U.S. patent application number 11/894310 was filed with the patent office on 2007-12-20 for biological signal management.
This patent application is currently assigned to CardioNet, Inc.. Invention is credited to Eric Baumann, Lev Korzinov.
Application Number | 20070293776 11/894310 |
Document ID | / |
Family ID | 34808368 |
Filed Date | 2007-12-20 |
United States Patent
Application |
20070293776 |
Kind Code |
A1 |
Korzinov; Lev ; et
al. |
December 20, 2007 |
Biological signal management
Abstract
Systems and techniques for managing biological signals. In one
implementation, a method includes receiving a cardiac biological
signal that includes information describing events, determining a
merit of each event based on one or more of a severity of a cardiac
condition associated with the event and a quality of the event, and
handling a subset of the events that meet a merit criterion. The
subset can be handled for medical purposes.
Inventors: |
Korzinov; Lev; (San Diego,
CA) ; Baumann; Eric; (San Diego, CA) |
Correspondence
Address: |
FISH & RICHARDSON, PC
P.O. BOX 1022
MINNEAPOLIS
MN
55440-1022
US
|
Assignee: |
CardioNet, Inc.
|
Family ID: |
34808368 |
Appl. No.: |
11/894310 |
Filed: |
August 20, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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10770702 |
Feb 2, 2004 |
|
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11894310 |
Aug 20, 2007 |
|
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Current U.S.
Class: |
600/509 |
Current CPC
Class: |
A61B 5/364 20210101;
A61B 5/363 20210101; A61B 5/361 20210101; A61B 5/316 20210101 |
Class at
Publication: |
600/509 |
International
Class: |
A61B 5/0402 20060101
A61B005/0402 |
Claims
1. An apparatus comprising: instrumentation that comprises one or
more sensors for sensing a time-variant physiological parameter of
an individual, and a data processing device configured to perform
data processing activities, the activities including identifying
events in the sensed physiological parameter, allocating events
into categories based on characteristics of the sensed
physiological parameter, discarding at least some of the events
based on characteristics of the sensed physiological parameter, and
associating data describing times when the events that are not
discarded occurred with data describing the categories of the
events, wherein each event comprises a period of time when an
information content of the physiological parameter is of increased
medical relevance, and a data output configured to output the
associations of the data describing the times and the data
describing the categories.
2. The apparatus of claim 1, wherein allocating the events into
categories comprises determining a relevance of the sensed
physiological parameter during a first event to a physiological
condition.
3. The apparatus of claim 1, wherein discarding at least some of
the events comprises prioritizing a first collection of events
allocated to a first category based on characteristics of the
sensed physiological parameter during the events in the first
collection.
4. The apparatus of claim 1, wherein the instrumentation comprises:
a first module that comprises the collection of electrodes for
sensing an electrical activity of a heart; a second module; and a
wireless data link between the first module and the second
module.
5. The apparatus of claim 4, wherein the second module comprises
the data output.
6. The apparatus of claim 4, wherein the second module comprises
the data processing device.
7. The apparatus of claim 4, wherein the first module comprises a
patient-portable sensing module.
8. The apparatus of claim 1, wherein the instrumentation further
comprises a memory configured to store the associations of the data
describing the times and the data describing the categories in
association with the physiological data of the events.
9. The apparatus of claim 1, wherein the data processing device is
configured to associate the data describing the times with the data
describing the categories by creating a data structure that
includes the data describing the times and the data describing the
categories.
10. A method comprising: sensing, at a patient-portable sensor
module, physiological electrical activity of an individual;
identifying a collection of events in the sensed physiological
electrical activity, wherein each event comprises a period of time
when an information content of the sensed physiological electrical
activity is of increased medical relevance; discarding at least one
event based on characteristics of the sensed electrical activity;
and transmitting data describing the events in the collection that
are not discarded to a receiver in a vicinity of the
patient-portable sensor module.
11. The method of claim 10, wherein transmitting the data
describing the events comprises transmitting the data describing
the events to a medical system receiver.
12. The method of claim 10, wherein transmitting the data
describing the events comprises transmitting the data describing
the events over a wireless data link.
13. The method of claim 10, further comprising allocating events in
the collection into categories based on characteristics of the
sensed electrical activity of each event.
14. The method of claim 13, wherein discarding at least one event
comprises discarding a certain event based on a merit of the
certain event relative to the events allocated to the category of
the certain event.
15. An apparatus comprising: a monitoring instrument that comprises
one or more sensing elements for sensing a time-variant
physiological parameter of a monitored individual, a data
processing device configured to perform data processing activities,
the activities including identifying an event in the sensed
physiological parameter, determining a severity of the event based
on characteristics of the sensed physiological parameter during the
event, determining whether the event is sufficiently severe to
warrant immediate output, immediately outputting a description of
the event if it is determined that the event is sufficiently
severe, and storing data describing the event in association with
data describing a time when the event occurred if it is determined
that the event is not sufficiently severe, and a data output
configured to output data, wherein the event comprises a period of
time when an information content of the physiological parameter is
of increased medical relevance.
16. The apparatus of claim 15, wherein the monitoring instrument
further comprises an input device configured to receive an event
trigger input by which a user can manually trigger output of data
describing an event.
17. The apparatus of claim 15, wherein the monitoring instrument
comprises an electrocardiographic instrument.
18. A system comprising: a collection of electrocardiographic
monitoring instruments that each comprise a collection of
electrodes for sensing electrical activity of a heart of a
monitored individual, a data processing device configured to
perform data processing activities, the activities including
identifying an event in the sensed electrical activity, classifying
the event into a category based on characteristics of the sensed
electrical activity, and associating data identifying the monitored
individual and data describing the category of the event, and a
wireless signal output configured to output the association of the
data identifying the monitored individual and the data describing
the category of the event; and a receiver that comprises a wireless
input configured to receive the associations output from each of
the electrocardiographic monitoring instruments, wherein the event
comprises a period of time when an information content of the
sensed electrical activity is of increased medical relevance.
19. The system of claim 18, wherein the wireless receiver comprises
a router configured to direct the associations based at least in
part on the data identifying the monitored individual.
20. The system of claim 18, wherein the wireless receiver comprises
a router configured to direct the associations based at least in
part on a category of the event.
21. The system of claim 18, wherein the wireless signal output
comprises a radio-frequency transmitter.
22. The system of claim 18, wherein the wireless input comprises a
cellular phone transmitter.
23. The system of claim 18, wherein the wireless receiver comprises
a local receiver that is in the vicinity of the
electrocardiographic monitoring instruments.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation, and claims the benefit
of priority under 35 USC 120, of U.S. application Ser. No.
10/770,702, filed Feb. 2, 2004. The disclosure of the prior
application is considered part of, and is incorporated by reference
herein, the disclosure of this application.
BACKGROUND
[0002] This disclosure relates to the management of biological
signals.
[0003] Biological signals are electrical or optical streams that
include information describing or otherwise relating to the state
of a biological system. In the medical context, biological signals
generally include information relating to the physiological state
of an organism. Such information can be used to diagnose and treat
disease states of the organism and can be gathered using any of a
number of different techniques. Examples of such techniques include
electrical potential measurements (e.g., electrocardiography
(ECG's), electromyography, and electroencephalography), blood and
other body fluid analyte measurements (e.g., pulse oximetry, blood
glucose concentration, blood pH and other ion concentrations), and
mechanical measurements (e.g., blood pressure measurements, heart
sound transduction, height and weight measurements).
SUMMARY
[0004] The biological signal management systems and techniques
described here may include various combinations of the following
features.
[0005] In one aspect, a method includes receiving a cardiac
biological signal that includes an event relevant to a medical
purpose, determining a merit of the event for the medical purpose,
associating the event with a time span in which the event occurred
if the event's merit is among a certain number of the most
meritorious events that occurred in the time span, and handling the
association of the time span and the event.
[0006] The merit of the event can be determined by determining the
severity and the quality of the event. The quality of the event can
be determined by determining the noise in the event. An event can
be received after the event has been separated from another portion
of the cardiac biological signal. The event can also be identified
within the received cardiac biological signal. The event can be one
or more of an asystole event, a tachycardia event, a bradycardia
event, and an atrial fibrillation/flutter event based on
identifying characteristics of these events. The event can be
identified based on a frequency of heart beats.
[0007] A category of the event can be determined. The event can be
associated with the time span when the event merit places the event
within the certain number of the most meritorious events of the
category. The number of the most meritorious events can be
predetermined. The association can be handled by generating a data
structure having a time stamp associated with the event or by
transmitting the association to a remote receiver. The event can
have a greater relevance to a medical diagnostic purpose than an
average relevance of the biological signal.
[0008] In another aspect, a method includes receiving a cardiac
biological signal that includes information describing events,
determining a merit of each event based on one or more of a
severity of a cardiac condition associated with the event and a
quality of the event, and handling a subset of the events that meet
a merit criterion.
[0009] The subset can be handled for medical purposes. The merit
criterion can be based on merits of other events. The merit of each
event can be determined based on both the severity and the quality
of the event. The subset can be the events that have merits among a
certain number of the most meritorious and the subset can be the
events that occur within a certain time span. For example, the time
span can be predetermined. The subset of events can be transmitted
to a remote medical receiver.
[0010] In another aspect, a method includes receiving a biological
signal, identifying an event in the biological signal, determining
a merit of the event for the certain purpose, comparing the merit
of the event with a second merit of a second event to identify a
more meritorious event, creating an episode describing the more
meritorious event, associating the episode with a time span in
which the events occurred, and transmitting the association of the
episode and the time span to a remote receiver. The event can have
a greater relevance for a certain purpose than an average relevance
of the biological signal.
[0011] The episode can be associated with the time span by creating
a data structure including the episode and a time stamp indicating
when the event occurred. The episode can be created by redacting
the more meritorious event. A category of the event can also be
determined. The merit of the event can be compared with the second
merit of the second event of the same category. The association of
the episode and the time span can be associated with a collection
of associations of episodes and time spans. The resulting
collection of associations of episodes and time spans can be
transmitted to the remote receiver.
[0012] These biological signal management systems and techniques
may provide one or more of the following advantages. For example,
the management of biological signals can facilitate a coherent
approach to organization and presentation of the information
contained in the biological signals. Such management must address
various objectives that often oppose one another. For example, the
volume of data often should be reduced to minimize data handling
costs. At the same, relevant information should not be lost. These
objectives are of importance in the medical context, where data
review may be carried out by a physician or other trained personnel
and hence may prove costly. On the other hand, discarding medically
relevant information may hinder or even prevent appropriate
diagnosis and/or treatment.
[0013] The described biological management systems and techniques
can address these and other objectives by increasing the average
relevance of data that is handled. Such reductions in data clutter
can be used to quickly provide physicians with relevant
information, decreasing the cost of data review and increasing the
likelihood that diagnosis and/or treatment is appropriately
delivered.
[0014] Another set of opposing objectives relates to the timing of
data handling. In many data handling systems, continuous handling
of data is simply too costly. On the other hand, batch handling
that only occurs occasionally may result in improper delays. These
objectives are also of importance in the medical context, where
continuous data handling may be unnecessary or too costly, but
delayed handling may endanger patients.
[0015] The described biological management systems and techniques
can address these and other objectives by selecting the timing of
data handling to accommodate both the realities of data handling
and the need to ensure patient safety. For example, the timing of
handling can be selected to ensure timeliness in any prophylactic
or diagnostic efforts without requiring continuous processes.
[0016] The details of one or more implementations are set forth in
the accompanying drawings and the description below. Other
features, objects, and advantages will be apparent from the
description and drawings, and from the claims.
DESCRIPTION OF DRAWINGS
[0017] FIG. 1 shows a system in which a biological signal is
monitored for medical purposes.
[0018] FIG. 2 shows an example biological signal.
[0019] FIG. 3 shows a series of events in the biological signal of
FIG. 2.
[0020] FIG. 4 illustrates how certain characteristics can be used
to identify events.
[0021] FIGS. 5 and 6 show the biological signal of FIG. 2 divided
into a collection of time spans.
[0022] FIGS. 7 and 8 show data structures that associate one or
more events with a time span.
[0023] FIG. 9 shows a process in which events are associated with a
time span.
[0024] FIG. 10 shows a process for determining a measure of the
merit for an event.
[0025] FIG. 11 shows a data structure that can result from handling
of events associated with time spans.
[0026] FIG. 12 shows a data assembly that can result from handling
of events associated with time spans.
[0027] FIGS. 13 and 14 illustrate the handling of events associated
with time spans by transmission to a receiver.
[0028] FIG. 15 shows a system in which events associated with time
spans are handled by transmission to a receiver.
[0029] Like reference symbols in the various drawings indicate like
elements.
DETAILED DESCRIPTION
[0030] FIG. 1 shows a system 100 in which a biological signal
derived from an individual is monitored for medical purposes.
System 100 includes an individual 105, instrumentation 110, a
signal path 115, and a receiver 120. Individual 105 can be a
patient or a healthy individual for whom monitoring of one or more
biological signals is deemed to be appropriate. Instrumentation 110
can include one or more sensing, calibration, signal processing,
control, data storage, and transmission elements suitable for
generating and processing the biological signal, as well as
relaying all or a portion of the biological signal over path 115.
Path 115 can be any suitable medium for data transmission,
including wired and wireless media suitable for carrying optical
and/or electrical signals. The receiver 120 can include a receiver
element for receiving the transmitted signal, as well as various
data processing and storage elements for extracting and storing the
information carried by the transmission regarding the state of
individual 105. The receiver 120 can be a medical system in that
receiver 120 presents information to medical personnel or to a
medical expert system for analysis. The receiver 120 either can
reside remotely from instrumentation 110 in that receiver 120 is
not located at the same site (e.g., at the same hospital, nursing
home, or other medical care facility) as instrumentation 110 or the
receiver 120 can reside within the same general area or vicinity as
instrumentation 110 (e.g., within the same room, building, or
health care facility).
[0031] FIG. 2 shows an example of a biological signal 200. The
biological signal 200 is a time variant signal in that an attribute
205 of biological signal 200 changes with time 210. Attribute 205
of biological signal 200 may continuously change with time and may
never reach a steady state value as activity level, metabolic rate,
or other factors vary over the course of days, weeks, or even
longer periods of time.
[0032] Although attribute 205 of biological signal 200 may change
continuously, all of the changes may not have the same relevance to
a particular purpose for which the biological signal 200 is
monitored. FIG. 3 shows the biological signal 200 having a series
of events 305, 310, 315, 320, 325, 330, 335, 340, 345 identified.
Events 305, 310, 315, 320, 325, 330, 335, 340, 345 generally are
periods in time 210 when the information content of biological
signal 200 is deemed to be of increased relevance to a particular
purpose for which biological signal 200 is monitored. Events 305,
310, 315, 320, 325, 330, 335, 340, 345 need not be of equal or
predetermined duration. For example, event 335 is shorter than
event 320 and the duration of these and other events can depend on
the nature of the increased relevance to the particular purpose for
which biological signal 200 is monitored.
[0033] The increased relevance of events 305, 310, 315, 320, 325,
330, 335, 340, 345 can be determined using a number of approaches.
For example, events 305, 310, 315, 320, 325, 330, 335, 340, 345 can
represent responses to known or controlled stresses on an
organism.
[0034] Events 305, 310, 315, 320, 325, 330, 335, 340, 345 also can
be identified based on characteristics of biological signal 200 and
classified into categories based on the identifying
characteristics. Tables 1 and 2 lists example categories of cardiac
events and characteristics that can be used to identify the events.
The characteristics identified in Tables 1 and 2 can be used to
identify events during cardiac monitoring using
electrocardiography.
[0035] FIG. 4 illustrates an example of how the characteristics
identified in Table 1 can be used to identify cardiac events. In
this example, the attribute 205 of biological signal 200 that
changes with time 210 (shown in seconds) is heart rate (shown in
beats per minute (bpm)). In the illustrated example, the
predetermined heart rate for identifying Moderate Bradycardia is 60
bpm and the predetermined duration is 40 seconds. The predetermined
heart rate for identifying Severe Bradycardia is 40 bpm and the
predetermined duration is 15 seconds.
[0036] In FIG. 4, heart rate attribute 205 drops below 60 bpm at
time 405, where it remains until TABLE-US-00001 TABLE 1 Event
Category Identifying Characteristic(s) Duration VFIB Ventricular
fibrillation NA Long Pause/ No QRS detected for a predetermined
duration. e.g., 3 to 6 Asystole seconds VTACH Four or more V-beats
in row and heart rate more 4 V-beats than a predetermined value
(e.g., 100 to 200 bpm). Not associated with a VFIB event Patient
Patient indicates event is occurring Patient selected initiated
event Severe Heart rate over a predetermined time (e.g., 10 to 120
e.g., 10 to 120 Tachycardia seconds) is greater than a
predetermined value (e.g., seconds 161 to 220 bpm) Not associated
with a VTACH or a VFIB event Severe Heart rate over a predetermined
time (e.g., 10 to 120 e.g., 10 to 120 Bradycardia seconds) is less
than a predetermined value (e.g., 30 seconds to 39 bpm) Not
associated with an asystole or pause event Atrial Heart rate
greater than or equal to a predetermined e.g., 10 to 120
Fibrillation/ value (e.g., 100 to 220 bpm) seconds Flutter with
Associated with an Atrial Fibrillation/Flutter onset High HR event
Pause No QRS complex for a predetermined duration (e.g., e.g., 2
seconds 2 seconds to duration of Long Pause/Asystole event) to
duration of Long Pause/ Asystole event Atrial Irregular rhythm
e.g., 30 QRS Fibrillation/ Not associated with a VTACH and VFIB
event complexes Flutter onset Moderate Heart rate for a
predetermined duration (e.g., 10 to e.g., 10 to 120 Bradycardia 120
seconds) is less than a predetermined value and seconds greater
than predetermined value in a severe bradycardia event (e.g.,
severe bradycardia value to 60 bpm) Not associated with an
asystole, a pause, or a severe bradycardia event Moderate Heart
rate for a predetermined duration (e.g., 10 to e.g., 10 to 120
Tachycardia 120 seconds) is greater than a predetermined value
seconds and less than predetermined value in a severe tachycardia
event (e.g., 100 bpm to the severe tachycardia value) Not
associated with a VTACH, a VFIB, or a severe tachycardia event
[0037] time 410, 40 seconds later. The period between time 405 and
time 410 can be identified as a Moderate Bradycardia event. In
contrast, at time 415, heart rate attribute 205 drops below 40 bpm
where it remains until time 420, ten seconds later. Heart rate
attribute 205 also reaches a minimum of 35 bpm at a time 425.
Despite reaching this minimum, the duration of the period between
time 415 and time 420 (i.e., 10 seconds) is too short to be
identified as a Severe TABLE-US-00002 TABLE 2 EXAMPLE EVENT
IDENTIFYING IDENTIFYING CATEGORY CHARACTERISTICS THRESHOLD
TACHYCARDIA Sustained heart rate (e.g., heart rate for 10 to 1 -
Sustained heart rate exceeds 1 - Severe Tachycardia 120 seconds)
exceeds a heart rate threshold a High Heart Rate (HHR) 2 - Moderate
threshold of 190 bpm Tachycardia 2 - Sustained heart rate exceeds a
Low Heart Rate (LHR) threshold of 140 bpm ATRIAL FIBRILLATION Loss
of synchrony between the atria and the 1 - Heart rate exceeds a
Atrial 1 - Atrial Fibrillation/ ventricles (shown, e.g., by
variability in Fibrillation High Heart Rate Flutter with High HR
beat-to-beat period) (AFHHR) threshold of 130 bpm 2 - Atrial
Fibrillation 2 - No heart rate threshold PAUSE No QRS detected for
a specified threshold 1 - No QRS for a high threshold 1 - Asystole
duration of 4 seconds 2 - Pause 2 - No QRS for a low threshold of 2
seconds BRADYCARDIA Sustained heart rate (e.g., heart rate for 10
to 1 - Sustained heart rate is below 1 -Severe Bradycardia 120
seconds) is below a specified threshold a Low Heart Rate (LHR) 2 -
Moderate threshold of 35 bpm Bradycardia 2 - Sustained heart rate
is below a High Heart Rate (HHR) threshold of 40 bpm
Bradycardia event. At time 430, heart rate attribute 205 again
drops below 40 bpm, where it remains until time 435, five seconds
later. The duration of the period between time 430 and time 435 is
too short to be identified as a Severe Bradycardia event.
[0038] FIGS. 5 and 6 show that time 215 can be divided into a
collection of time spans 505, 510, 515, 520, 525, 605, 610, 615,
620, 625. Spans 505, 510, 515, 520, 525, 605, 610, 615, 620, 625
can have equal durations (such as spans 505, 510, 515, 520, 525) or
spans can be of variable durations (such as spans 605, 610, 615,
620, 625). In general, the duration of spans 505, 510, 515, 520,
525, 605, 610, 615, 620, 625 is proportional to the duration of the
events sought to be identified. The duration of spans 505, 510,
515, 520, 525, 605, 610, 615, 620, 625 can be selected based on
consideration of two or more factors, such as the number of events
likely to occur in each span and the need to handle events for a
particular purpose for which biological signal 200 is monitored. In
particular, if spans 505, 510, 515, 520, 525, 605, 610, 615, 620,
625 are too short, then spans 505, 510, 515, 520, 525, 605, 610,
615, 620, 625 may lack an event. On the other hand, if spans 505,
510, 515, 520, 525, 605, 610, 615, 620, 625 are too long, then the
delay in handling events may be too large. Such a delay may be
particularly harmful in the medical context, where an excessive
delay may hinder prophylactic or diagnostic efforts. In the context
of cardiac monitoring, a span duration of between one half and four
hours, such as between one and three hours or approximately two
hours, is effective to address such considerations.
[0039] The duration of spans 505, 510, 515, 520, 525, 605, 610,
615, 620, 625 can also accommodate physiological rhythms of a
biological system. For example, in cardiac monitoring, longer spans
may be appropriate at night or periods of decreased activity and
shorter spans may be appropriate during the day or periods of
increased activity. The duration of spans 505, 510, 515, 520, 525,
605, 610, 615, 620, 625 can also be adjusted based on an attribute
of biological signal 200. For example, in cardiac monitoring, the
duration of spans 505, 510, 515, 520, 525, 605, 610, 615, 620, 625
can include a fixed number of beats rather than a fixed time
period.
[0040] FIGS. 7 and 8 show data structures 700, 800 that associate
one or more sample events with a span. Data structures 700, 800 can
be used together or separately as alternative approaches to
associating events with a span. Data structure 700 includes an
event field 705 and a time stamp field 710. Event field 705
includes data describing a portion of a biological signal that has
been identified as an event. Event field 705 can include raw data
drawn from the biological signal or event field 705 can include an
episode of an event to describe the event. An episode is a
collection of information that summarizes the relevance of the
event to the purpose for which the event is monitored. For example,
an episode can be a redacted portion of an event (e.g., the first
three minutes worth of the event). Time stamp field 710 includes
data describing the time when the event described in event field
705 occurred. Time stamp field 710 can thus associate the event
with a span by identifying a time that falls within the time
span.
[0041] Data structure 800 is shown as a table of attribute-value
pairs but other data structures (including, for example, records,
files, lists, and other data structures) that associate similar
information can be used. Data structure 800 includes an event
category information field 805, span identification information
field 810, and allocation information fields 815, 820, 825. Event
category information field 805 describes one or more event
categories that are allocable to data structure 800. An event
category can be described by name, by an associated identification
number or other token, or by a pointer or other description of a
memory location that includes such information. Span identification
information field 810 describes the time span from which events of
a category identified in event category information field 805 are
allocable to data structure 800. The time span can be described
directly using, e.g., a start and stop time stamp, or the time span
can be described indirectly by a pointer or other description of a
memory location that includes such information. Each instance of
data structure 800 can be specific to a single span.
[0042] Allocation information fields 815, 820, 825 each describe a
certain event that is allocated to data structure 800. An event can
be allocated to data structure 800 when the event is of a category
described in event category information field 805 and when the
event occurred in a time span described in span identification
information field 810. Such allocations thus associate the event
with the described category and time span. Allocation information
fields 815, 820, 825 can describe an event by including an event
field and a time stamp field, such as fields 705, 710 of data
structure 700 (FIG. 7).
[0043] Data structure 800 can include one or more allocation
information fields. Single allocation fields decrease the size of
data structure 800 and may facilitate handling. Multiple allocation
fields increase the number of events associated with the span
identified by span identification information field 810 and may
provide more complete information when data structure 800 is
handled.
[0044] FIG. 9 shows a process 900 in which events are associated
with a time span. Events can be associated with a time span by
allocation to a data structure such as data structures 700, 800.
The process 900 can be performed by one or more data processing
devices that perform data processing activities. The activities of
process 900 can be performed in accordance with the logic of a set
of machine-readable instructions, a hardware assembly, or a
combination of these and/or other instructions. The device
performing process 900 can be deployed at any of a number of
different positions in a system in which a biological signal is
monitored. For example, in system 100 (FIG. 1), the device
performing process 900 can be deployed at instrumentation 110 or at
receiver 120.
[0045] The device performing process 900 receives the biological
signal at 905. The biological signal can be received in raw form or
after signal processing. The biological signal can be received in
digital or analog format. The receiving device can identify and
classify one or more events in the biological signal at 910. Events
can be identified and classified based on one or more attributes of
the biological signal, such as the identifying characteristics
described in Table 1.
[0046] The device performing process 900 can also determine a
measure of the merit of identified events at 915. A measure of the
merit of an event is a valuation of an event when applied to a
particular purpose. For example, when the biological signal is
monitored for diagnostic medical purposes, the measure of the merit
of an event can describe the diagnostic value of the information
content of the event. The measure of the merit of an event can be
based on a number of factors, including whether or not the event is
representative of the biological signal or of other events of the
same category in the biological signal, the quality (e.g., noise or
signal dropout) associated with the event, and even the category of
the event itself.
[0047] The device performing process 900 can determine if the
measure of the merit of an event identified at 910 is greater than
the measure of the merit of the least meritorious event of the same
category currently associated with the time span that includes the
identified event at decision 920. The least meritorious event of
the same category can be associated with the time span in a data
structure such as data structures 700, 800 (FIGS. 7 and 8). The
determination can be made by comparing the measure of the merit of
the identified event with the measure of the merit of the
associated, least meritorious event of the same category. If the
identified event is not as meritorious, the device performing
process 900 can discard the identified event at 925.
[0048] On the other hand, if the identified event is more
meritorious than the associated, least meritorious event of the
same category, then the device performing process 900 can discard
the latter at 930 and associate the more meritorious event
identified at 910 with the time span at 935. For example, the
device performing process 900 can allocate the more meritorious
event identified at 910 to the appropriate of fields 715, 805, 810
in data structures 700, 800 (FIGS. 7 and 8).
[0049] The device performing process 900 can determine if the end
of a time span in the biological signal has been reached at
decision 940. If the end of the span has not been reached, the
process 900 returns to 910 to identify and classify any additional
event(s) in the biological signal. If the end of the span has been
reached, the process proceeds to handle the allocated events at
945. The events can be handled alone or in association with other
information, including duration and classification information,
prior and subsequent events of the same or different categories,
and additional information retrieved from other biological signals.
TABLE-US-00003 TABLE 3 Event Category Event Grade VFIB 1 Long
Pause/Asystole 1 VTACH 1 Patient initiated event 1 Severe
Tachycardia 1 Severe Bradycardia 1 Atrial Fibrillation/Flutter with
High HR 2 Pause 2 Atrial Fibrillation/Flutter onset 2 Moderate
Bradycardia 2 Moderate Tachycardia 2
FIG. 10 shows a process 1000 for determining a measure of the merit
of an event. A data processing device can perform the process 1000
in isolation or as part of a larger process. For example, the
process 1000 can be performed within process 900 at 915 (FIG. 9).
The device performing process 1000 can determine the severity of an
event at 1005. The severity of an event is a measure of the gravity
of the event to the purpose for which the biological signal is
monitored. For example, when the biological signal is monitored for
diagnostic medical purposes, the severity of an event can be
indicative of the individual's physical discomfort or hardship
associated with a diagnosis that can be made using the event.
Severity can be graded on a discrete scale or on a continuous
scale. Table 3 shows example discrete grades of the severity of
various cardiac events when cardiac monitoring is performed for
prophylactic and diagnostic purposes. In Table 3, events are graded
on a two point scale, with an event grade of "1" indicating that
the event is more severe and an event grade of "2" indicating that
the event is less severe (e.g., a moderately sever event). For
example, event grade "1" can indicate an acute medical condition
that requires immediate medical attention, whereas event grade "2"
can indicate a chronic or other medical condition that does not
require immediate medical attention.
[0050] Another approach to determining the severity of an event
involves comparing characteristics of the biological signal during
the event with threshold values relating to various physiological
conditions associated with the events. For example, for a
tachycardia event as described in Table 2, the severity of a
tachycardia event can be determined using Equation 1: Tachy
Severity=(Heart Rate-Low Heart Rate)/(High Heart Rate-Low Heart
Rate) Equation 1 Similarly, the severity of a Bradycardia event,
and Atrial Fibrillation Event, and a Pause event can be determined
using the appropriate of Equations 2-4: Brady Severity=(High Heart
Rate-Low Heart Rate)/(High Heart Rate-Low Heart Rate) Equation 2
AFIB Severity=Heart Rate/Atrial Fibrillation High Heart Rate
Equation 3 Pause Severity=(Pause Duration-Low Threshold)/(High
Threshold-Low Threshold) Equation 4
[0051] The device performing process 1000 can also determine the
quality of the event at 1010. The quality of the event is a measure
of the likelihood that the event is suited to the purpose for which
the biological signal is monitored. One factor that can impact
quality is the amount or type of noise in the biological signal
during the event. For example, when the biological signal is a
cardiac signal monitored for diagnostic medical purposes, noise can
be determined using approaches such as those described in Wang, J.
Y. "A New Method for Evaluating ECG Signal Quality for Multi-lead
Arrhythmia Analysis," appearing in Proceedings of IEEE Computers in
Cardiology Conference 2002, pp. 85-88 and U.S. Pat. No. 5,967,994
to Jyh-Yun Wang, the contents of both of which are incorporated
herein by reference. Quality can be graded on a discrete scale or
on a continuous scale. TABLE-US-00004 TABLE 4 Severity Noise
Quality Low High Lowest Low Medium Low Low Low Low Medium High Low
Medium Medium Medium Medium Low High High High Low High Medium High
High Low High
[0052] The device performing process 1000 can determine the measure
of the merit of an event based at least in part on the severity and
quality of the event at 1015. The measure of the merit can be
graded on a discrete scale or on a continuous scale. The measure of
the merit can be determined using any of a number of different
approaches. Table 4 includes examples of various discrete merit
grades (lowest, low, medium, and high) that can be assigned to an
event when an event is determined to have the corresponding
severity and quality.
[0053] The handling of allocated events, such as those allocated
during a process such as process 900, can involve any of a number
of different activities. For example, event handling can include
notifying medical personnel about the event. Such notification can
be performed in response to the identification of an event
associated with an acute medical condition, such as those events
graded level "1" in Table 3. Event handling can also include the
assembly of more complex data structures, the transmission of
allocated events to, for example, a receiver such as receiver 120
(FIG. 1), or the storage of allocated events (for example, in
anticipation of assembly into more complex data structures or
transmission). Such data structure assembly, transmission, and
storage can be performed with events associated with medical
conditions that do not require immediate medical attention, such as
those graded level "2" in Table 3.
[0054] FIG. 11 shows a data structure 1100 that can result from
handling of events associated with time spans. The events and time
spans can be associated by repeated performance of process 900 by a
data processing device. Data structure 1100 includes a data
assembly 1105, a series of associated events 1110, and a series of
discarded events 1115. Data assembly 1105 includes a collection of
time span records, including time span records 1120, 1125, and
1130. Time span records 1120, 1125, 1130 can include information
identifying the duration of an associated time span. For example,
time span record 1120 can include information identifying that span
record 1120 lasts from 12 AM to 6 AM, whereas time span record 1130
can include information identifying that span record 1130 lasts
from 4 PM to 6 PM. Time span records 1120, 1125, 1130 can include
information identifying one or more categories of events associated
with time span records 1120, 1125, 1130, as well as a severity of
any associated category of events. For example, data structure 1100
can be devoted to events of a certain severity, such as level 2
events as discussed above.
[0055] Associated events 1110 includes a collection of event
records of one or more categories, including event records 1135,
1140, 1145, 1150. Associated events 1110 can be allocated to the
time spans in data assembly 1105 by allocation to an appropriate
time span record. Event records can include data describing the
event (such as raw data from the relevant portion of biological
signal 200). Associated events 1110 can be allocated to the
appropriate time span records through a series of pointers 1155.
For example, event records 1135, 1140, 1145 are allocated to time
span record 1120 through a first pointer 1155, whereas event record
1150 is associated with time span record 1125 through a second
pointer 1155. A time span record need not have an associated event
record. For example, no event record is associated with time span
record 1130. This lack can reflect that no appropriate event was
identified within the time span associated with time span record
1130.
[0056] Discarded events 1115 includes a collection of event records
of one or more categories. Discarded events 1115 are not associated
with the time spans in data assembly 1105 or with any of allocated
events 1110.
[0057] FIG. 12 shows another data assembly, namely a data
collection 1200, that can result from handling of events associated
with time spans. Data collection 1200 includes a data collection
title 1205, data collection metadata 1210, and a series of data
structures 1215. Data collection title 1205 can include information
identifying data collection 1200. Data collection metadata 1210 can
include information about the data in collection 1200, such as the
subject of the biological signal, parameters regarding the
instrument used to generate the biological signal, and date and
location information regarding the data generation process.
[0058] Series of data structures 1215 includes data structures
1220, 1225, 1230. Each data structure 1220, 1225, 1230 can result
from associating events of different categories with time spans and
can include one or more events of different categories. For
example, each data structure 1220, 1225, 1230 can include a data
structure such as data structure 1100. Since each data structure
1220, 1225, 1230 can include events from different categories
selected for high information content, data collection 1200 can
include a relatively large amount of information regarding a
biological signal but yet retain a high density of information
content.
[0059] FIGS. 13 and 14 illustrate another way that events
associated with time spans are handled, namely by transmission to a
receiver in a system such as receiver 120 in system 100. In
particular, as shown in FIG. 13, data can be gathered and events
can be allocated at instrumentation 110 to form one or more of
assemblies of data such as data structures 700, 800, 1100 and data
collection 1200. In response to a trigger, data assemblies can be
relayed over path 115 to receiver 120, where they are received as
shown in FIG. 14. Example triggers include the passage of a
predetermined period of time, user input indicating that
transmission is appropriate, or the identification of an event of
sufficient severity to warrant immediate transmission.
[0060] FIG. 15 shows one implementation of system 100 in which a
biological signal derived from an individual is monitored for
medical purposes. System 100 includes individual 105,
instrumentation 110, signal path 115, and receiver 120.
[0061] Instrumentation 110 can be adapted for electrocardiographic
monitoring of individual 105. Instrumentation 110 can include a
sensor module 1505 and a monitor module 1510. Sensor module 1505
can include three ECG leads with electrodes, as well as a two
channel ECG signal recorder and a wireless and/or wired data
output. Sensor module 1505 can also include a clip for attaching
sensor module to a belt, a neckpiece, or other item worn by
individual 105. Monitor module 1510 includes a data input that is
adapted to receive data output from sensor module 1505 as well as
one or more wireless and/or wired data outputs for data
communication over signal path 115. Monitor module 1510 also
includes a data processing device that performs data processing
activities in accordance with the logic of a set of
machine-readable instructions. The instructions can be realized in
digital electronic circuitry, integrated circuitry, specially
designed ASICs (application specific integrated circuits), computer
hardware, firmware, software, and/or combinations thereof. The
instructions can describe how to identify and/or handle events in
accordance with one or more of the techniques described herein. In
one implementation, monitor module 1510 also includes an
input/output device for interaction with a user (such as an event
trigger input with which a user can manually trigger the start of
an event.
[0062] Signal path 115 can include one or both of a wired data link
1515 and a wireless data link 1520 coupled to a data network 1525
to place instrumentation 110 in data communication with receiver
120. Wired data link 1515 includes a public network portion 1530
and a private or virtual private network portion 1535 bridged by a
server 1540. Public network portion 1530 provides for data
communication between instrumentation 110 and server 1540 over a
wired data link such as a telephone network. Private network
portion 1535 provides for private or virtually private data
communication from server 1540 to receiver 120. Server 1540 can
interface for data communication with both portions 1530, 1535. For
example, server 1540 can communicate directly with receiver 120
using the peer-to-peer protocol (PPP).
[0063] Wireless data link 1545 can include one or more wireless
receivers and transmitters 1550 such as a WiFi receiver, a cellular
phone relay station, and/or other cellular telephone infrastructure
to place instrumentation 110 in data communication with data
network 1525. In turn, data network 1525 communicates with receiver
120.
[0064] Receiver 120 includes a receiver server 1555, a data storage
device 1560, a call router 1565, a communications server 1570, and
one or more application servers 1575 that are all in data
communication with one another over one or more data links 1580.
Receiver server 1555 is a data processing device that receives and
transmits communications over signal path 115 and relays incoming
communications to data storage device 1560 and call router 1565 in
accordance with the logic of a set of machine-readable
instructions. Data storage device 1560 is a device adaptable for
the storage of information. Data storage device 1560 can be a
volatile and/or non-volatile memory that records information
electrically, mechanically, magnetically, and/or optically (such as
a disk drive). Call router 1565 is a data processing device that,
in accordance with the logic of a set of machine-readable
instructions, identifies the content of an incoming communication
and directs the communication to one or more appropriate
application servers 1575 based on that content. Communications
server 1570 is a data processing device that relays communications
between call router 1565 and one or more application servers 1575
over an external network. Application servers 1575 are data
processing devices that interact with a user or operate in
isolation to provide one or more monitoring services in accordance
with the logic of a set of machine-readable instructions. Data
links 1580 can be part of a local area and/or private network or
part of a wide area and/or public network.
[0065] In operation, sensor module 1505 can sense, amplify, and
record electrical signals relating to the activity of the heart.
Sensor module 1505 can also relay all or a portion of those signals
to monitor module 1510 where they can be managed. For example,
monitor module 1510 can manage the signals in accordance with one
or more of processes 900 and 1000 (FIGS. 9-10). As part of the
management, monitor module 1510 can transmit the signals to
receiver 120. The signals can be transmitted in association with a
time span. For example, the signals can be transmitted in one or
more of data structures 700, 800, 1100, 1200 (FIGS. 7-8 and
11-12).
[0066] The transmitted signals pass along data link 115 over one or
more of wired data link 1515 and wireless data link 1520 to
receiver 120. At receiver 120, the signals are received by server
1555 which causes at least a portion of the incoming signals to be
stored on data storage device 1560 and relayed to call router 1565.
The incoming signals stored on data storage device 1560 can be
stored in one or more of data structures 700, 800, 1100, 1200
(FIGS. 7-8 and 11-12).
[0067] The incoming signals relayed to call router 1565 are
directed to one or more appropriate application servers 1575 based
on the content of the signals. For example, when the signal relates
to a certain category of cardiac event, the signal can be directed
to a certain application server 1575 that is accessible to a
cardiologist having expertise with that certain category of event.
As another example, when the signal originates with an individual
who is under the care of a particular physician, the signal can be
directed to a certain application server 1575 that is accessible to
that physician. As yet another example, when the signal relates to
a certain category of cardiac event, the signal can be directed to
a certain application server 1575 that accesses an expert system or
other set of instructions for diagnosing and/or treating that
category of event. When appropriate, a signal can be routed to
communications server 1570 which in turn relays the signal to the
appropriate application server 1575 over an external network.
[0068] Communications can also be relayed from receiver 120 back to
individual 105 or to other individuals. For example, when a
physician or expert system identifies that care is needed, a
message requesting that the individual seek care can be returned to
individual 105 over data link 115. In urgent care situations, third
parties such as medical personnel can be directed to individual
105, either by receiver 120 or by instrumentation 110.
[0069] Various implementations of the systems and techniques
described here can be realized in digital electronic circuitry,
integrated circuitry, specially designed ASICs (application
specific integrated circuits), computer hardware, firmware,
software, and/or combinations thereof. These various
implementations can include one or more computer programs that are
executable and/or interpretable on a programmable system including
at least one programmable processor, which may be special or
general purpose, coupled to receive data and instructions from, and
to transmit data and instructions to, a storage system, at least
one input device, and at least one output device.
[0070] These computer programs (also known as programs, software,
software applications or code) may include machine instructions for
a programmable processor, and can be implemented in a high-level
procedural and/or object-oriented programming language, and/or in
assembly/machine language. As used herein, the term
"machine-readable medium" refers to any computer program product,
apparatus and/or device (e.g., magnetic discs, optical disks,
memory, Programmable Logic Devices (PLDs)) used to provide machine
instructions and/or data to a programmable processor, including a
machine-readable medium that receives machine instructions as a
machine-readable signal. The term "machine-readable signal" refers
to any signal used to provide machine instructions and/or data to a
programmable processor.
[0071] To provide for interaction with a user, the systems and
techniques described here can be implemented on a computer having a
display device (e.g., a CRT (cathode ray tube) or LCD (liquid
crystal display) monitor) for displaying information to the user
and a keyboard and a pointing device (e.g., a mouse or a trackball)
by which the user can provide input to the computer. Other kinds of
devices can be used to provide for interaction with a user as well;
for example, feedback provided to the user can be any form of
sensory feedback (e.g., visual feedback, auditory feedback, or
tactile feedback); and input from the user can be received in any
form, including acoustic, speech, or tactile input.
[0072] The systems and techniques described here can be implemented
in a computing environment that includes a back-end component
(e.g., as a data server), or that includes a middleware component
(e.g., an application server), or that includes a front-end
component (e.g., a client computer having a graphical user
interface or a Web browser through which a user can interact with
an implementation of the systems and techniques described here), or
any combination of such back-end, middleware, or front-end
components. The components of the environment can be interconnected
by any form or medium of digital data communication (e.g., a
communication network). Examples of communication networks include
a local area network ("LAN"), a wide area network ("WAN"), and the
Internet.
[0073] The computing environment can include clients and servers. A
client and server are generally remote from each other and
typically interact through a communication network. The
relationship of client and server arises by virtue of computer
programs running on the respective computers and having a
client-server relationship to each other.
[0074] A number of implementations have been described.
Nevertheless, it will be understood that various modifications may
be made. For example, information included in any of the data
structures can be handled as meta data describing the data
structures themselves and hence still associated with the data
structures. An event can be associated with a time span based on
the merit of the event exceeding a certain threshold. All events
that exceed such a threshold can remain associated with the time
span, rather than be discarded. Accordingly, other implementations
are within the scope of the following claims.
* * * * *