Method and device to monitor patients with kidney disease

• US 9,848,778 B2
• Filed: 03/15/2013
• Issued: 12/26/2017
• Est. Priority Date: 04/29/2011
• Status: Active Grant

• Current Assignee: Mozarc Medical US LLC
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Soykan, Orhan, Manda, VenKatesh R., Gerber, Martin T., Hobot, Christopher M., Ruetz, Linda L., Schu, Carl
• Primary Examiner(s): BASS, DIRK R
• Application Number:
  US13/844,257
• Publication Number:
  US 20140088442A1
• Time in Patent Office: 1,747 Days
• Field of Search: 600483, 600515, 600546
• CPC Class Codes: A61B 2560/0223 of calibration, e.g. protocols for calibrating sensors
• CPC Class Codes: A61B 5/0031 Implanted circuitry
• CPC Class Codes: A61B 5/0205 Simultaneously evaluating both cardiovascular conditions and different types of body conditions, e.g. heart and respiratory condition
• CPC Class Codes: A61B 5/0537 Measuring body composition by impedance, e.g. tissue hydration or fat content
• 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 5/14539 for measuring pH
• CPC Class Codes: A61B 5/14546 for measuring analytes not otherwise provided for, e.g. ions, cytochromes
• CPC Class Codes: A61B 5/201 Assessing renal or kidney functions
• CPC Class Codes: A61B 5/349 Detecting specific parameters of the electrocardiograph cycle
• CPC Class Codes: A61B 5/389 Electromyography [EMG]
• CPC Class Codes: A61B 5/4836 Diagnosis combined with treatment in closed-loop systems or methods A61B5/0036 takes precedence
• CPC Class Codes: A61B 5/6866 Extracorporeal blood circuits, e.g. dialysis circuits
• CPC Class Codes: A61B 5/7275 Determining trends in physiological measurement data; Predicting development of a medical condition based on physiological measurements, e.g. determining a risk factor
• CPC Class Codes: A61M 1/14 Dialysis systems; Artificial kidneys; Blood oxygenators semi-permeable membranes characterised by the material, manufacturing processes therefor B01D71/00 ; Reciprocating systems for treatment of body fluids, e.g. single needle systems for hemofiltration or pheresis
• CPC Class Codes: A61M 1/1601 Control or regulation
• CPC Class Codes: A61M 1/3609 Physical characteristics of the blood, e.g. haematocrit, urea
• CPC Class Codes: A61M 2205/18 with alarm
• CPC Class Codes: A61M 2205/3523 using telemetric means
• CPC Class Codes: A61M 2205/52 with memories providing a history of measured variating parameters of apparatus or patient
• CPC Class Codes: A61M 2205/70 with testing or calibration facilities
• CPC Class Codes: A61M 2230/20 : Blood composition characteristics
• CPC Class Codes: A61M 2230/207 : hematocrit
• CPC Class Codes: A61M 2230/208 : pH-value
• CPC Class Codes: A61M 2230/30 : Blood pressure A61M2230/04 takes precedence
• CPC Class Codes: B01D 2321/12 : Use of permeate
• CPC Class Codes: B01D 2321/40 : Automatic control of cleaning processes
• CPC Class Codes: B01D 61/243 : Dialysis
• CPC Class Codes: B01D 61/32 : Controlling or regulating
• CPC Class Codes: B01D 65/02 : Membrane cleaning or sterilisation ; Membrane regeneration
• CPC Class Codes: G16H 50/30 : for calculating health indices; for individual health risk assessment

Abstract

A medical monitoring device for monitoring electrical signals from the body of a subject is described. The medical monitoring device monitors electrical signals originating from a cardiac cycle of the subject and associates each cardiac cycle with a time index. The medical monitoring device applies a forward computational procedure to generate a risk score indicative of hyperkalemia, hypokalemia or arrhythmia of the subject. The medical monitoring device can adjust the forward computational procedure based upon clinical data obtained from the subject.

Claims

1. A medical system comprising:

a medical device including at least one of an electromyogram sensor and/or at least one of an electrocardiogram sensor for detecting a change in muscle or nerve activity of a subject and for producing at least one output electrical signal based on the change in muscle or nerve activity as detected by at least one received electrical signal, the output electrical signal being indicative of a serum potassium concentration of the subject;

a processor for applying a forward computational procedure to the at least one received electrical signal to generate a risk score for hyperkalemia, hypokalemia or arrhythmia;

a communication device indicating a condition of hyperkalemia, hypokalemia or arrhythmia of the subject based on the risk score;

wherein the electrocardiogram sensor includes one or more electrocardiogram electrodes for receiving one or more electrocardiogram features from the subject, the one or more electrocardiogram features including T-wave amplitude, R-wave amplitude, T-slope, ratio of T-wave amplitude to R-wave amplitude (T/R ratio), and T-wave flatness; and

wherein the processor applies an electrocardiogram algorithm for producing the output on the serum potassium concentration in the subject based on the value of the one or more electrocardiogram features, wherein the electrocardiogram algorithm is programmed into a computer readable medium and includes one or more of the following operational rules;

i) the output on the serum potassium concentration being a function of the R-wave amplitude;

ii) the output on the serum potassium concentration being a function of the T-wave amplitude;

iii) the output on the serum potassium concentration being a function of the T/R ratio; and

iv) the output on the serum potassium concentration being a function of the T-wave flatness.

2. The medical system of claim 1, further comprising one or more detectors including at least one of a nerve electrogram amplifier, an accelerometer, a strain gauge, and a pressure gauge for detecting the change in muscle or nerve activity.

3. The medical system of claim 1, wherein the medical device receiving at least one electrical signal is external to the subject or implantable in the subject.

4. The medical system of claim 1, wherein the electromyogram sensor is a skeletal muscle strain sensor.

5. The medical system of claim 1, wherein the electromyogram sensor is a blood pressure sensor.

6. The medical system of claim 1, wherein the output on the serum potassium concentration is a difference between a serum potassium concentration at time t₁ of the subject and a baseline potassium concentration at time t₀ of the subject, time t₁ being at least 10 minutes apart from t₀.

7. The medical system of claim 6, wherein the baseline serum potassium concentration is a value selected from the group consisting of a baseline serum potassium concentration of the subject obtained at a periodic blood draw, a baseline serum potassium concentration of the subject obtained at the onset of a dialysis session, and a baseline serum potassium concentration of the subject at the end of a dialysis session.

8. The medical system of claim 7, wherein the R-wave amplitude of operational rule i) is a difference between an R-wave amplitude at time t₁ of the subject and a baseline R-wave amplitude at time t₀ of the subject, the T-wave amplitude of operational rule ii) is a difference between a T-wave amplitude at time t₁ of the subject and a baseline T-wave amplitude at time t₀ of the subject, the T/R ratio of operational rule iii) is a difference between a T/R ratio at time t₁ of the subject and a baseline T/R ratio at time t₀ of the subject, and the T-wave flatness of operational rule iv) is a difference between an T-wave flatness at time t₁ of the subject and a baseline T-wave flatness at time t₀ of the subject.

9. The medical system of claim 8, wherein the baseline potassium concentration of the subject is 3.0 to 5.5 mM at time t₀.

10. The medical system of claim 1, wherein the one or more electrocardiogram electrodes include one or more of lead II, lead V2, lead V3 and lead V4.

11. The medical system of claim 1, wherein the one or more electrocardiogram electrodes consist of lead II only.

12. The medical system of claim 1, wherein the electrocardiogram algorithm includes one or more of the operational rules i), iii) and iv).

13. The medical system of claim 1, wherein the output on the serum potassium concentration is in positive correlation with the R-wave amplitude.

14. The medical system of claim 1, wherein the output on the serum potassium concentration is in negative correlation with the T-wave amplitude.

15. The medical system of claim 1, wherein the output on the serum potassium concentration is in negative correlation with the T-slope.

16. The medical system of claim 1, wherein the output on the serum potassium concentration is in positive correlation with the T-wave flatness.

17. The medical system of claim 1, wherein the one or more electrocardiogram electrodes includes a first set of electrodes consisting of lead II, lead V2, lead V3 and lead V4, and a second set of electrodes consisting of lead II only, wherein the electrocardiogram algorithm further includes a calibration rule that the medical system is operationally calibrated if one or more of the following is met:

v) a difference between the outputs according to rule ii) from the first set of electrodes and the second set of electrodes is no greater than 20%;

vi) a difference between the outputs according to rule iii) from the first set of electrodes and the second set of electrodes is no greater than 20%; and

vii) a difference between the outputs according to rule iv) from the first set of electrodes and the second set of electrodes is no greater than 20%.

18. The medical system of claim 1, wherein the one or more electrocardiogram electrodes includes a first set of electrodes consisting of lead II, lead V2, lead V3 and lead V4, and a second set of electrodes consisting of lead II only, wherein the electrocardiogram algorithm further includes a calibration rule that the medical system is operationally calibrated if one or more of the following is met:

v) a difference between the outputs according to rule ii) from the first set of electrodes and the second set of electrodes is no greater than 10%;

vi) a difference between the outputs according to rule iii) from the first set of electrodes and the second set of electrodes is no greater than 10%; and

vii) a difference between the outputs according to rule iv) from the first set of electrodes and the second set of electrodes is no greater than 10%.

19. The medical system of claim 1, further comprising a dialysis device such that the subject is under serum potassium concentration monitoring while being subject to a dialysis treatment by the dialysis device.

20. The medical system of claim 1, wherein the forward computational procedure generates a non-weighted or weighted sum of feature scores P1, P6, P7, P8 and P10 to calculate the risk score with the feature scores each assigned a zero or non-zero value based on the following:

P1 being a feature score based on P-R interval,

P6 being a feature score based on S-T segment depression,

P7 being a feature score based on T-wave inversion,

P8 being a feature score based on U-wave amplitude, and

P10 being a feature score based on heart rate variation.

21. The medical system of claim 1, wherein the forward computational procedure generates a non-weighted or weighted sum of feature scores P2, P3, P4, P5, P9 and P10 each assigned a zero or non-zero value based on the following:

P2 being a feature score based on QRS width,

P3 being a feature score based on Q-T interval,

P4 being a feature score based on P-wave amplitude,

P5 being a feature score based on P-wave peak,

P9 being a feature score based on T-wave amplitude, and

P10 being a feature score based on heart rate variation.

22. The medical system of claim 1, wherein the forward computational procedure generates a non-weighted or weighted sum of feature scores P1 through P16 each assigned a zero or non-zero value based on the following:

P1 being a feature score based on P-R interval,

P2 being a feature score based on QRS width,

P3 being a feature score based on Q-T interval,

P4 being a feature score based on P-wave amplitude,

P5 being a feature score based on P-wave peak,

P6 being a feature score based on S-T segment depression,

P7 being a feature score based on T-wave inversion,

P8 being a feature score based on U-wave amplitude,

P9 being a feature score based on T-wave amplitude,

P10 being a feature score based on heart rate variation,

P11 being a feature score based on ratio of T-wave amplitude to R-wave amplitude,

P12 being a feature score based on T-wave flatness,

P13 being a feature score based on T-slope;

P14 being a feature score based on T-wave peak to T-wave end (TpkTend),

P15 being a feature score based on QT/TpkTend, and

P16 being a feature score based on T-wave phase type.

24. A method comprising:

providing the system of claim 1;

applying to a subject one or more pulse sets generated by a pulse generator;

connecting at least one electromyogram sensor to the subject to receive at least one electrical signal from the subject in response to the one or more pulse sets;

generating an output from the at least one electromyogram sensor in response to the at least one electrical signal, the output being indicative of a level of serum potassium concentration of the subject;

applying a forward computational procedure to the output to generate a risk score; and

issuing an alert indicating a condition of hyperkalemia, hypokalemia or arrhythmia of the subject based on the risk score.

25. A method comprising:

providing the system of claim 1;

connecting at least one electrocardiogram sensor to a subject to receive one or more electrocardiogram features;

applying an electrocardiogram algorithm to the one or more electrocardiogram features to obtain an indicator for serum potassium concentration of the subject, wherein the electrocardiogram algorithm includes one or more of the following operational rules;

i) the output on the serum potassium concentration being a function of the R-wave amplitude;

ii) the output on the serum potassium concentration being a function of the T-wave amplitude;

iii) the output on the serum potassium concentration being a function of the T/R ratio; and

iv) the output on the serum potassium concentration being a function of the T-wave flatness;

applying a forward computational procedure to the output to generate a risk score; and

issuing an alert indicating a condition of hyperkalemia, hypokalemia or arrhythmia of the subject based on the risk score.

26. The medical system of claim 1, wherein the processor adjusts the forward computational procedure for future use according to an error signal based on the risk score and actual patient outcome.

27. The medical system of claim 26, wherein the processor applies the same forward computational procedure in response to the error signal being zero.

28. The medical system of claim 1, wherein the processor produces an output of the serum potassium concentration based on a value of the one or more electrocardiogram features.

23. A medical system comprising:

a medical device including at least one of an electromyogram sensor and/or at least one of an electrocardiogram sensor for detecting a change in muscle or nerve activity of a subject and for producing at least one output electrical signal based on the change in muscle or nerve activity as detected by at least one received electrical signal, the output electrical signal being indicative of a serum potassium concentration of the subject;

wherein the electrocardiogram sensor includes one or more electrocardiogram electrodes for receiving one or more electrocardiogram features from the subject, the one or more electrocardiogram features including T-wave amplitude, R-wave amplitude, T-slope, ratio of T-wave amplitude to R-wave amplitude (T/R ratio), and T-wave flatness; and

a processor produces an output on the serum potassium concentration in the subject based on a value of the one or more electrocardiogram features using an electrocardiogram algorithm programmed into a computer readable medium, wherein the electrocardiogram algorithm includes one or more of the following operational rules;

i) the output on the serum potassium concentration being a function of the R-wave amplitude;

ii) the output on the serum potassium concentration being a function of the T-wave amplitude;

iii) the output on the serum potassium concentration being a function of the T/R ratio; and

iv) the output on the serum potassium concentration being a function of the T-wave flatness.