means to increase the rate of flow of said fresh gas entering said patient circuit from said fresh gas supply, and said CPU including a comparator to compare the concentration of oxygen and anesthetic agent determined by said first gas monitor, said second gas monitor and the concentration of oxygen and anesthetic agent inputted by a user with said data input device when said increased flow of fresh gas is entering said patient circuit, said flow control means returning said rate of flow of said fresh gas entering said patient circuit from said fresh gas supply to said known rate when said comparator has completed comparing the oxygen and anesthetic agent concentrations.