U.S. patent application number 10/920568 was filed with the patent office on 2005-04-14 for medical event logbook system and method.
Invention is credited to Hartley, Jesse W., Hatlestad, John D., Lee, Kent, Ni, Quan, Stahmann, Jeffrey E..
Application Number | 20050080348 10/920568 |
Document ID | / |
Family ID | 34425953 |
Filed Date | 2005-04-14 |
United States Patent
Application |
20050080348 |
Kind Code |
A1 |
Stahmann, Jeffrey E. ; et
al. |
April 14, 2005 |
Medical event logbook system and method
Abstract
An event-based approach to collecting and organizing information
associated with events affecting respiration is presented. The
detection or prediction of an event affecting the respiration of a
patient initiates acquisition of information associated with the
event. The respiratory logbook system acquires information with the
event during the event and during intervals proximate in time to
the event. The information is organized as a respiratory log entry.
The user can access the information by operating a user interface.
The information may be presented in textual or graphical form.
Inventors: |
Stahmann, Jeffrey E.;
(Ramsey, MN) ; Hatlestad, John D.; (Maplewood,
MN) ; Hartley, Jesse W.; (Lino Lakes, MN) ;
Ni, Quan; (Shoreview, MN) ; Lee, Kent;
(Shoreview, MN) |
Correspondence
Address: |
Crawford Maunu PLLC
Suite 390
1270 Northland Drive
St. Paul
MN
55120
US
|
Family ID: |
34425953 |
Appl. No.: |
10/920568 |
Filed: |
August 17, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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60504749 |
Sep 18, 2003 |
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Current U.S.
Class: |
600/529 ;
600/484 |
Current CPC
Class: |
A61N 1/3601 20130101;
A61B 5/02405 20130101; A61B 5/0803 20130101 |
Class at
Publication: |
600/529 ;
600/484 |
International
Class: |
A61B 005/08 |
Claims
What is claimed is:
1. A method for organizing medical information, comprising:
detecting or predicting a respiratory event of a patient;
initiating, responsive to the detection or prediction of the
respiratory event, collection of medical information associated
with the respiratory event; collecting the medical information
associated with the respiratory event; and organizing the medical
information as a respiratory event log entry, wherein at least one
of detecting or predicting, initiating, collecting, and organizing
is performed at least in part implantably.
2. The method of claim 1, wherein collecting the medical
information associated with the respiratory event comprises
collecting the medical information during the respiratory
event.
3. The method of claim 1, wherein collecting the medical
information associated with the respiratory event comprises
collecting the medical information proximate in time to the
respiratory event.
4. The method of claim 1, wherein at least one of detecting or
predicting the respiratory event, initiating the collecting of
medical information, collecting the medical information, and
organizing the medical information is performed at least in part
implantably.
5. The method of claim 1, wherein detecting or predicting the
respiratory event comprises detecting or predicting the respiratory
event based on physiological conditions affecting the patient.
6. The method of claim 1, wherein detecting or predicting the
respiratory event comprises detecting or predicting the respiratory
event based on non-physiological conditions affecting the
patient.
7. The method of claim 1, wherein detecting or predicting the
respiratory event comprises detecting or predicting a disordered
breathing event.
8. The method of claim 1, wherein detecting or predicting the
respiratory event comprises detecting or predicting a presence of a
non-rhythm pulmonary disease.
9. The method of claim 1, wherein collecting the medical
information associated with the respiratory event comprises
collecting respiratory information.
10. The method of claim 1, wherein collecting the medical
information associated with the respiratory event comprises
collecting cardiac information.
11. The method of claim 1, wherein organizing the information as
the respiratory log entry comprises organizing the information as
one of a group of respiratory log entries of a respiratory
logbook.
12. The method of claim 11, wherein the group of respiratory log
entries are organized chronologically.
13. The method of claim 11, wherein the group of respiratory log
entries are organized by event type.
14. The method of claim 1, further comprising storing the organized
information.
15. The method of claim 1, further comprising transmitting at least
one of the collected information and the organized information.
16. The method of claim 1, further comprising displaying the
organized information.
17. A respiratory event logbook system, comprising: an event
detector configured to detect or predict a respiratory event
affecting the patient; a data acquisition unit, coupled to the
event detector, and configured to collect medical information
associated with the respiratory event responsive to the detection
or prediction of the respiratory event; and a processor, coupled to
the data acquisition unit, and configured to organize the collected
medical information associated with the respiratory event as a
respiratory event log entry, wherein at least one of the event
detector, the data acquisition unit, and the processor includes an
implantable component.
18. The system of claim 17, wherein at least one of the event
detector, the data acquisition unit, and the processor comprises an
implantable component.
19. The system of claim 17, wherein the respiratory event comprises
a disordered breathing event.
20. The system of claim 17, wherein the respiratory event comprises
a non-rhythm pulmonary event.
21. The system of claim 17, wherein the medical information
comprises respiratory information.
22. The system of claim 17, wherein the medical information
comprises cardiac information.
23. The system of claim 17, wherein: the data acquisition unit
comprises a temporary buffer configured to temporarily store the a
portion of the medical information associated with the respiratory
event; and further comprising a memory configured for long term
storage of the medical information associated with the respiratory
event.
24. The system of claim 17, wherein the processor is configured to
organize medical information associated with a plurality of
respiratory events as a respiratory event logbook.
25. The system of claim 24, further comprising a user interface
coupled to the processor and configured to provide access to the
respiratory event logbook.
26. The system of claim 25, wherein the user interface comprises a
display configured to display information associated with the
plurality of respiratory events.
27. The system of claim 25, wherein the user interface comprises an
input mechanism configured to select one or more of the plurality
of respiratory events.
28. The system of claim 25, wherein the user interface is
configured to display a menu of one or more of the plurality of
respiratory events.
29. The system of claim 25, wherein: the processor is configured to
generate summary information associated with one or more of the
plurality of respiratory events; and the user interface is
configured to display the summary information.
30. The system of claim 25, wherein the user interface is
configured to display graphical information.
31. The system of claim 25, wherein the user interface is
configured to display textual information.
32. A system for organizing information associated with respiratory
events, comprising: means for detecting or predicting a respiratory
event of the patient; means for initiating, responsive to the
detection or prediction of the respiratory event, collection of
medical information associated with the respiratory event; means
for collecting the medical information associated with the
respiratory event; and means for organizing the collected medical
information as a respiratory event log entry, wherein at least one
of the means for detecting, the means for predicting, the means for
initiating, the means for collecting, and the means for organizing
includes an implantable component.
33. The system of claim 32, further comprising means for collecting
the medical information during the respiratory event.
34. The system of claim 32, further comprising means for collecting
the medical information proximate in time to the respiratory
event.
35. The system of claim 32, further comprising means for detecting
or predicting a disordered breathing event.
36. The system of claim 32, further comprising means for detecting
or predicting a presence of a non-rhythm pulmonary disease.
37. The system of claim 32, further comprising means for organizing
the information as one of a group of respiratory log entries of a
respiratory logbook.
38. The system of claim 37, further comprising means for accessing
the respiratory logbook.
Description
RELATED PATENT DOCUMENTS
[0001] This application claims the benefit of Provisional Patent
Application Ser. No. 60/504,749, filed on Sep. 18, 2003, to which
priority is claimed pursuant to 35 U.S.C. .sctn.119(e) and which is
hereby incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to acquiring and organizing
information related to medical events affecting the patient.
BACKGROUND OF THE INVENTION
[0003] The human body functions through a number of interdependent
physiological systems controlled through various mechanical,
electrical, and chemical processes. The metabolic state of the body
is constantly changing. For example, as exercise level increases,
the body consumes more oxygen and gives off more carbon dioxide.
The cardiac and pulmonary systems maintain appropriate blood gas
levels by making adjustments that bring more oxygen into the system
and dispel more carbon dioxide. The cardiovascular system
transports blood gases to and from the body tissues. The
respiratory system, through the breathing mechanism, performs the
function of exchanging these gases with the external environment.
Together, the cardiac and respiratory systems form a larger
anatomical and functional unit denoted the cardiopulmonary
system.
[0004] Various disorders may affect the cardiovascular,
respiratory, and other physiological systems. For example, heart
failure is a clinical syndrome that impacts a number of
physiological processes. Heart failure is an abnormality of cardiac
function that causes cardiac output to fall below a level adequate
to meet the metabolic demand of peripheral tissues and internal
organs. Heart failure is often referred to as congestive heart
failure (CHF) due to the accompanying venous and pulmonary
congestion. Congestive heart failure may have a variety of
underlying causes, including ischemic heart disease (coronary
artery disease), hypertension (high blood pressure), and diabetes,
among others.
[0005] There are a number of diseases and disorders that primarily
affect respiration, but also impact other physiological systems.
Emphysema and chronic bronchitis are grouped together and are known
as chronic obstructive pulmonary disease (COPD). Pulmonary system
disease also includes tuberculosis, sarcoidosis, lung cancer,
occupation-related lung disease, bacterial and viral infections,
and other conditions.
[0006] Chronic obstructive pulmonary disease generally develops
over many years, typically from exposure to cigarette smoke,
pollution, or other irritants. Over time, the elasticity of the
lung tissue is lost, and the lungs become distended, unable to
expand and contract normally. As the disease progresses, breathing
becomes labored, and the patient grows progressively weaker. Other
types of non-rhythm related pulmonary diseases or disorders include
restrictive pulmonary diseases, infections pulmonary diseases,
diseases of the pleural cavity, and pulmonary vasculature, for
example.
[0007] Breathing disorders include various forms of rhythm-related
disorders such as sleep apnea and hypopnea, among other forms.
Disordered breathing is a respiratory system condition that affects
a significant percentage of patients between 30 and 60 years.
Disordered breathing, including apnea and hypopnea, may be caused,
for example, by an obstructed airway, or by derangement of the
signals from the brain controlling respiration. Disordered
breathing occurs when a patient experiences insufficient
respiration with or without respiratory effort. Disordered
breathing can originate from a deficiency in the central nervous
system (central disordered breathing) or from an obstructed airway
(obstructive disordered breathing). Lack of respiratory effort may
result from a disruption of signals from the central nervous system
to the respiratory muscles.
[0008] Central disordered breathing events are characterized by
insufficient respiration and a concurrent lack of respiratory
effort. Because the central nervous system signals that control
breathing are interrupted, the patient's natural breathing reflex
is not triggered. The patient makes no effort to breath or the
respiratory effort is otherwise disrupted. Respiration ceases or is
insufficient during the disordered breathing event.
[0009] An obstructive disordered breathing event may occur due to
an obstruction of a patient's airway. For example, the patient's
the tongue or other soft tissue of the throat may collapse into the
patient's airway. The breathing reflex is triggered, but
respiration is disrupted because of the occluded airway. Disordered
breathing events may include central disordered breathing events,
obstructive disordered breathing events, or mixed disordered
breathing events that are a combination of obstructive and central
types.
[0010] Sleep disordered breathing is particularly prevalent and is
associated with excessive daytime sleepiness, systemic
hypertension, increased risk of stroke, angina and myocardial
infarction. Disordered breathing can be particularly serious for
patients concurrently suffering from cardiovascular
deficiencies.
[0011] Various types of disordered respiration have been
identified, including, apnea (interrupted breathing), hypopnea
(shallow breathing), tachypnea (rapid breathing), hyperpnea (heavy
breathing), and dyspnea (labored breathing). Combinations of the
respiratory cycles described above may be observed, including, for
example, periodic breathing and Cheyne-Stokes respiration (CSR).
Cheyne-Stokes respiration is particularly prevalent among heart
failure patients, and may contribute to the progression of heart
failure.
[0012] Because of the complex interactions between the
cardiovascular, pulmonary, and other physiological systems as well
as the need for early detection of various disorders, an effective
approach to acquiring and organizing information related to
respiratory events is desired. The present invention fulfills these
and other needs, and addresses other deficiencies of prior art
implementations and techniques
SUMMARY OF THE INVENTION
[0013] Embodiments of the invention relate to acquiring and
organizing information related to medical events affecting the
patient. One embodiment of the invention involves a method for
organizing medical information. The method involves detecting or
predicting a respiratory event of a patient. Responsive to the
detection or prediction of the respiratory event, collection of
medical information associated with the respiratory event is
initiated. The medical information is collected and organized as a
respiratory event log entry. At least one of detecting or
predicting the respiratory event, collecting the medical
information and organizing the medical information is performed
implantably.
[0014] In accordance with another embodiment of the invention, a
method for accessing medical information involves collecting
medical information associated with respiratory events. The
collection of medical information associated with respiratory
events includes initiating, responsive to the detection or
prediction of the respiratory event, collection of medical
information associated with each respiratory event. The medical
information is collected and organized a respiratory logbook. A
user interface is provided for accessing the respiratory logbook.
At least one of detecting or predicting the respiratory event,
collecting the medical information and organizing the medical
information is performed implantably.
[0015] Another embodiment of the invention involves a method for
organizing respiratory information associated with medical events.
Responsive to the detection and/or prediction of a medical event,
the system initiates collection of respiratory information
associated with the medical event. The respiratory information is
collected and organized as a medical event log entry. At least one
of detecting or predicting the medical event, collecting the
respiratory information and organizing the respiratory information
is performed implantably.
[0016] In accordance with a further embodiment of the invention, a
method for accessing respiratory information associated with
medical events of a patent involves collecting and organizing
respiratory information associated with medical events. Collection
of the respiratory information is implemented by initiating,
responsive to the detection or prediction of a medical event,
collection of respiratory information associated with each medical
event. The respiratory information is collected and organized in a
medical event logbook. A user interface provides access to the
medical event logbook. At least one of detecting or predicting the
medical event, collecting the respiratory information and
organizing the respiratory information is performed
implantably.
[0017] Yet another embodiment involves a method for organizing
medical event information. According to this method, a medical
event is predicted. The system collects information associated with
conditions affecting the patient prior to the occurrence of the
medical event. The medical event is detected, and the system
collects information during the medical event. The collected
information is organized as a medical event log entry. At least one
of detecting the medical event, predicting the medical event,
collecting the respiratory information and organizing the
respiratory information is performed implantably. In accordance
with another embodiment of the invention, a medical event logbook
system includes an event detector configured to detect or predict a
medical event. A data acquisition unit is coupled to the event
detector and is configured to collect, responsive to the detection
or prediction of the medical event, respiratory information
associated with the medical event. The system also includes
processor configured to organize the acquired respiratory
information as a medical event log entry. At least one of the event
detector, the data acquisition unit, and the processor includes an
implantable component.
[0018] In accordance with a further embodiment, a respiratory event
logbook system includes an event detector configured to detect or
predict a respiratory event affecting the patient. A data
acquisition unit is coupled to the event detector and is configured
to collect medical information associated with the respiratory
event responsive to the detection or prediction of the respiratory
event. The system includes a processor configured to organize the
collected medical information associated with the respiratory event
as a respiratory event log entry. At least one of the event
detector, the data acquisition unit, and the processor includes an
implantable component.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIGS. 1A-1C are flowcharts of methods for acquiring and
organizing information as event log entries in accordance with
embodiments of the invention;
[0020] FIG. 2 is a block diagram of a respiratory logbook system in
accordance with embodiments of the invention;
[0021] FIG. 3 illustrates an exemplary depiction of a user
interface display that may be used with a respiratory logbook
system in accordance with embodiments of the invention;
[0022] FIG. 4 is a block diagram of a medical system that may be
used to implement a respiratory logbook system in accordance with
embodiments of the invention;
[0023] FIG. 5 is a partial view of an implantable device that may
include circuitry for implementing a respiratory logbook in
accordance with embodiments of the invention;
[0024] FIG. 6 is a graph illustrating a respiration waveform that
may be acquired and organized as a portion of a respiratory log
entry in accordance with embodiments of the invention;
[0025] FIG. 7 is a diagram illustrating an implantable
transthoracic cardiac device that may be used in connection with
acquiring and organizing data for a respiratory logbook in
accordance with embodiments of the invention;
[0026] FIG. 8 is a block diagram illustrating a medical system
including a patient-internal device cooperating with a
patient-external device to acquire and organize information in a
respiratory logbook in accordance with embodiments of the
invention;
[0027] FIG. 9A provides a timing diagram illustrating the
acquisition of respiration logbook information for a detected event
affecting respiration in accordance with embodiments of the
invention;
[0028] FIG. 9B provides a timing diagram illustrating the
acquisition of respiratory logbook information for a predicted
event affecting respiration in accordance with embodiments of the
invention;
[0029] FIG. 10A illustrates a marked respiratory waveform in
accordance with embodiments of the invention; and
[0030] FIG. 10B illustrates a marked respiration waveform that is
time aligned with an electrocardiogram (ECG) graph in accordance
with embodiments of the invention.
[0031] While the invention is amenable to various modifications and
alternative forms, specifics thereof have been shown by way of
example in the drawings and will be described in detail below. It
is to be understood, however, that the intention is not to limit
the invention to the particular embodiments described. On the
contrary, the invention is intended to cover all modifications,
equivalents, and alternatives falling within the scope of the
invention as defined by the appended claims.
DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS
[0032] In the following description of the illustrated embodiments,
references are made to the accompanying drawings that form a part
hereof, and in which is shown by way of illustration, various
embodiments in which the invention may be practiced. It is to be
understood that other embodiments may be utilized and structural
and functional changes may be made without departing from the scope
of the present invention.
[0033] Early detection and diagnosis of various types of diseases
and syndromes may enhance the likelihood of successful treatment.
However, the onset of some types of medical disorders may be very
gradual and/or occur in discrete episodes, or at times that are
inconvenient for collecting data, making early detection more
difficult. Early diagnosis may depend on the recognition of changes
in various physiological conditions that may not be apparent during
yearly or even monthly check-ups.
[0034] In one example, breathing rhythm disorders often are present
only while the patient is asleep. Sleep disordered breathing
assessments depend upon acquiring data while the patient is asleep.
Diagnosis of sleep disorders typically involves the use of a
polysomnographic sleep study performed at a dedicated sleep
facility. However, such studies are costly, inconvenient to the
patient, and may not accurately represent the patient's typical
sleep behavior.
[0035] In a polysomnographic sleep study, the patient is
instrumented for data acquisition and observed by trained
personnel. Assessment of sleep disordered breathing in a laboratory
setting presents a number of obstacles to acquiring an accurate
picture of events occurring during sleep. For example, spending a
night in a sleep laboratory typically causes a patient to
experience a condition known as "first night syndrome," involving
disrupted sleep during the first few nights in an unfamiliar
location. In addition, sleeping while instrumented and observed may
not result in a realistic perspective of the patient's normal sleep
patterns.
[0036] Many types of medical events occur in discrete episodes.
Periodic monitoring of patient information may not be the most
effective way to collect data related to discrete events. Due to
the transient nature of events, collecting a snapshot of patient
information on a daily or weekly basis, or according to another
time schedule, may not always capture event information. Continuous
monitoring allows detection of aperiodic or infrequent events.
However, the amount of memory required for storing patient
information on a substantially continuous basis may be
prohibitive.
[0037] Embodiments of the invention are directed to an event-based
approach to storing and organizing information associated with
medical and/or respiratory events. A logbook entry includes
information, e.g., respiratory and/or medical information, acquired
during time intervals surrounding an event. In one aspect of the
invention, respiratory information collected in response to a
medical event is organized as a medical event log entry. In another
aspect of the invention, medical information collected in response
to a respiratory event is organized as a respiratory event log
entry.
[0038] A number of logbook entries form a logbook that may be
accessed by the user through a user interface. The processes
described herein enhance the ability to acquire and store
information about discrete events. Further, the event logbook
format provides an intuitive approach for organizing and presenting
the information to patients or physicians.
[0039] FIG. 1A is a flowchart illustrating a method of acquiring
and organizing respiratory information collected in response to a
medical event. The medical event may involve various types of
events affecting one or more of the respiratory system,
cardiovascular system, nervous system, muscle systems, and/or other
physiological systems or combinations of physiological systems of
the patient. The system implementing the method may be programmable
to detect or predict a particular type of event, for example, a
cardiac event, such as cardiac arrhythmia or an ectopic beat. The
system may collect information about one or more respiratory
parameters during, before and/or after the medical event.
[0040] In response to the detection or prediction 112 of the
medical event, collection 114 of respiratory information for the
medical event logbook entry is initiated. In some embodiments, the
respiratory information is collected 116 during the event. In other
embodiments, the respiratory information is collected 116 during
the event and during a time period proximate to the event.
Information may be collected during the event, during a period of
time preceding the event, and/or during a period of time following
the event. In some embodiments, the information may be collected
prior to the prediction or detection of the event.
[0041] To facilitate collection of respiratory information
preceding the prediction or detection of the event, respiratory
conditions may be monitored, e.g., on a continuous or periodic
basis, and stored in a temporary buffer. Temporary storage is
required to provide information prior to the event prediction or
detection, e.g., onset data. The size of the temporary storage
buffer may vary according to the medical events for which onset
data is desired. Due to the varied nature of onset data
requirements and the reality of limited storage in the system, the
system may allow different onset data lengths and different
sampling rates for the temporarily stored data. In the preferred
embodiment the system would use a circular buffer to store the
temporary data such that the oldest data is replaced by the newest
data.
[0042] Once initiated, collection of respiratory information, which
may involve storage of the information in long term memory, may be
performed on a substantially continuous basis, or it may be
performed periodically. Long term storage of data acquired
periodically may be beneficial when the event is relatively
prolonged, such an in the case of a disease or disorder that may
linger for several days or weeks. The type of data collected, data
collection frequency, and/or data collection intervals may be
selectable by the user. Further, the system may be programmable to
use different data collection regimens under different conditions
over the course of the event. For example, the system may be
programmable to collect data more frequently during sleep or during
particular stages of the disease progression, for example. The
system may be programmed to collect data on a continuous basis
during some time intervals, and periodically during other time
intervals, for example.
[0043] Collecting information preceding the event facilitates
enhanced identification of conditions that may be used to detect or
predict the occurrence of future events. For example, acquiring
information preceding a medical event allows for the identification
and assessment of physiological conditions present immediately
before and leading up to the medical event. The identification of
precursor conditions for medical events may facilitate increased
sensitivity and/or accuracy in detecting or predicting occurrences
of the future events.
[0044] The acquired respiratory information is organized 118 as a
medical event log entry. A medical event logbook may comprise a
number of entries, each entry corresponding to a separate medical
event. The medical events represented in the medical event logbook
may comprise, for example, cardiovascular system events, nervous
system events, respiratory system events, or any other medical
events affecting the patient. The event entries included in medical
event log may be organized according to various categories,
including for example, event type, event time/date, order of
occurrence of the event, therapy provided to treat the event, among
other categories. The selection of categories used to organize the
information may be programmable by the user. The organized
information may be stored in long term memory, displayed, printed,
and/or transmitted to a separate device. In one approach, the
medical event comprises a cardiac event. Respiratory information
collected before, during and/or after the cardiac event may be
stored as a log entry in a cardiac arrhythmia logbook, for
example.
[0045] In one embodiment of the invention, the collected
information for the events is optionally accessible 120 through an
interactive user interface. Selection of events to the accessed may
involve a hierarchical selection menu, or other selection method,
for example. In one implementation, the user may select a log entry
from the menu by activating an input mechanism. Upon selection of
the log entry, the user interface may provide graphical or textual
depictions of the collected respiratory information associated with
the medical event.
[0046] FIG. 1B is a flow chart for an embodiment involving
collecting medical information associated with a respiratory event.
The respiratory event may be detected or predicted 122. The event
may include any detectable or predictable respiratory event, such
as disordered breathing (apnea, hypopnea, tachypnea), coughing
and/or breathing irregularities associated with pulmonary diseases
and disorders such as asthma, pulmonary edema, chronic obstructive
pulmonary disease, and/or pleural effusion, among others.
[0047] In response to the detection or prediction 122 of the
respiratory event, collection 124 of medical information for the
respiratory event logbook entry is initiated. The medical
information may be collected 124 during the event and/or during a
time period proximate to the event. Information may be collected
during the event, during a period of time preceding the event,
and/or during a period of time following the event. In some
embodiments, the information may be collected prior to the
prediction or detection of the respiratory event.
[0048] To facilitate collection of medical information preceding
the prediction or detection of the respiratory event, the medical
information may be monitored, e.g., on a continuous or periodic
basis, and stored in a temporary buffer. Temporary storage is
required to provide information prior to the event prediction or
detection, e.g., onset data. The duration of the temporary storage
may vary according to the respiratory events for which onset data
is desired. For example, temporary storage of about one minute may
be sufficient to understand onset conditions for an obstructive an
apnea event whereas temporary storage of about one day may be
required to understand onset conditions for an asthma event.
[0049] Due to the varied nature of onset data requirements and the
reality of limited storage in the system, the system may allow
different onset data lengths and different sampling rates for the
temporarily stored data. In a preferred embodiment, the system uses
a circular buffer to store the temporary data such that the oldest
data is replaced by the newest data.
[0050] Once initiated, collection of respiratory information, which
may involve storage of the information in long term memory, may be
performed on a substantially continuous basis, or it may be
performed during discrete intervals. Long term collection of data
on a periodic basis may be beneficial when the event is relatively
prolonged, such an in the case of a disease or disorder that may
linger for several days or weeks. Various collection parameters,
such as the type of data collected, data collection frequency,
and/or data collection intervals may be selectable by the user.
Further, the system may be programmable to use different data
collection regimens under different conditions over the course of
the event. For example, the system may be programmed to collect
data more frequently during sleep or during particular stages of
the disease progression, for example. The system may be programmed
to collect data on a substantially continuous basis during some
time intervals, and periodically during other time intervals, for
example.
[0051] Collecting medical information preceding the respiratory
event facilitates enhanced identification of conditions that may be
used to detect or predict the occurrence of future events. For
example, acquiring information preceding the event affecting
patient respiration allows for the identification and assessment of
physiological conditions present immediately before and leading up
to the event. In one scenario, the patient may experience a period
of hyperventilation prior to an apnea event. Collecting respiratory
information prior to the apnea event allows the identification of
hyperventilation as a precursor condition. The identification of
precursor conditions for apnea facilitate increased sensitivity
and/or accuracy in detecting or predicting future occurrences of
apnea.
[0052] Additionally, or alternatively, medical information
preceding the respiratory event may provide insight into conditions
that predispose the patient to certain respiratory events.
Acquiring information preceding the event may provide allow
identification of the triggering or causal factors of the event.
For example, an asthma attack may be induced by increased exercise
or a sudden change in ambient temperature, e.g., the patient moving
from a warmer location to a colder location. Collection of medical
information preceding the asthma attack allows the factors that
precipitate the respiratory event to be identified. Such
information may be used to enhance the detection and/or prediction
of future events.
[0053] Information collected following the event may be used to
assess the acute effects of the event. Episodes of disordered
breathing, for example, may be associated with acute physiological
effects, including negative intrathoracic pressure, hypoxia, and
arousal from sleep. Such effects may be detectable for a period of
time following the respiratory event.
[0054] For example, obstructive sleep apneas are typically
terminated by arousal from sleep that occurs several seconds after
the apneic peak, allowing the resumption of airflow. Coincident
with arousal from sleep, and continuing for some period of time
after termination of the event, surges in sympathetic nerve
activity, blood pressure, and heart rate occur.
[0055] During obstructive apnea events, the effort to generate
airflow increases. Attempted inspiration in the presence of an
occluded airway results in an abrupt reduction in intrathoracic
pressure. The repeated futile inspiratory efforts associated with
obstructive sleep apnea may trigger a series of secondary
responses, including mechanical, hemodynamic, chemical, neural, and
inflammatory responses. Collection of data following obstructive
sleep apnea events may be used to determine the presence and/or
severity of the secondary responses to obstructive apnea events.
The post-event information enhances the ability to evaluate the
impact of the secondary responses upon the patient.
[0056] As previously described, obstructive sleep apnea events are
typically terminated by arousal from sleep. However, arousals are
not usually required for the resumption of breathing in central
sleep apnea events. In the case of central apnea events, the
arousals follow the initiation of breathing. Arousals following
central apnea events may facilitate the development of oscillations
in ventilation by recurrently stimulating hyperventilation and
reducing PaCO.sub.2 below the apneic threshold. Once triggered, the
pattern of alternating hyperventilation and apnea may be sustained
by the combination of increased respiratory drive, pulmonary
congestion, arousals, and apnea-induced hypoxia causing PaCO.sub.2
oscillations above and below the apneic threshold. Shifts in the
patient's state of consciousness, particularly with repeated
arousals, may further destabilize breathing. Collecting information
during central apnea events and before and/or after the occurrence
of the events may allow identification of the oscillations
associated with central apnea.
[0057] The collected medical information, which may be stored in
long term memory, transmitted, printed and/or displayed is
organized as a respiratory logbook entry 128. The medical
information may include various physiological and non-physiological
data. For example, respiratory system data, cardiovascular system
data, nervous system data, posture, activity, medical history data,
environmental data (temperature, altitude, air quality) and other
types of medical information may be organized as a respiratory
logbook entry. The respiratory logbook entry may be stored,
transmitted, printed and/or displayed.
[0058] A respiratory event logbook may comprise a number of
entries, each entry corresponding to a separate respiratory event.
The event entries included in medical event log may be organized
according to various categories, including for example, event type,
event time/date, order of occurrence of the event, therapy provided
to treat the event, among other categories. The selection of
categories used to organize the information may be programmable by
the user. The organized information may be stored in long term
memory, displayed, printed, and/or transmitted to a separate
device.
[0059] The collected information for the events may be optionally
accessible 130 through an interactive user interface. The
interactive user interface may provide access to one or more log
entries through activation of a selection process, involving a
hierarchical selection menu, or other selection method, for
example. In one implementation, the user may select a log entry
from the menu by activating an input mechanism. Upon selection of
the log entry, the user interface may provide graphical or textual
depictions of the collected respiratory information associated with
the medical event.
[0060] Relating to both FIGS. 1A and 1B, the event information of
the logbook may be stored in long term memory using various storage
methodologies. For example, the logbook may utilize a flat file
system, hierarchical database, relational database, or distributed
database. Data for a group of events may be analyzed and/or
summarized in various formats. Graphical and/or textual summary
information may be displayed on the user interface and/or otherwise
communicated to the user. For example, histograms, trend graphs,
and/or other analytical tools or formats may be generated based on
the logbook event entries. A logbook display may have the ability
to display trends of the patient's apnea/hypopnea index, histograms
of number of apneas/hypopneas and/or obstructive/central events per
night, sleep stage diagram (shows the stage of sleep for each
night), heart rate trend during the night, oxygen saturation trend
during the night.
[0061] In various embodiments, collection of medical information
may be initiated responsive to prediction of a medical event. In
this scenario, information may be collected prior to the prediction
of the medical event, prior to the detection of the medical event,
during the event, and/or following the event. FIG. 1C is a
flowchart illustrating an embodiment of the invention involving
collecting medical information responsive to prediction and
detection of a medical event. In this scenario, a medical event is
predicted 132, initiating collection of information 134. Prior to
the prediction, medical conditions affecting the patient may be
monitored continuously or during discrete intervals and stored in a
temporary buffer. Information contained in the temporary buffer
represents information occurring before the prediction and may be
collected for the medical event log entry. In addition, information
may be collected after the prediction and before the detection of
the event. If the event is detected 135, information may be
collected during 136 and after the detected event. The collected
information is organized 138 as an event log entry.
[0062] The approaches illustrated and described herein are
generally presented in terms of a respiratory logbook system
configured to organize medical information associated with
respiratory events. Those skilled in the art will recognize that
analogous approaches may be used to implement organization of
respiratory information associated with medical events in a medical
logbook system.
[0063] FIG. 2 is a block diagram of a logbook system 200 in
accordance with embodiments of the invention. The respiratory
logbook system 200 implements an event-driven method of collecting
and organizing data related to events affecting patient
respiration.
[0064] Various patient conditions may be monitored through sensors
222, patient input devices 223, and/or information systems 224.
Data associated with patient conditions may be stored in short term
memory 240. One or more of the patient conditions may be used by
event detection circuitry 236 to detect or predict the occurrence
of an event affecting respiration. Detection or prediction of an
event affecting. respiration initiates the long term storage of
information associated with the event by the event information
processor 232 into the long term memory 260. For example, the event
information processor 232 may collect information supplied by one
or more of the sensors 222, patient input devices 223, and
information systems 224 before, during, and/or after the detection
and/or prediction of the event. The collected information
associated with each event is organized as a respiratory logbook
entry in the respiratory logbook. The respiratory logbook, or
portions thereof, may be stored in long term memory 260,
transmitted to a remote device 255, and/or displayed on a display
device 270.
[0065] The embodiment illustrated in FIG. 2 includes a respiration
sensor 245 that senses a physiological condition modulated by
patient respiration. In one embodiment, the respiration sensor may
comprise a transthoracic impedance sensor. Other methods of sensing
respiration are also possible. Such methods may include, for
example, the use of patient-external respiratory bands, respiration
flowmeter measurements, implantable or patient-external breath
sound detection, blood oxygen levels, and/or other processes. The
respiration sensor 245 may be used, for example, to acquire a
respiration waveform before, during, and/or after an event
affecting the patient respiration. The respiration waveform may be
a component of the respiratory log entry for the event.
[0066] Information about various conditions affecting the patient
and associated with the event may be acquired using sensors 222,
patient input devices 223 and/or other information systems 224. The
sensors 222 may comprise patient-internal and/or patient-external
sensors coupled through leads or wirelessly to the interface 231 of
the respiratory logbook system 200. The sensors may sense various
physiological and/or non-physiological conditions affecting patient
respiration or other physiological systems. The patient input
device 223 allows the patient to input information relevant to
conditions affecting the patient that may be useful in generating a
respiratory event log. For example, the patient input device 223
may be particularly useful for acquiring information known to the
patient, such as information related to patient smoking, drug use,
recent exercise level, and/or other patient activities, perceptions
and/or symptoms. The information provided by the patient-input
device may include patient-known information relevant to the event
affecting respiration that is not automatically sensed or detected
by the respiratory logbook system 200.
[0067] The respiratory logbook system 200 may also include one or
more information systems 224 such as a remote computing device
and/or a network-based server. The event information processor 232
may access the information systems 224 to acquire information from
databases and/or other information sources stored on or generated
by the remote computing devices and/or servers. The information
acquired from the information system s 224 may be recorded in the
respiratory logbook along with other information relevant to the
event affecting respiration. In one exemplary implementation, the
respiratory logbook system 200 may access an internet connected air
quality server to collect data related to environmental conditions,
such as an ambient pollution index. In another implementation, the
respiratory logbook system 200 may access the patient's medical
history through a patient information server.
[0068] The sensors 222, patient input devices 223, and information
systems 224 are coupled to other components of the respiratory
logbook system 200 through interface circuitry 231. The interface
231 may include circuitry for energizing the sensors 222 and/or for
detecting and/or processing signals generated by the sensors. The
interface 231 may include, for example, driver circuitry,
amplifiers, filters, sampling circuitry, and/or A/D converter
circuitry for conditioning the signals generated by the
sensors.
[0069] The interface 231 may also include circuitry 250 for
communicating with the patient input device 223, information
systems 224, a device programmer 255, an APM system (not shown), or
other remote devices. Communication with the patient input device
223, information systems 224 and/or a remote device programmer 255
and/or other remote devices may be implemented using a wired
connection or through a wireless communication link, such as a
Bluetooth or other wireless link. The communication circuitry 250
may also provide the capability to wirelessly communicate with
various sensors, including implantable, subcutaneous, cutaneous,
and/or non-implanted sensors.
[0070] The respiratory logbook system 200 may optionally be
implemented as a component of a medical device that includes a
therapy system, such as a cardiac rhythm management system 201. The
cardiac rhythm management system 201 may include cardiac electrodes
225 electrically coupled to the patient's heart. Cardiac signals
sensed by cardiac sense circuitry 220 may be used in the detection
and treatment of various anomalies of the heart rhythm. Anomalous
heart rhythms may include, for example, a rhythm that is too slow
(bradycardia), a heart rhythm that is too fast (tachycardia),
and/or a heart rhythm that involves insufficiently synchronized
contractions of the atria and/or ventricles, a symptom of
congestive heart failure.
[0071] If an arrhythmia is detected by the cardiac rhythm
management system, then a cardiac therapy circuit 215 may deliver
cardiac therapy to the heart in the form of electrical stimulation
pulses, such as pacing and/or cardioversion/defibrillation pulses.
The cardiac signals and/or cardiac conditions, e.g., arrhythmia
conditions, derived or detected through the use of the cardiac
signals may be associated with an event affecting respiration. The
cardiac information associated with the event may be acquired and
organized by the respiratory logbook system 200.
[0072] A user interface may be used to view and/or access the
respiratory logbook information. FIG. 3 illustrates an exemplary
depiction of a user interface display 300. An area 305 of the
display may be used to provide textual or graphical information
about respiratory events. As illustrated in FIG. 3, a menu 310 of
respiratory events may be presented and may enable the user to
access additional information related to the respiratory event. The
menu 310 may provide a summary of parameters associated with the
events contained in the respiratory logbook. As illustrated in FIG.
3, one or more summary parameter headings, such as episode number
321, date/time 322, type 323, duration 324, sleep stage 325, and/or
environment 326, among other parameter headings, may be presented
at the top of the menu 310 or in another convenient location. The
summary parameter headings 321-326 may be programmable, and
additional or alternative parameter headings to those depicted in
FIG. 3 may be selected, for example.
[0073] The type parameter 323 may contain abbreviations for various
respiratory events. For example AP-C and AP-O. may abbreviate
central and obstructive apneas respectively, HP abbreviates a
hypopnea, CS abbreviates Cheyne-Stokes respiration and RSB
abbreviates rapid-shallow breathing.
[0074] The respiratory events displayed as menu items in the menu
310 may be selected by a user according to episode number,
date/time, duration, type, number, or by other criteria. The menu
items may be selected for display based on various criteria ranges
and/or thresholds. For example, in the example screen illustrated
in FIG. 3, different groups of events selected as menu items may be
selected by activating the modify query button 331. The modify
query button 331 and other buttons illustrated on the display may
be voice activated, activated through touching the display screen,
or by operating a keyboard or pointing device, for example.
[0075] In one implementation, activation of the modify query button
331 initiates a dialog session that allows the user to select
respiratory events to be presented in the menu according various
criteria such as by date/time, duration, type, number, or by other
criteria ranges or thresholds. In one example, the user may select
all apnea events to be presented as menu items. In another example,
the user may select all events that occurred between a first date
and a second date. In yet another example, the user may select all
events that occurred while the patient experienced certain
environmental conditions, e.g., ambient temperature range and/or
humidity range. In yet another example, the user may choose to
select all events of the respiratory logbook. The selection
criteria may be displayed in an episode query selection area 332 of
the display. The episode query selection area 332 in the depiction
of a respiratory logbook display shown in FIG. 3 indicates that all
episodes have been selected to be displayed as menu items.
[0076] The menu 310 allows the user to choose respiratory events
for which additional textual and/or graphical information is
displayed. The additional information provides more detailed
information about the selected events beyond the summary
information presented in the menu 310. In the exemplary
illustration depicted in FIG. 3, the selections are indicated by
check marks 307 beside the selected respiratory events. For
convenience, the display may include a select all button 351 and/or
a select none button 352. Activation of the select all button 351
causes all events in the menu 310 to be selected. Activation of the
select none button 352 causes all events in the menu 310 to be
deselected.
[0077] Following selection of one or more episodes in the menu,
activation of the detail button 342 causes detailed textual
information associated with a selected event to be presented on the
display screen. The detail information may be displayed in the area
of the screen 305 previously occupied by the menu 310, for example.
The user may scroll back and forth through the textual information
for the one or more selected events using the prev button 341 and
the next button 343. The textual information may be printed upon
activation of the print button 344, or may be saved to a disk, or
other storage medium, through activation of the save to disk button
355.
[0078] Graphical information associated with the selected events
may be displayed upon activation of the signals button 362. In one
implementation, a respiration waveform acquired during, before
and/or after a selected event may be displayed in the area 305 of
the display previously used for the menu 310. Waveforms of other
parameters, e.g., cardiac rhythm, patient activity, may
additionally or alternatively be displayed. In one implementation,
a marked waveform may be displayed. For example, a marked
respiration waveform may include the respiration waveform acquired
before, during, and after the event, along with one or more symbols
aligned with the respiration waveform to indicate the occurrence of
one or more conditions. The symbol may provide a numerical value or
a textual description associated with the respiration
characteristic, e.g., average respiration rate, expiratory slope,
etc. In one example, various characteristics of disordered
breathing events including quantifiable characteristics, such as
episode duration, blood oxygen saturation, disordered breathing
type, and/or other detected characteristics may also be displayed
along with the respiration waveform. A user may scroll through the
waveforms associated with the selected events using the prev and
next buttons 341, 343.
[0079] FIG. 4 is a block diagram of a medical system that may be
used to implement a respiratory logbook system in accordance with
embodiments of the invention. The medical system may include, for
example, one or more patient-internal medical devices 420 and one
or more patient-external medical devices 430. Each of the
patient-internal 420 and patient-external 430 medical devices may
include one or more of a patient monitoring unit 427, 437, a
diagnostics unit 429, 439, and/or a therapy unit 428, 438.
Respiratory logbook circuitry 411, as described more fully in
connection with FIG. 2 above, including an external device
interface, event detector/predictor, event information processor
and/or memory, for example, can be housed in a patient internal
medical device 420, a patient external medical device 430, a remote
system such as advanced patient medical (APM) system 440 or in any
combination of the above-mentioned devices 420, 430, 440.
[0080] The patient-internal medical device 420 may be a fully or
partially implantable device that performs monitoring, diagnosis,
and/or therapy functions. The patient-external medical device 430
may perform monitoring, diagnosis and/or therapy functions external
to the patient (i.e., not invasively implanted within the patient's
body). The patient-external medical device 430 may be positioned on
the patient, near the patient, or in any location external to the
patient. It is understood that a portion of a patient-external
medical device 430 may be positioned within an orifice of the body,
such as the nasal cavity or mouth, yet can be considered external
to the patient (e.g., mouth pieces/appliances, tubes/appliances for
nostrils, or temperature sensors positioned in the ear canal).
[0081] The patient-internal and patient-external medical devices
420, 430 may be coupled to one or more sensors 421, 422, 431, 432,
patient input devices 424, 434 and/or other information acquisition
devices 426, 436. The sensors 421, 422, 431, 432, patient input
devices 424, 434, and/or other information acquisition devices 426,
436 may be employed to detect conditions relevant to the
monitoring, diagnostic, and/or therapeutic functions of the
patient-internal and patient-external medical devices 420, 430.
[0082] The medical devices 420, 430 may each be coupled to one or
more patient-internal sensors 421, 431 that are fully or partially
implantable within the patient. The medical devices 420, 430 may
also be coupled to patient-external sensors 422, 432 positioned on
the patient, near the patient, or in a remote location with respect
to the patient. The patient-internal 421, 431 and patient-external
422, 432 sensors may be used to sense conditions, such as
physiological or environmental conditions, that affect the
patient.
[0083] The patient-internal sensors 421 may be coupled to the
patient-internal medical device 420 through implanted leads. In one
example, an internal endocardial lead system is used to couple
sensing electrodes to an implantable pacemaker or other cardiac
rhythm management device. One or more of the patient-internal
sensors 421, 431 may be equipped with transceiver circuitry to
support wireless communication between the one or more
patient-internal sensors 421, 431 and the patient-internal medical
device 420 and/or the patient-external medical device 430.
[0084] The patient-external sensors 422, 432 may be coupled to the
patient-internal medical device 410 and/or the patient-external
medical device 420 through leads or through wireless connections.
Patient-external sensors 422 preferably communicate with the
patient-internal medical device 420 wirelessly. Patient-external
sensors 432 may be coupled to the patient-external medical device
430 through leads or through a wireless link.
[0085] The medical devices 420, 430 may be coupled to one or more
patient-input devices 424, 434. The patient-input devices 424, 434
facilitate manual transfer of information to the medical devices
420, 430 by the patient. The patient input devices 424, 434 may be
particularly useful for inputting information concerning patient
perceptions, such as how well the patient feels, and patient-known
information such as patient smoking, drug use, or other activities
that are not automatically sensed or detected by the medical
devices 420, 430. In one implementation, a device programmer may be
used to facilitate patient input to a medical device 420, 430.
[0086] The medical devices 420, 430 may be connected to one or more
information systems 426, 436, for example, a database that stores
information useful in connection with the monitoring, diagnostic,
or therapy functions of the medical devices 420, 430. In one
implementation, one or more of the medical devices 420, 430 may be
coupled through a network to an information system server that
provides information about environmental conditions affecting the
patient, e.g., the pollution index for the patient's location.
[0087] In one embodiment, the patient-internal medical device 420
and the patient-external medical device 430 may communicate through
a wireless link between the medical devices 420, 430. For example,
the patient-internal and patient-external devices 420, 430 may be
coupled through a short-range radio link, such as Bluetooth or a
wireless link. The communications link may facilitate
uni-directional or bi-directional communication between the
patient-internal 420 and patient-external 430 medical devices. Data
and/or control signals may be transmitted between the
patient-internal 420 and patient-external 430 medical devices to
coordinate the functions of the medical devices 420, 430.
[0088] In one embodiment, the patient-internal and patient-external
medical devices 420, 430 may be used within the structure of an
advanced patient management system. Advanced patient management
systems involve a system of medical devices that are accessible
through various communications technologies. For example, patient
data may be downloaded from one or more of the medical devices
periodically or on command, and stored at a patient information
server. The physician and/or the patient may communicate with the
medical devices and the patient information server, for example, to
acquire patient data or to initiate, terminate or modify
therapy.
[0089] The patient-internal medical device 420 and the
patient-external medical device 430 may be coupled through a
wireless or wired communications link to a patient information
server that is part of an advanced patient management system 440.
The APM patient information server 440 may be used to download and
store data collected by the patient-internal and patient-external
medical devices 420, 430.
[0090] The data stored on the APM patient information server 440
may be accessible by the patient and the patient's physician
through terminals 450, e.g., remote computers located in the
patient's home or the physician's office. The APM patient
information server 440 may be used to communicate to one or more of
the patient-internal and patient-external medical devices 420, 430
to effect remote control of the monitoring, diagnosis, and/or
therapy functions of the medical devices 420, 430.
[0091] In one scenario, the patient's physician may access patient
data transmitted from the medical devices 420, 430 to the APM
patient information server 440. After evaluation of the patient
data, the patient's physician may communicate with one or more of
the patient-internal or patient-external devices 420, 430 through
the APM system 440 to initiate, terminate, or modify the
monitoring, diagnostic, and/or therapy functions of the
patient-internal and/or patient-external medical systems 420, 430.
Systems and methods involving advanced patient management
techniques are further described in the previously incorporated
U.S. Pat. Nos. 6,336,903, 6,312,378, 6,270,457, and 6,398,728.
[0092] In one scenario, the patient-internal and patient-external
medical devices 420, 430 may not communicate directly with each
other, but may communicate indirectly through the APM system 440.
In this embodiment, the APM system 440 may operate as an
intermediary between two or more of the medical devices 420, 430.
For example, data and/or control information may be transferred
from one of the medical devices 420, 430 to the APM system 440. The
APM system 440 may transfer the data and/or control information to
another of the medical devices 420, 430.
[0093] As previously indicated, respiratory logbook circuitry 411,
including an external device interface, event detector/predictor,
event information processor and memory, for example, can be housed
in a patient internal medical device 420, a patient external
medical device 430, an advanced patient medical (APM) system 440 or
in any combination of the above-mentioned devices. For explanatory
purposes, in the following discussion, the respiratory logbook
circuitry 411 is described as being housed within the patient
internal medical device 420. As previously discussed, the patient
internal medical device 420 is coupled to various sensors, 421,
422, patient input devices 424, and/or other information systems
426. These sensing and detection devices may be used to detect
conditions relevant to events affecting respiration. One or more
patient input devices 424 allow the patient to enter information
associated with the events into the medical device 420. Further, a
variety of information systems 426 may be accessible by the
patient-internal medical device 420, including, for example,
network or internet-based information systems. The information
systems 426 may provide event-related information such as local
pollution levels, local temperature, humidity, etc. For example,
the conditions associated with events affecting respiration may be
any of the conditions referred to in Tables 1-3, or other
conditions.
[0094] In accordance with various embodiments of the invention, the
respiratory logbook circuitry 411 may comprise circuitry configured
to evaluate one or more patient conditions to detect or predict the
occurrence of an event affecting patient respiration. In response
to the detection or prediction of such an event, the respiratory
logbook circuitry initiates the collection of information related
to the event. In one scenario, the respiratory logbook circuitry
may initiate collection of information from sensors 421, 431, 422,
432 or other input devices 424, 434, 426, 436 coupled to any
combination of the patient internal medical device, 420 patient
external medical device 430 and a remote device, such as the APM
server 440. The respiratory logbook circuitry may initiate
collection of information associated with any of the patient
conditions listed in Tables 1-3.
[0095] Information associated with the event affecting respiration
may be acquired before, during and/or after the respiratory event.
Information may be acquired for a time period beginning a short
time, e.g., up to about 5 minutes, prior to the prediction and/or
detection of a respiratory event and/or ending a short time, e.g.,
up to about 2 minutes, following the termination of the respiratory
event. In various embodiments of the invention, acquired
information related to the event affecting respiration may be
immediately transmitted to a separate computing device 430, 440,
450, the acquired information may be stored in the patient-internal
device 420. The information may be organized and displayed on a
display unit 452 as discussed in connection with FIG. 3.
[0096] The patient-internal sensors 421, 431, patient-external
sensors 422, 432, patient input devices 424, 434, and/or
information systems 426, 436 may be used to acquire a variety of
information related to respiratory logbook events. The acquired
information may include both physiological and non-physiological
contextual conditions affecting the patient. Physiological
conditions may include a broad category of conditions associated
with the internal functioning of the patient's physiological
systems, including the cardiovascular, respiratory, nervous, muscle
and other systems. Examples of physiological conditions include
blood chemistry, patient posture, patient activity, respiration
quality, sleep quality, among others.
[0097] Contextual conditions generally encompass non-physiological,
patient-external or background conditions. Contextual conditions
may be broadly defined to include, for example, present
environmental conditions, such as patient location, ambient
temperature, humidity, air pollution index. Contextual conditions
may also include historical/background conditions relating to the
patient, including the patient's normal sleep time and the
patient's medical history, for example. Methods and systems for
detecting some contextual conditions, including, for example,
proximity to bed detection, are described in commonly owned U.S.
Patent Application entitled "Methods and Devices for Detection of
Context When Addressing A Medical Condition of a Patient," Ser. No.
10/269611, filed Oct. 11, 2002, which is incorporated by reference
herein in its entirety.
[0098] Table 1 provides a list of representative patient conditions
that may be used in connection with a respiratory logbook in
accordance with embodiments of the invention. Table 1 presents
representative physiological and non-physiological patient
conditions that may be acquired and used in connection with a
respiratory logbook. Table 1 also presents illustrative sensing
methods that may be employed to sense the conditions. It will be
appreciated that information and detection methods other than those
provided in Table 1 may be used in connection with a respiratory
logbook and are considered to be within the scope of the
invention.
1TABLE 1 Sensor type or Detection Condition Type Condition method
Physiological Cardiovascular System Heart rate EGM, ECG Heart rate
variability QT interval Ventricular filling pressure Intracardiac
pressure sensor Blood pressure Blood pressure sensor Respiratory
System Snoring Accelerometer Microphone Respiration pattern
Transthoracic impedance (Tidal volume Minute sensor (AC)
ventilation Respiratory rate) Patency of upper airway Intrathoracic
impedance sensor Pulmonary congestion Transthoracic impedance
sensor (DC) Nervous System Sympathetic nerve activity Muscle
sympathetic nerve Activity sensor Brain activity EEG Blood
Chemistry CO2 saturation Blood analysis O2 saturation Blood alcohol
content Adrenalin Brain Natriuretic Peptide (BNP) C-Reactive
Protein Drug/Medication/Tobacco use Muscle System Muscle atonia EMG
Eye movement EOG Patient activity Accelerometer, MV, etc. Limb
movements Accelerometer, EMG Jaw movements Accelerometer, EMG
Posture Multi-axis accelerometer Contextual Environmental Ambient
temperature Thermometer Humidity Hygrometer Pollution Air quality
website Time Clock Date Clock Barometric pressure Barometer Ambient
noise Microphone Ambient light Photodetector Altitude Altimeter
Location GPS, proximity sensor Proximity to bed Proximity to bed
sensor Historical/Background Historical sleep time Patient input,
previously detected sleep onset times Medical history Patient input
Age Recent exercise Weight Gender Body mass index Neck size
Emotional state Psychological history Daytime sleepiness Patient
perception of sleep quality Drug, alcohol, nicotine use
[0099] As previously mentioned, long term storage of respiratory
logbook information may be initiated by detection or prediction of
various types of events affecting the respiration of the patient.
The triggering event may comprise, for example, a disordered
breathing event, a cardiac arrhythmia episode, an event related to
a pulmonary disease or disorder such as asthma, pulmonary edema,
chronic obstructive pulmonary disease, and/or pleural effusion, an
episode of coughing and/or other breathing irregularities, or an
event related to the normal activity of the patient, such as sleep
or exercise, among other events. The event may also be triggered by
the patient using, for example, the patient input device 424,
434.
[0100] Detection of various pulmonary diseases/disorders may
initiate long term storage of data for a respiratory logbook entry.
Pulmonary diseases/disorders may be organized into broad categories
encompassing disorders of breathing rhythm and non-rhythm pulmonary
diseases and/or disorders. Breathing rhythm disorders include
various syndromes characterized by patterns of disordered breathing
that produce insufficient respiration, for example, sleep apnea,
hypopnea, and Cheyne-Stokes Respiration (CSR), among others.
Breathing rhythm disorders are not necessarily accompanied by
alteration of pulmonary structures.
[0101] Non-rhythm pulmonary diseases or disorders typically involve
physical changes to lung structures, such as loss of elasticity of
the lung tissue, obstruction of airways with mucus, limitation of
the expansion of the chest wall during inhalation, fibrous tissue
within the lung, excessive pressure in the pulmonary arteries,
and/or other characteristics. Pulmonary diseases or disorders that
are not rhythm related are referred to herein as non-rhythm
pulmonary diseases and may include obstructive pulmonary diseases,
restrictive pulmonary diseases, infectious pulmonary diseases,
pulmonary vasculature disorders, and pleural cavity disorders, for
example.
[0102] In various embodiments of the invention, acquisition of
information may be triggered by detection of a presence of a
non-rhythm related pulmonary disease/disorder. Detection of a
presence of the pulmonary disease/disorder may be based on a
predetermined level of physiological changes and/or disease
symptoms associated with the disease or disorder. The presence of
various pulmonary diseases that may trigger acquisition of data may
include, for example, obstructive pulmonary diseases (e.g., chronic
bronchitis, emphysema, asthma), restrictive pulmonary diseases
(e.g., sarcoidosis, pulmonary fibrosis, pneumoconiosis), infections
pulmonary diseases (e.g., bronchitis, pneumonia, bronchiolitis,
tuberculosis, and bronchiectasis), pulmonary vasculature diseases
(e.g., pulmonary hypertension, pulmonary edema, pulmonary embolism,
atalectasis), and diseases of the pleural cavity (e.g., pleural
effusion, pneumothorax, and hemothorax).
[0103] In accordance with various embodiments of the invention, the
presence of a non-rhythm pulmonary disease may be assessed by
evaluating conditions indicative of the non-rhythm pulmonary
disease. In one example, the presence of a non-rhythm pulmonary
disease may be assessed by comparing conditions indicative of
physiological changes or symptoms caused by the disease to
threshold criteria. If the conditions indicative of physiological
changes or symptoms caused by the disease are consistent with
threshold levels, the system may determine that the non-rhythm
pulmonary disease or disorder is present.
[0104] In another example, assessment of disease presence may be
based on relative changes in one or more conditions indicative of
physiological changes or symptoms caused by the disease. For
example, diagnosis of a non-rhythm pulmonary disease may be
effected by evaluating the changes in conditions indicative of
physiological changes or symptoms caused by the disease. The
changes in the one or more conditions may be compared to threshold
criteria. If changes in the conditions indicative of physiological
changes or symptoms caused by the disease are consistent with
threshold levels, the non-rhythm pulmonary disease or disorder may
be present.
[0105] In a further example, the threshold criteria may involve
relationships between the conditions indicative of physiological
changes or symptoms caused by the disease. The presence of a
non-rhythm pulmonary disease may be assessed by evaluating
relationships between conditions indicative of physiological
changes or symptoms caused by the disease. For example, assessment
of a disease may involve the determination that levels or amounts
of two or more conditions have a certain relationship with one
another. If relationships between the conditions indicative of
physiological changes or symptoms caused by the disease are
consistent with threshold relationship criteria, the non-rhythm
pulmonary disease or disorder may be present.
[0106] In another implementation, detection of a rhythm related
pulmonary event, e.g., a disordered breathing event, triggers the
acquisition of information associated with respiration. A
disordered breathing event may be detected by sensing and analyzing
various conditions indicative of disordered breathing. Table 2
presents examples of how a representative subset of the
physiological and non-physiological (contextual) conditions
provided in Table 1 may be used in connection with disordered
breathing detection.
2TABLE 2 Examples of how condition may be used in disordered
Condition Type Condition breathing detection Physiological Heart
rate Decrease in heart rate may indicate disordered breathing
episode. Increase in heart rate may indicate autonomic arousal from
a disordered breathing episode. Decrease in heart rate may indicate
the patient is asleep. Heart rate variability Disordered breathing
causes heart rate variability to decrease. Changes in HRV
associated with sleep disordered breathing may be observed while
the patient is awake or asleep Ventricular filling May be used to
identify/predict pulmonary congestion pressure associated with
respiratory disturbance. Blood pressure Swings in on-line blood
pressure measures are associated with apnea. Disordered breathing
generally increases blood pressure variability - these changes may
be observed while the patient is awake or asleep. Snoring Snoring
is associated with a higher incidence of obstructive sleep apnea
and may be used to detect disordered breathing. Snoring indicates
the patient is asleep. Respiration Respiration patterns including,
e.g., respiration rate, pattern/rate may be used to detect
disordered breathing episodes. Respiration patterns may be used to
determine the type of disordered breathing. Respiration patterns
may be used to detect that the patient is asleep. Patency of upper
Patency of upper airway is related to obstructive sleep airway
apnea and may be used to detect episodes of obstructive sleep
apnea. Pulmonary Pulmonary congestion is associated with
respiratory congestion disturbances. Sympathetic nerve End of apnea
associated with a spike in SNA. Changes activity in SNA observed
while the patient is awake or asleep may be associated with sleep
disordered breathing CO2 Low CO2 levels initiate central apnea. May
be used to predict central apnea risk. O2 O2 desaturation occurs
during severe apnea/hypopnea episodes. May be used to evaluate
presence and severity of sleep disordered breathing event. Blood
alcohol content Alcohol tends to increase incidence of snoring
& obstructive apnea. Adrenalin End of apnea associated with a
spike in blood adrenaline. Brain Natriuretic A marker of heart
failure status, which is associated with Peptide (BNP)
Cheyne-Stokes Respiration C-Reactive Protein A measure of
inflammation that may be related to apnea. Drug/Medication/ These
substances may affect the incidence of both Tobacco use central
& obstructive apnea. Muscle atonia Muscle atonia may be used to
discriminate REM from non-REM sleep. Eye movement Eye movement may
be used to detect REM and non- REM sleep. Non- Temperature Ambient
temperature may be a condition predisposing physiological/ the
patient to episodes of disordered breathing and may Contextual be
useful in disordered breathing detection. Humidity Humidity may be
a condition predisposing the patient to episodes of disordered
breathing and may be useful in disordered breathing detection.
Pollution Pollution may be a condition predisposing the patient to
episodes of disordered breathing and may be useful in disordered
breathing detection. Posture Posture may be used to confirm or
determine the patient is asleep. Activity Patient activity may be
used in relation to sleep detection. Location Patient location may
used to determine if the patient is in bed as a part of sleep
detection. Altitude Lower oxygen concentrations at higher altitudes
tends to cause more central apnea
[0107] The acquisition of information may be triggered by a
prediction that a disordered breathing event is likely to occur. In
this implementation, an occurrence of disordered breathing may be
predicted based on one or more sensed conditions, such one or more
of the physiological and/or non-physiological conditions listed in
Table 1. The conditions listed in Table 1 may serve a variety of
purposes in predicting disordered breathing. For example, a first
subset of the conditions listed in Table 1 may comprise conditions
predisposing the patient to disordered breathing. Another subset,
possibly overlapping the first subset, may comprise precursor
conditions indicating an imminent occurrence of a disordered
breathing event. Another subset of the conditions may be employed
to verify that the predicted disordered breathing event occurred
and/or to classify the disordered breathing episode as to origin,
e.g., central or obstructive, and/or as to type, e.g., apnea,
hypopnea, Cheyne-Stokes Respiration (CSR). Table 3 provides further
examples of how physiological and/or contextual conditions may be
used in disordered breathing prediction.
3TABLE 3 Examples of how condition is used in disordered breathing
Condition prediction Heart rate Decrease in heart rate may indicate
disordered breathing episode. Decrease in heart rate may indicate
the patient is asleep. Increase in heart rate may indicate
autonomic arousal from disordered breathing. Heart rate variability
May be used to determine sleep state Ventricular filling pressure
May be used to identify/predict pulmonary congestion associated
with respiratory disturbance. Blood pressure Swings in on-line
blood pressure measures are associated with apnea. Snoring Snoring
is associated with a higher incidence of obstructive sleep apnea
and may be used to detect disordered breathing. Respiration
Respiration patterns may be used to detect disordered breathing
signals/respiration patterns episodes. Respiration patterns may be
used to determine the type of disordered breathing. Respiration
patterns may be used to detect that the patient is asleep.
Hyperventilation may be used to predict disordered breathing.
Previous episodes of disordered breathing may be used to predict
further episodes. One form of disordered breathing may be used to
predict another form of disordered breathing Patency of upper
airway Patency of upper airway is related to obstructive sleep
apnea and may be used to detect episodes of obstructive sleep
apnea. Pulmonary congestion Pulmonary congestion is associated with
respiratory disturbances. Sympathetic nerve activity End of apnea
associated with a spike in SNA CO2 saturation Low CO2 levels
initiate central apnea. O2 saturation O2 desaturation occurs during
severe apnea/hypopnea episodes. Blood alcohol content Alcohol tends
to increase incidence of snoring & obstructive apnea. Adrenalin
End of apnea associated with a spike in blood adrenaline. BNP A
marker of heart failure status, which is associated with
Cheyne-Stokes Respiration C-Reactive Protein A measure of
inflammation that may be related to apnea. Drug/Medication/Tobacco
These substances may affect incidence of both central & use
obstructive apnea. Muscle atonia Muscle atonia may be used to
detect REM and non-REM sleep. Eye Movement Eye movement may be used
to detect REM and non-REM sleep. Temperature Ambient temperature
may be a condition predisposing the patient to episodes of
disordered breathing. Humidity Humidity may be a condition
predisposing the patient to episodes of disordered breathing.
Pollution Pollution may be a condition predisposing the patient to
episodes of disordered breathing. Posture Posture may be used to
determine if the patient is asleep. Posture may be a condition
predisposing the patient to episodes of disordered breathing.
Activity Patient activity may be used in relation to sleep
detection. Sleep stage NREM sleep is associated with a higher
incidence of DB episodes Location Patient location may used to
determine in the patient is in bed as a part of sleep detection.
Altitude Lower oxygen concentration associated with high altitudes
predisposes patients to more central apnea
[0108] Detection or prediction of disordered breathing may involve
comparing one condition or multiple conditions to one or more
thresholds or other indices indicative or predictive of disordered
breathing. A threshold or other index indicative or predictive of
disordered breathing may comprise a predetermined level of a
particular condition, e.g., blood oxygen level less than a
predetermined amount. A threshold or other index indicative or
predictive of disordered breathing may involve a change in a level
of a particular condition, e.g., heart rate decreasing from a sleep
rate to a lower rate within a predetermined time interval.
[0109] In one approach, the relationships between the conditions
may be indicative or predictive of disordered breathing. In this
embodiment, disordered breathing detection or prediction may be
based on the existence and relative values associated with two or
more conditions. For example, if condition A is present at a level
of x, then condition B must also be present at a level of f(x)
before disordered breathing is detection or predicted.
[0110] The thresholds and/or relationships indicative or predictive
of disordered breathing may be highly patient specific. The
thresholds and/or relationships indicative of disordered breathing
may be determined on a case-by-case basis by monitoring conditions
affecting the patient and monitoring disordered breathing episodes.
The analysis may involve determining levels of the monitored
conditions and/or relationships between the monitored conditions
associated, e.g., statistically correlated, with disordered
breathing episodes. The thresholds and/or relationships used in
disordered breathing detection or prediction may be updated
periodically to track changes in the patient's response to
disordered breathing.
[0111] In various implementations, disordered breathing events may
be detected through analysis of the patient's respiration patterns.
Methods and systems of disordered breathing detection based on
respiration patterns that may be utilized in a respiratory logbook
system are further described in commonly owned U.S. patent
application entitled "Detection of Disordered Breathing," Ser. No.
10/309,770, attorney docket number GUID.054PA, filed Dec. 4, 2002
which is incorporated herein by reference.
[0112] Prediction of disordered breathing may involve analysis of
conditions predisposing the patient to disordered breathing.
Additionally, or alternatively, prediction of disordered breathing
may be based on the detection of precursor conditions that indicate
a likelihood that one or more episodes of disordered breathing will
occur during the next time period, such as over the course of the
night. Methods and systems for predicting disordered breathing that
may be implemented in a respiratory logbook system are further
described in commonly owned U.S. patent application Ser. No.
10/643,016 (Docket No. GUID.088PA), filed Aug. 18, 2003, which is
incorporated herein by reference.
[0113] Respiratory events may be more likely to occur during sleep.
For example, episodes of disordered breathing can occur when the
patient is awake, however, most disordered breathing events occur
during sleep. The onset and termination or sleep, sleep state,
and/or stage of sleep may comprise events that initiate acquisition
of information organized in a respiratory logbook. Methods and
systems for detecting sleep that may be implemented in the context
of a respiratory logbook are described in commonly owned U.S.
patent application Ser. No. 10/309,771 (Docket No. GUID.064PA),
filed Dec. 4, 2002, which is incorporated herein by reference.
[0114] Methods and systems for detecting REM sleep and/or other
sleep states are described in commonly owned U.S. patent
application Ser. No. 10/643,006 (Docket No. GUID.060PA), filed Aug.
18, 2003, which is incorporated herein by reference.
[0115] Information collected in accordance with the invention may
involve information related to sleep and/or sleep quality. Methods
and systems related to collection, assessment, and organization of
sleep-related information are described in commonly owned U.S.
patent application Ser. No. 10/642,998 (Docket No. GUID.058PA),
filed Aug. 18, 2003, U.S. Patent Application identified by Attorney
Docket No. GUID.182PA, and entitled "Sleep Logbook," concurrently
filed with this patent application, and U.S. Patent application
identified by Attorney Docket No. GUID.106PA, and entitled
"Autonomic Arousal Detection Method and System," filed concurrently
with this patent application, all of which are incorporated herein
by reference.
[0116] FIG. 5 is a partial view of an implantable device that may
include circuitry for implementing a respiratory logbook in
accordance with embodiments of the invention. In this example, the
implantable device comprises a cardiac rhythm management device
(CRM) 500 including an implantable pulse generator 505 electrically
and physically coupled to an intracardiac lead system 510. The
respiratory logbook system may alternatively be implemented in a
variety of implantable monitoring, diagnostic, and/or therapeutic
devices, such as an implantable cardiac monitoring device, an
implantable drug delivery device, or an implantable
neurostimulation device, for example.
[0117] Portions of the intracardiac lead system 510 are inserted
into the patient's heart 590. The intracardiac lead system 510
includes one or more electrodes configured to sense electrical
cardiac activity of the heart, deliver electrical stimulation to
the heart, sense the patient's transthoracic impedance, and/or
sense other physiological parameters, e,g, cardiac chamber pressure
or temperature. Portions of the housing 501 of the pulse generator
505 may optionally serve as a can electrode.
[0118] Communications circuitry is disposed within the housing 501
for facilitating communication between the pulse generator 505 and
an external communication device, such as a portable or bed-side
communication station, patient-carried/worn communication station,
or external programmer, for example. The communications circuitry
can also facilitate unidirectional or bidirectional communication
with one or more implanted, external, cutaneous, or subcutaneous
physiologic or non-physiologic sensors, patient-input devices
and/or information systems.
[0119] The pulse generator 505 may optionally incorporate a motion
detector 520 that may be used to sense various respiration-related
conditions. For example, the motion detector 520 may be optionally
configured to sense snoring, activity level, and/or chest wall
movements associated with respiratory effort, for example. The
motion detector 520 may be implemented as an accelerometer
positioned in or on the housing 501 of the pulse generator 505. If
the motion sensor is implemented as an accelerometer, the motion
sensor may also provide respiratory, e.g. rales, coughing, and
cardiac, e.g. S1-S4 heart sounds, murmurs, and other acoustic
information.
[0120] The lead system 510 of the CRM 500 may incorporate one or
more transthoracic impedance sensors that may be used to acquire
the patient's respiration waveform, or other respiration-related
information. The transthoracic impedance sensor may include, for
example, one or more intracardiac electrodes 541, 542, 551-555, 563
positioned in one or more chambers of the heart 590. The
intracardiac electrodes 541, 542, 551-555, 563 may be coupled to
impedance drive/sense circuitry 530 positioned within the housing
of the pulse generator 505.
[0121] In one implementation, impedance drive/sense circuitry 530
generates a current that flows through the tissue between an
impedance drive electrode 551 and a can electrode on the housing
501 of the pulse generator 505. The voltage at an impedance sense
electrode 552 relative to the can electrode changes as the
patient's transthoracic impedance changes. The voltage signal
developed between the impedance sense electrode 552 and the can
electrode is detected by the impedance sense circuitry 530. Other
locations and/or combinations of impedance sense and drive
electrodes are also possible.
[0122] The voltage signal developed at the impedance sense
electrode 552, illustrated in FIG. 6, is proportional to the
patient's transthoracic impedance and represents the patient's
respiration waveform. The transthoracic impedance increases during
respiratory. inspiration 610 and decreases during respiratory
expiration 620. The peak-to-peak transition of the transthoracic
impedance is. proportional to the amount of air moved in one
breath, denoted the tidal volume. The amount of air moved per
minute is denoted the minute ventilation. A normal "at rest"
respiration pattern, e.g., during non-REM sleep, includes regular,
rhythmic inspiration--expiration cycles without substantial
interruptions, as indicated in FIG. 6.
[0123] Returning to FIG. 5, the lead system 510 may include one or
more cardiac pace/sense electrodes 551-555 positioned in, on, or
about one or more heart chambers for sensing electrical signals
from the patient's heart 590 and/or delivering pacing pulses to the
heart 590. The intracardiac sense/pace electrodes 551-555, such as
those illustrated in FIG. 5, may be used to sense and/or pace one
or more chambers of the heart, including the left ventricle, the
right ventricle, the left atrium and/or the right atrium. The lead
system 510 may include one or more defibrillation electrodes 541,
542 for delivering defibrillation/cardiove- rsion shocks to the
heart.
[0124] The pulse generator 505 may include circuitry for detecting
cardiac arrhythmias and/or for controlling pacing or defibrillation
therapy in the form of electrical stimulation pulses or shocks
delivered to the heart through the lead system 510. Circuitry for
implementing a respiratory logbook 535, including interface
circuitry, an event detector, an event processor, and/or memory
circuitry, as described in connection with the FIG. 2, may be
housed within the pulse generator 505. The respiratory logbook
circuitry may be coupled to various sensors, patient input devices,
and/or information systems through leads or through wireless
communication links.
[0125] FIG. 7 is a diagram illustrating an implantable
transthoracic cardiac device that may be used in connection with
acquiring and organizing data for a respiratory logbook in
accordance with embodiments of the invention. The implantable
device illustrated in FIG. 7 is an implantable transthoracic
cardiac sensing and/or stimulation (ITCS) device that may be
implanted under the skin in the chest region of a patient. The ITCS
device may, for example, be implanted subcutaneously such that all
or selected elements of the device are positioned on the patient's
front, back, side, or other body locations suitable for sensing
cardiac activity and delivering cardiac stimulation therapy. It is
understood that elements of the ITCS device may be located at
several different body locations, such as in the chest, abdominal,
or subclavian region with electrode elements respectively
positioned at different regions near, around, in, or on the
heart.
[0126] Circuitry for implementing a respiratory logbook system may
be positioned within the primary housing of the ITCS device. The
primary housing (e.g., the active or non-active can) of the ITCS
device, for example, may be configured for positioning outside of
the rib cage at an intercostal or subcostal location, within the
abdomen, or in the upper chest region (e.g., subclavian location,
such as above the third rib). In one implementation, one or more
electrodes may be located on the primary housing and/or at other
locations about, but not in direct contact with the heart, great
vessel or coronary vasculature.
[0127] In another implementation, one or more electrodes may be
located in direct contact with the heart, great vessel or coronary
vasculature, such as via one or more leads implanted by use of
conventional transvenous delivery approaches. In another
implementation, for example, one or more subcutaneous electrode
subsystems or electrode arrays may be used to sense cardiac
activity and deliver cardiac stimulation energy in an ITCS device
configuration employing an active can or a configuration employing
a non-active can. Electrodes may be situated at anterior and/or
posterior locations relative to the heart.
[0128] In the configuration shown in FIG. 7, a subcutaneous
electrode assembly 707 can be positioned under the skin in the
chest region and situated distal from the housing 702. The
subcutaneous and, if applicable, housing electrode(s) can be
positioned about the heart at various locations and orientations,
such as at various anterior and/or posterior locations relative to
the heart. The subcutaneous electrode assembly 707 is coupled to
circuitry within the housing 702 via a lead assembly 706. One or
more conductors (e.g., coils or cables) are provided within the
lead assembly 706 and electrically couple the subcutaneous
electrode assembly 707 with circuitry in the housing 702. One or
more sense, sense/pace or defibrillation electrodes can be situated
on the elongated structure of the electrode support, the housing
702, and/or the distal electrode assembly (shown as subcutaneous
electrode assembly 707 in the configuration shown in FIG. 7).
[0129] It is noted that the electrode and the lead assemblies 707,
706 can be configured to assume a variety of shapes. For example,
the lead assembly 706 can have a wedge, chevron, flattened oval, or
a ribbon shape, and the subcutaneous electrode assembly 707 can
comprise a number of spaced electrodes, such as an array or band of
electrodes. Moreover, two or more subcutaneous electrode assemblies
707 can be mounted to multiple electrode support assemblies 706 to
achieve a desired spaced relationship amongst subcutaneous
electrode assemblies 707.
[0130] In particular configurations, the ITCS device may perform
functions traditionally performed by cardiac rhythm management
devices, such as providing various cardiac monitoring, pacing
and/or cardioversion/defibrillation functions. Exemplary pacemaker
circuitry, structures and functionality, aspects of which can be
incorporated in an ITCS device of a type that may benefit from
multi-parameter sensing configurations, are disclosed in commonly
owned U.S. Pat. Nos. 4,562,841; 5,284,136; 5,376,476; 5,036,849;
5,540,727; 5,836,987; 6,044,298; and 6,055,454, which are hereby
incorporated herein by reference in their respective entireties. It
is understood that ITCS device configurations can provide for
non-physiologic pacing support in addition to, or to the exclusion
of, bradycardia and/or anti-tachycardia pacing therapies. Exemplary
cardiac monitoring circuitry, structures and functionality, aspects
of which can be incorporated in an ITCS of the present invention,
are disclosed in commonly owned U.S. Pat. Nos. 5,313,953;
5,388,578; and 5,411,031, which are hereby incorporated herein by
reference in their respective entireties.
[0131] An ITCS device can incorporate circuitry, structures and
functionality of the subcutaneous implantable medical devices
disclosed in commonly owned U.S. Pat. Nos. 5,203,348; 5,230,337;
5,360,442; 5;366,496; 5,397,342; 5,391,200; 5,545,202; 5,603,732;
and 5,916,243 and commonly owned U.S. patent applications Ser. No.
60/462,272, filed Apr. 11, 2003; Ser. No. 10/462,001, filed Jun.
13, 2003; Ser. No. 10/465,520, filed Jun. 19, 2003; Ser. No.
10/820,642, filed Apr. 8, 2004; and Ser. No. 10/821,248, filed Apr.
8, 2004, all of which are incorporated herein by reference.
[0132] The housing of the ITCS device may incorporate components of
a respiratory logbook system 705, including a memory, interface,
event processor and/or event detector circuitry. The respiratory
logbook circuitry may be coupled to one or more sensors, patient
input devices, and/or information systems as described in
connection with FIG. 2.
[0133] In one implementation, the ITCS device may include an
impedance sensor configured to sense the patient's transthoracic
impedance. The impedance sensor may include the impedance
drive/sense circuitry incorporated with the housing 702 of the ITCS
device and coupled to impedance electrodes positioned on the can or
at other locations of the ITCS device, such as on the subcutaneous
electrode assembly 707 and/or lead assembly 706. In one
configuration, the impedance drive circuitry generates a current
that flows between a subcutaneous impedance drive electrode and a
can electrode on the primary housing of the ITCS device. The
voltage at a subcutaneous impedance sense electrode relative to the
can electrode changes as the patient's transthoracic impedance
changes. The voltage signal developed between the impedance sense
electrode and the can electrode is sensed by the impedance
drive/sense circuitry.
[0134] Communications circuitry is disposed within the housing 702
for facilitating communication between the ITCS device and an
external communication device, such as a portable or bed-side
communication station, patient-carried/worn communication station,
or external programmer, for example. The communications circuitry
can also facilitate unidirectional or bidirectional communication
with one or more external, cutaneous, or subcutaneous physiologic
or non-physiologic sensors.
[0135] FIG. 8 is a block diagram illustrating a medical system 800
including a patient-internal device 810 that cooperates with a
patient-external device 820 to acquire and organize information in
a respiratory logbook in accordance with embodiments of the
invention. In this example, the respiratory logbook is displayed on
a display device 860 coupled to the patient-external device 820.
Alternatively, the display device 860 could be coupled to the
patient-internal device 810.
[0136] In one embodiment, the patient-internal device 810 may
comprise, for example, an implantable cardiac rhythm management
system (CRM) such as a pacemaker, defibrillator, cardiac
resynchronizer, or the like. In another embodiment, the
patient-internal device 810 may comprise, for example, an
implantable transthoracic cardiac sensing and/or stimulation device
(ITCS) as described in connection with FIG. 7. The patient-external
device 820 may comprise an external breathing therapy device such
as a continuous positive airway pressure device (CPAP), bi-level
positive airway pressure device (bi-PAP) or other positive airway
pressure device, generically referred to herein as xPAP
devices.
[0137] A typical CPAP device delivers air pressure through a nasal
mask worn by the patient. The application of continuous positive
airway pressure keeps the patient's throat open, reducing or
eliminating the obstruction causing apnea. Positive airway pressure
devices may be used to provide a variety of respiration therapies,
including, for example, continuous positive airway pressure (CPAP),
bi-level positive airway pressure (bi-level PAP), proportional
positive airway pressure (PPAP), auto-titrating positive airway
pressure, ventilation, gas or oxygen therapies. Some positive
airway pressure devices may also be configured to provide both
positive and negative pressure, such that negative pressure is
selectively used (and de-activated) when necessary, such as when
treating Cheyne-Stokes breathing, for example. The term xPAP will
be used herein as a generic term for any device using forms of
positive airway pressure (and negative pressure when necessary),
whether continuous or otherwise.
[0138] An xPAP device 820 develops a positive air pressure that is
delivered to the patient's airway through tubing 832 and mask 854
connected to the xPAP device 820. Positive airway pressure devices
are often used to treat disordered breathing. In one configuration,
for example, the positive airway pressure provided by the xPAP
device 820 acts as a pneumatic splint keeping the patient's airway
open and reducing the severity and/or number of occurrences of
disordered breathing due to airway obstruction. In addition to
delivering breathing therapy, the xPAP device 820 may provide a
number of monitoring and/or diagnostic functions in relation to the
respiratory system. For example, the xPAP device 820 may sense
respiration using an oxygen sensor, a microphone, a flow meter,
and/or other respiration sensing methods.
[0139] Components used in connection with acquiring and organizing
respiratory logbook information may be implemented by the
patient-internal CRM 810 device, by the patient-external xPAP 820
device, or by both devices. Further, the CRM and the xPAP devices
may be coupled to a remote computing device such as a patient
management server using wireless or wired link.
[0140] The CRM 810 may provide a first set of monitoring,
diagnostic, and/or therapeutic functions to the patient. The xPAP
device 820 may provide a second set of monitoring, diagnostic,
and/or therapeutic functions to the patient. The CRM device 810,
the xPAP device 820, or both may include sensors for sensing
conditions associated with events affecting respiration such as
those identified in Tables 1-3.
[0141] In one embodiment, sensors coupled to the CRM device 810 may
sense a first set of conditions associated with events affecting
respiration. The sensed information may be transmitted to
respiratory logbook circuitry incorporated in the xPAP device 820.
Sensors coupled to the xPAP device 820 may sense a second set of
conditions associated with events affecting respiration. The
information sensed by the xPAP device and the CRM device may be
organized by circuitry in the xPAP device into respiratory logbook
format.
[0142] In another embodiment, sensors coupled to the xPAP device
820 may sense a first set of information associated with events
affecting respiration and transmit the information to the CRM
device. Circuitry in the CRM device may combine the information
acquired by the xPAP device sensors with information acquired by
sensors coupled to the CRM device to generate the respiratory
logbook.
[0143] FIG. 9A provides a timing diagram illustrating the
acquisition of respiratory logbook information for a detected event
affecting respiration in accordance with embodiments of the
invention. The respiratory logbook system senses and stores in a
temporary buffer a sliding scale window 910 of one or more patient
conditions, such as those listed in Tables 1-3. The selection of
information that is sensed and stored may be programmable by the
physician. The selection of the information to be acquired may be
based on the patient's medical history. For example, if the patient
suffers from sleep apnea, or another form of disordered breathing,
the respiratory logbook would preferably be programmed to sense
conditions associated with disordered breathing. Conversely, if the
patient suffers from chronic obstructive pulmonary disorder, a
different set of conditions from those used for disordered
breathing could be sensed.
[0144] If an event affecting respiration is detected 915, then
pre-event information 930 acquired prior to the event is stored.
Information is collected and stored during 940 the event. Upon
detection that the event has terminated 945, post-event information
950 is collected and stored for a period of time after the
termination of the event. The event and post-event information 940,
950 may be acquired on a continuous basis, or the information may
be acquired during discrete intervals. After the post-event
information 950 is collected, the acquired information 930, 940,
950 is organized as a logbook entry. The respiratory logbook system
begins sensing for the next event.
[0145] FIG. 9B provides a timing diagram illustrating the
acquisition of respiratory logbook information for a predicted
event affecting respiration in accordance with embodiments of the
invention. The respiratory logbook system senses and stores in a
temporary buffer a sliding scale window 910 of one or more patient
conditions, such as those listed in Tables 1-3. The conditions that
are sensed and stored are programmable and may be selected based on
the patient's medical history. For example, the information sensed
and stored may include information that has been effectively used
to predict the one or more types of events affecting the patient's
respiration. If an event affecting respiration is predicted 912,
then pre-prediction information 920 is acquired and stored. When
the event affecting respiration is detected 915, then pre-event
information 930 acquired prior to the event is stored. Information
940 is collected and stored during the event. Upon detection that
the event has terminated 945, information 950 is collected and
stored for a period of time after the termination of the event. The
pre-event, event and post-event information 930, 940, 950 may be
acquired on a continuous basis, or the information may be acquired
during discrete intervals. After the post-event information 940 is
collected, the acquired information 920, 930, 940, 950 is organized
as a logbook entry. The respiratory logbook begins sensing for the
next event.
[0146] As previously discussed in connection with FIG. 3, the
respiratory logbook display may include information presented in
graphical format. In one embodiment, the user may choose to view a
marked respiration waveform, for example. FIGS. 10A and 10B provide
examples of marked respiration waveforms that may be acquired and
organized in a respiratory logbook. FIG. 10A illustrates a marked
respiration waveform in accordance with embodiments of the
invention. In one embodiment, information related to a marked
respiration waveform may be acquired continuously as a moving
snapshot of respiration-related conditions. In another embodiment,
the information related to the marked respiration waveform may be
acquired in response to one or more triggering events. For one
example, the triggering event may comprise an instruction from a
physician or through an advanced patient management system to begin
data collection. In another example, the triggering event may
comprise detection of various respiration conditions, such as
detection of the disordered breathing, or the detection of sleep.
In this scenario, the triggering event may initiate the collection
of respiration-related data during an interval of time that may
include time periods prior to, during, and/or following the
disordered breathing event.
[0147] As illustrated in FIG. 10A, the marked respiration waveform
1010 may comprise respiration symbols positioned at locations
relative to the respiration waveform to indicate when respiratory
events occur or the time when characteristics are calculated. In
this example, the respiration waveform 1010 is marked with
respiration symbols 1020 denoting the time between peaks on the
waveform and hypopnea symbols denoting when an hypopnea is detected
1030 and when an hypopnea ends 1035 after 22 seconds. In addition,
other symbols indicating respiration characteristics and/or
disordered breathing characteristics described above may be
superimposed on the respiration waveform. The marked respiration
waveform may be displayed on a display device to allow the
patient's physician to view respiratory disturbances and/or other
characteristics.
[0148] In addition to displaying the respiration waveform 1010, the
display may show other measurements and/or other waveforms. In FIG.
10B, an electrocardiogram (ECG) 1050 is shown above respiration
waveform 1010. The ECG 1050 is time-aligned with respiration
waveform 1010 and can be marked with indicators corresponding to
the occurrence of breathing and/or cardiac events, for example.
Markers 1060 indicating sensed ventricular events (Vs) and paced
ventricular events (Vp) are displayed above the ECG in FIG. 10B.
Displaying marked respiration waveforms and other waveforms related
to patient conditions allows the patient's physician to verify, for
example, that a disordered breathing event was properly detected.
This confirmation may be used to guide diagnostics and/or therapy.
Symbols annotating cardiac and respiratory events provide further
diagnostic information for physicians.
[0149] A number of the examples presented herein involve block
diagrams illustrating functional blocks used for in accordance with
embodiments of the present invention. It will be understood by
those skilled in the art that there exist many possible
configurations in which these functional blocks can be arranged and
implemented.
[0150] The examples depicted herein provide examples of possible
functional arrangements used to implement the approaches of the
invention. The components and functionality depicted as separate or
discrete blocks/elements in the figures in general can be
implemented in combination with other components and functionality.
The depiction of such components and functionality in individual or
integral form is for purposes of clarity of explanation, and not of
limitation. It is also understood that the components and
functionality depicted in the Figures and described herein can be
implemented in hardware, software, or a combination of hardware and
software.
[0151] Various modifications and additions can be made to the
preferred embodiments discussed hereinabove without departing from
the scope of the present invention. Accordingly, the scope of the
present invention should not be limited by the particular
embodiments described above, but should be defined only by the
claims set forth below and equivalents thereof,
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