Reperfusion protection in resuscitation

• US 9,950,134 B2
• Filed: 09/07/2016
• Issued: 04/24/2018
• Est. Priority Date: 01/24/2006
• Status: Active Grant

• Current Assignee: Zoll Medical Corporation (Asahi Kasei Corporation)
• Original Assignee: Zoll Medical Corporation (Asahi Kasei Corporation)
• Inventors: Freeman, Gary A.
• Primary Examiner(s): Louis, LaToya M
• Application Number:
  US15/258,293
• Publication Number:
  US 20170056612A1
• Time in Patent Office: 594 Days
• CPC Class Codes: A61M 16/0081 Bag or bellow in a bottle
• CPC Class Codes: A61M 16/12 by mixing different gases
• CPC Class Codes: A61M 16/202 electrically actuated
• CPC Class Codes: A61M 2016/0413 with detectors of CO2 in exhaled gases
• CPC Class Codes: A61M 2202/0007 introduced into the body
• CPC Class Codes: A61M 2202/0225 Carbon oxides, e.g. Carbon dioxide
• CPC Class Codes: A61M 2205/502 User interfaces, e.g. screens or keyboards
• CPC Class Codes: A61M 2230/005 Parameter used as control input for the apparatus
• CPC Class Codes: A61M 2230/202 partial carbon oxide pressure, e.g. partial dioxide pressure (P-CO2)
• CPC Class Codes: A61M 2230/208 pH-value
• CPC Class Codes: A61M 2230/40 Respiratory characteristics

Abstract

An apparatus and method for resuscitating a patient suffering from cardiac arrest or another condition in which normal circulation has been interrupted. A ventilator is used for delivering a gas mixture to the patient. The ventilator is configured to adjust the partial pressure of CO2 to one or more partial pressures high enough to slow expiration of CO2 from the patient'"'"'s lungs and thereby maintain a reduced pH in the patient'"'"'s tissues for a period of time following return of spontaneous circulation.

Claims

1. A system for assisting resuscitation of a patient, the system comprising:

at least one processor and associated memory; and

a ventilator configured to communicatively couple to the at least one processor, the at least one processor configured to;

receive at least two measurements of a CO₂ concentration in an airway of the patient,

determine whether return of spontaneous circulation (ROSC) has occurred based on a comparison of the at least two measurements of the CO₂ concentration in the airway of the patient,

receive one or more input signals indicative of a concentration of CO₂ in a tissue of the patient,

process the one or more input signals indicative of the concentration of CO₂ of the tissue of the patient to provide a measurement of the concentration of CO₂ in the tissue of the patient,

determine a CO₂ partial pressure adjustment for an inspiratory gas mixture, based at least in part on the measurement of the concentration of CO₂ in the tissue of the patient, to impact a pH of the tissue of the patient during a period of time following ROSC,

generate an instruction indicative of the determined CO₂ partial pressure adjustment, and

provide the instruction to the ventilator, wherein the ventilator is configured to adjust a CO₂ partial pressure in the inspiratory gas mixture based on the instruction.

2. The system of claim 1, wherein the at least one processor is communicatively coupled to at least one sensor configured to measure CO₂ concentration in the airway of the patient and further wherein the at least one processor is further configured to receive from the at least one sensor the at least two measurements of the CO₂ concentration in the airway of the patient.

3. The system of claim 1, wherein the at least one processor is further configured to determine, based on the one or more input signals indicative of the concentration of CO₂ in the tissue of the patient, whether ROSC has occurred.

4. The system of claim 1, wherein the CO₂ partial pressure adjustment impacts the pH of the patient'"'"'s tissues for a predetermined period of time following ROSC.

5. The system of claim 1 further comprising at least one sensor and associated processing configured to determine the pH of the tissue of the patient.

6. The system of claim 5, wherein the at least one processor is further configured to determine the CO₂ partial pressure adjustment based at least in part on the pH of the tissue of the patient.

7. The system of claim 5, wherein the CO₂ partial pressure adjustment is effective to maintain the pH below 7.0 during the period of time following ROSC.

8. The system of claim 5, wherein the CO₂ partial pressure adjustment is effective to maintain the pH at a constant level for a first portion of the period of time following ROSC.

9. The system of claim 8, wherein the CO₂ partial pressure adjustment is effective to increase the pH at a first rate during a second portion of the period of time following ROSC, wherein the second portion of the period of time is subsequent to the first portion of the period of time.

10. The system of claim 9, wherein the first rate comprises no more than 0.4 pH units/minute.

11. The system of claim 9, wherein an absolute value of the pH at the end of the second portion of the period of time is no more than 6.8.

12. The system of claim 11, wherein the pH increases at a second rate during a third portion of the period of time, wherein the third portion of the period of time is subsequent to the second portion of the period of time.

13. The system of claim 12, wherein the CO₂ partial pressure adjustment is effective such that, if the pH during the third portion of the period of time is less than 6.8, the second rate comprises approximately 0.4 pH units/minute or less;

and, if the pH during the third portion of the period of time is greater than 7, the second rate comprises approximately 0.2 pH units/minutes or less.

14. The system of claim 12, wherein each of the first portion, the second portion, and the third portion of the period of time comprises up to approximately five minutes.

15. The system of claim 1, further comprising a display, wherein the at least one processor is configured to provide the instruction to the display.

16. The system of claim 1 further comprising valves configured to adjust the inspiratory gas mixture.

17. The system of claim 16 wherein the valves are further configured to add CO₂ to the inspiratory gas mixture based on the determined CO₂ partial pressure adjustment.

18. The system of claim 16 wherein the at least one processor is further configured to electronically control the valves at least in response to the determination that ROSC has occurred.

19. The system of claim 1 further comprising a user interface configured to capture input indicating that ROSC has occurred.

20. The system of claim 1 wherein the CO₂ partial pressure adjustment comprises an change of a partial pressure of CO₂ gas in the inspiratory mixture from a first partial pressure to one or more second partial pressures high enough to slow expiration of CO₂ from the lungs of the patient and thereby maintain a reduced pH in the tissue of the patient, wherein the reduced pH is approximately at or below a pH level present in the tissue subsequent to an adverse cardiac event and immediately prior to ROSC.