U.S. patent application number 14/666126 was filed with the patent office on 2015-09-17 for physiological monitor calibration system.
The applicant listed for this patent is Cercacor Laboratories, Inc.. Invention is credited to Ammar Al-Ali, Massi Joe E. Kiani.
Application Number | 20150257689 14/666126 |
Document ID | / |
Family ID | 47148935 |
Filed Date | 2015-09-17 |
United States Patent
Application |
20150257689 |
Kind Code |
A1 |
Al-Ali; Ammar ; et
al. |
September 17, 2015 |
PHYSIOLOGICAL MONITOR CALIBRATION SYSTEM
Abstract
A calibration system is disclosed for calibrating a first
physiological monitoring device using a second physiological
monitoring device. The first physiological monitor measures a first
indication of a physiological parameter. The second physiological
monitor measures a second indication of the physiological
parameter. The first and second indications are used to calibrate
the first physiological monitoring device.
Inventors: |
Al-Ali; Ammar; (Tustin,
CA) ; Kiani; Massi Joe E.; (Laguna Niguel,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Cercacor Laboratories, Inc. |
Irvine |
CA |
US |
|
|
Family ID: |
47148935 |
Appl. No.: |
14/666126 |
Filed: |
March 23, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13274306 |
Oct 15, 2011 |
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14666126 |
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11746451 |
May 9, 2007 |
8998809 |
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13274306 |
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61393551 |
Oct 15, 2010 |
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60800512 |
May 15, 2006 |
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Current U.S.
Class: |
702/104 |
Current CPC
Class: |
Y10T 436/144444
20150115; A61B 5/14542 20130101; A61B 5/7475 20130101; A61B 5/0022
20130101; G16H 40/40 20180101; A61B 5/145 20130101; A61B 5/14546
20130101; G01N 33/66 20130101; A61B 2560/0228 20130101; A61B 5/6846
20130101; A61B 2560/0223 20130101; A61B 5/742 20130101; A61B
2562/0295 20130101; A61B 5/14532 20130101; A61B 5/7275 20130101;
A61B 5/6801 20130101; A61B 5/1495 20130101; A61B 5/1459
20130101 |
International
Class: |
A61B 5/145 20060101
A61B005/145 |
Claims
1. (canceled)
2. A measurement device comprising: a measurement module that
obtains a noninvasive physiological parameter measurement from a
sensor coupled to a patient; and a calibration module, implemented
in a hardware processor, that: receives an alternative
physiological parameter measurement; determines an offset value
based at least in part on a difference between the noninvasive
physiological parameter measurement and the alternative
physiological parameter measurement; calibrates the measurement
module based at least in part on the offset value; tracks an age of
the offset value over time; outputs the offset value for
presentation on a display; and provides an indication to a user of
the age of the offset value.
3. The measurement device of claim 2, wherein the noninvasive
physiological parameter measurement comprises a set of
measurements.
4. The measurement device of claim 2, wherein the alternative
physiological parameter measurement comprises a set of
measurements.
5. The measurement device of claim 2, wherein the calibration
module further provides a user interface control enabling a user to
provide an additional offset value.
6. The measurement device of claim 2, wherein the presentation of
the offset value on the display is modified over time to reflect
the age of the offset value over time.
7. The measurement device of claim 2, wherein the calibration
module further provides a user interface control enabling a user to
input the alternative physiological parameter measurement into the
measurement device.
8. The measurement device of claim 2, wherein the sensor measures a
hemoglobin parameter.
9. A system for calibrating a measurement device, the system
comprising: a measurement module configured to: receive a signal
from a physiological sensor; obtain a noninvasive measurement value
of a physiological parameter responsive to the signal; and a
calibration module comprising a hardware processor, the calibration
module configured to: receive an input reflecting an invasive
measurement value for the physiological parameter; calculate a
calibration value based at least in part on a difference between
the noninvasive measurement value and the invasive measurement
value; calibrate the measurement device using the calibration
value; and output an age of the calibration value for display to a
user.
10. The system of claim 9, wherein the calibration module is
further configured to receive the input reflecting the invasive
measurement value at the user interface from the user.
11. The system of claim 9, wherein the calibration module is
further configured to receive input reflecting the invasive
measurement value over a network.
12. The system of claim 9, wherein the calibration module is
further configured to receive a modification value to the
calibration value via the user interface.
13. The system of claim 12, wherein the modification value
comprises an incremental adjustment.
14. The measurement device of claim 9, wherein the user interface
modifies a depiction of the calibration value output for display
based on the age of the offset value.
15. A method of calibrating a measurement device, the method
comprising: by a noninvasive measurement device, acquiring, from a
sensor coupled to a patient, noninvasive physiological parameter
measurements; receiving an alternative physiological parameter
measurement at the noninvasive measurement device; determining an
offset value based at least in part on a difference between the
noninvasive physiological parameter measurements and the
alternative physiological parameter measurement; calibrating the
noninvasive measurement device based at least in part on the offset
value; tracking an age of the offset value over time; and
displaying a representation of the offset value on a user interface
of the noninvasive measurement device, wherein the representation
of the offset value is based at least in part on the age of the
offset value.
16. The method of claim 15, further comprising providing a user
interface on the noninvasive measurement device, the user interface
configured to provide functionality for a user to input the
alternative physiological parameter measurement.
17. The method of claim 15, further comprising providing a user
interface on the noninvasive measurement device, the user interface
configured to provide functionality for a user to modify the offset
value.
18. The method of claim 15, further comprising providing a user
interface on the noninvasive measurement device, the user interface
configured to provide functionality for a user to provide an
additional offset value
19. The method of claim 15, wherein the noninvasive physiological
parameter is hemoglobin.
20. The method of claim 15, wherein the noninvasive physiological
parameter is glucose.
Description
RELATED APPLICATIONS
[0001] This application is a continuation of U.S. application Ser.
No. 13/274,306, filed Oct. 15, 2011, titled "Physiological Monitor
Calibration System," the disclosure of which is hereby incorporated
by reference in its entirety and which claims priority under 35
U.S.C. .sctn.119(e) as a nonprovisional of U.S. Provisional
Application No. 61/393,551, filed Oct. 15, 2010, titled
"Physiological Monitor Calibration System," the disclosure of which
is hereby incorporated by reference in its entirety. U.S.
application Ser. No. 13/274,306 also claims priority under 35
U.S.C. .sctn.120 as a continuation-in-part of U.S. application Ser.
No. 11/746,451, filed May 9, 2007, titled "Systems and Methods for
Calibrating Minimally Invasive and Non-Invasive Physiological
Sensor Devices," the disclosure of which is hereby incorporated by
reference in its entirety and which claims priority under 35 U.S.C.
.sctn.119(e) as a nonprovisional of U.S. Provisional Application
No. 60/800,512, filed May 15, 2006, titled "Systems and Methods for
Calibrating Minimally Invasive and Non-Invasive Physiological
Sensor Devices," the disclosure of which is hereby incorporated by
reference in its entirety.
BACKGROUND
[0002] Diabetes is a common cause of kidney disease, blindness
among adults under the age of 65, and limb amputation. The effects
of diabetes can be greatly reduced, if not eliminated all together,
with proper monitoring of blood glucose. Many glucose monitors in
use today require that a person be pricked with a sharp object in
order to draw a small amount of blood to test for glucose levels.
This process of measuring blood is often painful and uncomfortable.
Although minimally and non-invasive blood glucose systems are being
developed, they generally suffer from signal processing challenges
affecting accuracy. One common challenge of minimally invasive
glucose monitoring systems is referred to as drift. Drift generally
occurs during the first few hours or days that a minimally invasive
monitor's probe is inserted in the body and may cause
inaccuracies.
SUMMARY
[0003] Aspects of the present disclosure include systems and
methods for calibrating minimally invasive and non-invasive
physiological sensor devices. The calibration is used to improve
accuracy. In some embodiments, when the system begins taking
measurements, the system may experience drift. FIG. 1 illustrates a
graph 100 of glucose levels 101 in a patient vs. measured glucose
103 measured by a minimally invasive glucose monitor affected by
drift. As illustrated, for a period of time, referred to herein as
the calibration period, the measured glucose is less accurate due
to, for example, drift. In minimally invasive systems, drift may be
caused by protein buildup on the implanted device. In other
systems, drift or other inaccuracies may be caused by any number of
other issues known to an artisan from the disclosure herein. As
with all patient monitors, more accurate and more reliable systems
are preferred.
[0004] In an embodiment, a minimally invasive glucose monitor is
described. The minimally invasive glucose monitor includes a probe
which is inserted into a patient. The probe nearly continuously
measures the patient's glucose levels and reports glucose
information to the minimally invasive glucose monitor. The
minimally invasive glucose monitor also includes a calibration
input for receiving glucose information about the patient derived
from a reliable glucose monitor. The glucose information received
from the reliable glucose monitor is used to calibrate the
minimally invasive glucose monitor. The minimally invasive glucose
monitor may also include one or more outputs for outputting glucose
and calibration related information. The inputs and outputs can be
wired or wireless.
[0005] Although described with respect to glucose monitoring, a
person of skill in the art will recognize that the present
calibration system can be used to monitor and calibrate other
physiological parameters, such as, for example, blood oxygen
levels, blood carbon monoxide levels, blood pH levels,
methemoglobin levels, pulse rates, trend or physiological traces,
or any other physiological parameter. In addition, although
described with respect to a minimally invasive patient monitor, the
present disclosure is also applicable to the calibration of both
invasive and non-invasive patient monitors.
[0006] In an embodiment, a method of calibrating a glucose
measurement device is disclosed. The method includes acquiring a
first indication of a glucose measurement from a first device,
acquiring a second indication of a glucose measurement from a
second device, and calibrating the second device using the first
indication from the first device and the second indication from the
second device. In an embodiment, the first and second devices
comprise patient monitors. In an embodiment, the first and second
devices are operably connected to the same patient. In an
embodiment, the first and second indications are obtained at
substantially the same time. In an embodiment, calibration
comprises one or more of modeling, scaling, transforming, finding a
best fit, finding a linear fit, filtering, adaptive correlation,
and cross correlation. In an embodiment, the first device comprises
an invasive physiological measurement device. In an embodiment, the
second device comprises a minimally invasive physiological
measurement device. In an embodiment, the second device comprises a
non invasive physiological measurement device.
[0007] In an embodiment, a method of calibrating a physiological
measurement device is disclosed. The method includes acquiring a
first indication of one or more physiological measurements from a
first device, acquiring a second indication of the one or more
physiological measurements from a second device, and calibrating
the second device using the first indication from the first device
and the second indication from the second device. In an embodiment,
the first and second devices comprise patient monitors. In an
embodiment, the first and second devices are operably connected to
the same patient. In an embodiment, the first and second
indications are obtained at substantially the same time. In an
embodiment, calibration comprises one or more of modeling, scaling,
transforming, finding a best fit, finding a linear fit, filtering,
adaptive correlation, and cross correlation. In an embodiment, the
one or more physiological parameters comprise one or more of
glucose, blood oxygen, pH, blood carbon monoxide levels, and
methemoglobin. In an embodiment, the first device comprises an
invasive physiological measurement device. In an embodiment, the
second device comprises a minimally invasive physiological
measurement device. In an embodiment, the second device comprises a
non invasive physiological measurement device.
[0008] In an embodiment, a calibration system for calibrating a
physiological measurement monitor is disclosed. The calibration
system includes a first physiological monitor, a calibration module
including a first input for inputting measured physiological data
and a second input for inputting reliable data indicative of one or
more physiological parameters. The calibration module is configured
to calibrate the first physiological monitor using the information
inputted over the first and second inputs. In an embodiment, the
calibration system also includes a second physiological monitor for
measuring the reliable data indicative of one or more physiological
parameters. In an embodiment, the second physiological monitor
comprises an invasive physiological measurement device. In an
embodiment, the first physiological monitor comprises a minimally
invasive physiological measurement device. In an embodiment, the
first physiological monitor comprises a non invasive physiological
measurement device. In an embodiment, the calibration system also
includes one or more signal outputs. In an embodiment, the one or
more signal outputs comprise a display output. In an embodiment,
the one or more signal outputs comprise a trend output. In an
embodiment, the one or more signal outputs comprise a waveform
output. In an embodiment, the waveform output comprises a
synthesized waveform. In an embodiment, the waveform output
comprises a scaled waveform. In an embodiment, the one or more
signal outputs comprise an error output.
[0009] In an embodiment, a method of calibrating a physiological
measurement device is disclosed. The method of calibrating a
physiological measurement includes acquiring a first indication of
a glucose measurement from a first device, acquiring a second
indication of a glucose measurement from a second device, and
comparing the first indication and the second indication. Based on
the comparison of the first indication and the second indication,
if the first and second indications are not the same or close, the
method also includes calibrating the second device using the first
indication from the first device and the second indication from the
second device, waiting an amount of time and requiring the first
and second indications, comparing the reacquired first and second
indications, and based on the comparison of the reacquired first
and second indications, recalibrating the second device using the
reacquired first and second indications.
[0010] In an embodiment, the amount of time comprises a
predetermined amount of time. In an embodiment, the amount of time
comprises about 5 minutes or less to about 12 hours or more. In an
embodiment, the predetermined amount of time comprises about 5
minutes to about 10 minutes. In an embodiment, the predetermined
amount of time comprises about 1 hour to about 2 hours. In an
embodiment, the method also includes dynamically determining the
amount of time. In an embodiment, dynamically determining comprises
determining an amount of time based on the comparison of the first
and second indications. In an embodiment, dynamically determining
comprises determining an amount of time based on the comparison of
the reacquired first and second indications.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The drawings and the associated descriptions are provided to
illustrate embodiments of the disclosure and not to limit the scope
of the claims.
[0012] FIG. 1 illustrates a graph of actual glucose v. measured
glucose for a glucose monitor experiencing drift.
[0013] FIG. 2 illustrates a calibration system.
[0014] FIG. 3 illustrates a minimally invasive glucose monitor.
[0015] FIG. 4 illustrates a glucose calibration system.
[0016] FIG. 4A illustrates another embodiment of a glucose
calibration system.
[0017] FIG. 4B illustrates yet another embodiment of a glucose
calibration system.
[0018] FIG. 5 illustrates a flow chart of an embodiment of a
calibration system.
[0019] FIG. 6 illustrates a flow chart of another embodiment of a
calibration system.
[0020] FIG. 7 illustrates another embodiment of a calibration
system.
[0021] FIG. 8 illustrates a flow chart of an embodiment of a
calibration process.
[0022] FIGS. 9 through 11 illustrate embodiments of physiological
monitor displays.
DETAILED DESCRIPTION
[0023] Embodiments of the present disclosure include systems and
methods for calibrating a physiological monitoring device. A
reliable, often invasive, method of measuring a physiological
parameter is used to calibrate measurements of a minimally invasive
or non-invasive physiological measurement device. In an embodiment,
the reliable monitor and the minimally invasive or non-invasive
monitor measure the same physiological parameter from the same
patient within a time period deemed appropriate. In an embodiment,
a patient can be set up with a long term, minimally invasive
physiological measurement device with minimized discomfort during
the initialization period. In an embodiment, a patient can use a
minimally invasive physiological measurement device to continuously
measure a physiological parameter, using an invasive measurement
device periodically to calibrate the minimally invasive
physiological measurement device. In an embodiment, the
physiological parameter is one or more of glucose, blood oxygen,
pH, blood carbon monoxide levels, and methemoglobin.
[0024] FIG. 2 illustrates a calibration system 200. The calibration
system includes a parameter calculator 201. The parameter
calculator includes one or more inputs 203 for reliable data
indicative of one or more parameters and one or more inputs 205 for
measurement data. The reliable data indicative of one or more
parameters is communicated from a reliable, often invasive, patient
monitor. The measurement data is communicated from a physiological
sensor.
[0025] The parameter calculator 201 uses the reliable data
indicative of one or more parameters to calibrate, if necessary,
the measurement data or information derived from the measurement
data. Calibration may include modeling, scaling, transforming,
finding a best fit, finding a linear fit, filtering, adaptive
correlation, cross correlation, or any other calibration steps
known to a skilled artisan from the disclosure herein.
[0026] The parameter calculator 201 can calculate one or more
physiological parameters and output information indicative of that
parameter. The parameter calculator 201 may also advantageously
calculate trend data and synthesize or scale waveform data. The
parameter calculator 201 includes one or more outputs, such as, for
example, parameter data output 207, trend data output 209,
synthesized, scaled, or actual waveform output 211, or calibration
data output 213. The parameter data output 207 communicates data
indicative of one or more physiological measurements. The trend
data output 209 communicates data indicative of trend information
for the one or more physiological measurements. The synthesized,
scaled, or actual waveform data output 211 communications waveform
data which has been synthesized, scaled, or unaltered. The
calibration data output 213 communicates information related to
calibrations performed by the parameter calculator 201. The outputs
207, 209, 211, 213 can communicate with display 215, a separate
patient monitoring device, or other device configured to receiving
physiological parameter information.
[0027] In an embodiment, the parameter calculator 201 is included
within a single device. In an embodiment, the parameter calculator
201 is included within several separate devices. In an embodiment,
the parameter calculator 201 comprises a processor, processor
board, or OEM board. In an embodiment, the parameter calculator 201
is portable. In an embodiment, the parameter calculator 201
comprises a desktop parameter calculator. Data communicated between
the various components of the calibration system can be
communicated through cables or wirelessly. A skilled artisan will
also understand from the disclosure herein, that other inputs
and/or outputs can be included with the system of the present
disclosure. For example, an error data output can be used to
communicate the error calculated between the measured data and the
reliable data.
[0028] FIG. 3 illustrates an embodiment of a minimally invasive
glucose monitor. As illustrated, a minimally invasive glucose
monitor 301 is attached to a patient 300. The minimally invasive
glucose monitor 301 includes a probe 303 which is inserted into the
body, often just beneath the skin. The probe 303 measures glucose
levels in the patient 300. The probe 303 communicates the
measurements to the minimally invasive glucose monitor 301. In an
embodiment, the probe 303 is attached to the monitor 301. In an
embodiment, the probe is separate from the monitor 301. In an
embodiment, the probe 303 communicates through a cable connection
with the monitor 301. In an embodiment, the probe 303 communicates
wirelessly with monitor 301. In an embodiment, the monitor 301 is
attached to the patient 300 by attachment piece 309. In an
embodiment, the monitor 301 includes a display 305. In an
embodiment, the monitor includes one or more buttons 307.
[0029] In operation, the minimally invasive glucose monitor 301
continuously, nearly continuously, or intermittently (periodically
or otherwise) measures blood glucose using probe 303. The probe
detects glucose levels present in the body and communicates the
glucose levels to the minimally invasive glucose monitor 301. The
minimally invasive glucose monitor 301 calculates the patient's
glucose level based upon information acquired from probe 105.
Examples of a minimally invasive glucose monitor and probe are
described in U.S. Pat. No. 6,613,379, entitled "Implantable Analyte
Sensor," issued to Ward et al., and U.S. Pat. No. 6,695,860,
entitled "Transcutaneous Sensor Insertion Device," also issued to
Ward et al, the entire contents of both of which are herein
incorporated by reference.
[0030] FIG. 4 illustrates an embodiment of a glucose calibration
system. For example, the glucose level of a patient 300 is measured
by a minimally invasive glucose monitor 301. As described above,
the minimally invasive glucose monitor 301 includes a probe 303
inserted into the patient 300 for measuring glucose levels. The
glucose level of patient 300 is also measured by a reliable glucose
monitor 401. The reliable glucose monitor 401 communicates data
indicative of glucose levels in patent 300 to the minimally
invasive glucose monitor 201. The minimally invasive glucose
monitor 301 uses the communicated reliable data indicative of
glucose levels in patent 300 to calibrate glucose information
communicated by probe 303.
[0031] In an embodiment, the reliable glucose monitor 401
communicates with the minimally invasive glucose monitor 301
through a cable or a wireless connection. In an embodiment, the
reliable glucose monitor 401 and the minimally invasive glucose
monitor 301 communicate with a separate calibration unit either
through a cable or wirelessly. In an embodiment, the minimally
invasive glucose monitor 301 communicates with the reliable glucose
monitor 401. In an embodiment, the minimally invasive glucose
monitor 301 communicates a command to take a measurement to the
reliable glucose monitor 401.
[0032] In an embodiment, the reliable glucose monitor 401 is
operably connected to an IV line 409. The IV line 409 is operably
connected to a catheter 411 which is inserted into a vein of the
patient 300. The reliable glucose monitor 401 is also operably
connected to an IV line 405 which is operably connected to an fluid
bag 407. In operation, the reliable glucose monitor 401
intermittently draws blood from patient 300 through catheter 411
and IV line 409 and tests the blood for glucose levels. When the
reliable glucose monitor 401 is not drawing blood from the patient
300, it supplies fluid to the patient 300 from fluid bag 407 and IV
line 405 through IV line 409 and catheter 411. In an embodiment,
the reliable glucose monitor 401 uses glucose test strips to
measure glucose levels in the blood. In an embodiment, the reliable
glucose monitor 401 uses chemicals analyses to test the glucose
levels.
[0033] In an embodiment, the reliable glucose monitor 401 is
programmed to take measurements at predetermined intervals. In an
embodiment, the measurements are taken in intervals of about 5
minutes to about 12 hours. In an embodiment, the measurements are
taken in intervals of about 5 minutes to about 10 minutes. In an
embodiment, the measurements are taken in intervals of about 1 to
about 2 hours. In an embodiment, the measurement intervals are
dynamically determined based on calibration feedback as described
below. In an embodiment, the minimally invasive glucose monitor
301, or another intermediary device communicate a take measurement
command to the reliable glucose monitor. In an embodiment, the
minimally invasive or intermediary device communicate a take
measurement command in predetermined or dynamically determined
intervals as described above.
[0034] FIG. 4A illustrates another embodiment of a glucose
calibration system in which glucose test strips and a glucose test
meter are used to measure glucose levels. A user uses the glucose
test strips and glucose test meter to measure glucose levels. Once
measured, the glucose test meter communicates the glucose levels to
the minimally invasive glucose meter for calibration.
[0035] FIG. 4B illustrates yet another embodiment of a glucose
calibration system. In this embodiment, a glucose test meter is
incorporated into the minimally invasive glucose monitor. A user
uses the glucose test strips in conjunction with the minimally
invasive glucose monitor to calibrate the minimally invasive
glucose measurements. In an embodiment, the minimally invasive
glucose monitor alerts a user that a reliable glucose measurement
should be taken for calibration purposes.
[0036] FIG. 5 illustrates a flow chart of an embodiment of a
calibration system. The system begins by nearly continuously
acquiring minimally invasive glucose measurements at block 501. The
system then moves on to block 503 where the system acquires
reliable glucose data. The system then moves on to block 505, where
a calibration module compares the invasive blood glucose
measurement to the acquired minimally invasive glucose
measurement.
[0037] Once the measurements are compared, the system moves on to
decision block 507, where the system looks to see if the
measurements are the same or similar. Similar being defined herein
as within a predetermined threshold. If the acquired minimally
invasive measurement is the same or similar to the acquired
reliable glucose data, then the system moves on to block 511 where
the glucose reading is outputted, either to a display, a patient
monitor, or to another device. If the minimally invasive
measurement is not similar, or within a predetermined threshold,
then the system moves on to block 509 where the minimally invasive
measurements are calibrated. Once calibration is complete, the
system moves on to block 511 where the glucose reading is
outputted. The system then moves to block 513, where the system
decides whether or not the calibration period is complete. If the
calibration period is not complete, the system moves to block 515
where it waits a predetermined period of time. After the period of
time is complete, the system returns to block 503 and repeats the
calibration process. If at block 513, the calibration period is
completed, then the system moves to block 517 where the system
communicates a calibration complete signal.
[0038] In an embodiment, the determination of whether the
calibration period is complete is based on an averaging of
calibration periods required by other minimally invasive monitors.
In an embodiment, the determination of whether the calibration
period is compete is based on one or more comparisons of the
reliable data and the minimally invasive measurement information.
In one embodiment, the determination of whether the calibration
period is complete is based on an averaging of calibration periods
required by other minimally invasive monitors and one or more
comparisons of the reliable data and the minimally invasive
measurement information.
[0039] FIG. 6 illustrates a flow chart of another embodiment of a
calibration system. The system begins by nearly continuously
acquiring minimally invasive glucose measurements at block 601. The
system then moves on to block 603 where the system acquires
reliable glucose data. The system then moves on to block 605, where
a calibration module compares the invasive blood glucose
measurement to the acquired minimally invasive glucose
measurement.
[0040] Once the measurements are compared, the system moves on to
decision block 607, where the system looks to see if the
measurements are similar. If the acquired minimally invasive
measurement is the same or similar to the acquired reliable glucose
data, then the system moves on to block 611 where the predetermined
wait period of block 617 is recalculated. The recalculation can be
based on the number of accurate readings made by the minimally
invasive device and/or the accuracy level of the readings made by
the minimally invasive device and/or any other parameter which is
useful for determining the duration between calibration cycles. The
system then moves on to block 613 where the glucose readings are
outputted.
[0041] If the minimally invasive measurement is not similar, or
within a predetermined threshold, then the system moves on to block
609 where the minimally invasive measurements are calibrated. The
system then moves on to block 613 where the glucose readings are
outputted. Once calibration is complete, the system moves on to
block 615, where the system decides whether or not the calibration
period is complete. If the calibration period is not complete, the
system moves to block 617 where it waits the predetermined period
of time, either as initially set or as dynamically recalculated at
block 611. After the period of time is complete, the system returns
to block 503 and repeats the calibration process. If at block 615,
the calibration period is completed, then the system moves to block
619 where the system communicates a calibration complete
signal.
Another Example Calibration System
[0042] FIG. 7 illustrates another embodiment of a calibration
system 700. The calibration system 700 can implement any of the
features described above with respect to FIGS. 1 through 6. In
addition, the calibration system 700 can implement additional
features that can advantageously enable a clinician to compare
noninvasive physiological parameter measurements with alternative
measurements. The calibration system 700 can enable field
calibrations of physiological parameters that can supplement any
factory calibration provided during manufacture of the calibration
system 700.
[0043] The calibration system 700 includes a measurement module 710
and a calibration module 712. Each of these modules 710, 712 can be
implemented in hardware and/or software. The measurement module 710
can acquire, receive, or otherwise obtain signals reflecting
physiological information from one or more sensors 720. The one or
more sensors 720 can be any of the sensors described above or any
other physiological sensor(s), including, for example, optical
sensors, glucose sensors, pulse oximetry sensors, hemoglobin
sensors, dishemoglobin sensors, acoustic sensors, ECG sensors, EEG
sensors, and the like.
[0044] The measurement module 710 can analyze the physiological
information to measure one or more physiological parameters,
analytes, or concentrations thereof, including, but not limited to,
oxygen saturation (SpO.sub.2), total hemoglobin (SpHb), glucose,
respiratory rate, and the like. The measurement module 710 can
output parameter data, trend data, and/or synthesized, scaled, or
actual waveforms, to a display 730 (see FIGS. 9 and 10).
[0045] The calibration module 712 receives, acquires, or otherwise
obtains an alternative measurement 722. In one embodiment, the
alternative measurement is a calibration measurement that enables
the calibration module 712 to calibrate one or more of the
measurements made by the measurement module 710. The alternative
measurement 722 can be an invasive measurement, such as a
measurement made in a hospital lab, a minimally-invasive
measurement, or the like. As used herein, the term "invasive," in
addition to having its ordinary meaning, can also mean
minimally-invasive. The alternative measurement 722 can be related
to a parameter measured by the measurement module 710. For
instance, if the measurement module 710 noninvasively measures
hemoglobin of a patient, the alternative measurement 722 can be an
invasive measurement for the same patient. The alternative
measurement 722 can also be a noninvasive measurement from another
noninvasive sensor, or even a different type of noninvasive sensor.
Multiple alternative measurements 722 can be input into the
calibration module 712.
[0046] In one embodiment, the alternative measurement(s) 722 is
input into the calibration module 712 by a clinician. The
calibration module 712 can expose a user interface for presentation
to the clinician (or other user), for example, on the display 730.
The user interface can include one or more user interface controls,
such as context menus, buttons, or the like that enable the
clinician to input the alternative measurement 722. The alternative
measurement 722 can also be received from another device, for
example, over a network (such as a hospital network, a LAN, a WAN,
the Internet, or a combination of the same). The alternative
measurement 722 can also be received from a second sensor coupled
with a patient.
[0047] The calibration module 712 can output the alternative
measurement 722 in conjunction with or separate from the
measurement(s) obtained by the measurement module 710. In one
embodiment, the calibration module 712 outputs a value that
reflects the alternative measurement 722 next to, alongside, above,
below, or in relation to the measurement obtained by the
measurement module 710. The calibration module 712 can output the
alternative measurement 722 instead of the noninvasive measurement
obtained by the measurement module 710. The calibration module 712
can also average or otherwise combine the noninvasive measurement
and the alternative measurement 722. The calibration module 712 can
also use the alternative measurement 722 or measurements to adjust
a calibration curve corresponding to the noninvasive
measurement.
[0048] In another embodiment, the calibration module 722 outputs
the difference between the alternative measurement 722 and the
measurements obtained by the measurement module 710. Further, the
alternative measurement 722 can be a value that represents a
difference between a noninvasive measurement and a second (e.g.,
invasive) measurement. Thus, this difference can be input (e.g., by
a clinician) into the parameter calculator 701 instead of the
actual alternative measurement 722 itself.
[0049] The calibration module 722 can output a trend graph, line,
or trend data points that reflect differences between the
alternative measurement 722 and the noninvasive measurements over
time. This trend graph can be output or overlaid on the same trend
graph display output by the measurement module 710. Thus, in
certain embodiments, the trend graph or graphs shown on the display
730 can include a trend line (or set of data points) reflecting the
noninvasive measurement values together with a trend line (or set
of data points) reflecting an offset. The offset can be the
difference between the noninvasive measurement values and the
alternative measurement value 722. Examples of such offsets are
shown in FIGS. 9 and 10 (described below).
[0050] FIG. 8 illustrates a flow chart of an embodiment of a
calibration process 800. The calibration process 800 can be
implemented by any of the systems or parameter calculators
described herein, including the parameter calculator 700. The
calibration process 800 enables a physiological monitor to be
calibrated, in certain embodiments, by receiving an alternative
measurement and displaying the alternative measurement (or an
offset derived from that measurement) together with one or more
noninvasive measurements.
[0051] At block 802, noninvasive physiological parameter
measurements are acquired. These measurements can be acquired by
the measurement module 710 from a sensor coupled with a patient. At
block 804, an alternative physiological parameter measurement is
received. This measurement can be received with the calibration
module 720, as described above.
[0052] At block 806, a trend graph of the noninvasive physiological
parameter measurements is output. A second trend graph is output at
block 808. This second trend graph reflects a difference between
the noninvasive physiological parameter measurements and the
alternative physiological parameter measurement. If desired (e.g.,
by a clinician), the process 800 can be repeated to acquire
multiple alternative measurements and to display these alternative
measurements as trends together with a trend of the noninvasive
measurements.
[0053] FIGS. 9 and 10 illustrate embodiments of physiological
monitors 900, 1000 having parameter displays 910, 1010. The
displays 910, 1010 include several features in the depicted
embodiment, including parameter values 920, trend graphs 930, 1030,
and a measurement input button 940. The measurement input 940 is an
example of a user interface control that provides functionality for
a clinician or other user to input one or more alternative
measurements. Additional buttons 950 located on the physiological
monitor 900 can control a variety of other tasks. The features
shown in FIGS. 9 and 10 can be implemented by the calibration
module 712 described above.
[0054] Referring specifically to FIG. 9, the trend graph 930
includes a measurement waveform 932 and an offset waveform 934. The
measurement waveform 932 is an example trend graph for a
noninvasive physiological parameter, representing values of that
parameter for a given patient over time. The offset waveform 934 is
an example trend graph that is offset or biased from the trend
graph 932. The offset waveform 934 can represent the difference
between noninvasive physiological measurements and an alternative
physiological measurement. In one embodiment, the offset waveform
934 is displayed on the trend graph 930 in response to an
alternative measurement being entered using the button 940. In the
depicted embodiment, the measurement waveform 932 represents SpHb,
or hemoglobin, values, and the offset waveform 934 represents
values derived from a invasive or minimally invasive hemoglobin.
The offset waveform 934 is termed CHb, or calibrated hemoglobin, in
the display 910.
[0055] In one embodiment, the calibration provided by the offset
waveform 934 is terminated when a probe or sensor is taken off of
the patient. The calibration can therefore be reset in certain
embodiments. However, the offset waveform 934 instead may not be
terminated when the probe is taken off.
[0056] Referring to FIG. 10, the trend graph 1030 includes a
measurement waveform 1032 as before and an offset waveform 1034,
also as before. However, a second offset waveform 1036 is also
shown, which represents an offset or bias obtained from a second
alternative measurement. Thus, multiple alternative measurements
can be taken and displayed as offsets or biases from the
noninvasively-measured parameter values. In one embodiment, an
initial alternative measurement is taken at an initial time, such
as shortly before, shortly after, or at about the time that the
noninvasive measurements commence. Thereafter, a second alternative
measurement is taken partway through a monitoring session (such as
a hospital stay).
[0057] Instead of displaying both offsets from the first and second
alternative measurements, the offset from the second alternative
measurement can be displayed in place of the first offset once the
second alternative measurement is received by the physiological
monitor 1000. In another implementation, the offsets from the first
and second alternative measurements can be combined, for example,
by averaging. In still other embodiments, the first and second
alternative measurements can be used to adjust a calibration curve
specific to the individual being measured.
[0058] Further, the alternative measurement data from many patients
can be used to improve factory calibration settings of the
physiological monitor. The alternative measurements and/or their
offsets can be averaged, for instance, to determine an average
offset to be applied to the factory calibration setting. The
measurements can be averaged based on type of patient, type of
patient condition, age, gender, and so forth.
[0059] In FIG. 11, another embodiment of a patient monitor 1100 is
shown that includes a user interface 1100. The user interface 1100
can be generated at least in part by the calibration module 712.
The example user interface 1100 shown outputs parameter values
instead of waveforms, including an SpO.sub.2 value 1112, a heart
rate value 1114, a respiratory rate value 1116, and a noninvasive
total hemoglobin value 1118. The parameter values shown in this
example are merely examples, and fewer or more parameters can be
shown in other implementations.
[0060] An offset value 1120 is also shown next to the hemoglobin
value 1118. The offset value 1120 can represent a difference
between the noninvasive total hemoglobin measurement 1118 and an
alternative measurement, such as an invasive or minimally-invasive
measurement (or optionally another noninvasive sensor). This offset
value 1120 can be used in place of the offset waveforms described
above. Of course, in some embodiments, the offset value 1120 can be
depicted on a user interface together with an offset waveform. The
value of the offset 1120 is "+1.0" in the depicted embodiment. In
some embodiments, the offset value 1120 is represented as a
positive or negative deviation from the hemoglobin value 1118.
[0061] In some embodiments, a clinician or user directly enters the
offset value 1120 into the patient monitor 1100. Various types of
user interface controls can be used by the clinician or user to
input the offset value 1120. As an example, buttons 1130 are shown
on the patient monitor 1100 below menu options 1142, 1144 on the
user interface 1100. Selection of the appropriate buttons 1130 can
cause the offset value 1120 to increase or decrease in value. For
purposes of illustration, step values of +0.1 and -0.1 are shown as
menu options 1142, 1144. Thus, for example, selection of the +0.1
value via a corresponding button 1130 can cause the offset value
1120 shown to increase by 0.1. The step values shown are merely
examples and can vary in different implementations. Further, the
step values can be represented as percentages, such as percentage
differences from the alternative measurement, in some
embodiments.
[0062] In other embodiments, the offset value 1120 is communicated
to the patient monitor 1100 over a network, for example, from a lab
that generates an invasive value or from another computing device.
A lab technician or other individual can input the invasive value
into a computing system, which then transmits the invasive value to
the patient monitor 1100. The patient monitor 1100 can then
calculate the difference between a current noninvasive measurement
and the invasive value and output this difference as the offset
value 1120. In another embodiment, the invasive value received from
the lab (or other computing device) has a time stamp associated
with it. The patient monitor 1100 may then calculate the offset
value 1120 by comparing the invasive value with the noninvasive
value that occurred at the same time or a close time to the
timestamp of the invasive value.
[0063] In other embodiments, the actual alternative measurement is
shown in place of or in addition to an offset value 1120. Further,
the clinician or user can enter the actual invasive measurement
instead of an offset value 1120 in some embodiments. In addition,
user interface controls other than buttons, such as touch screen
inputs, can be employed to add offset values or alternative
measurements.
[0064] Other features that may be employed by the patient monitor
1100 can include a feature that displays an indication of the age
of the offset value 1120. This feature can include a timestamp of
when the value was either obtained (e.g., at the lab) or when the
value was input into the patient monitor 1100. The patient monitor
1100 can include further user interface controls that enable a
clinician or other user to input the timestamp, or the timestamp
can be obtained directly from the lab or other computing device
over a network. In another embodiment, the appearance of the offset
value 1120 can change to reflect the aging of the offset value
1120. Any of the following display features can equally apply to
the parameter value itself (e.g., the hemoglobin value 1118). For
instance, the offset value 1120 (or parameter value 1118) can be
one color when first entered (such as green) but change to another
color (such as red) as the offset value 1120 ages. In another
embodiment, the offset value 1120 (or parameter value 1118) blinks
with a frequency that depends on the age of the offset value 1120.
In another embodiment, the offset value 1120 begins blinking when
the age of the offset value 1120 reaches a certain threshold. In
yet another embodiment, the offset value 1120 can be reset to a
value 0 when a threshold time has passed. Showing the age of the
offset value 1120 in any of these ways or using other techniques
can assist a clinician in determining the relevancy of the offset
value 1120. Age-related techniques may also be implemented using
the trend graph user interfaces described above with respect to
FIGS. 9 and 10, including blinking, changing color, showing
timestamps, and the like.
CONCLUSION
[0065] Although the foregoing inventions have been described in
terms of certain preferred embodiments, other configurations are
possible. For example, an invasive blood pressure monitor can be
used to calibrate a non-invasive blood pressure monitor. In
addition, various types of physiological monitors can be used to
calibrate various other types of physiological monitors. For
example, a minimally invasive physiological monitor can be used to
calibrate a non-invasive physiological monitor.
[0066] The modules described herein of certain embodiments may be
implemented as software modules, hardware modules, or a combination
thereof. In general, the word "module," as used herein, can refer
to logic embodied in hardware or firmware or to a collection of
software instructions executable on a processor. Additionally, the
modules or components thereof may be implemented in analog
circuitry in some embodiments.
[0067] Conditional language used herein, such as, among others,
"can," "could," "might," "may," "e.g.," and the like, unless
specifically stated otherwise, or otherwise understood within the
context as used, is generally intended to convey that certain
embodiments include, while other embodiments do not include,
certain features, elements and/or states. Thus, such conditional
language is not generally intended to imply that features, elements
and/or states are in any way required for one or more embodiments
or that one or more embodiments necessarily include logic for
deciding, with or without author input or prompting, whether these
features, elements and/or states are included or are to be
performed in any particular embodiment.
[0068] Depending on the embodiment, certain acts, events, or
functions of any of the methods described herein can be performed
in a different sequence, can be added, merged, or left out all
together (e.g., not all described acts or events are necessary for
the practice of the method). Moreover, in certain embodiments, acts
or events can be performed concurrently, e.g., through
multi-threaded processing, interrupt processing, or multiple
processors or processor cores, rather than sequentially.
[0069] The various illustrative logical blocks, modules, circuits,
and algorithm steps described in connection with the embodiments
disclosed herein can be implemented as electronic hardware,
computer software, or combinations of both. To clearly illustrate
this interchangeability of hardware and software, various
illustrative components, blocks, modules, circuits, and steps have
been described above generally in terms of their functionality.
Whether such functionality is implemented as hardware or software
depends upon the particular application and design constraints
imposed on the overall system. The described functionality can be
implemented in varying ways for each particular application, but
such implementation decisions should not be interpreted as causing
a departure from the scope of the disclosure.
[0070] The various illustrative logical blocks, modules, and
circuits described in connection with the embodiments disclosed
herein can be implemented or performed with a general purpose
processor, a digital signal processor (DSP), an application
specific integrated circuit (ASIC), a field programmable gate array
(FPGA) or other programmable logic device, discrete gate or
transistor logic, discrete hardware components, or any combination
thereof designed to perform the functions described herein. A
general purpose processor can be a microprocessor, but in the
alternative, the processor can be any conventional processor,
controller, microcontroller, or state machine. A processor can also
be implemented as a combination of computing devices, e.g., a
combination of a DSP and a microprocessor, a plurality of
microprocessors, one or more microprocessors in conjunction with a
DSP core, or any other such configuration.
[0071] The blocks of the methods and algorithms described in
connection with the embodiments disclosed herein can be embodied
directly in hardware, in a software module executed by a processor,
or in a combination of the two. A software module can reside in RAM
memory, flash memory, ROM memory, EPROM memory, EEPROM memory,
registers, a hard disk, a removable disk, a CD-ROM, or any other
form of computer-readable storage medium known in the art. An
exemplary storage medium is coupled to a processor such that the
processor can read information from, and write information to, the
storage medium. In the alternative, the storage medium can be
integral to the processor. The processor and the storage medium can
reside in an ASIC. The ASIC can reside in a user terminal. In the
alternative, the processor and the storage medium can reside as
discrete components in a user terminal.
[0072] While the above detailed description has shown, described,
and pointed out novel features as applied to various embodiments,
it will be understood that various omissions, substitutions, and
changes in the form and details of the devices or algorithms
illustrated can be made without departing from the spirit of the
disclosure. As will be recognized, certain embodiments of the
inventions described herein can be embodied within a form that does
not provide all of the features and benefits set forth herein, as
some features can be used or practiced separately from others. The
scope of certain inventions disclosed herein is indicated by the
appended claims rather than by the foregoing description. All
changes which come within the meaning and range of equivalency of
the claims are to be embraced within their scope.
* * * * *