The present invention generally relates to physiological data processing and more particularly, to a system, method and device for determining one or more physiological parameters of a person.
Monitoring vital signs is traditionally done on supine patients at rest. Field based measurements are typically done with a care giver or researcher controlling the person's position (e.g., posture) and degree of movement in order to minimise movement artefacts such as orthstatic changes and effects on the body due to work effort of orientation. Normally tests are performed under various conditions in a clinic manually, using such devices as blood pressure cuffs, electrocardiogram (ECG) devices, face masks and using treadmills for exertion tests.
Measuring vital signs over time (in the field) provides more useful information to allow an understanding of a person's physiological state. However, body activity level may affect a person's vital signs and hence the interpretation thereof.
An ECG measures the electrical activity of a person's heart over time captured by electrodes attached to the person's skin. The ECG waveform data, however, may be adversely impacted due to the activity level (movement) of the person, noise, environmental factors, posture, and/or other factors. For example, movement of a person wearing the skin electrodes connected to an ECG device may cause the ECG waveform data to be nearly unusable. Thus, a system for monitoring a person's heart that considers the movement of the person, environmental factors, posture of the person, and signal noise is needed.
These and other advantages may be provided by one or more embodiments of the present invention.
The above objectives and other objectives are obtained by a method of monitoring the heart of a person, comprising:
The objectives are further obtained by a method of monitoring the heart of a person, comprising:
The objectives are also obtained by a computer program product, comprising a computer usable medium having a computer readable program code embodied therein, said computer readable program code adapted to be executed to implement a method for monitoring the heart of a person, the method comprising:
The objectives are further obtained by a method of monitoring a vital sign of a person, comprising:
The objectives are also obtained by a method of monitoring a vital sign of a person, comprising:
The invention is further described in the detailed description that follows, by reference to the noted drawings by way of non-limiting illustrative embodiments of the invention, in which like reference numerals represent similar parts throughout the drawings. As should be understood, however, the invention is not limited to the precise arrangements and instrumentalities shown. In the drawings:
In the following description, for purposes of explanation and not limitation, specific details are set forth, such as particular networks, communication systems, computers, terminals, devices, components, techniques, data and network protocols, software products and systems, operating systems, development interfaces, hardware, etc. in order to provide a thorough understanding of the present invention.
However, it will be apparent to one skilled in the art that the present invention may be practiced in other embodiments that depart from these specific details. Detailed descriptions of well-known networks, communication systems, computers, terminals, devices, components, techniques, data and network protocols, software products and systems, operating systems, development interfaces, and hardware are omitted so as not to obscure the description.
Embodiments of the present invention address the issue of monitoring a person's vital signs in the field (e.g., at home, in a gym, at work, etc.) and while the person is engaging in any activity, which may include running, walking, jumping, and/or playing sports (e.g., basketball, football, tennis, racquetball, baseball, etc.). The present invention provides a novel way to derive valid vital sign data such as heart rate data from ECG waveform data and breathing rate data collected during various activity levels and/or under other conditions using a combination of biomechanical sensors, physiological sensors and algorithms that process the data over time.
Thus, example embodiments of the present invention generally relate to physiological data processing and more particularly, to a system, method and device for determining one or more physiological parameters of a person and decoupling (removing) movement based artifacts by changing the frequency components analysed and/or by performing time or frequency domain subtraction of such components resulting in the desired physiological vital sign. Vital sign measurements such as heart and breathing waveforms can be disturbed by movement artifacts. Movement of the person can create various interfering signals from lead movement, sensor to skin impedance changes, tissue ionic disturbances and un wanted tissue electrical signals. In some embodiments, these interfering signals may be removed from the desired signal (e.g., heart rate and/or breathing rate) by adapting the frequency used to collected the desired signals, such as by reducing the bandwidth of an input filter, employing one or more notch filters, and/or performing phase analyses. Additionally the interfering signal can be analyzed and used with the total signal to determine the desired physiological vital sign signal (without the interfering signal).
In one example embodiment, the present invention uses an ECG sensor system and an activity level monitoring system such as an accelerometer. Based on the activity level of the person, portions of the ECG waveform data may be filtered out so as not to provide an inaccurate ECG waveform data. Specifically, the activity level of a person is monitored during collection of ECG waveform data and when the activity level is below a threshold level, the ECG waveform data is output (and processed) including, for example, the P, Q, R, S and T portions. However, when the activity level is above a threshold level, the ECG waveform data is filtered and only a portion of the ECG waveform data is output (and processed) such as only the R portion, which may be used to determine heart rate, etc. Thus, in this example embodiment, the activity level reaching a threshold level acts as a triggering condition that triggers filtering of the ECG waveform data. Other embodiments may use additional or different sensors such as environmental sensors (e.g., temperature, humidity, wind, air pressure, altitude, speed (such as vehicle speed or velocity), underwater depth, GPS location, etc.) and/or other physiological sensors (e.g., measuring posture, body temperature, respiration, skin resistance, breathing rate, etc.) to allow triggering (between filtering and not filtering the ECG waveform data) based on one or more other triggering conditions or events.
The data used by embodiments of the present invention may be collected and processed by a device such as a BioHarness BT (or the BioHarness or BioHarness HxM), which is commercially available and manufactured by Zephyr Technology of Annapolis, Md. See
One example algorithm for monitoring the person's heart is described below in conjunction with
The remainder of the processes of
If at 130 it is determined that the person's activity level during the collection of the set of ECG waveform data is above the predetermined threshold, the ECG waveform data is filtered (e.g., to reject noise) at 160 such as by filtering out the Q, S, and T portions (e.g., as explained with regard to
The filtered ECG waveform data is output at 170 and processed at 180. For example, from the filtered ECG waveform data the process may determine the heart rate, the R to R wave timing, and the R to R wave variability.
In addition, Maximum Heart Rate or HRmax may be determined by processing the heart rate to determine the highest heart rate during the activity by performing a moving average (e.g., with a 10 or 15 second trailing window). In addition, Heart Rate Recovery or HRR may also be determined, which is the decrease in heart rate from the time activity stops (Tstop) to a predetermined time (Tlo). In some embodiments of the present invention, the algorithm may compute the HRR using data of the heart rate thirty seconds after the activity stops (i.e., after the activity falls below a threshold) and is computed as the high heart rate (just prior to stoppage of the activity) minus the heart rate thirty seconds after stopping the activity.
Finally, at 190 the processed ECG waveform data (from 150) and the processed filtered ECG waveform data (from 180) are output at 190.
In one embodiment, the output of the unfiltered ECG waveform data (from 140) and the filtered ECG waveform data (from 170 are performed sequentially for each heart beat so that the clinician can view one graphical representation of the person's heart as shown in
It is worth noting that throughout the collection of data and at various activity levels (both above and below the activity threshold level or other triggering event), the person's heart rate (in this embodiment), R to R timing, R to R variability and other information may readily be determined. In prior art systems, where ECG waveform data may simply be discarded due to inaccuracies caused by high inactivity levels, there would be gaps in the heart rate and other data. In addition, because high activity levels often result in high heart rates, such gaps can be especially critical.
The threshold levels of the above conditions to trigger not filtering may be the same or different from the threshold levels to trigger filtering.
In still other embodiments, combinations of any of the above conditions may be used to trigger filtering (and not filtering). For example, the combination of a heart rate above a threshold and a SNR of the ECG waveform above a threshold may be required to not filter the ECG waveform data. As another example, filtering may be triggered only if the activity level is above a threshold and the heart rate is below a threshold.
Referring again to
Thus, embodiments of the present invention may be used to provide unfiltered ECG waveform data when it less likely to be corrupted (and filtered ECG waveform data at other times) such as when (1) the person is lying or sitting (but filtered when standing); (2) when the person is not running (or not walking); (3) when the person's heart rate is a above a threshold (and more likely to be of interest to the clinician); (4) when the person provides a user input to indicate a user request (indicating the user is feeling palpitations, chest pain, or undergoing some other event); etc.
In some embodiments, instead of filtering the ECG waveform data, no ECG waveform data (filtered or not) is outputted or, alternately measured, unless one or more conditions are satisfied. For example, it may be desirable to only measure and record ECG waveform when the person is under exertion such as when their heart rate is above a threshold. In such an embodiment, the trigger condition sensor 440 may supply its output to actuate the ECG sensor system whose output would be directly supplied to the recorder 450. The method steps may include monitoring one or more trigger conditions, determining whether a trigger condition is satisfied, and collecting and output ECG waveform data if a trigger condition is satisfied.
Algorithms of the present invention can be used while a person is carrying out random events (or exercises) or is performing requested (known) behaviour.
The present invention may be embodied, at least in part, as a computer system (one or more co-located or distributed computers) or cluster executing one or more computer programs stored on a tangible medium. The algorithm may be executed (and computer system located) local or remote from the user. The algorithm may be executed on a computer system that also includes other functions such a telephone or other device (e.g., an IPhone®, IPad®, or Blackberry®), which may have processing and communications capabilities. As discussed, the algorithm may also be stored and executed on the collection device or a separate remote device.
Consequently, in one embodiment the method of monitoring the heart of a person, comprises collecting a plurality of sets of ECG waveform data of the person, wherein each set of ECG waveforms, derived numbers such as heart rate and data including a Q portion, an R portion, an S portion, and a T portion for each heart beat and storing the ECG waveform data in a memory. Concurrently with said collecting a plurality of sets of ECG waveform data of the person, the method comprises collecting data of an activity level of the person and storing data the activity level in a memory. The method may further include for each of the plurality of sets of ECG waveform data, determining whether the activity level of the person during collection of a set of ECG waveform data exceeds a threshold; outputting the set of ECG waveform data if the activity level of the person during collection of the set of ECG waveform data does not exceed the threshold; and if the activity level of the person during collection of the set of ECG waveform data exceeds the threshold, filtering the ECG waveform data to provide data of the R portion of the ECG for each heart beat of the set of ECG waveform data and not provide data of the Q portion, S portion, or T portion for each heart beat of the set of data; and outputting the filtered ECG waveform data. The activity of the person during collection of at least one set of ECG waveform data exceeds the threshold, the method may further comprise determining the heart rate of the person over the plurality of the sets of ECG waveform data.
In another embodiment, the method of monitoring the heart of a person may comprise collecting a plurality of sets of ECG waveform data of the person; wherein each set of ECG waveform data includes a Q portion, an R portion, an S portion, and a T portion for each heart beat; storing the ECG waveform data in a memory; concurrently with said collecting a plurality of sets of ECG waveform data of the person, collecting data of an activity level of the person; storing data the activity level in a memory; for each of the plurality of sets of ECG waveform data, determining whether the activity level of the person during collection of a set of ECG waveform data exceeds a threshold; outputting the set of ECG waveform data if the activity level of the person during collection of the set of ECG waveform data does not exceed the threshold; and if the activity level of the person during collection of the set of ECG waveform data exceeds the threshold, filtering the ECG waveform data to exclude the Q portion, S portion, and T portion for each heart beat of the set of data and not excluding the R portion for each heart beat of the set of data; and outputting the filtered ECG waveform data. Wherein activity of the person during collection of at least one set of ECG waveform data exceeds the threshold, the method may further comprise determining the heart rate of the person over the plurality of the sets of ECG waveform data.
In yet another embodiment, the invention may comprise a computer program product, comprising a computer usable medium having a computer readable program code embodied therein, said computer readable program code adapted to be executed to implement a method for monitoring the heart of a person, the method comprising receiving a plurality of sets of ECG waveform data of the person; wherein each set of ECG waveform data includes a Q portion, an R portion, an S portion, and a T portion for each heart beat; storing the ECG waveform data in a memory; receiving data of an activity level of the person collected concurrently with the collection the plurality of sets of ECG waveform data of the person; storing data the activity level in a memory; for each of the plurality of sets of ECG waveform data, determining whether the activity level of the person during collection of a set of ECG waveform data exceeds a threshold; outputting the set of ECG waveform data if the activity level of the person during collection of the set of ECG waveform data does not exceed the threshold; and if the activity level of the person during collection of the set of ECG waveform data exceeds the threshold, filtering the ECG waveform data to exclude the Q portion, S portion, and T portion for each heart beat of the set of data and not excluding the R portion for each heart beat of the set of data; and outputting the filtered ECG waveform data. The activity of the person during collection of at least one set of ECG waveform data exceeds the threshold, the method may further comprise determining the heart rate of the person over the plurality of the sets of ECG waveform data.
In yet another embodiment, the invention may comprise a method of monitoring a vital sign of a person, comprising collecting a plurality of sets of physiological waveform data of the person; for each of the plurality of sets of physiological waveform data, determining whether a trigger condition is satisfied during collection of a set of physiological waveform data; outputting the set of physiological waveform data if the trigger condition is not satisfied during collection of the set of physiological waveform data; and if the trigger condition is satisfied during collection of the set of ECG waveform data, filtering the physiological waveform data and outputting the filtered physiological waveform data.
In yet another embodiment, the invention may comprise a method of monitoring a vital sign of a person, comprising collecting a plurality of sets of physiological waveform data of the person; for each of the plurality of sets of physiological waveform data, determining whether a trigger condition is satisfied during collection of a set of physiological waveform data; outputting the set of physiological waveform data if the trigger condition is not satisfied during collection of the set of physiological waveform data; and if the trigger condition is satisfied during collection of the set of physiological waveform data, performing the steps of: determining whether an interfering signal can be extracted from the set of physiological waveform data and if so, extracting the interfering signal from the physiological waveform data and outputting the physiological waveform data with the interfering signal extracted; if the interfering signal cannot be extracted from the physiological waveform data, filtering the physiological waveform data and outputting the filtered physiological waveform data. The physiological waveform data may comprise breathing waveform data or ECG waveform data. The interference signal may be determined by data from an accelerometer.
In yet another embodiment, the invention may comprise a method of monitoring a vital sign of a person, comprising collecting a plurality of sets of physiological waveform data of the person; for each of the plurality of sets of physiological waveform data, determining whether a trigger condition is satisfied during collection of a set of physiological waveform data; outputting the set of physiological waveform data if the trigger condition is not satisfied during collection of the set of physiological waveform data; and if the trigger condition is satisfied during collection of the set of ECG waveform data, extracting a noise signal from the physiological waveform data and outputting the physiological waveform data with the noise signal extracted. The trigger condition may comprise a SNR below a threshold and/or an activity level above a threshold.
It is to be understood that the foregoing illustrative embodiments have been provided merely for the purpose of explanation and are in no way to be construed as limiting of the invention. Words used herein are words of description and illustration, rather than words of limitation. In addition, the advantages and objectives described herein may not be realized by each and every embodiment practicing the present invention. Further, although the invention has been described herein with reference to particular structure, materials and/or embodiments, the invention is not intended to be limited to the particulars disclosed herein. Rather, the invention extends to all functionally equivalent structures, methods and uses, such as are within the scope of the appended claims. Those skilled in the art, having the benefit of the teachings of this specification, may affect numerous modifications thereto and changes may be made without departing from the scope and spirit of the invention.
This application claims priority to U.S. Provisional Patent Application Ser. No. 61/438,298, filed 1 Feb. 2011, the complete disclosure of which is incorporated herein by reference.
Number | Date | Country | |
---|---|---|---|
61438298 | Feb 2011 | US |