U.S. patent application number 11/737173 was filed with the patent office on 2008-10-23 for infection monitoring.
This patent application is currently assigned to MEDTRONIC, INC.. Invention is credited to Martin T. Gerber, John C. Rondoni.
Application Number | 20080262332 11/737173 |
Document ID | / |
Family ID | 40344366 |
Filed Date | 2008-10-23 |
United States Patent
Application |
20080262332 |
Kind Code |
A1 |
Gerber; Martin T. ; et
al. |
October 23, 2008 |
INFECTION MONITORING
Abstract
A method includes monitoring an indicator of infection in
proximity to an implanted active therapy delivering medical device
and providing information regarding the monitored indicator to the
implanted medical device. The method further includes determining
whether the information regarding the monitored indicator is
indicative of infection in proximity to the implanted medical
device.
Inventors: |
Gerber; Martin T.; (Maple
Grove, MN) ; Rondoni; John C.; (Plymouth,
MN) |
Correspondence
Address: |
CAMPBELL NELSON WHIPPS, LLC
408 ST. PETER STREET, SUITE 240
ST. PAUL
MN
55102
US
|
Assignee: |
MEDTRONIC, INC.
Minneapolis
MN
|
Family ID: |
40344366 |
Appl. No.: |
11/737173 |
Filed: |
April 19, 2007 |
Current U.S.
Class: |
600/361 ;
600/547; 600/549 |
Current CPC
Class: |
A61M 5/16836 20130101;
A61M 2205/3523 20130101; A61B 5/14539 20130101; A61B 5/0031
20130101; A61B 5/01 20130101; A61B 5/6846 20130101; A61M 2205/3561
20130101; A61N 1/3756 20130101; A61B 5/076 20130101; A61M 2205/18
20130101; A61B 5/145 20130101; A61M 5/14276 20130101; A61B 5/053
20130101; A61M 2205/3368 20130101; A61N 1/37258 20130101; A61N
1/36521 20130101 |
Class at
Publication: |
600/361 ;
600/547; 600/549 |
International
Class: |
A61B 5/145 20060101
A61B005/145; A61B 5/01 20060101 A61B005/01; A61B 5/053 20060101
A61B005/053 |
Claims
1. A method comprising: monitoring an indicator of infection in
proximity to an implanted active therapy delivering medical device;
providing information regarding the monitored indicator to the
implanted medical device; and determining whether the information
regarding the monitored indicator is indicative of infection in
proximity to the implanted medical device.
2. The method of claim 1, wherein determining whether the
information regarding the monitored indicator is indicative of
infection is performed in the implanted device.
3. The method of claim 1, further comprising transmitting the
information regarding the monitored indicator to an external
device, wherein determining whether the information regarding the
monitored indicator is indicative of infection is performed in the
external device.
4. The method of claim 1, wherein the implanted medical device is
an infusion device.
5. The method of claim 1, wherein the implanted device is an
electrical signal generator.
6. The method of claim 1, wherein monitoring the indicator of
infection comprises monitoring temperature.
7. The method of claim 1, wherein monitoring the indicator of
infection comprises monitoring pH.
8. The method of claim 1, wherein monitoring the indicator of
infection comprises monitoring impedance.
9. The method of claim 1, wherein monitoring the indicator of
infection comprises monitoring a biological indicator of
infection.
10. An active implantable therapy delivering medical device
comprising: a hermetically sealed housing; a power source disposed
in the housing; electronics disposed in the housing and operably
coupled to the power source, the electronics capable of controlling
therapeutic output from the device; a sensor located in proximity
to the housing and being operably coupled to the electronics, the
sensor capable of detecting information regarding an indicator of
infection and transmitting the information to the electronics; and
a computer readable medium containing instructions that when
implemented by the electronics cause the device to determine
whether the information is indicative of infection.
11. The device of claim 10, further comprising an alarm operably
coupled to the electronics, wherein the computer readable medium
further contains instructions that when implemented by the
electronics cause the device to activate the alarm if a
determination is made that the information is indicative of
infection.
12. The device of claim 10, wherein the active implantable therapy
delivering medical device is an infusion device.
13. The device of claim 10, wherein the active implantable therapy
delivering medical device is an electrical signal generator.
14. A system comprising: an active implantable therapy delivering
medical device comprising: a hermetically sealed housing; a power
source disposed in the housing; first electronics disposed in the
housing and operably coupled to the power source, the first
electronics capable of controlling therapeutic output from the
active implantable therapy delivering device; a sensor located in
proximity to the housing and being operably coupled to the
electronics, the sensor capable of detecting information regarding
an indicator of infection and transmitting the information to the
electronics; and a wireless transmitter operably coupled to the
electronics and capable of transmitting the information regarding
the indicator of infection; and a second device comprising: second
electronics; a wireless receiver operably coupled to the
electronics and capable of receiving the information regarding the
indicator of infection from the active implantable medical device;
and a computer readable medium containing instructions that when
implemented by the second electronics cause the second device to
determine whether the information is indicative of infection.
15. The system of claim 14, wherein the active implantable therapy
delivering medical device is an infusion device.
16. The system of claim 14, wherein the active implantable therapy
delivering medical device is an electrical signal generator.
17. The system of claim 14, wherein the second device is a
programmer device.
18. The method of claim 1, monitoring the indicator of infection in
proximity to the implanted active therapy delivering medical device
comprises sensing the indicator via a sensor located on or in a
housing of the device.
19. The device of claim 10, wherein the sensor is located one or in
the housing.
20. The system of claim 14, wherein the sensor is located on or in
the housing of the active implantable therapy delivering medical
device.
Description
FIELD
[0001] This disclosure relates, inter alia, to implantable medical
devices. More particularly, it relates to systems, devices and
methods for monitoring infection in proximity to medical devices
implanted in patients.
BACKGROUND
[0002] Infection associated with implantation of medical devices is
a serious health and economic concern. Today, infections associated
with implanted medical devices are not very common due to care and
precautions taken during surgical implantation of the devices.
However, when infection associated with an implanted medical device
(IMD) does occur, explanting the device is often the only
appropriate course of action.
[0003] For IMDs having a battery powered component, such as
implantable cardiac pacemakers, cardioverter/defibrillators having
pacing capabilities, other electrical stimulators including spinal
cord, deep brain, nerve, and muscle stimulators, infusion devices,
cardiac and other physiologic monitors, cochlear implants, etc.,
the battery powered component is typically enclosed in a housing
that is implanted subcutaneously at a surgically prepared site,
referred to as a "pocket". Associated devices, such as elongated
medical electrical leads or drug delivery catheters, extend from
the pocket to other subcutaneous sites or deeper into the body to
organs or other implantation sites.
[0004] Surgical preparation and implantation are conducted in a
sterile field, and the IMD components are packaged in sterile
containers or sterilized prior to introduction into the sterile
field. However, despite these precautions, there always is a risk
of introduction of microbes into the pocket. Surgeons therefore
typically apply disinfectant or antiseptic agents to the skin at
the surgical site prior to surgery, directly to the site before the
incision is closed, and prescribe oral antibiotics for the patient
to ingest during recovery.
[0005] Despite these precautions, infections do occur. In addition,
once the pocket becomes infected, the infection can migrate along
the lead or catheter to the heart, brain, spinal canal or other
location in which the lead or catheter is implanted. Such a
migrating infection can become intractable and life-threatening,
requiring removal of the IMD in the pocket and associated devices,
such as leads and catheters. Removal of a chronically implanted
lead or catheter can be difficult and dangerous. Accordingly,
aggressive systemic drug treatment is prescribed to treat such
infections. However, early detection of infection associated with
implanted medical devices may allow for earlier intervention,
resulting in fewer device explants.
SUMMARY
[0006] The present disclosure describes, inter alia, systems,
devices and methods that can be used to monitor an infection in
proximity to an implantable medical device, such as an active
therapy delivering medical device.
[0007] In an embodiment, a method for monitoring an indicator of
infection is described. The method includes monitoring an indicator
of infection in proximity to an implanted active therapy delivering
medical device and providing information regarding the monitored
indicator to the implanted medical device. The method further
includes determining whether the information regarding the
monitored indicator is indicative of infection in proximity to the
implanted medical device.
[0008] By providing devices, systems and methods that allow for
monitoring of infection in proximity to an implanted active therapy
delivering medical device, early intervention and treatment may be
administered, which may result in fewer device explants. Such
methods, systems and devices, not only can serve to reduce costly
medical explant surgery but also can provide implant patients with
added peace of mind. These and other advantages will be readily
understood from the following detailed descriptions when read in
conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a diagrammatic representation of a perspective
view of an environment of an infusion system implanted in a
patient.
[0010] FIG. 2 is a diagrammatic representation of a perspective
view of an environment of an electrical signal generator system
implanted in a patient
[0011] FIGS. 3A-D are a diagrammatic representations of a
perspective views of environments of medical devices implanted in
patients.
[0012] FIG. 4 is a diagrammatic representation of an external
device in wireless communication with an implantable medical
device.
[0013] FIGS. 5A-B is a diagrammatic representation of a side view
(5A) and back view (B) of an implantable medical device system
having sensor(s) in proximity to the implantable device.
[0014] FIG. 6 is a schematic block diagram of representative
components of a representative implantable medical device.
[0015] FIG. 7 is a flow diagram of a representative method.
[0016] FIGS. 8A-C are schematic block diagrams of a representative
implantable medical devices or systems.
[0017] The drawings are not necessarily to scale. Like numbers used
in the figures refer to like components, steps and the like.
However, it will be understood that the use of a number to refer to
a component in a given figure is not intended to limit the
component in another figure labeled with the same number.
DETAILED DESCRIPTION
[0018] In the following detailed description, reference is made to
the accompanying drawings that form a part hereof, and in which are
shown by way of illustration several specific embodiments of
devices, systems and methods. It is to be understood that other
embodiments are contemplated and may be made without departing from
the scope or spirit of the present invention. The following
detailed description, therefore, is not to be taken in a limiting
sense.
[0019] All scientific and technical terms used herein have meanings
commonly used in the art unless otherwise specified. The
definitions provided herein are to facilitate understanding of
certain terms used frequently herein and are not meant to limit the
scope of the present disclosure.
[0020] As used in this specification and the appended claims, the
singular forms "a", "an", and "the" encompass embodiments having
plural referents, unless the content clearly dictates otherwise. As
used in this specification and the appended claims, the term "or"
is generally employed in its sense including "and/or" unless the
content clearly dictates otherwise.
[0021] As used herein, "active therapy delivering implantable
medical device" or the like means an implantable medical device
that includes a power source and electronics operably coupled to
the power source to control delivery of therapy to a patient.
Non-limiting examples of active therapy delivering implantable
medical devices include implantable infusion devices and
implantable electrical signal generators, such as cardiac
defibrillators, pacemakers, neurostimulators, gastric stimulators,
and cochlear implants. Active implantable medical devices typically
are used in conjunction with associated implantable medical
devices, such as catheters or leads.
[0022] Unless otherwise indicated, all numbers expressing feature
sizes, amounts, and physical properties used in the specification
and claims are to be understood as being modified in all instances
by the term "about." Accordingly, unless indicated to the contrary,
the numerical parameters set forth in the foregoing specification
and attached claims are approximations that can vary depending upon
the desired properties sought to be obtained by those skilled in
the art utilizing the teachings disclosed herein.
[0023] The recitation of numerical ranges by endpoints includes all
numbers subsumed within that range (e.g. 1 to 5 includes 1, 1.5, 2,
2.75, 3, 3.80, 4, and 5) and any range within that range.
[0024] The present disclosure describes, inter alia, systems,
devices and methods that may be used to monitor infection in
proximity to an implanted active therapy delivering medical device.
Referring to FIGS. 1 and 2, general representative environments for
implanted active therapy delivering medical devices 1 and
associated devices 20 are shown. Active medical device 1 is
subcutaneously implanted in an abdominal region of a patient. A
distal portion of associated device 20 is intrathecally inserted
into the patient's spinal canal through a lumbar puncture and
advanced rostrally to a desired location (FIG. 1) or epidurally
placed along a suitable location of spinal cord (FIG. 2). Proximal
end of associated device 20 is tunneled subcutaneously to location
of active device 1, where it may be connected to active device 1.
While distal portion of associated device 20 is shown in FIGS. 1
and 2 as being located in or on spinal cord, it will be understood
that associated device 20 may be placed at any location in patient
for which it is desirable to administer therapy generated or
delivered by active medical device 1.
[0025] In the embodiment shown in FIG. 1, active implantable device
1 is an infusion device, and associated device 20 is a catheter.
Catheter 20 is typically a flexible tube with a lumen running from
the proximal end of catheter 20 to one or more delivery regions
that are typically located at the distal portion of catheter 20.
Proximal portion of catheter 20 is connected to infusion device 20.
Distal portion of catheter 20 is positioned at a target location in
the patient to deliver fluid containing therapeutic agent from
infusion device 1 to patient through a delivery region of catheter
20. Infusion device 1, such as Medtronic Inc.'s SynchroMed.TM. II
implantable programmable pump system, includes a reservoir (not
shown) for housing a therapeutic substance and a refill port 45 in
fluid communication with reservoir. The reservoir may be refilled
by percutaneously inserting a needle (not shown) into patient such
that needle enters refill port 45, and fluid containing therapeutic
substance may be delivered into reservoir from needle via refill
port 45. Infusion device 1 shown in FIG. 1 also includes a catheter
access port 30 that is in fluid communication with the catheter 20.
Fluid may be injected into or withdrawn from patient through
catheter 20 via catheter access port 30 by percutaneously inserting
a needle into access port 30. Each entry of needle across patient's
skin to gain access refill port 45 or access port 30 results in the
possibility of infection in proximity to the active medical device
1.
[0026] In the embodiment shown in FIG. 2, active implantable device
1 is an electrical signal generator, such as Medtronic Inc.'s
Restore.TM. Advanced implantable neurostimulator, and associated
devices 20, 20' are a lead extension 20 and lead 20'. Lead 20'
includes one or more electrical contacts (not shown) on its
proximal end portion and one or more electrodes on its distal end
portion 26. The contacts and electrodes are electrically coupled
via wires running through lead 20'. Electrical signals generated by
the signal generator 1 may be delivered to lead 20 through the
contacts and then to the patient through the electrodes. As shown
in FIG. 2, lead 20' may be connected to signal generator 1 through
a lead extension 20. Extension 20 includes one or more contacts at
the proximal and distal end portions that are electrically coupled
through wires running through extension 20. Of course it will be
understood that with some systems lead 20' may be directly
connected to electrical signal generator 1 without use of a lead
extension 20. It will be further understood that more than one lead
20' or lead extension 20 may be employed per signal generator
1.
[0027] While FIGS. 1 and 2 depict systems infusion devices and
electrical signal generators, it will be understood that the
teachings described herein may be applicable to virtually any known
or future developed active implantable therapy delivering medical
device.
[0028] Referring to FIG. 3, alternative locations for implanting a
medical device 1 are shown. As depicted in FIG. 3A, device 1 may be
implanted in the pectoral region 7 of a patient. Alternatively,
device 1 may be implanted in the head of a patient, more
specifically behind the patient's ear (FIG. 3B), in the patient's
abdomen (FIG. 3C) or in the patient's lower back or buttocks (FIG.
3D). Of course, device 1 may be placed in any medically acceptable
location in patient.
[0029] Referring to FIG. 4, an external device 40 in wireless
communication with implantable device 1 is shown. External device
40 may communicate with implantable device 1 through patient's
skin, which is represented by the dashed line in FIG. 4. In various
embodiments implantable device 1 carries out the various infection
monitoring methods, or portions thereof, described herein. In some
other embodiments the combination of implantable device 1 and
external device 40 carry out the various infection monitoring
methods, or portions thereof, described herein. In various
embodiments, where implantable device 1 is a programmable device,
external device 40 may be a programmer device, such as Medtronic
Inc.'s N'Vision.TM. clinician programmer. Of course external device
may be any device capable of wirelessly communicating with
implantable device 1, such as a patient programmer, a computer, a
personal data assistant, or the like. As shown in FIG. 4,
implantable device 1 contains a wireless transmitter or receiver
18, and external device 40 contains a wireless transmitter or
receiver 18 to allow implantable device 1 and external device 40 to
communicate. External device 40 and implantable device 1 may be
capable of one-way (external device 40 to implantable device 1 or
implantable device 1 to external device 40) or two-way
communication.
[0030] Referring to FIG. 5, sensor(s) 50, 50' associated with
implantable active medical device 1 is shown. FIG. 5A is a side
view of a representative active device 1 and associated device 20.
FIG. 5B is a back view of a representative active device 1. One or
more sensor 50, 50' may be located in proximity to device 1; e.g.,
disposed on, in, or near housing 60 of device 1. Sensor 50, 50' may
be any device capable of detecting and transmitting information
regarding an indicator of infection to device 1. If housing 60 is
hermetically sealed, feedthroughs (not shown) may be used to
provide electrical connectivity through housing 60 while
maintaining the hermetic seal. While not shown, it will be
understood that one or more sensor capable of detecting an
indicator of infection may be located on, in, or about accessory
device 20. Examples of physical or chemical stimuli that may serve
as indicators of infection are temperature, impedance, pH, and
biological markers of infection.
[0031] Changes in temperature in proximity to implanted device 1
may be used as an indicator of infection in proximity to device 1.
The temperature of body tissue at a site of infection is generally
greater than that of body tissue at a location removed from the
site of infection. Accordingly, an increase in temperature in
proximity to an implanted medical device 1 may serve as an
indicator of infection. Any suitable sensor 50, 50' capable of
detecting temperature or changes in temperature may be employed.
For example, temperature sensor 50, 50' may include a thermocouple,
a thermistor, a junction-based thermal sensor, a thermopile, a
fiber optic detector, an acoustic temperature sensor, a quartz or
other resonant temperature sensor, a thermo-mechanical temperature
sensor, a thin film resistive element, or the like.
[0032] Changes in impedance of tissue in proximity to implanted
device 1 may be used as an indicator of infection in proximity to
device 1. For example, an increase in fluid in tissue is often
observed at a site of an infection. Accordingly, a decrease in
impedance of tissue in proximity may serve as an indicator of
infection. In the case of impedance measurement, detection or
monitoring, sensors 50, 50' are electrodes. Impedance may be
measured between two electrodes. Current or voltage is applied
between the electrodes with one electrode at any given time serving
as a source and the other serving as a sink. In various
embodiments, electrodes will be positioned at opposing surfaces of
housing 60 of device 1. In other embodiments, one electrode may be
located on accessory device 20, e.g. on a lead, and one may be
located on housing of device 1. Alternatively, one electrode may be
located on accessory device 20 and housing 60 of device 1 may serve
as a return electrode, in a manner similar to unipolar signal
generators. Further, it will be understood that more than one
electrode pair may be employed to monitor impedance.
[0033] In instances where device 1 is an electrical signal
generator, the electrical components used for generating
therapeutic electrical signals may also be used for generating
signals for impedance monitoring. In instances where device 1 is
not an electrical signal generator, e.g. device 1 is an infusion
pump, components capable of generating appropriate electrical
signals for testing impedance of body tissue may be incorporated
into device 1. Any impedance detection components or circuitry may
be employed. For example, an ohm meter or a wheatstone bridge
design may be used to measure or detect changes in impedance or
resistance. Examples of additional suitable components or circuitry
are described in, for example, the following patents and
applications assigned to Medtronic, Inc.: US 2006/0259079; US
2006/0036186; US 2004/0162591; US 2003/0176807; U.S. Pat. No.
5,876,353; U.S. Pat. No. 5,824,029; and U.S. Pat. No.
5,282,840.
[0034] Changes in pH in proximity to implanted device 1 may be used
as an indicator of infection in proximity to device 1. As pH may
serve as a general indicator of the state of a tissue, a change in
pH may be indicative of infection. Accordingly, a sudden or gradual
change in pH in proximity to an implanted medical device 1 may
serve as an indicator of infection. Any suitable sensor 50, 50'
capable of detecting pH or changes in pH may be employed.
[0035] Any biological markers of infection may be detected in
accordance with the teachings presented herein. Non-limiting
examples of biological markers of infection include viral, fungal,
or bacterial proteins or nucleic acids or fragments thereof. As
most infections associated with implantable medical devices appear
to be due to infection due to Staphlococcus aureus, Staphlococcus
epidermis, Pseudomonus auruginosa and Candidia Sp., detection of
proteins, nucleic acids, or fragments thereof of such
microorganisms may be beneficial. Alternatively, detection of
indicators of an immune response may be detected. For example, an
increase in a pro-inflammatory cytokine. Non-limiting examples of
proinflammatory cytokines include tumor necrosis factor (TNF; also
known as TNF.alpha. or cachectin), interleukin (IL)-1.alpha.,
IL-113, IL-2; IL-5, IL-6, IL-8, IL-15, IL-18, interferon .gamma.
(IFN-.gamma.); platelet-activating factor (PAF), thromboxane;
soluble adhesion molecules; vasoactive neuropeptides; phospholipase
A2; plasminogen activator inhibitor (PAI-1); free radical
generation; neopterin; CD14; prostacyclin; neutrophil elastase;
protein kinase; monocyte chemotactic proteins 1 and 2 (MCP-1,
MCP-2); macrophage migration inhibitory factor (MIF), high mobility
group box protein 1 (HMGB-1), and other known factors. Indication
of an immune response may also be detected by an decrease in an
anti-inflammatory cytokine in proximity to device 1. Non-limiting
examples of anti-inflammatory cytokines include IL-4, IL-10, IL-17,
IL-13, IL-1a, and TNF.alpha. receptor. It will be recognized that
some of proinflammatory cytokines may act as anti-inflammatory
cytokines in certain circumstances, and vice-versa. Such cytokines
are typically referred to as plieotropic cytokines. An immune
response may also be detected by measuring changes (baseline versus
after device implant or other event, a first point after device
implant or other event versus a second point after device implant
or other event, etc.) in the presence of other factors involved in
an immune response. Non-limiting examples of such other factors
include TGF, PDGF, VEGF, EGF, FGF, I-CAM, and nitric oxide. In
addition, an immune response may be detected by changes in
chemokines, such as 6cKine and MIP3beta, and chemokine receptors,
including CCR7 receptor. Further, an immune response may be
measured by changes in immune cell population (upregulated
Langerhans cells, dendritic cells, lymphocytes), or immune cell
surface co-stimulatory molecules (Major Histocompatibility, CD80,
CD86, CD28, CD40). An immune response may also be detected by
measuring changes in other factors involved in the inflammatory
cascade, for example in the signal transduction cascades including
factors such as NF.kappa.-B, Egr-1, Smads, toll-like receptors, and
MAP kinases. In addition, an immune response may be detected by a
change in the presence of an exogenous antigen believed to have
caused an inflammatory response, such as, e.g., a bacteria, a
virus, or a fungus.
[0036] Any sensor capable of detecting such biological markers
indicative of infection may be used. In various embodiments, a
biosensor is used to detect the presence of a molecule in proximity
to implanted device 1. Any known or future developed biosensor may
be used. The biosensor may have, e.g., an enzyme, an antibody, a
receptor, or the like operably coupled to, e.g., a suitable
physical transducer capable of converting the biological signal
into an electrical signal. In some situations, receptors or enzymes
that reversibly bind the molecule being detected may be preferred.
In various embodiments, sensor 50, 50' includes an electrode with
an ion selective coating that is capable of directly transducing
the amount of a particular substance. An example of this type of
transducer is described in the paper "Multichannel
semiconductor-based electrodes for in vivo electrochemical and
electrophysiological studies in rat CNS" by Craig G. van Home,
Spencer Bement, Barry J. Hoffer, and Greg A. Gerhardt, published in
Neuroscience Letters, 120 (1990) 249-252. In various embodiments,
sensor 50, 50' may be a sensor as described in, e.g., U.S. Pat. No.
5,978,702, entitled TECHNIQUES OF TREATING EPILEPSY BY BRAIN
STIMULATION AND DRUG INFUSION or U.S. 2005/0209513, entitled
COLLECTING SLEEP QUALITY INFORMATION VIA A MEDICAL DEVICE, filed
Apr. 15, 2004, and published Sep. 22, 2005.
[0037] Modifications of the teachings presented in the above-cited
references may be made to account for one or more biological marker
of infection.
[0038] For certain biological markers, e.g. proteins or nucleic
acids or fragments thereof of microorganisms responsible for
infection, merely the presence of such markers may be indicative of
an infection. For other markers that may be present in a patient
lacking an infection, e.g. cytokines and chemokines, increases or
decreases in the levels of such markers may be indicative of an
infection.
[0039] For the above-discussed indicators of infection or other
indicator of infection, a determination of the presence of
infection in proximity to implanted device 1 may be made in any
suitable fashion. For example, a determination of infection may be
made if a given indicator is detected at, above or below a
predetermined threshold value. For example, if a temperature of
101.degree. F. (38.3 C) is detected, a determination may be made
that an infection is present in proximity to implanted device 1.
Alternatively or in addition, a determination of infection may be
made if a given indicator is detected at, above or below a
predetermined value for a predetermined period of time. For
example, if a temperature of 100.degree. F. (37.8 C) or greater is
detected for two hours or more is detected for two hours or more, a
determination may be made that an infection is present in proximity
to implanted device 1. Of course other types of trends in
information regarding indicators of infection may be used
advantageously to improve the accuracy of determinations of
infections in proximity to an implanted medical device. Additional
information regarding use of thresholds determining infection in
proximity to an implantable medical device is provided in U.S.
patent application Ser. No. ______, entitled "Indicator Metrics For
Infection Monitoring", filed on even date herewith, naming Martin
Gerber and John Rondoni as inventors, and having P0028530.00 as an
attorney docket number, which application is hereby incorporated
herein by reference in its entirety to the extent it does not
conflict with the disclosure presented herein.
[0040] For the above-discussed indicators of infection or other
indicator of infection, it may be desirable to compare levels of
the indicators at a location in proximity to device 1 and at a
location removed from device. Such comparisons may allow for a
reduction in false positive detections. For example, elevation in
temperature in proximity to device 1 may be due to localized
infection or may be due to increased activity of the patient;
increases in inflammatory cytokines in proximity to the device may
be due to localized infection or a more general immune response;
etc. By comparing the level of an indicator of infection in
proximity to an implanted device to the level at a location removed
from the device, a more accurate determination of whether an
infection is present in proximity to the device may be made.
Additional information regarding monitoring an indicator of
infection at two locations is provided in U.S. patent application
Ser. No. ______, entitled "Implantable Therapy Delivery System
Having Multiple Temperature Sensors", filed on even date herewith,
naming Martin Gerber and John Rondoni as inventors, and having
P0028539.00 as an attorney docket number, which application is
hereby incorporated herein by reference in its entirety to the
extent it does not conflict with the disclosure presented
herein.
[0041] Information regarding a first indicator of infection may be
used to determine whether an infection is present in proximity to
the implanted device 1. In addition, one or more second indicators
of infection may be used to determine whether the indication based
on the first indicator is accurate. Additional information
regarding infection monitoring using two or more indicators of
infection is provided in U.S. patent application Ser. No. ______,
entitled "Multi-Parameter Infection Monitoring", filed on even date
herewith, naming Martin Gerber and John Rondoni as inventors, and
having P0028531.00 as an attorney docket number, which application
is hereby incorporated herein by reference in its entirety to the
extent it does not conflict with the disclosure presented
herein.
[0042] Referring to FIG. 6, some representative electronic
components of an implantable medical device 1 according to various
embodiments are shown in block form. Active implantable medical
device 1 as depicted in the embodiment shown in FIG. 6 includes a
clock 100, a processor 110, a memory 120, a therapy output or
delivery component 130, a telemetry component 140, a sensor 150, a
power management module 160, a power source 170, an alert module
185, and a system reset module 190. Other components of active
implantable medical device 1 can include, e.g., a diagnostics
module (not shown). All components except the power source 170 can
be configured on one or more Application Specific Integrated
Circuits (ASICs) or may be one or more discrete components, or a
combination of both. Also, all components, except the clock and
power source are connected to bidirectional data bus 180 that is
non-multiplexed with separate address and data lines.
[0043] Processor 110 may be synchronous and typically operates on
low power, such as Motorola 68HC11 synthesized core operating with
a compatible instruction set. Clock 100 counts the number of
seconds since a fixed date for date/time stamping of events and may
be used for therapy control. Memory 120 includes memory sufficient
for operation of device 1, such as volatile Random Access Memory
(RAM) for example static RAM, nonvolatile Read Only Memory (ROM),
Electrically Erasable Programmable Read Only Memory (EEPROM) for
example Flash EEPROM, and register arrays configured on ASICs.
Direct Memory Access (DMA) is available to selected modules such as
telemetry module 140 or sensor module 150, so that the selected
modules can request control of data bus 180 and write data directly
to memory 120 bypassing processor 110. System Reset 190 controls
operation of ASICs and modules during power-up of device 1, so
ASICs and modules registers can be loaded and brought on-line in a
stable condition.
[0044] Telemetry 140 module or other wireless module provides for
communication between implantable device 1 and external device 40
such as a programmer. Communication may be bi-directional.
Telemetry module 140 generally includes a telemetry antenna, a
receiver 18 (see, e.g., FIG. 4), a transmitter 48 (see, e.g., FIG.
4), and a telemetry processor. Telemetry modules are generally
known in the art and are further detailed in U.S. Pat. No.
5,752,977, entitled "Efficient High Data Rate Telemetry Format For
Implanted Medical Device" issued to Grevious et al. (May 19, 1998).
While module 140 is referred to herein as "telemetry" module, it
will be understood that other forms of wireless communication may
readily be substituted where appropriate for telemetry. Examples of
forms of wireless communication include Bluetooth.RTM., 802.11, and
Medical Implant Communication Service (MICS) frequency band
communication.
[0045] Therapy module 130 refers to components for carrying out the
delivery or generation of therapeutic output to be delivered to a
patient from active device 1. One of skill in the art will
appreciate that the components may vary on a device-by-device basis
and a therapy-by-therapy basis. For example, therapy module 130 may
contain an oscillator if device 1 is an electrical signal generator
and may contain a pumping mechanism if device 1 is an infusion
device.
[0046] Sensor module 150 includes circuitry associated with one or
more sensors 50, 50' and may include other components for
transmitting sensed information from sensor 50, 50' to, e.g.,
processor 110 or memory 120. Sensor module 150 or other components
of device 1 may include one or more analog to digital converters to
convert analog signals generated by sensor 50 into digital signals
usable by processor 110, as well as suitable filter and amplifier
circuitry.
[0047] Alert module 185 may issue an alert, e.g. an audible alert
or tactile alert, such as a vibration. An alert may be issued if
information indicative of an infection is detected. The alert will
serve to prompt the patient to seek medical attention.
[0048] While not shown, device 1 may be rechargeable and include a
recharge module. Additional information regarding rechargeable
implantable medical devices and infection monitoring is provided in
U.S. patent application Ser. No. ______, entitled "CONTROLLING
TEMPERATURE DURING RECHARGE FOR TREATMENT OF A CONDITION", filed on
even date herewith, naming Martin Gerber and John Rondoni as
inventors, and having attorney docket number P0028540.00, which
application is hereby incorporated herein by reference in its
entirety to the extent that it does not conflict with the
disclosure presented herein.
[0049] It will be understood that the components described in FIGS.
1-6 are but examples of components that an implantable device 1 may
have and that many other device or system configurations may be
employed to carry out the methods described below. However, for the
sake of convenience, the discussion that follows with regard to the
method illustrated in the flow diagram of FIG. 7 will refer to
components as described with regard to FIGS. 1-6.
[0050] Referring to FIG. 7, a flow diagram of a representative
method is shown. According to various embodiments, a method
includes monitoring an indicator of infection in proximity to an
implantable medical device 1 (500) and providing the monitored
information to the implanted device 1 (510). For example a sensor
50, 50' located in proximity to the device 1 may be operably
coupled to electronics of the device 1 so that information detected
by sensor 50, 50' is transmitted to electronics. The information
may be used by processor 110, stored in memory 120, or the like.
The method further includes determining whether the information
regarding the indicator of infection is indicative of infection in
proximity to device 1 (520). The determination (520) may be made
within device 1, e.g. by processor 110 or detection circuit (not
shown), or may be made by external device 40. Monitored information
may be provided to external device 40 via telemetry module 140. If
it is determined that the monitored indicator is not indicative of
an infection, the indicator may continued to be monitored (500). If
the monitored information is indicative of an infection, an alert
may be provided to the patient (530). The alert may include a
sensory indication, such as an audible indication or a tactile
indication, such as a vibration, or visual indication. A visual
indication may include, for example, text or an image. The alert
may be issued by implanted device 1, e.g. by activation of an
alarm, or an external device 40, such as a programmer. If the
indication is visual, the alert will be presented to the patient or
clinician by an external device. While not shown, it will be
understood that monitoring of the indicator of infection (500) may
continue following an alert being issued (530).
[0051] FIGS. 8A-C are block diagrams of representative devices or
systems. It will be understood that one or more components
described with regard to FIGS. 1-6 may be included or carry out a
function of one or more modules described in FIGS. 8A-C. As shown
in FIGS. 8A-C, a system or device suitable for carrying out methods
as discussed with regard to FIG. 7 may include a sensor module 630,
a determination module 640, and an alert module 650. Determination
module 640 may make a determination as to whether information from
sensor module 630 is indicative of an infection (520). If the
sensed information is indicative of infection, alert module 650 may
provide an alert (530). As shown in FIG. 8A, all of the components
may be included within an implantable medical device 1.
Alternatively, some of the components may be included in an
external device 40 as shown in FIGS. 8B-C. Thus, as shown in FIG.
8B, alert module 650 may be included in an external device 40. In
the embodiment shown in FIG. 8C, determination module 640 and alert
module 650 may be included in an external device 40. Of course, a
variety of other distributions of modules between an implantable
medical device and an external device are possible.
[0052] One of skill in the art will understand that components or
steps described herein regarding a given embodiment or set of
embodiments may readily be omitted, substituted, or added from,
with, or to components or steps of other embodiments or sets of
embodiments, as appropriate or desirable.
[0053] It will be further understood that a computer readable
medium containing instructions that when implemented cause an
implantable medical device (or system including an implantable
medical device) to perform the methods described herein are
contemplated. In an embodiment, the computer readable medium
contains instructions that when implemented cause an implantable
medical device to (i) monitor an indicator of infection in
proximity to the implanted active therapy delivering medical
device; and (ii) determine whether the information regarding the
monitored indicator is indicative of infection in proximity to the
implanted medical device.
[0054] Devices including computer readable medium are also
contemplated. In an embodiment, an active implantable therapy
delivering medical device includes a hermetically sealed housing, a
power source disposed in the housing, and electronics disposed in
the housing. The electronics are operably coupled to the power
source and are capable of controlling therapeutic output from the
device. The device further includes a sensor located in proximity
to the housing. The sensor is operably coupled to the electronics
and is capable of detecting information regarding an indicator of
infection and transmitting the information to the electronics. The
device also includes a computer readable medium containing
instructions that when implemented by the electronics cause the
device to determine whether the information is indicative of
infection.
[0055] Systems including computer readable medium are also
contemplated. In an embodiment, a system includes an active
implantable therapy delivering medical device and a second device.
The active implantable therapy delivering medical device includes a
hermetically sealed housing, a power source disposed in the
housing, and first electronics disposed in the housing. The first
electronics are operably coupled to the power source and are
capable of controlling therapeutic output from the active
implantable therapy delivering device. The active implantable
therapy delivering medical device further includes a sensor located
in proximity to the housing. The sensor is being operably coupled
to the electronics and capable of detecting information regarding
an indicator of infection and transmitting the information to the
electronics. The device also includes a wireless transmitter
operably coupled to the electronics. The wireless transmitter is
capable of transmitting the information regarding the indicator of
infection. The second device includes second electronics, and a
wireless receiver operably coupled to the electronics. The wireless
receiver is capable of receiving the information regarding the
indicator of infection from the active implantable medical device.
The second device further includes a computer readable medium
containing instructions that when implemented by the second
electronics cause the second device to determine whether the
information is indicative of infection in proximity to the active
implantable therapy delivering medical device.
[0056] In addition, the principles of the methods, systems and
devices described herein may be used for detecting various other
potential adverse health issues associated with an implantable
medical device. For example, temperature, pH, impedance, and
various indicators of infection may also be used to determine
whether a hematoma, edema, or seroma is present in proximity to an
implanted device. Accordingly, monitoring of such other potential
adverse health issues is within the scope of the present
disclosure.
[0057] Patent applications directed to infection monitoring that
may provide additional insight into the teachings provided herein
include the following patent applications filed on even date
herewith: (i) U.S. patent application Ser. No. ______, entitled
"Infection Monitoring", naming Martin Gerber and John Rondoni as
inventors, and having P0028529.00 as an attorney docket number;
(ii) U.S. patent application Ser. No. ______, entitled "Refined
Infection Monitoring", naming Martin Gerber and John Rondoni as
inventors, and having P0028541.00 as an attorney docket number; and
(iii) U.S. patent application Ser. No. ______, entitled "Event
Triggered Infection Monitoring", naming Martin Gerber and John
Rondoni as inventors, and having P0028528.00 as an attorney docket
number. Each of the above-referenced patent applications is hereby
incorporated herein by reference in their respective entireties to
the extent that they do not conflict with the disclosure presented
herein.
[0058] Thus, embodiments of the INFECTION MONITORING are disclosed.
One skilled in the art will appreciate that the present invention
can be practiced with embodiments other than those disclosed. The
disclosed embodiments are presented for purposes of illustration
and not limitation, and the present invention is limited only by
the claims that follow.
* * * * *