News Column

Patent Issued for Collecting Sleep Quality Information via a Medical Device

July 7, 2014



By a News Reporter-Staff News Editor at Pain & Central Nervous System Week -- Medtronic, Inc. (Minneapolis, MN) has been issued patent number 8758242, according to news reporting originating out of Alexandria, Virginia, by NewsRx editors (see also Medtronic, Inc.).

The patent's inventors are Miesel, Keith A. (St. Paul, MN); Heruth, Kenneth T. (Edina, MN).

This patent was filed on March 12, 2010 and was published online on June 24, 2014.

From the background information supplied by the inventors, news correspondents obtained the following quote: "In some cases, an ailment that a patient has may affect the quality of the patient's sleep. For example, chronic pain may cause a patient to have difficulty falling asleep, and may disturb the patient's sleep, e.g., cause the patient to wake. Further, chronic pain may cause the patient to have difficulty achieving deeper sleep states, such as one or more of the nonrapid eye movement (NREM) sleep states. Other ailments that may negatively affect patient sleep quality include movement disorders, psychological disorders, sleep apnea, congestive heart failure, gastrointestinal disorders and incontinence. In some cases, these ailments are treated via an implantable medical device (IMD), such as an implantable stimulator or drug delivery device.

"Further, in some cases, poor sleep quality may increase the symptoms experienced by a patient due to an ailment. For example, poor sleep quality has been linked to increased pain symptoms in chronic pain patients. The link between poor sleep quality and increased symptoms is not limited to ailments that negatively impact sleep quality, such as those listed above. Nonetheless, the condition of a patient with such an ailment may progressively worsen when symptoms disturb sleep quality, which in turn increases the frequency and/or intensity of symptoms."

Supplementing the background information on this patent, NewsRx reporters also obtained the inventors' summary information for this patent: "In general, the invention is directed to techniques for collecting information that relates to the quality of patient sleep via a medical device, such as an implantable medical device (IMD). In particular, values for one or more metrics that indicate the quality of the patient's sleep are determined based on physiological parameters monitored by a medical device. In some embodiments, sleep quality information is presented to a user based on the sleep quality metric values. A clinician, for example, may use the presented sleep quality information to evaluate the effectiveness of therapy delivered to the patient by the medical device, to adjust the therapy delivered by the medical device, or to prescribe a therapy not delivered by the medical device in order to improve the quality of the patient's sleep.

"The medical device monitors one or more physiological parameters of the patient. Example physiological parameters that the medical device may monitor include activity level, posture, heart rate, respiration rate, respiratory volume, blood pressure, blood oxygen saturation, partial pressure of oxygen within blood, partial pressure of oxygen within cerebrospinal fluid, muscular activity, core temperature, arterial blood flow, melatonin level within one or more bodily fluids, and galvanic skin response. In order to monitor one or more of these parameters, the medical device may include, be coupled to one or more sensors, each of which generates a signal as a function of one or more of these physiological parameters.

"The medical device may determine a value of one or more sleep quality metrics based on the one or more monitored physiological parameters, and/or the variability of one or more of the monitored physiological parameters. In other embodiments, the medical device records values of the one or more physiological parameters, and provides the physiological parameter values to a programming device, such as a clinician programming device or a patient programming device. In such embodiments, the programming device determines values of one or more sleep quality metrics based on the physiological parameter values received from the medical device and/or the variability of one or more of the physiological parameters. The medical device may provide the recorded physiological parameter values to the programming device in real time, or may provide physiological parameter values recorded over a period of time to the programming device when interrogated by the programming device.

"Sleep efficiency and sleep latency are example sleep quality metrics for which a medical device or programming device may determine values. Sleep efficiency may be measured as the percentage of time while the patient is attempting to sleep that the patient is actually asleep. Sleep latency may be measured as the amount of time between a first time when the patient begins attempting to fall asleep and a second time when the patient falls asleep, and thereby indicates how long a patient requires to fall asleep.

"The time when the patient begins attempting to fall asleep may be determined in a variety of ways. For example, the medical device may receive an indication from the patient that the patient is trying to fall asleep, e.g., via a patient programming device in embodiments in which the medical device is an implantable medical device. In other embodiments, the medical device may monitor the activity level of the patient, and the time when the patient is attempting to fall asleep may be identified by determining whether the patient has remained inactive for a threshold period of time, and identifying the time at which the patient became inactive. In still other embodiments, the medical device may monitor patient posture, and the medical device or a programming device may identify the time when the patient is recumbent, e.g., lying down, as the time when the patient is attempting to fall asleep. In these embodiments, the medical device may also monitor patient activity, and either the medical device or the programming device may confirm that the patient is attempting to sleep based on the patient's activity level.

"As another example, the medical device may determine the time at which the patient begins attempting to fall asleep based on the level of melatonin within one or more bodily fluids, such as the patient's blood, cerebrospinal fluid (CSF), or interstitial fluid. The medical device may also determine a melatonin level based on metabolites of melatonin located in the saliva or urine of the patient. Melatonin is a hormone secreted by the pineal gland into the bloodstream and the CSF as a function of exposure of the optic nerve to light, which synchronizes the patient's circadian rhythm. In particular, increased levels of melatonin during evening hours may cause physiological changes in the patient, which, in turn, may cause the patient to attempt to fall asleep. The medical device may, for example, detect an increase in the level of melatonin, and estimate the time that the patient will attempt to fall asleep based on the detection.

"The time at which the patient has fallen asleep may be determined based on the activity level of the patient and/or one or more of the other physiological parameters that may be monitored by the medical device as indicated above. For example, a discernable change, e.g., a decrease, in one or more physiological parameters, or the variability of one or more physiological parameters, may indicate that the patient has fallen asleep. In some embodiments, a sleep probability metric value may be determined based on a value of a physiological parameter monitored by the medical device. In such embodiments, the sleep probability metric value may be compared to a threshold to identify when the patient has fallen asleep. In some embodiments, a plurality of sleep probability metric values are determined based on a value of each of a plurality of physiological parameters, the sleep probability values are averaged or otherwise combined to provide an overall sleep probability metric value, and the overall sleep probability metric value is compared to a threshold to identify the time that the patient falls asleep.

"Other sleep quality metrics that may be determined include total time sleeping per day, the amount or percentage of time sleeping during nighttime or daytime hours per day, and the number of apnea and/or arousal events per night. In some embodiments, which sleep state the patient is in, e.g., rapid eye movement (REM), or one of the nonrapid eye movement (NREM) states (S1, S2, S3, S4) may be determined based on physiological parameters monitored by the medical device, and the amount of time per day spent in these various sleep states may be a sleep quality metric. Because they provide the most 'refreshing' type of sleep, the amount of time spent in one or both of the S3 and S4 sleep states, in particular, may be determined as a sleep quality metric. In some embodiments, average or median values of one or more sleep quality metrics over greater periods of time, e.g., a week or a month, may be determined as the value of the sleep quality metric. Further, in embodiments in which values for a plurality of the sleep quality metrics are determined, a value for an overall sleep quality metric may be determined based on the values for the plurality of individual sleep quality metrics.

"In some embodiments, the medical device delivers a therapy. At any given time, the medical device delivers the therapy according to a current set of therapy parameters. For example, in embodiments in which the medical device is a neurostimulator, a therapy parameter set may include a pulse amplitude, a pulse width, a pulse rate, a duty cycle, and an indication of active electrodes. Different therapy parameter sets may be selected, e.g., by the patient via a programming device or a the medical device according to a schedule, and parameters of one or more therapy parameter sets may be adjusted by the patient to create new therapy parameter sets. In other words, over time, the medical device delivers the therapy according to a plurality of therapy parameter sets.

"In embodiments in which the medical device determines sleep quality metric values, the medical device may identify the current therapy parameter set when a value of one or more sleep quality metrics is collected, and may associate that value with the therapy parameter set. For example, for each available therapy parameter set the medical device may store a representative value of each of one or more sleep quality metrics in a memory with an indication of the therapy programs with which that representative value is associated. A representative value of sleep quality metric for a therapy parameter set may be the mean or median of collected sleep quality metric values that have been associated with that therapy parameter set. In other embodiments in which a programming device determines sleep quality metric values, the medical device may associate recorded physiological parameter values with the current therapy parameter set in the memory.

"A programming device according to the invention may be capable of wireless communication with the medical device, and may receive sleep quality metric values or recorded physiological parameter values from the medical device. In either case, when the programming device either receives or determines sleep quality metric values, the programming device may provide sleep quality information to a user based on the sleep quality metric values. For example, the programming device may be a patient programmer, and may provide a message to the patient related to sleep quality. The patient programmer may, for example, suggest that the patient visit a clinician for prescription of sleep medication or for an adjustment to the therapy delivered by the medical device. As other examples, the patient programmer may suggest that the patient increase the intensity of therapy delivered by the medical device during nighttime hours relative to previous nights, or select a different therapy parameter set for use during sleep than the patient had selected during previous nights. Further, the patient programmer may provide a message that indicates the quality of sleep to the patient to, for example, provide the patient with an objective indication of whether his or her sleep quality is good, adequate, or poor.

"In other embodiments, the programming device is a clinician programmer that presents information relating to the quality of the patient's sleep to a clinician. The clinician programmer may present, for example, a trend diagram of values of one or more sleep quality metrics over time. As other examples, the clinician programmer may present a histogram or pie chart illustrating percentages of time that a sleep quality metric was within various value ranges.

"In embodiments in which the medical device associates sleep quality metric values or physiological parameter values with therapy parameter sets, the programming device may receive representative values for one or more sleep quality metrics or the physiological parameter values from the medical device, and information identifying the therapy parameter set with which the representative values are associated. In embodiments in which the programming device receives physiological parameter values from a medical device, the programming device may determine sleep quality metric values associated with the plurality of parameter sets based on the physiological parameter values, and representative sleep quality metric values for each of the therapy parameter sets based on the sleep quality metric values associated with the therapy parameter sets. In some embodiments, the programming device may determine the variability of one or more of the physiological parameters based on the physiological parameter values received from the medical device, and may determine sleep quality metric values based on the physiological parameter variabilities.

"The programming device may display a list of the therapy parameter sets to the clinician ordered according to their associated representative sleep quality metric values. Such a list may be used by the clinician to identify effective or ineffective therapy parameter sets. Where a plurality of sleep quality metric values are determined, the programming device may order the list according to values of a user-selected one of the sleep quality metrics.

"In other embodiments, a system according to the invention does not include a programming device. For example, an external medical device according to the invention may include a display, determine sleep quality metric values, and display sleep quality information to a user via the display based on the sleep quality metric values.

"In one embodiment, the invention is directed to a method in which at least one physiological parameter of a patient is monitored via a medical device that delivers a therapy to the patient. A value of a metric that is indicative of sleep quality is determined based on the at least one physiological parameter. A current therapy parameter set is identified, and the sleep quality metric value is associated with the current therapy parameter set.

"In another embodiment, the invention is directed to a medical system comprising a medical device and a processor. The medical device delivers a therapy to a patient, and monitors at least one physiological parameter of a patient based on a signal received from at least one sensor. The processor determines a value of a metric that is indicative of sleep quality based on the at least one physiological parameter, identifies a current therapy parameter set, and associates the sleep quality metric value with the current therapy parameter set.

"In another embodiment, the invention is directed to a medical system comprising means for monitoring at least one physiological parameter of a patient, means for determining a value of a metric that is indicative of sleep quality based on the at least one physiological parameter, means for identifying a current therapy parameter set used by a medical device to delivery therapy to the patient, and means for associating the sleep quality metric value with the current therapy parameter set.

"In another embodiment, the invention is directed to a medical system comprising an implantable medical device and an external programming device including a display. The implantable medical device delivers a therapy to a patient, monitors at least one physiological parameter of the patient, and determines a plurality of values of a metric that is indicative of sleep quality based on the at least one physiological parameter. The external programming device receives sleep quality metric values from the implantable medical device, and presents sleep quality information to a user via the display based on the sleep quality metric values.

"In another embodiment, the invention is directed to a programming device comprising a telemetry circuit, a user interface including a display, and a processor. The processor receives sleep quality metric values from a medical device via the telemetry circuit, and presents sleep quality information to a user via the display based on the sleep quality metric values.

"In another embodiment, the invention is directed to a computer-readable medium comprising program instructions. The program instructions cause a programmable processor to receive sleep quality metric values from a medical device, and present sleep quality information to a user via a display based on the sleep quality metric values.

"In another embodiment, the invention is directed to a method in which a plurality of signals are monitored, each of the signals generated by a sensor as a function of at least one physiological parameter of a patient. When the patient is attempting to sleep is identified. When the patient is asleep is identified based on at least one of the signals. A value of a metric that is indicative of sleep quality is determined based on the identifications of when the patient is attempting to sleep and asleep.

"In another embodiment, the invention is directed to a medical system comprising a plurality of sensors and a processor. Each of the plurality of sensors generates a signal as a function of at least one physiological parameter of a patient. The processor monitors the signals generated by the sensors, identifies when the patient is attempting to sleep, identifies when the patient is asleep based on at least one of the signals, and determines a value of a metric that is indicative of sleep quality based on the identifications of when the patient is attempting to sleep and asleep.

"The invention may be capable of providing one or more advantages. For example, by providing information related to the quality of a patient's sleep to a clinician and/or the patient, a system according to the invention can improve the course of treatment of an ailment of the patient, such as chronic pain. Using the sleep quality information provided by the system, the clinician and/or patient can, for example, make changes to the therapy provided by a medical device in order to better address symptoms which are disturbing the patient's sleep. Further, a clinician may choose to prescribe a therapy that will improve the patient's sleep, such as a sleep inducing medication, in situations where poor sleep quality is increasing symptoms experienced by the patient.

"The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims."

For the URL and additional information on this patent, see: Miesel, Keith A.; Heruth, Kenneth T.. Collecting Sleep Quality Information via a Medical Device. U.S. Patent Number 8758242, filed March 12, 2010, and published online on June 24, 2014. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=8758242.PN.&OS=PN/8758242RS=PN/8758242

Keywords for this news article include: Therapy, Chronic Pain, Medtronic Inc., Nervous System Diseases, Neurologic Manifestations.

Our reports deliver fact-based news of research and discoveries from around the world. Copyright 2014, NewsRx LLC


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Source: Pain & Central Nervous System Week


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