Metabolic monitoring, a method and apparatus for indicating a health-related condition of a subject

• US 9,384,324 B2
• Filed: 09/30/2014
• Issued: 07/05/2016
• Est. Priority Date: 02/26/2004
• Status: Expired due to Fees

• Current Assignee: Diabetes Tools Sweden AB
• Original Assignee: Diabetes Tools Sweden AB
• Inventors: Wallander, Ulf Frederik, Liljeryd, Lars Gustaf
• Primary Examiner(s): Natnithithadha, Navin
• Assistant Examiner(s): WEARE, MEREDITH H
• Application Number:
  US14/503,008
• Publication Number:
  US 20150019139A1
• Time in Patent Office: 644 Days
• US Class Current: 1/1
• 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 5/021 Measuring pressure in heart or blood vessels A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/024 Detecting, measuring or recording pulse rate or heart rate A61B5/0205, A61B5/021 take precedence
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/222 combined with detection or measurement of physiological parameters, e.g. heart rate
• CPC Class Codes: A61B 5/4866 Evaluating metabolism A61B5/083 takes precedence
• CPC Class Codes: A61B 5/7225 Details of analog processing, e.g. isolation amplifier, gain or sensitivity adjustment, filtering, baseline or drift compensation A61B5/30, A61B5/316 take precedence; transformers for specific applications H01F38/00; amplifiers H03F
• CPC Class Codes: A61B 5/7267 involving training the classification device
• 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: A61B 5/746 Alarms related to a physiological condition, e.g. details of setting alarm thresholds or avoiding false alarms alarms per se G08B
• CPC Class Codes: G16H 50/30 for calculating health indices; for individual health risk assessment
• CPC Class Codes: G16Z 99/00 Subject matter not provided for in other main groups of this subclass

Abstract

An apparatus for indicating a health-related condition of a subject has an input interface for receiving a sequence of samples of a first biological quantity derived by a first measurement method, the first measurement method being an invasive measurement and having a first impact on the subject, and for receiving a sequence of samples of a second biological quantity derived by a second measurement method, the second measurement method being a non-invasive measurement and having a second impact on the subject, wherein the first biological quantity gives a more accurate indication of the health-related condition of the subject than the second biological quantity, wherein the first biological quantity and the second biological quantity have a correlation to the health-related condition of the subject, and wherein the second impact is smaller than the first impact; a predictor for providing, for a certain time, for which no sample for the first biological quantity exists, an estimated value of the first biological quantity using samples for the first biological quantity and, as far as available, samples for the second quantity; and an output interface for outputting the estimated value or data derived from the estimated value so that an indication for the health-related condition of the subject is obtained.

Claims

1. An apparatus for indicating a health-related condition of a subject, comprising:

an analytical device for sampling a biological quantity as part of a measurement method, where the biological quantity is related to the health-related condition of the subject;

an input interface for receiving a raw sequence of samples of the biological quantity from the analytical device;

a processor for processing the raw sequence of samples to obtain a processed sequence, the processor comprising an interpolator for providing data on an interpolated sample for a missing sample of the biological quantity using one or more samples at a preceding time instant or one or more samples at a subsequent time instant to obtain an interpolated sequence representing samples of the raw sequence and the interpolated sample;

a low-pass filter for filtering the processed sequence to obtain a filtered sequence, the filtered sequence having a useful variation and a reduced non-useful variation compared to the processed sequence before filtering, wherein the low-pass filter has a cut-off frequency;

a cut-off frequency calculator being arranged to determine the cut-off frequency of the low-pass filter, by;

for a plurality of different cut-off frequency values, low-pass filtering the samples of the raw sequence to obtain filtered test signals;

for each filtered test signal, deriving a residual value based on the difference of the samples of the raw sequence and the filtered test signal to obtain a residual representation; and

based on the residual representation, determining the cut-off frequency of the low-pass filter adapted to the raw sequence of samples; and

an output interface for processing the filtered sequence or for processing an enhanced sequence derived from the filtered sequence and for outputting an indication of the health-related condition of the subject based on the filtered sequence or the enhanced sequence derived from the filtered sequence.

2. Apparatus in accordance with claim 1, further comprising:

a second processor for deriving the enhanced sequence from the filtered sequence, wherein the second processor comprises a combiner or a signal conditioning means such as an amplifier for modifying the filtered sequence.

3. Apparatus in accordance with claim 2, wherein the input interface is configured for receiving a further raw sequence of a different biological quantity derived by a further measurement method,

wherein the filter is configured for filtering the further raw sequence to obtain a further filtered sequence, and

wherein the second processor comprises a combiner for combining the filtered sequence and the further filtered sequence to derive the enhanced sequence.

4. Apparatus in accordance with claim 3, in which the measurement method is a blood or plasma glucose measurement, and

in which the further measurement method is a heart rate measurement, a blood pressure measurement or a method for obtaining a product of heart rate and blood pressure.

5. Apparatus in accordance with claim 3, in which the combiner is arranged for performing a sample-wise multiplication.

6. Apparatus in accordance with claim 1, in which the biological quantity is a blood glucose level, a blood lipid level or a blood insulin level of the subject.

7. Apparatus in accordance with claim 1, in which the health-related condition is a diabetes-related or glucose-related or insulin-related metabolic disorder.

8. Apparatus in accordance with claim 1, in which the biological quantity is a blood glucose level.

9. Apparatus in accordance with claim 1, in which the output interface is configured for outputting at least an increase indication, a decrease indication or a remain unchanged indication as a trend of the filtered sequence or the enhanced sequence, the trend being representative of a useful variation of the health-related condition of the subject.

10. Apparatus in accordance with claim 9, in which the output interface is arranged to

indicate the trend by an acoustic indicator, an optical indicator or a mechanical indicator, so that the decrease indication, the increase indication or the remain unchanged indication are acoustically, optically or mechanically different from each other.

11. Apparatus in accordance with claim 9, in which the output interface is arranged to derive and output the trend from an actual value of the filtered sequence or the enhanced sequence, and a timely preceding value of the filtered sequence or the enhanced sequence.

12. Apparatus in accordance with claim 1, in which the residual value for a filtered test signal is a mean squared difference of the samples of the raw sequence and corresponding samples of the filtered test signal.

13. Apparatus in accordance with claim 1, in which the cut-off frequency calculator is arranged to determine the cut-off frequency based on the residual representation by:

determining a first line representing a trend of residual energies for relatively lower cut-off frequency values;

determining a second line representing a trend of residual energies for relatively higher cut-off frequency values; and

determining an intersection point of the first line and the second line, wherein determining the cut-off frequency adapted to the raw sequence of samples based on the residual representation comprises selecting the cut-off frequency of the low-pass filter corresponding to the intersection point.

14. Apparatus in accordance with claim 1, wherein deriving the residual value for each filtered test signal comprises deriving residual energy for each filtered test signal.

15. A method for indicating a health-related condition of a subject, comprising:

receiving, at an input interface, a raw sequence of samples of a biological quantity from an analytical device for sampling the biological quantity as part of a measurement method, where the biological quantity is related to the health-related condition of the subject;

processing the raw sequence of samples using a processor to obtain a processed sequence, comprising providing data on an interpolated sample for a missing sample of the biological quantity using one or more samples at a preceding time instant or one or more samples at a subsequent time instant to obtain an interpolated sequence representing samples of the raw sequence and the interpolated sample;

determining signal-adaptively, on the basis of the raw sequence of samples and using a cut-off frequency calculator, a cut-off frequency of a low-pass filter, by;

for a plurality of different cut-off frequency values, low-pass filtering the samples of the raw sequence to obtain filtered test signals;

for each filtered test signal, deriving a residual value based on the difference of the samples of the raw sequence and the filtered test signal to obtain a residual representation; and

based on the residual representation, determining the cut-off frequency of the low-pass filter adapted to the raw sequence of samples;

filtering the processed sequence using the low-pass filter with the determined cut-off frequency, to obtain a filtered sequence, the filtered sequence having a useful variation and a reduced non-useful variation compared to the processed sequence before filtering;

optionally deriving, using a further processor, an enhanced sequence from the filtered sequence; and

processing the filtered sequence or processing the enhanced sequence and outputting, at an output interface, an indication of the health-related condition of the subject based on the filtered sequence or the enhanced sequence.

16. A non-transitory digital storage medium having stored thereon a computer program having a program code for performing a method for indicating a health-related condition of a subject, the method comprising:

receiving, from an analytical device for sampling of a biological quantity related to the health-related condition of the subject as part of a measurement method, a raw sequence of samples of the biological quantity;

processing the raw sequence of samples to obtain a processed sequence, comprising providing data on an interpolated sample for a missing sample of the biological quantity using one or more samples at a preceding time instant or one or more samples at a subsequent time instant to obtain an interpolated sequence representing samples of the raw sequence and the interpolated sample;

determining signal-adaptively, on the basis of the raw sequence of samples, a cut-off frequency, by;

for a plurality of different cut-off frequency values, low-pass filtering the samples of the raw sequence to obtain filtered test signals;

for each filtered test signal, deriving a residual value based on the difference of the samples of the raw sequence and the filtered test signal to obtain a residual representation; and

based on the residual representation, determining the cut-off frequency adapted to the raw sequence of samples;

low-pass filtering the processed sequence in accordance with the determined cut-off frequency, to obtain a filtered sequence, the filtered sequence having a useful variation and a reduced non-useful variation compared to the processed sequence before filtering;

optionally deriving an enhanced sequence from the filtered sequence; and

processing the filtered sequence or processing the enhanced sequence and outputting an indication of the health-related condition of the subject based on the filtered sequence or the enhanced sequence, when the computer program is running on a computer.