Endovascular heat exchange systems and methods with blood flow monitoring and notification functions
Endovascular heat exchange systems and methods wherein a heat exchange catheter is positionable within the vasculature of a patent to exchange heat with the patient's flowing blood. The rate at which heat is being exchanged is determined and quantitative blood flow determinations may be made based on the rate of heat exchange. The system provides notification(s) to personnel when one or more blood flow-related events occur(s), such as a) resumption or continuation of effective spontaneous circulation; b) cessation of absence of effective spontaneous circulation, c) the occurrence of spontaneous or cardiac-compression-generated circulation that is below a minimum effective blood flow rate and e) the occurrence of spontaneous or cardiac-compression-generated circulation that is at or above a minimum effective blood flow rate.
1. A system comprising:
a heat exchange catheter having a heat exchange surface that is insertable into subject's vasculature;
a programmable controller;
apparatus for circulating heat exchange fluid through the heat exchange catheter while inserted in the subject's vasculature such that heat will be exchanged across the heat exchange surface between heat exchange fluid being circulated through the heat exchange catheter and blood that flows through the subject's vasculature in heat exchange proximity to the heat exchange surface;
one or more sensors for measuring a rate at which heat is being exchanged between heat exchange fluid being circulated through the heat exchange catheter and blood flowing through the subject's vasculature in heat exchange proximity to the heat exchange surface; and
wherein the controller receives signals from said one or more sensors and is programmed to use those received signals to determine a rate, if any, at which heat is being exchanged across the heat exchange surface and to ascertain whether the determined rate, if any, is indicative of an occurrence of at least one event selected from: a) resumption or continuation of effective spontaneous circulation; b) cessation or of absence of effective spontaneous circulation, c) the occurrence of spontaneous or cardiac-compression-generated circulation that is below a minimum effective blood flow rate and d) the occurrence of spontaneous or cardiac-compression-generated circulation that is at or above a minimum effective blood flow rate;
wherein, when the system is being used in a subject who lacks effective spontaneous circulation and is receiving cardiac compressions, the system determines the rate, if any, at which heat is being exchanged across the heat exchange surface while cardiac compressions are ongoing and determines, while the cardiac compressions are ongoing, when the determined rate, if any, is indicative of a resumption or continuation of effective spontaneous circulation.
2. A system according to claim 1 further comprising notification apparatus to notify a caregiver or other medical personnel of the occurrence of said at least one event.
3. A system according to claim 2 wherein the notification apparatus comprises a visible display.
4. A system according to claim 2 wherein the notification apparatus comprises an audible alarm.
5. A system according to claim 2 wherein the notification apparatus comprises a visible display and an audible alarm.
6. A system according to claim 3 wherein the visible display comprises a variable indicator that shows real time variation in blood flow rate.
7. A system according to claim 3 wherein the visible display comprises a visual indicator of when said at least one event is occurring.
8. A system according to claim 7 wherein the visual indicator comprises one or more light emitters.
9. A system according to claim 2 wherein the notification apparatus provides a) a first notification indicating the resumption or continuation of effective spontaneous circulation; b) a second notification indicating the cessation or absence of effective spontaneous circulation, c) a third notification indicating when spontaneous or cardiac-compression-generated circulation is occurring but is failing to generate minimum effective blood flow and d) a fourth notification indicating when spontaneous or cardiac-compression-generated circulation is occurring and is generating at least minimum effective blood flow.
10. A system according to claim 9 wherein the first notification comprises a light of a first color, the second notification comprises a light of a second color, the third notification comprises a light of a third color and the fourth notification comprises a light of a fourth color.
11. A system according to claim 10 wherein at least the second and third notifications are accompanied by audible alarms.
12. A modification package for modifying an existing endovascular temperature management system which comprises: a) apparatus for recirculating heat exchange fluid through a heat exchange catheter that is positionable within a subject's vasculature such that heat will be exchanged, across a heat exchange surface of the catheter, between heat exchange fluid being circulated through the heat exchange catheter and blood that flows through the subject's vasculature in heat exchange proximity to the heat exchange surface, b) a programmable controller programmed to control operation of the system so as to adjust or maintain a desired subject body temperature and c) sensors useable for measuring the temperature of heat exchange fluid entering the catheter and the temperature of heat exchange fluid exiting the catheter and to generate signals based on those measured temperatures;
wherein, the modification package comprises executable code stored on a storage medium and deliverable to the controller to program the controller to use signals received from said sensors to determine the occurrence of at least one event selected from; resumption or continuation of effective spontaneous circulation; cessation or absence of effective spontaneous circulation, the occurrence of spontaneous or cardiac-compression-generated circulation that is below a minimum effective blood flow rate; and the occurrence of spontaneous or cardiac-compression generated circulation that is at or above a minimum effective blood flow rate;
wherein the executable code programs the controller such that, when the endovascular temperature management system is being used in a subject who lacks effective spontaneous circulation and is receiving cardiac compressions, the controller uses said signals received from said sensors to determine, while the cardiac compressions are ongoing, when a resumption of effective spontaneous circulation occurs.
13. A modification package according to claim 12 wherein the code further programs the controller to issue notification signals to a notification apparatus which notifies personnel of the occurrence of said at least one event.
14. A modification package according to claim 13 wherein the existing endovascular temperature management system includes an existing notification apparatus that performs other functions and wherein the code causes the controller to send notification signals to the existing notification apparatus so that the existing notification apparatus notifies personnel of the occurrence of said at least one event in addition to performance of its other functions.
15. A modification package according to claim 14 wherein the existing notification apparatus comprises a liquid crystal display.
16. A system comprising a modification package according to claim 13 further in combination with a notification apparatus module which is connectable to the existing endovascular temperature management system to receive the notification signals and to provide a display or other notification upon occurrence of said at least one event.
17. A system according to claim 16 wherein the notification apparatus hardware module comprises a visible display.
18. A system according to claim 16 wherein the notification apparatus module comprises an audible alarm.
19. A system according to claim 16 wherein the notification apparatus module comprises a visible display and an audible alarm.
20. A system according to claim 17 wherein the visible display comprises a variable indicator that shows real time variation in blood flow rate.
21. A system according to claim 17 wherein the visible display comprises a visual indicator of when said at least one event is occurring.
22. A system according to claim 21 wherein the visual indicator comprises one or more light emitters.
23. A system according to claim 17 wherein the notification apparatus module provides a) a first notification indicating the resumption or continuation of effective spontaneous circulation; b) a second notification indicating the cessation of absence of effective spontaneous circulation, c) a third notification indicating when spontaneous or cardiac-compression generated circulation is occurring but is failing to generate minimum effective blood flow and d) a fourth notification indicating when spontaneous or cardiac-compression-generated circulation is occurring and is generating at least minimum effective blood flow.
24. A system comprising:
a heat exchange catheter having a heat exchange surface that is insertable into subject's vasculature;
a programmable controller;
apparatus for circulating heat exchange fluid through the heat exchange catheter while inserted in the subject's vasculature such that heat will be exchanged across the heat exchange surface between heat exchange fluid being circulated through the heat exchange catheter and blood that flows through the subject's vasculature in heat exchange proximity to the heat exchange surface;
one or more sensors for measuring a rate at which heat is being exchanged between heat exchange fluid being circulated through the heat exchange catheter and blood flowing through the subject's vasculature in heat exchange proximity to the heat exchange surface; and
wherein the controller receives signals from said one or more sensors and is programmed to use those received signals to determine a rate, if any, at which heat is being exchanged across the heat exchange surface and to ascertain whether the determined rate, if any, is indicative of an occurrence of at least one event selected from: a) resumption or continuation of effective spontaneous circulation; b) cessation or of absence of effective spontaneous circulation, c) the occurrence of spontaneous or cardiac-compression-generated circulation that is below a minimum effective blood flow rate and d) the occurrence of spontaneous or cardiac-compression-generated circulation that is at or above a minimum effective blood flow rate;
wherein, when the system is being used in a subject who lacks effective spontaneous circulation and is receiving cardiac compressions, the system determines, the rate, if any, at which heat is being exchanged across the heat exchange surface while cardiac compressions are ongoing and determines while the cardiac compressions are ongoing whether the determined rate, if any, indicates that the cardiac compressions are generating circulation that is above or below a minimum effective blood flow rate.
25. A modification package for modifying an existing endovascular temperature management system which comprises: a) apparatus for recirculating heat exchange fluid through a heat exchange catheter that is positionable within a subject's vasculature such that heat will be exchanged, across a heat exchange surface of the catheter, between heat exchange fluid being circulated through the heat exchange catheter and blood that flows through the subject's vasculature in heat exchange proximity to the heat exchange surface, b) a programmable controller programmed to control operation of the system so as to adjust or maintain a desired subject body temperature and c) sensors useable for measuring the temperature of heat exchange fluid entering the catheter and the temperature of heat exchange fluid exiting the catheter and to generate signals based on those measured temperatures:
wherein, the modification package comprises executable code stored on a storage medium and deliverable to the controller to program the controller to use signals received from said sensors to determine the occurrence of at least one event selected from: resumption or continuation of effective spontaneous circulation; cessation or absence of effective spontaneous circulation, the occurrence of spontaneous or cardiac-compression-generated circulation that is below a minimum effective blood flow rate; and the occurrence of spontaneous or cardiac-compression generated circulation that is at or above a minimum effective blood flow rate;
wherein the executable code programs the controller such that, when the endovascular temperature management system is being used in a subject who lacks effective spontaneous circulation and is receiving cardiac compressions, the controller uses said signals received from said sensors to determine while the cardiac compressions are ongoing, whether the cardiac compressions are generating circulation that is above or below a minimum effective blood flow rate.