Method and apparatus for measuring heart-related parameters and deriving human status parameters from sensed physiological and contextual parameters

Abstract

A monitor device and associated methodology are disclosed which provide a self contained, relatively small and continuously wearable package for the monitoring of heart related parameters, including ECG. The detection of heart related parameters is predicated on the location of inequipotential signals located within regions of the human body conventionally defined as equivalent for the purpose of detection of heart related electrical activity, such as on single limbs. Amplification, filtering and processing methods and apparatus are described in conjunction with analytical tools for beat detection and display.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is a continuation of co-pending U.S. application Ser. No. 10 / 940,889 entitled Method and Apparatus for Measuring Heart Related Parameters filed Sep. 13, 2004, which claims the benefit of U.S. Provisional Application Ser. No. 60 / 502,764, filed Sep. 12, 2003; U.S. Provisional Application Ser. No. 60 / 510,013, filed Oct. 9, 2003; and U.S. Provisional Application Ser. No. 60 / 555,280, filed Mar. 22, 2004.BACKGROUND[0002]1. Field[0003]The present invention relates to a method and apparatus for accurately measuring heart related parameters from within a conventionally defined equivalence region of the human body. More particularly, a method and apparatus is disclosed for measuring an ECG signal and other heart related parameters such as heart beats or heart rate from a single limb of the human body. Most specifically, the heart related parameters are taken from the upper left or right arm.[0004]2. Description of the Related Art[0...

AI Technical Summary

Benefits of technology

[0024]A monitor device and associated methodology are disclosed which provide a self contained, relatively small and wearable package for the monitoring of heart related parameters, including ECG. The monitor device is primarily a simple, unobtrusive housing which is wearable in the sense that it is temporarily affixed to the user's body, but also wearable in the sense described in Stivoric, et al., U.S. Pat. No. 6,527,711, issued Mar. 4, 2003, the disclosure of which is incorporated by reference hereto. Stivoric teaches that the sizing, flexibility and location of items attached to the body significantly affect the ability of the wearer to recognize the item as part of the body, reducing the irritation factor associated with wearing such an item for extended periods of time. Furthermore, the use of the appropriate shapes, materials and locations reduces the interference of the item with normal body movement and activity. Each of these factors increases the wearability of the item and therefore increases the compliance of the wearer with the need for long term and continuous wear.

[0025]More specifically, the monitor device may be of a type described in Teller, et al., U.S. Pat. No. 6,605,038, issued Aug. 12, 2003, the specification of which is incorporated herein by reference. The primary focus of the monitor device itself is to provide the functionality described below in a housing or other package which is comfortable for long term wear, remains in place during normal daily activity so as to continuously provide a quality signal or data record and also reduces the noise or other interference to that signal or record created by the device itself. One focus of the device is to provide a self-contained housing which incorporates all or at least the majority of the operating hardware. The monitor device, in addition to the Teller device, may further include, as an accessory or rigid housing substitute, a large sized adhesive strip, similar to that used for cuts and abrasions which contains the sensor package within the current location of the absorbent material. Reduction of weight and bulk is very important to increasing the ability for the device to remain affixed in both the right location and with proper contact to the body, especially under rigorous conditions, such as exercise. The device is easy to put on and take off without need for extensive or clinical skin preparation, if any. The device is provided with an appropriate type and strength of adhesive required to keep the weight of the device from disconnecting any snaps or other connections, or pulling the electrode off of the skin. One primary advantage of the device is the elimination of long lead wires which, in addition to being unsightly and inconvenient, act as large antennas for creating noise input to the system. Reduction in the amount of snap connections also reduces these noises, which are common for Holter and loop devices. While not necessarily possible with the current state of processor and sensor size, it is clearly contemplated that the instant system, given the appropriate miniaturization of hardware, could be as simple as sliding on a watch or pair of glasses, utilizing the same basic methodology and equipment identified herein.

[0032]The system is designed to collect data continuously, with no interaction of the wearer necessary, but such interaction is permitted for additional functionality such as particular time stamping capabilities, as necessary. The ability to continuously monitor the heart related parameters limits the need for a manual trigger at the time of an event or the detection of a threshold condition based upon the status of the derived data, as described above. While the system is designed to collect data continuously, in some embodiments the user may utilize the timestamp button to signal that certain heart rate parameters should be collected for the time period around the timestamp. An additional functionality of the device is context and activity detection. Through the use of both the physiological and contextual sensors provided in the device, the ability to learn, model, or ascertain what combinations of data parameters relate to certain activities can be achieved. The ability to detect and discern the type of activity in which the user is engaged relieves the user of the need to manually log these activities to correlate with the heart output data during subsequent review.

[0035]Additionally, the device may be combined with other like devices in a cooperative array, which may be utilized to further process or analyze the signals derived therefrom. For example, in the case of a pregnant woman, a first such device may be positioned to detect the mother's heart related parameters in a location unlikely to detect the fetal heart related parameters and a second such device, especially in the form of an adhesive or other patch, might be located immediately adjacent the fetus on the mother's abdomen. The signals from the mother's device could be utilized to eliminate the noise of the mother's heart related parameters from the fetus' data stream.

[0036]Feedback from the system can take many forms, including the standard visual graphical methods, but a preferred embodiment would include audio feedback as well. This audio component may be in the form of a sound that resonates / conducts through the body, like a bone phone or other variant, to make this feeling more intimate and body like, even if the sound is manufactured digitally to represent the beat. A digital or analog stethoscope could be included in the system to assist in the production of an appropriate sound. Such a device on the abdomen could alternatively be made up of an array of Doppler or ECG electrodes to reduce the need to search for the most appropriate signal location. The device may also be adapted to work in conjunction with an implantable device or other consumed data detector.

Problems solved by technology

Such devices, while highly accurate, are very expensive and cumbersome and thus do not lend themselves well to ambulatory or long term uses such as in a free living environment.

The physical bulk and inconvenient accessories of this device restricts its continuous use to a relatively short time frame.

Consequently, the sensors are not easily interchanged and may limit physical or hygienic activity.

Holter monitors are relatively expensive and for the reasons listed above, are not comfortable for long term and / or active wear situations.

While some success with respect to longer term wearability and comfort is achieved, these loop monitor devices are still inconvenient for everyday use, and include lead wires from the device, snap on sensors affixed to the body by adhesives which require daily skin preparation and periodic re-alignment of the sensors to the original positions.

Implantable loop recorders have also been developed, which provide similar functionality, with the attendant inconvenience and risks associated with an invasive implant.

This device is not utilized for continuous monitoring, and has memory capability for only a limited number of event records.

Chest strap monitors of this type, while promoted for use in exercise situations, are not particularly comfortable to wear and are prone to lift off of the body during use, particularly when the wearer lies on his or her back.

Such watches, while comfortable to wear, only make measurements when touched in this particular manner and thus are not suitable for monitoring ECG and heart rate continuously over long periods of time or while conducting everyday activities such as eating, sleeping, exercising or even keyboarding at a computer.

Moreover, the traditional model rejects the measurement of the action potential from two locations on the same limb.

Another significant shortcoming of ambulatory devices is electrical noise.

A significant noise problem exists in that environment, including the heart action of the mother, as well as the significant noise and distortion caused by the fetus' location within a liquid sac inside the mother's abdomen.

The system, like many of the prior art, is unconcerned with the wearability of the monitoring device or the ability to continuously monitor the subject over a long period of time.

None of the above systems identified above combine wearability and accuracy in a compact device.

Although there are some examples in the prior art that recognize the possibility of inequipotential pairs within a single equivalence region, that the teachings of the prior art fail to utilize these pairs for obtaining a viable signal.

There are several barriers to the ability to utilize these signals from unconventional locations, including the small amplitude of the signal, which can be less than one tenth of the signal measured at most conventionally placed electrode locations, the high amount of noise with respect to that signal, as well as the significant effort and risk required to overcome limitations in accuracy, amplitude, and noise obtained from unconventional placements.

Additionally, what is lacking in the art is the ability to combine the continuous monitoring of the heart related parameters with a device which can detect, identify and record the physical activities of the wearer and correlate the same to the heart related parameters.

Each of these factors increases the wearability of the item and therefore increases the compliance of the wearer with the need for long term and continuous wear.

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