Control of respiratory oxygen delivery

• US 6,186,142 B1
• Filed: 11/13/1998
• Issued: 02/13/2001
• Est. Priority Date: 07/25/1997
• Status: Expired due to Fees

• Current Assignee: Minnesota Innovative Technologies and Instruments
• Original Assignee: Minnesota Innovative Technologies and Instruments
• Inventors: Nordman, Catherine A., Schmidt, Matthew F., Buan, John S.
• Primary Examiner(s): Dawson, Glenn K.
• Application Number:
  US09/191,574
• Time in Patent Office: 823 Days
• Field of Search: 128/204.18, 128/204.21, 128/204.23, 128/204.26, 128/207.18
• US Class Current: 128/204.23
• CPC Class Codes: A61M 16/0051 with alarm devices
• CPC Class Codes: A61M 16/026 specially adapted for predicting, e.g. for determining an information representative of a flow limitation during a ventilation cycle by using a root square technique or a regression analysis
• CPC Class Codes: A61M 16/0677 Gas-saving devices therefor
• CPC Class Codes: A61M 16/08 Bellows; Connecting tubes having means for taking samples G01N1/22; Water traps; Patient circuits
• CPC Class Codes: A61M 16/0816 Joints or connectors
• CPC Class Codes: A61M 16/101 using an oxygen concentrator
• CPC Class Codes: A61M 2016/0021 with a proportional output signal, e.g. from a thermistor
• CPC Class Codes: A61M 2202/0007 introduced into the body
• CPC Class Codes: A61M 2202/0208 Oxygen
• CPC Class Codes: A61M 2202/03 Gases in liquid phase, e.g. cryogenic liquids
• CPC Class Codes: A61M 2205/3561 local, e.g. within room or hospital
• CPC Class Codes: A61M 2230/005 Parameter used as control input for the apparatus
• CPC Class Codes: A61M 2230/205 partial oxygen pressure (P-O2)
• CPC Class Codes: A61M 2230/63 Motion, e.g. physical activity

Abstract

Methods and systems for supplying respiratory oxygen to patients when the patients are inhaling are disclosed. The methods and systems may rely on delivery devices that are selectively placed in fluid communication with either a respiration sensor or a source of oxygen. The methods and systems may actively monitor for exhalations, as well as monitor for oxygen in the oxygen source. The respiration sensor may preferably be a flow sensor.

Claims

1. A method of delivering respiratory oxygen to a patient comprising:

providing an oxygen delivery system comprising an oxygen delivery device, a respiration sensor, and an oxygen source;

placing the delivery device in fluid communication with the respiration sensor and monitoring variations in respiration with the respiration sensor to determine when the patient is inhaling;

placing the oxygen source in fluid communication with the delivery device;

delivering oxygen to the delivery device from the oxygen source when the patient is inhaling;

removing the respiration sensor from fluid communication with the delivery device when delivering oxygen to the delivery device from the oxygen source;

placing the respiration sensor in fluid communication with the delivery device after delivering oxygen to the delivery device from the oxygen source;

monitoring variations in respiration with the respiration sensor after delivering oxygen to the delivery device from the oxygen source to determine when the patient is exhaling;

resuming the monitoring of variations in respiration with the respiration sensor to determine that the patient is inhaling after determining that the patient has exhaled; and

monitoring a signal produced by the respiration sensor when it is not in fluid communication with the delivery device; and

compensating for drift in the signal generated by the respiration sensor based on the monitoring when the respiration sensor is not in fluid communication with the delivery device.

2. A method according to claim 1, wherein the respiration sensor comprises a flow sensor.

3. A method according to claim 1, wherein the system comprises a valve in fluid communication with the oxygen delivery device, the respiration sensor, and the oxygen delivery device, and further wherein the valve can place only one of the respiration sensor and the oxygen source in fluid communication with the delivery device at any given time.

4. A method according to claim 3, wherein the valve comprises a three port, two way valve with one port connected to the oxygen source, another port connected to the respiration sensor and a common port connected to the oxygen delivery device.

5. A method according to claim 3, further comprising monitoring the respiration sensor to detect oxygen in the oxygen source when switching the delivery device between fluid communication with the respiration sensor and the oxygen source.

6. A method according to claim 1, wherein the oxygen delivery device comprises a nasal cannula.

7. A method of delivering respiratory oxygen to a patient comprising:

providing an oxygen delivery system comprising an oxygen delivery device, a respiration sensor, and an oxygen source;

placing the delivery device in fluid communication with the respiration sensor and monitoring variations in respiration with the respiration sensor to determine when the patient is inhaling;

placing the oxygen source in fluid communication with the delivery device;

delivering oxygen to the delivery device from the oxygen source when the patient is inhaling;

removing the respiration sensor from fluid communication with the delivery device when delivering oxygen to the delivery device from the oxygen source;

placing the respiration sensor in fluid communication with the delivery device after delivering oxygen to the delivery device from the oxygen source;

monitoring the respiration sensor to detect oxygen in the oxygen source; and

monitoring a signal produced by the respiration sensor when it is not in fluid communication with the delivery device; and

compensating for drift in the signal generated by the respiration sensor based on the monitoring when the respiration sensor is not in fluid communication with the delivery device.

8. A method according to claim 7, further comprising:

monitoring variations in respiration with the respiration sensor after delivering oxygen to the delivery device from the oxygen source to determine when the patient is exhaling;

resuming the monitoring of variations in respiration with the respiration sensor to determine that the patient is inhaling after determining that the patient has exhaled.

9. A method according to claim 7, wherein the respiration sensor comprises a flow sensor.

10. A method of delivering respiratory oxygen to a patient comprising:

providing an oxygen delivery system comprising an oxygen delivery device, a flow sensor, and an oxygen source;

placing the delivery device in fluid communication with the flow sensor and monitoring variations in respiration with the flow sensor to determine when the patient is inhaling;

placing the oxygen source in fluid communication with the delivery device;

delivering oxygen to the delivery device from the oxygen source when the patient is inhaling;

removing the flow sensor from fluid communication with the delivery device when delivering oxygen to the delivery device from the oxygen source;

placing the flow sensor in fluid communication with the delivery device after delivering oxygen to the delivery device from the oxygen source;

monitoring a zero-flow offset signal produced by the flow sensor when it is not in fluid communication with the delivery device; and

compensating for drift in the zero-flow offset signal generated by the flow sensor based on the monitoring when the flow sensor is not in fluid communication with the delivery device.

11. A method according to claim 10, further comprising venting the flow sensor to atmosphere.

12. A method of delivering respiratory oxygen to a patient comprising:

providing an oxygen delivery system comprising an oxygen delivery device, a bidirectional flow sensor vented to atmosphere, and an oxygen source;

placing the delivery device in fluid communication with the flow sensor and monitoring variations in respiration with the flow sensor to determine when the patient is inhaling;

placing the oxygen source in fluid communication with the delivery device;

delivering oxygen to the delivery device from the oxygen source when the patient is inhaling;

removing the flow sensor from fluid communication with the delivery device when delivering oxygen to the delivery device from the oxygen source;

placing the flow sensor in fluid communication with the delivery device after delivering oxygen to the delivery device from the oxygen source;

monitoring variations in respiration with the flow sensor when it is in fluid communication with the delivery device to determine when the patient is exhaling before resuming the monitoring of variations in respiration with the flow sensor to determine that the patient is inhaling;

monitoring a zero-flow offset signal produced by the flow sensor when it is not in fluid communication with the delivery device;

compensating for drift in the zero-flow offset signal generated by the flow sensor based on the monitoring when the flow sensor is not in fluid communication with the delivery device; and

monitoring the flow sensor to detect oxygen in the oxygen source when switching the delivery device from fluid communication with either of the oxygen source and the flow sensor.

13. A system for delivering respiratory oxygen to a patient comprising:

a delivery line adapted for connection to an oxygen delivery device located on a patient;

a source line adapted for connection to an oxygen source;

a respiration sensor;

at least one valve in fluid communication with the delivery line, the source line and the respiration sensor;

wherein the at least one valve places the delivery line in fluid communication with only one of the source line and the respiration sensor at any given time;

means for monitoring the respiration sensor for variations in respiration of a patient;

means for determining when the patient is inhaling and exhaling based on the monitoring of the respiration sensor;

means for preventing a determination that the patient is inhaling until after a determination that the patient has exhaled has been made; and

means for monitoring a zero-flow offset signal produced by the respiration sensor when it is not in fluid communication with the delivery line; and

means for compensating for drift in the zero-flow offset signal generated by the respiration sensor based on the monitoring of the respiration sensor when it is not in fluid communication with the delivery line.

14. A system according to claim 13, wherein the respiration sensor comprises a flow sensor.

15. A system according to claim 14, wherein the flow sensor is vented to atmosphere.

16. A system according to claim 13, further comprising means for monitoring the respiration sensor to detect oxygen in the source line when switching the delivery line from fluid communication with either of the source line and respiration sensor.

17. A system for delivering respiratory oxygen to a patient comprising:

a delivery line adapted for connection to an oxygen delivery device located on a patient;

a source line adapted for connection to an oxygen source;

a respiration sensor;

at least one valve in fluid communication with the delivery line, the source line and the respiration sensor;

wherein the at least one valve places the delivery line in fluid communication with only one of the source line and the respiration sensor at any given time;

means for monitoring the respiration sensor to detect oxygen in the source line; and

means for monitoring a zero-flow offset signal produced by the respiration sensor when it is not in fluid communication with the delivery line; and

means for compensating for drift in the zero-flow offset signal generated by the respiration sensor based on the monitoring of the respiration sensor when it is not in fluid communication with the delivery line.

18. A system according to claim 17, wherein the means for monitoring the respiration sensor performs the monitoring function when switching the delivery line from fluid communication with either of the source line and the respiration sensor.

19. A system according to claim 17, wherein the respiration sensor comprises a flow sensor.

20. A system according to claim 19, wherein the flow sensor is vented to atmosphere.