WO2003024323A1

WO2003024323A1 - Method and apparatus for providing continuous ecg measurements in patient monitors

Info

Publication number: WO2003024323A1
Application number: PCT/US2002/026650
Authority: WO
Inventors: David Alan Sitzman; Robert Michael Farrell
Original assignee: GE Medical Systems Information Technologies Inc
Current assignee: GE Medical Systems Information Technologies Inc
Priority date: 2001-09-17
Filing date: 2002-08-21
Publication date: 2003-03-27
Anticipated expiration: 2004-03-17

Abstract

A method and apparatus for continuously monitoring a clinically valuable ECG measurement. The method including positioning a plurality electrodes (8) on a patient (12) and continuously acquiring signals (14) from the plurality of electrodes (8). One or more processors (16, 20, 22) process the signals (14) to produce a plurality of leads (18) and then, analyze the leads (18). Software algorithms calculate at least one clinically valuable ECG measurement based on the leads (18). The method is implemented on a patient monitor (10).

Description

METHOD AND APPARATUS FOR PROVIDING CONTINUOUS ECG MEASUREMENTS IN PATIENT MONITORS

BACKGROUND OF THE INVENTION

The present invention relates to a method and apparatus for providing continuous diagnostic quality, clinically valuable ECG measurements, and specifically, to a method and apparatus for providing these measurements using a patient monitor.

Electrocardiogram (ECG) signals have proved to be an important factor in determining the health of patients and detecting early signs of heart dysfunction. Key measurements recognized within an ECG signal such as the PR interval, QRS duration, and QT interval, are indicators of heart abnormalities and pathological conditions. These measurements can also be used to detect or to recognize the presence of different drugs within the body.

Currently, producing a diagnostic quality, clinically valuable ECG (i.e., an ECG from which a clinical diagnosis can be made) is time-consuming and expensive. Acquiring an ECG requires a specialized instrument called an electrocardiograph. The ECG signal produced by the electrocardiograph is much more accurate and clinically valuable for diagnostic puiposes than the cardiac waveform (i.e., the waveform represnting the electrical activity of the heart) generated by conventional patient monitoring equipment. Since hospitals have a limited supply of electrocardiographs, they are generally wheeled from patient to patient by a technician. Once an electrocardiograph is wheeled to the patient, ten different electrodes are placed over the chest and limbs of the patient to provide the twelve leads (or "views") that combine to form a very accurate indication of the clinical state of the heart. The electrocardiograph runs for only ten seconds and typically produces a printout of the signal along with some patient information and sometimes, an analysis of the waveforms. While the electrocardiograph is currently the most effective means for evaluating the heart's electrical activity, acquiring the ECG signals in this manner is expensive, time consuming, and does not allow continuous acquisition of clinically valuable ECG signals. Patient monitors typically allow continuous monitoring of the vital signs of severely ill patients. One of the parameters that is often monitored is the electrical activity of the heart. This is used to generate a cardiac waveform, from which heart rate and various irregularities in the cardiac function can be detected. The cardiac waveform is typically acquired via five electrodes connected to the patient. The signals from the five electrodes are processed and combined in various forms to generate as many as seven clinically important and recognized leads (or "views" of the heart). Nevertheless, the existing patient monitors are incapable of analyzing the cardiac waveform to indicate to the clinician key clinically valuable measurements of cardiac function such as PR interval, QRS duration, QT interval, P-wave axis, T-wave axis, QRS axis, and P-wave duration. If the clinician needs this information, and cannot wait for an electrocardiograph and operator to arrive, he/she must print a recording of the cardiac waveform from the central station, and manually measure the desired intervals and durations using hand-held calipers. This process is costly, time consuming and (because clinical practices vary from clinician to clinician) yields inconsistent results from reading to reading and from clinician to clinician.

SUMMARY OF THE INVENTION

Accordingly, it is an advantage to provide a patient monitor, for continuously acquiring an ECG signal from a patient, and including a software algorithm for measuring, displaying, and trending clinically valuable ECG measurements including PR interval, QRS duration, QT interval, P-wave axis, T-wave axis, QRS axis, and P- wave duration. In a preferred embodiment, the patient monitor is capable of providing the measurements using only five patient electrodes generating seven leads or signals.

The invention also provides a method for continuously acquiring clinically valuable ECG signals and measuring and trending key ECG measurements using a patient monitor. The patient monitor is equipped with a software algorithm that delivers automatic and continuous ECG measurements that include PR interval, QRS duration, QT interval, P-wave axis, T-wave axis, QRS axis, and P-wave duration.

It is an advantage of the invention to provide a patient monitor that reduces the amount of time a clinician spends manually measuring clinically valuable cardiac parameters. The time saved allows the clinician to devote more time to other patients, thereby increasing productivity. By automating the measurement process, it also reduces the human error found during manual measurement. This leads to faster and more accurate readings of clinically valuable parameters such as PR interval, QRS duration, QT interval, P-wave axis, T-wave axis, QRS axis, and P-wave duration.

It is another advantage of the invention to provide continuous and automatic measurement and trending of clinically valuable parameters such as PR interval, QRS duration, QT interval, P-wave axis, T-wave axis, QRS axis, and P-wave duration of ECG signals.

It is another advantage of the invention to provide a method of computing the measurements from a seven lead ECG which uses five electrodes instead of the conventional ten electrodes required to produce a twelve lead ECG. Eliminating five electrodes results in more comfort for the patient and costs less to maintain than ten electrodes.

As is apparent from the above, it is an advantage of the invention to provide a method for continuously measuring, displaying, and trending clinically valuable ECG measurements. Other features and advantages of the invention will become apparent by consideration of the detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG.l illustrates a patient, and a patient monitor embodying the invention connected to the patient. FIG.2 illustrates the preferred electrode configuration for the patient monitor shown in FIG.l .

FIG.3 illustrates a schematic view of the patient monitor shown in FIG.l .

DETAILED DESCRIPTION

Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of "including," "comprising," or "having" and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items.

FIG. 1 depicts the invention in use. Patient monitor 10 is coupled to the patient 12 by placing a series of electrodes 8 on the patient's chest. The preferred electrode configuration consists of five electrodes and is shown in FIG. 2. The first electrode 8A is placed on the patient's right upper chest in the second intercostal space from the midclavicular line. The second electrode 8B is positioned in the same manner, yet located on the patient's left upper chest instead of the right. The third electrode 8C is placed on the patient's right lower chest located in the fifth intercostal space from the midaxillary line. Situated in the same manner on the patient's left lower chest rests the fourth electrode 8D. The final electrode 8E is positioned on the anterior chest of the patient 12.

FIG. 3 illustrates a schematic diagram of the invention. Patient monitor 10 receives the ECG signals 14 acquired from electrodes 8 placed on the patient's chest. For this example, the use of five electrodes 8 producing five signals 14 is shown in the diagram. The signals 14 are transmitted to a signal conditioning circuit 16 located within the patient monitor 10. Here, the signals 14 are processed into the various leads 18. For example, the conditioning circuit 16 produces seven leads 18 from the five signals 14. Once the ECG leads 18 are generated, they are analyzed by two different processors 20 and 22. The first processor 20 utilizes a software package or series of algorithms, such as the EK-Pro™ brand software program, to recognize certain characteristics of the leads 18. The processor 20 establishes beat detection, classifies the beats and performs rhythm analysis as well as generates ST segment data from the input ECG leads 18. The processor 20 also performs the function of continuously trending the leads. This information is sent to the display unit 26 to be communicated to a user or clinician.

Still referring to FIG. 3, processor 22 analyzes the leads 18 and performs the necessary calculations to generate or determine the clinically valuable ECG measurements. The processor 22 implements software that is designed to recognize, measure, and trend such measurements. In the preferred embodiment, this process is an automated and continuous method of generating measurements including the PR interval, QRS duration, QT interval, P-wave axis, T-wave axis, QRS axis, and P-wave duration. In other embodiments however, the process may be manually initiated by the clinician. This design would reduce the processing power required by the monitor since it would not be constantly analyzing the waveforms. The QT interval may include the rate-corrected QT interval (QTc) or even the QT dispersion interval. The measurements calculated by the second processor 22 proceed to the display unit 26 where the measurements are displayed to the user. The second processor 22 is also capable of continually trending these measurements and displaying them as such.

As shown in FIG. 3, the patient monitor 10 is equipped with an alarm circuit 30. The processors 20 and 22 can each feed into the circuit 30, or each feed into a separate circuit 30 designated for each processor, or even have a circuit 30 incorporated into each processor. The alarm circuit 30 is activated when a parameter or a series of parameters are not within the designated range for that parameter or series. These parameters may include the clinically valuable ECG measurements, the calculated heart rate, rhythm, ST data or such. The circuit 30 signals to the user in some fashion (sound, visual, etc.) that a parameter or series of parameters is not within the appropriate range and indicates which parameter(s) are outside the range. In some embodiments, the alarm circuit 30 or the source of the alarm has the option of remaining active until the parameter settles within the appropriate range or has a manual termination option.

In a further embodiment of the invention, the patient monitor 10 features a manual data input 34. This data input 34 allows the user to annotate and/or edit the existing data generated and analyzed by each of the processors 20 and 22.

Thus, the invention provides, among other things, an automatic and continuous calculation of clinically valuable ECG measurements. Various features and advantages of the invention are set forth in the following claims. .

Claims

CLAIMSWhat is claimed is:

1 . A method of continuously monitoring a clinically valuable ECG measurement, the method comprising the acts of:

positioning a plurality electrodes (8) on a patient (12);

continuously acquiring signals (14) from the plurality of electrodes (8);

processing the signals (14) to produce a plurality of leads (18) based on the signals (14);

analyzing the leads (18); and

calculating at least one clinically valuable ECG measurement based on the leads (18).

2. A method as set forth in claim 1, further comprising the act of trending the signal and measurement.

3. A method as set forth in claim 2, further comprising the act of displaying the trended signal and trended measurement to a user.

4. A method as set forth in claim 1 , wherein the act of continuously acquiring signals is performed using a patient monitor (10).

5. A method as set forth in claim 1, wherein the clinically valuable ECG measurement is a one of PR interval, QRS duration, QT interval, P-wave axis, T-wave axis, QRS axis, or P-wave duration.

6. A method as set forth in claim 5, wherein the act of calculating clinically valuable ECG measurements includes the acts of:

calculating the QT interval;

analyzing the QT interval measurement; and signaling an alarm based on the analysis of the QT interval measurement.

7. A method as set forth in claim 1 , further comprising the act of editing the leads (18).

8. A patient monitor (10) providing a continuous clinically valuable ECG signal and a clinically valuable ECG measurement, the monitor comprising:

a plurality of inputs for receiving input signals (14) from a respective plurality of electrodes (8) attached to a patient (12);

an analysis module (16) for combining the signals (14) to produce a plurality of leads (18) from the plurality of signals (14); and

a software program for measuring, displaying, and trending a clinically valuable ECG measurement.

9. A monitor (10) as set forth in claim 8, further comprising an algorithm implementation to produce seven leads (18) from the five signals (14).

10. A monitor (10) as set forth in claim 8, further comprising a display format providing a trended plot of the signals and at least one clinically valuable ECG measurement.

1 1. A monitor (10) as set forth in claim 8, further comprising an implementation to allow users to edit and annotate data.

12. A method of continuously monitoring a clinically valuable ECG measurement, the method comprising the acts of:

positioning a plurality of electrodes (8) on a patient (12);

continuously acquiring signals (14) from the plurality of electrodes (8);

processing the signals (14); combining the signals (14) to generate a plurality of leads (18) based on the signals (14);

analyzing the leads (18);

calculating at least one clinically valuable ECG measurement from at least one lead (18);

displaying the measurement to the user on a patient monitor (10); and

trending the measurements.

13. A method as set forth in claim 12, further comprising the act of trending the measurements.

14. A method as set forth in claim 12, wherein the clinically valuable ECG measurement refers to PR interval, QRS duration, QT interval, P-wave axis, T-wave axis, QRS axis, or P-wave duration.

15. A method as set forth in claim 12, further comprising the act of editing the leads (18).