Implantable cardiac device and method for monitoring blood-glucose concentration

• US 8,517,941 B1
• Filed: 10/23/2007
• Issued: 08/27/2013
• Est. Priority Date: 10/23/2007
• Status: Active Grant

• Current Assignee: Pacesetter Incorporated (Abbott Laboratories Incorporated)
• Original Assignee: Pacesetter Incorporated (Abbott Laboratories Incorporated)
• Inventors: Wenzel, Brian Jeffrey
• Primary Examiner(s): Mallari, Patricia
• Assistant Examiner(s): Ramachandran, Vasuda
• Application Number:
  US11/877,004
• Time in Patent Office: 2,135 Days
• Field of Search: 600372-374, 600/377, 600/365
• US Class Current: 600/365
• CPC Class Codes: A61B 5/0031 Implanted circuitry
• CPC Class Codes: A61B 5/14503 invasive, e.g. introduced into the body by a catheter or needle or using implanted sensors A61B5/1459, A61B5/1464, A61B5/1473, A61B5/1482, A61B5/14865 take precedence
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/14535 for measuring haematocrit
• CPC Class Codes: A61B 5/14552 Details of sensors specially adapted therefor
• CPC Class Codes: A61B 5/1495 Calibrating or testing of in-vivo probes
• CPC Class Codes: A61M 2005/14208 with a programmable infusion control system, characterised by the infusion program
• CPC Class Codes: A61M 2005/1726 the body parameters being measured at, or proximate to, the infusion site
• CPC Class Codes: A61M 2205/3507 with implanted devices, e.g. external control
• CPC Class Codes: A61M 2205/3523 using telemetric means
• CPC Class Codes: A61M 2205/3561 local, e.g. within room or hospital
• CPC Class Codes: A61M 2205/3584 using modem, internet or bluetooth
• CPC Class Codes: A61M 5/14276 specially adapted for implantation
• CPC Class Codes: A61N 1/3605 Implantable neurostimulators for stimulating central or peripheral nerve system
• CPC Class Codes: A61N 1/36557 controlled by chemical substances in blood

Abstract

An implantable medical device, implantable cardiac stimulation device, implantable defibrillator or pacemaker provides continuous monitoring of blood-glucose concentration in the blood of a patient. Blood-glucose concentration and blood-glucose concentration trends are calculated by measuring changes in the hematocrit of the patient. An external blood-glucose monitor may be used to provide blood-glucose calibration values to the implantable device to enhance accuracy of blood-glucose concentration values. The implantable device compares the blood-glucose concentration and/or concentration trends with acceptable limits and generates appropriate warning signals. The implantable device may optionally control one or more therapeutic devices to maintain blood-glucose concentration within an acceptable range. The enhanced control of blood-glucose concentration reduces the risk of arrhythmia and enhances the effectiveness of cardiac pacing and/or defibrillation.

Claims

1. A method for monitoring blood-glucose concentration of a patient using an implantable medical device, the method comprising:

(a) measuring hematocrit using an implantable sensor;

(b) determining a plurality of hematocrit values at a plurality of times;

(c) comparing the plurality of hematocrit values determined at the plurality of times to monitor a change in hematocrit;

(d) determining, using a processor, a change in blood-glucose concentration using the change in hematocrit;

(e) determining a rate of change in hematocrit from the change in hematocrit over a period of time; and

(f) using the rate of change in hematocrit to determine a rate of change of blood-glucose concentration.

2. The method of claim 1, wherein the method further comprises:

obtaining a blood-glucose calibration value from a blood-glucose sensor;

and using the change in hematocrit and the blood-glucose calibration value to determine the change in blood-glucose concentration and generate a subsequent blood-glucose concentration value.

3. The method of claim 2, wherein the blood-glucose sensor is a component of a blood-glucose concentration measurement device external to the patient and wherein the method further comprises wirelessly receiving the blood-glucose calibration value from the blood-glucose concentration measurement device.

4. The method of claim 1, further comprising:

generating an alert that can be sensed by the patient if the blood-glucose concentration value is indicative of hypoglycemia or hyperglycemia.

5. The method of claim 1, wherein the implantable medical device comprises:

a therapeutic device,

and wherein the method further comprises controlling the therapeutic device in response to the blood-glucose concentration value to change the concentration of glucose in the blood if the blood-glucose concentration value is indicative of hypoglycemia or hyperglycemia.

6. The method of claim 1, wherein the implantable medical device provides electrical stimulation to an organ of the patient according to parameters, and wherein the method comprises:

causing a change in the parameters of the electrical stimulation provided to the organ in response to the change in blood-glucose concentration.

7. The method of claim 1, wherein the implantable medical device comprises a blood-glucose elevating system, and wherein the method further comprises:

causing the blood-glucose elevating system to elevate the blood-glucose concentration of the patient if the change in blood-glucose concentration is indicative of hypoglycemia.

8. The method of claim 1, wherein the implantable medical device is in communication with an arousal device capable of waking up the patient, and wherein the method further comprises:

triggering the arousal device if the change in blood-glucose concentration is indicative of hypoglycemia.

9. The method of claim 1, wherein the implantable medical device comprises a blood-glucose elevating system, and wherein the method further comprises:

causing the blood-glucose elevating system to elevate the blood-glucose concentration of the patient if the change in blood-glucose concentration is indicative of increased risk of hypoglycemia-induced arrhythmia.

10. A system for monitoring blood-glucose concentration in a patient, comprising:

an implantable hematocrit sensor that monitors changes in hematocrit and determines a rate of change in hematocrit;

and a blood glucose monitor that determines changes in blood-glucose concentration using the rate of change in hematocrit monitored by the implantable hematocrit sensor.

11. The system of claim 10, further comprising:

an effector that controls one or more of application of a therapy and communication of a diagnosis in response to the changes in blood-glucose concentration.

12. The system of claim 10, further comprising:

a warning system that is configured to deliver, automatically, an alert if the changes in blood-glucose concentration are indicative of hypoglycemia;

and wherein the warning system delivers the alert to one or more of the patient, a physician, a clinician, a nurse, a manufacturer, and a caregiver.

13. The system of claim 10, further comprising:

an effector that automatically increases the blood-glucose concentration of the patient if the changes in blood-glucose concentration are indicative of hypoglycemia.

14. The system of claim 10, further comprising:

an arousal system is configured to cause the patient to wake up if the patient is sleeping and the changes in blood-glucose concentration are indicative of an elevated risk of hypoglycemia-induced arrhythmia.

15. The system of claim 10, wherein:

the blood-glucose monitor and implantable hematocrit sensor are part of an implantable medical device; and

wherein the system further comprises an external blood-glucose monitor that determines a blood-glucose calibration value and transmits the blood-glucose calibration value to the implantable medical device.

16. A system for monitoring blood-glucose level, comprising:

a calibration sensor for measuring a first blood-glucose value;

a memory for storing the first blood-glucose value;

a hematocrit sensor for measuring a rate of change in hematocrit;

and a monitor for determining a second blood-glucose value based on the first blood-glucose value and the rate of change in hematocrit.

17. They system of claim 16, wherein:

the calibration sensor is configured to be external to the patient;

the hematocrit sensor is implantable in the patient;

and the calibration sensor is at least intermittently in communication with the monitor via a wireless communication link.