Control device for supplying supplemental respiratory oxygen

• US 6,371,114 B1
• Filed: 05/08/2000
• Issued: 04/16/2002
• Est. Priority Date: 07/24/1998
• Status: Expired due to Term

• 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): Weiss, John G.
• Assistant Examiner(s): MITCHELL, TEENA KAY
• Application Number:
  US09/463,614
• Time in Patent Office: 708 Days
• Field of Search: 128/204.18, 128/204.21, 128/204.23, 128/204.26, 128/207.18, 128/205.24, 128/205.11, 128/202.22, 128/205.23
• 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 16/101 using an oxygen concentrator
• CPC Class Codes: A61M 2016/0021 with a proportional output signal, e.g. from a thermistor
• CPC Class Codes: A61M 2016/0024 with an on-off output signal, e.g. from a switch
• CPC Class Codes: A61M 2016/0027 pressure meter
• 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 2230/205 partial oxygen pressure (P-O2)
• CPC Class Codes: A61M 2230/63 Motion, e.g. physical activity

Abstract

Methods and systems for supplying supplemental oxygen to patients for use in sub-acute care which maintains healthy blood oxygen content in the patients by controlled dosing of oxygen with a measured response to the patient'"'"'s actual blood oxygen content are disclosed. The dosing can be provided by simple ON/OFF control over the delivery of oxygen or the amount of oxygen delivered to the patient with each inhalation can be varied in response to the patient'"'"'s need as determined by a more sophisticated control scheme, such as a PID loop control algorithm, that utilizes the difference between the patient'"'"'s actual blood oxygen content and a target blood oxygen content and/or trends in the blood oxygen content. The systems and methods are particularly directed at patients receiving supplemental oxygen in a sub-acute care environment.

Claims

1. A system for delivering respiratory oxygen to a patient, the system comprising:

a blood oxygen content level sensor (14);

a supplemental oxygen source (20);

a valve (26) in fluid communication with the supplemental oxygen source (20); and

a controller (10) capable of operating the valve (26), the controller restricting supplemental oxygen flow through the valve when the blood oxygen content level measured by the blood oxygen content level sensor (14) is above a desired value.

2. A system according to claim 1, further comprising:

means for determining when the blood oxygen content level measured by the blood oxygen content level sensor (14) is invalid, wherein the controller (10) operates the valve (26) to deliver a default amount of supplemental oxygen to the patient when the measured blood oxygen content is invalid; and

means for determining when the blood oxygen content level measured by the blood oxygen content level sensor (26) is valid after being invalid, wherein the controller (10) operates the valve (26) to restrict supplemental oxygen flow through the valve when the blood oxygen content level measured by the blood oxygen content level sensor (14) is above a desired value.

3. A system according to claim 1, wherein the controller (10) variably restricts supplemental oxygen flow through the valve (26) to deliver a variable dose of supplemental oxygen from the supplemental oxygen source to the patient, wherein the variable dose of supplemental oxygen is at least partially determined based on the measured blood oxygen content.

4. A system according to claim 3, wherein the controller (10) determines the variable dose of supplemental oxygen at least partially based on a difference between a desired value for the measured blood oxygen content level and the measured blood oxygen content level.

5. A system according to claim 3, wherein the controller (10) determines the variable dose of supplemental oxygen at least partially based on a trend in measured blood oxygen content level as measured at different times.

6. A system according to claim 1, further comprising a respiration sensor (40) and a delivery line (26a) adapted for connection to an oxygen delivery device (18), wherein the valve (26) is in fluid communication with the supplemental oxygen source (20), the respiration sensor and the delivery line, and further wherein the controller (10) places the delivery line in fluid communication through the valve with only one of the supplemental oxygen source and the respiration sensor at the same time.

7. A system according to claim 6, wherein the controller (10) places the delivery line (26a) in fluid communication with the supplemental oxygen source only when the patient is inhaling.

8. A system according to claim 6, wherein the respiration sensor (40) comprises a flow sensor.

9. A system according to claim 6, further comprising:

means for monitoring drift in an offset signal produced by the respiration sensor (40) when it is not in fluid communication with the delivery line (26a); and

means for compensating for the drift in the offset signal generated by the respiration sensor (40).

10. A system according to claim 6, further comprising means for monitoring the respiration sensor (40) to detect oxygen in the supplemental oxygen source (20) when removing the respiration sensor from or placing the respiration sensor in fluid communication with the delivery line (26a).

11. A method of sensing variations in respiration of a patient during the delivery of supplemental oxygen to the patient, the method being characterized by:

monitoring a respiration sensor (40) in fluid communication with the respiratory flow of a patient to determine when the patient is inspiring air;

removing the respiration sensor (40) from fluid communication with the respiratory flow of the patient when delivering supplemental oxygen to the patient from a supplemental oxygen source (20); and

placing the respiration sensor (40) in fluid communication with the respiratory flow of the patient after delivering the supplemental oxygen to the patient.

12. A method according to claim 11, further comprising monitoring the respiration sensor (40) to determine when the patient is expiring air.

13. A method according to claim 12, wherein the respiration sensor (40) is monitored to determine when the patient is inspiring air only after the patient has expired air.

14. A method according to claim 11, wherein the respiration sensor (40) comprises a flow sensor.

15. A method according to claim 11, wherein the respiration sensor (40) comprises a bi-directional flow sensor.

16. A method according to claim 14, further comprising venting the flow sensor (40) to atmosphere.

17. A method according to claim 11, further comprising:

monitoring drift in an offset signal produced by the respiration sensor (40) when it is not in fluid communication with the respiratory flow of the patient; and

compensating for the drift in the offset signal generated by the respiration sensor (40).

18. A method according to claim 11, further comprising monitoring the respiration sensor (40) to detect oxygen in the supplemental oxygen source when removing the respiration sensor from or placing the respiration sensor in fluid communication with the respiratory flow of the patient.

19. A system for delivering respiratory oxygen to a patient, the system comprising

a delivery line (26a) adapted for connection to an oxygen delivery device (18);

a source line (26b) adapted for connection to an oxygen source (20);

a respiration sensor (40); and

a valve (26) in fluid communication with the delivery line (26a), the source line (26b) and the respiration sensor (40);

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

20. A system according to claim 19, wherein the respiration sensor (40) comprises a flow sensor.

21. A system according to claim 19, wherein the flow sensor (40) is vented to atmosphere.

22. A system according to claim 19, further comprising:

means for monitoring drift in an offset signal produced by the respiration sensor (40) when it is not in fluid communication with the delivery line (26a); and

means for compensating for the drift in the offset signal generated by the respiration sensor (40).

23. A system according to claim 19, further comprising means for monitoring the respiration sensor (40) to detect oxygen in the source line (26b) when removing the respiration sensor from or placing the respiration sensor in fluid communication with the delivery line (26a).