Claims for Patent: 5,558,083

Summary for Patent: 5,558,083

Title:	Nitric oxide delivery system
Abstract:	A nitric oxide delivery system that is useable with any of a variety of gas delivery systems that provide breathing gas to a patient. The system detects the flow of gas delivered from the gas delivery system at various times and calculates the flow of a stream of nitric oxide in a diluent gas from a gas control valve. The flow of gas from the gas delivery system and the flow established from the flow control valve create a mixture having the desired concentration of nitric oxide for the patient. The system does not have to interrogate the particular gas delivery system being used but is an independent system that can be used with various flows, flow profiles and the like from gas delivery systems.
Inventor(s):	Bathe; Duncan P. L. (Madison, WI), Kohlmann; Thomas S. (McFarland, WI), Pinkert; John R. (Madison, WI), Tham; Robert Q. (Middleton, WI)
Assignee:	Ohmeda Inc. (Liberty Corner, NJ)
Application Number:	08/156,175
Patent Claims:	1. A nitric oxide delivery system for providing a predetermined concentration of nitric oxide to a patient, said nitric oxide delivery system having a connection means adapted to be fluidly connected to a supply of nitric oxide having a known concentration of nitric oxide, said nitric oxide delivery system further comprising a patient circuit having an inspiratory limb adapted to receive a breathing gas from a gas delivery system and communicate the breathing gas to a patient, a flow transducer located in said inspiratory limb of said patient breathing circuit for sensing the total flow of gas delivered by a gas delivery system to the patient and providing a signal indicative of such flow, input means for providing a signal indicative of the predetermined concentration of nitric oxide to be delivered to said inspirator limb of said breathing circuit, a flow control valve controlling the flow of nitric oxide from a supply of nitric oxide, conduit means in said inspiratory limb of said patient breathing circuit receiving the flow of nitric oxide from said flow control valve and combining the flow into the flow of gas from a gas delivery system, and a signal processor responsive to the signal from said flow transducer and to the signal indicative of the predetermined concentration to provide a signal to said flow control valve to establish a flow of nitric oxide through said flow control valve to said conduit means in an amount to establish a nitric oxide concentration delivered to a patient in the predetermined concentration. 2. A nitric oxide delivery system as defined in claim 1 wherein said conduit means combines the flow of the nitric oxide from a supply of nitric oxide and the flow of gas from a gas delivery system at a point downstream from said flow transducer. 3. A nitric oxide delivery system as defined in claim 1 wherein said means for providing a signal indicative of the predetermined nitric oxide concentration to be delivered to a patient comprises a control means operable by a user. 4. A nitric oxide delivery system as defined in claim 1 wherein said signal processor is a central processing unit (CPU). 5. A nitric oxide delivery system as defined in claim 4 wherein said means for providing a signal indicative of the predetermined nitric oxide concentration to be delivered to a patient comprises an electronic input device operable by a user to select said predetermined nitric oxide concentration and send an electrical signal to said CPU indicative of the selected concentration. 6. A nitric oxide delivery system as defined in claim 5 wherein said control valve is an electrically operated proportional control valve operable by an electrical signal from said CPU. 7. A nitric oxide delivery system as defined in claim 6 further including a sensor to detect at least the concentration of NO in the gas delivered to a patient. 8. A nitric oxide delivery system as defined in claim 1 further including a purge valve located in the path of flow of nitric oxide from a supply of nitric oxide, said purge valve being operable by said signal processor to purge said nitric oxide delivery system of other gases and to fill such system with nitric oxide from the supply of nitric oxide. 9. A nitric oxide delivery system for providing a predetermined concentration of nitric oxide to a patient, said system comprising a supply of nitric oxide having a known concentration, a gas delivery system for providing a breathing gas for delivery to a patient, said nitric oxide delivery system comprising a patient adapter receiving the breathing gas from said gas delivery system and connecting to a patient, said patient adapter having a passageway therethrough, a flow transducer within said patient adapter for sensing the total flow of breathing gas delivered by said gas delivery system and generating a signal indicative of such flow, control means for generating a signal indicative of the predetermined concentration of nitric oxide to be delivered to the patient from said patient adapter, a flow control valve controlling the flow of nitric oxide from said supply of nitric oxide, conduit means receiving the flow of the nitric oxide from said flow control valve and introducing the flow into said patient adapter, said flow of nitric oxide mixing within said patient adapter at a point downstream in said passageway from said flow transducer, and a signal processor responsive to the signal from said flow transducer representative of the sensed flow and to the signal from said control means to calculate and provide a signal to said flow control valve to establish a flow through said flow control valve to said patient adapter in an amount sufficient to establish a nitric oxide concentration delivered from said patient adapter to the patient in the predetermined amount. 10. A nitric oxide delivery system as defined in claim 9 wherein said patient adapter further includes a gas sensor adapted to sense the concentration of NO in the gas to be delivered to a patient. 11. A nitric oxide delivery system as defined in claim 10 wherein said signal processor is a central processing unit (CPU). 12. A nitric oxide delivery system as defined in claim 9 wherein said gas delivery system is a mechanical ventilator. 13. A nitric oxide delivery system as defined in claim 9 wherein said gas delivery system is a gas blender providing a continuous flow of gases. 14. A nitric oxide delivery system as defined in claim 9 wherein the gas is delivered to the patient through a wye piece and said patient adapter connects directly to the wye piece. 15. A method of providing a predetermined concentration of nitric oxide to a patient, said method comprising the steps of: (a) providing a supply of pressurized nitric oxide gas of a known concentration, (b) providing a gas delivery system for delivering A flow of gas to a patient, (c) providing a patient breathing circuit having an inspiratory limb for receiving the flow of gas from the gas delivery system to deliver the flow of gas to a patient, (d) sensing the total flow of the gas delivered by the gas delivery system to a patient at a point in the inspiratory limb of the patient breathing circuit, (e) providing a signal indicative of the flow sensed in step (d), (f) providing a signal indicative of the predetermined concentration of nitric oxide to be delivered to a patient, (g) mixing a flow of gas from the gas delivery system and a flow of nitric oxide from the pressurized nitric oxide supply, (h) using the signals provided in steps (e) and (f) to control a flow of nitric oxide from the pressurized nitric oxide supply to establish a nitric oxide concentration delivered to the patient circuit in a predetermined amount. 16. A method as defined in claim 15 wherein said step of mixing the flow of gas from the gas delivery system and the flow of nitric oxide from the nitric oxide supply occurs at a point downstream in the flow toward the patient with respect to the point at which the flow of gas from the gas delivery system is sensed. 17. A method as defined in claim 15 wherein said step of providing a signal indicative of the predetermined concentration to be delivered to the patient comprises manually determining the signal by the user through an electronic input device. 18. A method as defined in claim 15 further including the step of: (i) detecting the concentration of nitric oxide in the gas delivered to the patient. 19. A nitric oxide delivery system for providing a predetermined concentration of nitric oxide to a patient, said nitric oxide delivery system having a connection means adapted to be fluidly connected to a supply of nitric oxide of a known concentration, said nitric oxide delivery system further comprising an inspiratory conduit adapted to receive a breathing gas from a gas delivery system and communicate the breathing gas to a patient, a flow transducer for sensing the total flow of gas delivered by a gas delivery system through said inspiratory conduit to a patient and providing a signal indicative of such flow, an electronic input device operable by a user to select said predetermined nitric oxide concentration and to provide an electrical signal indicative of the predetermined concentration of nitric oxide to be delivered to a patient, an electrically operated proportional flow control valve controlling the flow of nitric oxide from a supply of nitric oxide, a mixing chamber within said inspiratory conduit receiving the flow of nitric oxide from said flow control valve and combining the flow into the flow of gas from a gas delivery system, a central processing unit (CPU) responsive to the signal from said flow transducer and to the electrical signal from said electronic input device indicative of the predetermined concentration to provide an electrical signal to operate said flow control valve to establish a flow of nitric oxide through said control valve to said conduit means in an amount to establish a nitric oxide concentration delivered to a patient in the predetermined amount and sensor means to detect the concentration of NO, O.sub.2 and NO.sub.2 in the gas delivered to a patient. 20. A nitric oxide delivery system for providing a predetermined concentration of nitric oxide to a patient, said system comprising a supply of nitric oxide having a known concentration, a mechanical ventilator for providing a plurality of breaths of varying flow of breathing gas for delivery to a patient, said nitric oxide delivery system comprising a flow transducer for sensing the flow of breathing gas delivered by said ventilator and generating a signal indicative of such flow, control means for generating a signal indicative of the predetermined concentration of nitric oxide to be delivered to the patient, a flow control valve controlling a flow of nitric oxide from said supply of nitric oxide, conduit means receiving the flow of the nitric oxide from said flow control valve and introducing the flow into the flow of gas from said ventilator, a central processing unit (CPU) responsive to the signal from said flow transducer representative of the sensed flow during each breath and said signal from said control means to calculate and provide a signal from said central processing unit to said flow control valve based on such calculation to establish a flow for the next succeeding breath through said flow control valve to said conduit means during each breath in an amount sufficient to establish a nitric oxide concentration delivered to the patient in the predetermined concentration. 21. A nitric oxide delivery system as defined in claim 20 wherein said CPU calculates the signal to the flow control valve based upon the following equation: 22. A nitric oxide delivery system as defined in claim 21 wherein said CPU signals said flow control valve to establish the flow of nitric oxide from said flow control valve at predetermined time intervals. 23. A nitric oxide delivery system for providing a predetermined concentration of nitric oxide to a patient, said system comprising a supply of nitric oxide having a known concentration, a gas delivery system for providing a flow of breathing gas for delivery to a patient, said gas delivery system comprising a flow transducer for sensing the flow of breathing gas delivered by said gas delivery system and generating a signal indicative of such flow, control means for generating a signal indicative of the predetermined concentration of nitric oxide to be delivered to a patient, a flow control valve controlling a flow of nitric oxide from said supply of nitric oxide, conduit means receiving the flow of the nitric oxide from said flow control valve and introducing the flow into the flow of gas from said gas delivery system, a signal processor responsive to the signal from said flow transducer representative of the sensed flow and to the signal from said control means to provide a signal to said flow control valve to establish a flow through said flow control valve to said conduit means in an amount sufficient to establish a nitric oxide concentration delivered to a patient in the predetermined amount, said system further including a gas analyzing bench to analyze NO, O.sub.2 and NO.sub.2 in the stream of breathing gas delivered to the patient. 24. A nitric oxide delivery system as defined in claim 23 further including an alarm system operable by a signal from said signal processor indicative of the concentration of NO analyzed by said gas analyzing bench. 25. A nitric oxide delivery system for providing a predetermined concentration of nitric oxide to a patient, said nitric oxide delivery system having a patient circuit having an inspiratory limb adapted to be connected to a patient, a gas delivery system for supplying a breathing gas to a patient through said inspiratory limb of said patient circuit and having a supply of nitric oxide and a supply of an inert gas, said nitric oxide delivery system further comprising a flow transducer located in said inspiratory limb of said patient breathing circuit for sensing the flow of gas delivered by said gas delivery system to a patient and providing a signal indicative of such flow, means for providing a signal indicative of the predetermined concentration of nitric oxide to be delivered to said breathing circuit, a flow control valve controlling the flow of nitric oxide from said supply of nitric oxide, conduit means receiving the flow of the nitric oxide from said flow control valve and combining the flow into the flow of gas from said gas delivery system, a flow control valve controlling the flow of inert gas from said pressurized supply of inert gas and a signal processor responsive to the signal from said flow transducer and to the signal indicative of the predetermined concentration to provide a signal to said flow control valve to establish a flow of nitric oxide through said control valve to said conduit means in an amount to establish a predetermined nitric oxide concentration delivered to said patient breathing circuit and to provide a signal to said inert gas flow control valve to selectively add inert gas to said conduit means to reduce the concentration of nitric oxide delivered to the patient breathing circuit to attain a predetermined concentration of nitric oxide supplied to a patient. 26. A nitric oxide delivery system as defined in claim 25 wherein said inert gas is nitrogen. 27. A nitric oxide delivery system for providing a predetermined concentration of nitric oxide to a patient, said nitric oxide delivery system having a patient breathing circuit having an inspiratory limb adapted to be connected to a patient, a gas delivery system for supplying a breathing gas to a patient through said inspiratory limb of said patient circuit and having a pressurized supply of nitric oxide and a pressurized supply of oxygen, said nitric oxide delivery system further comprising a flow transducer located in said inspiratory limb of said patient breathing circuit for sensing the flow of gas delivered by a gas delivery system to a patient and providing a signal indicative of such flow, means for providing a signal indicative of the predetermined concentration of nitric oxide to be delivered to said patient breathing circuit, a flow control valve controlling the flow of nitric oxide from said supply of nitric oxide, a flow control valve controlling the flow of oxygen to be delivered to said patient breathing circuit, conduit means receiving the flow of nitric oxide from said flow control valve and combining the flow into the flow of gas from said gas delivery system, a flow control valve controlling the flow of oxygen from the pressurized supply of oxygen and a signal processor responsive to the signal from said flow transducer and to the signal indicative of the predetermined concentration of nitric oxide to provide a signal to said flow control valve to establish a flow of nitric oxide through said control valve to said conduit means in an amount to establish a predetermined nitric oxide concentration delivered to said patient breathing circuit and to provide a signal to said oxygen flow control valve to selectively add oxygen to said conduit means to prevent the concentration of oxygen delivered to a patient from becoming reduced below a predetermined level necessary for a patient.