Method and apparatus for controlling a medical anesthesia delivery system

A medical anesthesia delivery system for administering respiration and anesthesia to a patient comprising:

• a) a gas supply for providing fresh breathing gas comprising a plurality of component gases;
• b) an anesthetic agent supply for providing anesthetic agent to said fresh breathing gas;
• c) a breathing circuit in communication with said gas supply and said anesthetic agent supply for delivering gas and agent mixture to and away from said patient's respiratory tract, the breathing circuit including a pop-off valve for releasing a pop-off flow of gas from the breathing circuit;
• d) flow sensor means for measuring the pop-off flow of gas released from said pop-off valve;
• e) user input means for permitting an operator to input desired concentrations for said component gases and said anesthetic agent in said breathing circuit;
• f) control means for controlling the concentration of at least one of said component gases in said breathing circuit and including:
• (i) means for increasing said fresh gas flow by a predetermined volume in response to a change in at least one of said desired concentrations inputted by a user with said user input;
• and (ii) means for minimizing said pop-off flow measured by said flow sensor means.

A method of controlling a medical anesthesia delivery system for administering respiration and anesthesia to a patient, the anesthesia delivery system including a gas supply for providing fresh breathing gas comprised of a plurality of component gases, an anesthetic agent supply for providing anesthetic agent to said fresh breathing gas, a breathing circuit in communication with said gas supply for delivering gas and anesthetic agent mixture to and away from said patient's respiratory tract, the breathing circuit including pop-off valve for releasing a pop-off flow of gas from the breathing circuit in response to a predetermined pressure differential, and a user interface for permitting a user to input values for desired concentrations of said component gases and said anesthetic agent in said breathing circuit, the method comprising the steps of:

• a) changing at least one of said user-input values;
• b) increasing the flow rate of fresh gas into said breathing circuit to a value based on the minute volume of gas delivered to the patient in response to the changing of said at least one of said user input values while maintaining or reducing the errors between measured values corresponding to the component gas and anesthetic agent concentrations and said user-set values;
• c) monitoring the pop-off flow of gas released from the pop-off valve;
• and
• d) terminating said increased flow rate when said pop-off flow of gas from said pop-off valve monitored in step c) exceeds a predetermined amount;
• e) minimizing the fresh gas flow.

A medical anesthesia delivery system for administering respiration and anesthesia to a patient comprising:

• a) a gas supply for providing fresh breathing gas comprised of a plurality of component gases;
• b) an anesthetic agent supply for providing anesthetic agent to said fresh breathing gas;
• c) a breathing circuit in communication with said gas supply and said anesthetic agent supply for delivering gas and anesthetic agent mixture to and away from said patient's respiratory tract, the breathing circuit including a pop-off valve for releasing a pop-off flow of gas from the breathing circuit in response to a predetermined pressure differential;
• d) gas flow sensor means for monitoring the pop-off flow of gas released from said pop-off valve;
• e) means for filling the breathing circuit with said fresh breathing gas and including means for terminating the filling when a predetermined pop-off flow from said pop-off valve is sensed by said gas flow sensor.