MEDICAL VENTILATOR WITH AUTONOMOUS CONTROL OF OXYGENATION

• US 20100186742A1
• Filed: 01/29/2010
• Published: 07/29/2010
• Est. Priority Date: 01/29/2009
• Status: Active Grant

• Current Assignee: Zoll Medical Corporation (Asahi Kasei Corporation)
• Original Assignee: Impact Instrumentation, Inc. (Asahi Kasei Corporation)
• Inventors: Beck, George, Sherman, Leslie H., LeCroy, Dorian
• Granted Patent: US 8,428,672 B2
• Time in Patent Office: Days
• US Class Current: 128/204.230
• CPC Class Codes: A61M 16/0051 with alarm devices
• CPC Class Codes: A61M 16/024 including calculation means, e.g. using a processor
• CPC Class Codes: A61M 16/101 using an oxygen concentrator
• CPC Class Codes: A61M 16/12 by mixing different gases
• CPC Class Codes: A61M 2016/1025 the O2 concentration
• 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 2205/502 User interfaces, e.g. screens or keyboards
• CPC Class Codes: A61M 2205/52 with memories providing a history of measured variating parameters of apparatus or patient
• CPC Class Codes: A61M 2230/205 partial oxygen pressure (P-O2)
• CPC Class Codes: A61M 2230/435 partial O2 pressure (P-O2)

Abstract

A portable critical care medical ventilator with autonomous control of oxygenation is provided. The system and method provide for significantly reducing the O₂ required to maintain an adequate O₂ concentration and as a result delivery of O₂ to the body'"'"'s tissues and does not require the clinician to enter initial values.

Claims

1. A method for delivering oxygen to a patient with a mechanical ventilator, the method comprising:

(a) supplying fractionally inspired oxygen (FlO₂) to a patient based on a target oxygen saturation (SpO₂), wherein the target SpO₂ is set a lower limit of clinical acceptability of SpO₂ for the patient to conserve oxygen;

(b) monitoring SpO₂ returned from the patient;

(c) determining an error between the monitored SpO₂ and the target SpO₂ and while the error is greater than a predetermined error iteratively performing,

(d) determining a gain factor such that increases to FlO₂ are greater than decreases for a magnitude of the determined error;

(e) determining a correction factor by multiplying the determined gain factor by the magnitude of the error; and

(f) applying the corrector factor to the supplied FlO₂.

2. The method as in claim 1, further comprising waiting a first predetermined time period before iteratively performing steps (c)-(f).

3. The method as in claim 2, wherein the first predetermined time period is about 40 seconds.

4. The method as in claim 2, wherein the gain factor is determined such that increases to FlO₂ are three times as great as decreases for the magnitude of the determined error.

5. The method as in claim 4, wherein if the correction factor is greater than a predetermined correction factor threshold, set the correction factor to the predetermined correction factor threshold.

6. The method as in claim 5, wherein the predetermined threshold is about 20 percent.

7. The method as in claim 5, further comprising, wherein if the supplied FlO₂ is adjusted more than a predetermined alert threshold with a second predetermined time period, issuing an alert to an operator of the mechanical ventilator.

8. The method as in claim 7, wherein the predetermined alert threshold is about 10 percent.

9. The method as in claim 7, wherein the predetermined alert threshold is about 10 percent and the second predetermined time period is about 10 minutes.

10. The method as in claim 4, further comprising:

determining if the monitored SpO₂ is below a predetermined safety threshold, wherein if the monitored SpO₂ is below the predetermined safety threshold for a predetermined safety time period, adjusting the FlO₂ to 1.0.

11. The method as in claim 10, wherein the predetermined safety threshold is about 88 percent.

12. The method as in claim 11, wherein the predetermined safety time period is about 20 seconds.

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

a ventilator for supplying fractionally inspired oxygen (FlO₂) to a patient based on a target oxygen saturation (SpO₂), wherein the target SpO₂ is set at the lower limit of clinical acceptability of SpO₂for the patient to conserve oxygen; and

an O₂ concentrator coupled to the ventilator for supplying oxygen to the ventilator,

wherein the ventilator monitors SpO₂ returned from the patient, determines an error between the monitored SpO₂ and the target SpO₂ and while the error is greater than a predetermined error, the ventilator iteratively determines a gain factor such that increases to FlO₂ are greater than decreases for a magnitude of the determined error, determines a correction factor by multiplying the determined gain factor by the magnitude of the error and applies the corrector factor to the supplied FlO₂.

14. The system as in claim 13, further comprising a patient ventilation circuit including a supply tube for supplying FlO₂ to the patient from the ventilator and a bidirectional connection for sending sensed or measured parameters of the patient to the ventilator.

15. The system as in claim 13, wherein the ventilator controls an output of the O₂ concentrator to maintain the corrected supplied FlO₂.

16. The system as in claim 13, wherein the ventilator mixes an output of the O₂ concentrator with ambient air to maintain the corrected supplied FlO₂.

17. The system as in claim 13, wherein the ventilator waits a first predetermined time period before iteratively applying the corrector factor to the supplied FlO₂.

18. The system as in claim 17, wherein the first predetermined time period is about 40 seconds.

19. The system as in claim 17, wherein the gain factor is determined such that increases to FlO₂ are three times as great as decreases for the magnitude of the determined error.

20. The system as in claim 19, wherein if the correction factor is greater than a predetermined correction factor threshold, the ventilator sets the correction factor to the predetermined correction factor threshold.

21. The system as in claim 20, wherein the predetermined threshold is about 20 percent.

22. The system as in claim 20, wherein if the supplied FlO₂ is adjusted more than a predetermined alert threshold with a second predetermined time period, the ventilator issues an alert to an operator of the ventilator.

23. The system as in claim 22, wherein the predetermined alert threshold is about 10 percent.

24. The system as in claim 22, wherein the predetermined alert threshold is about 10 percent and the second predetermined time period is about 10 minutes.

25. The system as in claim 19, wherein the ventilator determines if the monitored SpO₂ is below a predetermined safety threshold, and if the monitored SpO₂ is below the predetermined safety threshold for a predetermined safety time period, adjusts the FlO₂ to 1.0.

26. The system as in claim 25, wherein the predetermined safety threshold is about 88 percent.

27. The system as in claim 26, wherein the predetermined safety time period is about 20 seconds.