WO2007053820A1 - Systeme de detection de mouvement pour defibrillateur externe - Google Patents

Systeme de detection de mouvement pour defibrillateur externe Download PDF

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Publication number
WO2007053820A1
WO2007053820A1 PCT/US2006/060362 US2006060362W WO2007053820A1 WO 2007053820 A1 WO2007053820 A1 WO 2007053820A1 US 2006060362 W US2006060362 W US 2006060362W WO 2007053820 A1 WO2007053820 A1 WO 2007053820A1
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WO
WIPO (PCT)
Prior art keywords
patient
ecg
motion
ecg analysis
analysis
Prior art date
Application number
PCT/US2006/060362
Other languages
English (en)
Inventor
Rodney G. Stickney
Daniel W. Piraino
Patricia J. O'hearn
Cynthia P. Jayne
Original Assignee
Medtronic, Emergency Response Systems, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Medtronic, Emergency Response Systems, Inc. filed Critical Medtronic, Emergency Response Systems, Inc.
Publication of WO2007053820A1 publication Critical patent/WO2007053820A1/fr

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Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N1/00—Electrotherapy; Circuits therefor
    • A61N1/18—Applying electric currents by contact electrodes
    • A61N1/32—Applying electric currents by contact electrodes alternating or intermittent currents
    • A61N1/38—Applying electric currents by contact electrodes alternating or intermittent currents for producing shock effects
    • A61N1/39—Heart defibrillators
    • A61N1/3925—Monitoring; Protecting
    • A61N1/3931—Protecting, e.g. back-up systems
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/24—Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof
    • A61B5/316—Modalities, i.e. specific diagnostic methods
    • A61B5/318—Heart-related electrical modalities, e.g. electrocardiography [ECG]
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/72—Signal processing specially adapted for physiological signals or for diagnostic purposes
    • A61B5/7203—Signal processing specially adapted for physiological signals or for diagnostic purposes for noise prevention, reduction or removal
    • A61B5/7207—Signal processing specially adapted for physiological signals or for diagnostic purposes for noise prevention, reduction or removal of noise induced by motion artifacts
    • A61B5/721—Signal processing specially adapted for physiological signals or for diagnostic purposes for noise prevention, reduction or removal of noise induced by motion artifacts using a separate sensor to detect motion or using motion information derived from signals other than the physiological signal to be measured

Definitions

  • the present invention relates to the field of external, implantable, or subcutaneous defibrillators, and in particular to motion detection systems for external, implantable, or subcutaneous defibrillators.
  • Sudden cardiac arrest is a life-threatening cardiac emergency, typically caused by ventricular fibrillation, a condition where the human heart is unable to pump the volume of blood required by the human body.
  • the generally accepted therapy for restoring a normal rhythm to a heart experiencing ventricular fibrillation (VF) is to apply electrical defibrillation therapy.
  • This is the application of a strong electric pulse to the heart, which can be done using an external implantable, or subcutaneous cardiac defibrillator.
  • automated external defibrillators known as AEDs, have been successfully used by emergency responders such as firefighters, police officers and laypersons, having minimal or no medical training. AEDs are now easily accessible in many public places for use by lay rescuers while waiting for professional emergency medical service providers to arrive on the scene.
  • CPR cardiopulmonary resuscitation
  • CPR includes a technique in which the patient's chest is rhythmically compressed, in order to compress the heart so as to force blood flow through the circulatory system, and ventilation of the patient, by mouth-to-mouth breathing, with or without a intervening mask, or using a bag valve mask assembly where the rescuer squeezes a bag which forces air into a mask placed around the patient's mouth and nose.
  • some professional emergency medical responders use automated mechanical chest compression devices to administer chest compressions, chest compressions are more commonly applied to a patient manually, with the rescuers hands on the patient's chest, and the rescuer's body providing the compressive force.
  • AEDs analyze the patient's ECG to determine whether the heart is in a condition, where defibrillating shock is appropriate therapy.
  • SCA the treatment of SCA
  • treatment by defibrillating shock must be given within a very few minutes. Thus, every second counts.
  • Excessive patient motion has long been known to adversely affect the reliability of detected ECG data and its analysis.
  • Conventional AEDs have algorithms for detecting excessive motion (for example, motion, due to CPR) and interrupting ECG analysis if excessive motion is detected. ECG analysis may not be restarted until a cessation of excessive motion is detected. In some cases, there may be considerable delay in restarting ECG analysis, or the device may prompt for another cycle of CPR if excessive motion is ongoing, which will delay ECG analysis for the duration of the CFR cycle. But for treatment of VF to be successful, a defibrillating shock must be given within a very few minutes of its onset.
  • a method of operating a medical device capable of analyzing a patient's ECG includes the steps of: (a) determining if the patient is undergoing motion; (b) if it is determined that the patient is undergoing motion, providing an indication of patient motion; (c) after providing the indication, determining if the patient is undergoing motion, and if the patient is undergoing motion, starting ECG analysis after an elapsed time to .
  • the elapsed time T 0 may be measured from a point in time prior to the commencement of step (a).
  • the method may further include the steps of collecting ECG data of the patient, and initiating analysis of the ECG data prior to step (b).
  • the step (b) may further include the step of interrupting the prior initiated ECG analysis.
  • the method may further include the step of starting a timer when, the ECG analysis is commenced, to measure elapsed time.
  • T 0 may be substantially equal to or less than 30 seconds, or it may be substantially equal to or less than 10 seconds.
  • determining if the patient is undergoing motion may include sensing patient impedance and analyzing the sensed patient impedance.
  • the step of starting the ECG analysis after an elapsed time to may include the step of continuing the ECG analysis that had been interrupted in step (b).
  • the step of starting the ECG analysis after an elapsed time T 0 may include the step of commencing a new ECG analysis.
  • the indication may include a prompt informing the tiser that motion is present.
  • the prompt may include an instruction to the user to stop motion.
  • the prompt may include an instruction to the user to not touch the patient.
  • a defibrillator in another aspect, includes electrodes attachable to a patient and configured to sense ECG signals and impedance, and a processor capable of analyzing the sensed impedance to detect if motion is present; and, if motion is present, waiting for an elapsed time to before analysing the ECG signals.
  • the defibrillator may further include a user interface controlled by the processor, wherein the processor causes the user interface to inform the user if the processor determines that motion is present.
  • the user interface may provide a prompt to the user to stop motion if the processor determines that motion is present.
  • the prompt may include a voice prompt instructing the user to not touch the patient.
  • a method of operating a defibrillator having electrodes attached to a patient includes the steps of: starting an ECG analysis of the patient; starting a measurement of elapsed time when the ECG analysis is started; analyzing a patient parameter to determine if the patient is undergoing motion which would influence ECG analysis; and if the analyzing step determines that the patient is undergoing motion which would influence ECG analysis, and the time measurement shows that an elapsed time of To has not been reaches, interrupting the ECG analysis.
  • This method may further include the step of: after a time T 0 has been reached, analyzing the ECG.
  • the patient parameter may be impedance.
  • the step of analysing the ECG after a time to has been reached may includes the step of continuing the ECG analysis which had been interrupted.
  • the step of analyzing the ECG after a lime T 0 has been reached may include the step of commencing a new ECG analysis.
  • the method may further include the step of: if the analyzing step determines that the patient is undergoing motion which would influence ECG analysis and the time measurement shows that an elapsed time of to has not been reached, analyzing a second data set of a patient parameter to determine if the patient is undergoing motion which would influence ECG analysis; and if motion which would influence ECG analysis is present, waiting for an elapsed time T 0 before analyzing the
  • T 0 may be substantially equal to 30 seconds, or it may be substantially equal to 10 seconds.
  • the time to may be a time that is chosen prior to application of the electrodes to the patient.
  • Figure 1 is a block diagram of an external defibrillator
  • Figure 2 is a flowchart illustrating a process according to an embodiment of the invention.
  • an illustrative embodiment may be used in an external defibrillator 12.
  • the circuitry in the defibrillator 12 may be substantially like that of commercially available external defibrillators such as the LIFEPAK ® CR Plus defibrillator or the LIFEPAK 500 defibrillator sold by Medtronic Emergency Response Systems Inc. of Redmond, Washington.
  • Defibrillator 12 administers defibrillation therapy to patient 10 via electrodes 14 and 16, which may be adhesive electrode pads placed on the skin of patient 10.
  • the body of patient 10 provides an electrical path between electrodes 14 and 16.
  • Electrodes 14 and 16 are coupled to defibrillator 12 via conductors 18 and 20 and interface 22. Electrical impulses or signals may be sensed by defibrillator 12 via electrodes 14 and 16 and interface 22 for analysis by the microprocessor 26 to ascertain if the heart is in a condition which requires the application of defibrillation therapy (this is referred to as ECG analysis below). Electrical impulses or signals may also be delivered from defibrillator 12 to patient 10 via electrodes 14, 16, and interface 22.
  • Interface 22 includes a switch (not shown in Figure 1) that, when activated, couples an energy storage device 24 to electrodes 14 and 16. Energy storage device 24 stores the energy for a dosage of electrical energy or current to be delivered to patient 10.
  • Energy storage device 24 includes components, such as one or more capacitors, which store the energy to be delivered to patient 10 via electrodes 14 and 16. Before a defibrillation, pulse may be delivered to patient 10, energy storage device 24 must be charged.
  • the microprocessor 26 directs a charging circuit 28 to charge energy storage device 24 to a high voltage level. When the ECG analysis determines that defibrillation therapy is indicated, microprocessor 26 will automatically direct charging circuit 28 to begin charging. Or, in an alternative embodiment microprocessor 26 will direct charging circuit 28 to begin charging upon the instruction of the rescuer.
  • the rescuer may instruct microprocessor with one or more input devices 30A - 30N (hereinafter 30), such as one or more buttons, a keyboard, a touch screen, a voice recognition module or a pointing tool.
  • Microprocessor 26 monitors and analyses electrocardiogram (ECG) signals sensed via electrodes 14 and 16 and received via interface 22 and, in some embodiments, may display these signals via an output device 34 such as a display screen.
  • ECG electrocardiogram
  • Capacitor charging circuit 28 includes, for example, a flyback charger that transfers energy from a power source 32 to energy storage device 24.
  • Power source 32 may include one or more replaceable battery and/or an adapter to an exterior power source such as an electrical outlet.
  • power sources 32 also supplies power to components such, as microprocessor 26, input devices 30 and output devices 34, e.g., via a power supply circuit (not shown in Figure 1).
  • defibrillator 12 is ready to deliver the defibrillation shock.
  • the shock may be delivered automatically without further input by the rescuer.
  • defibrillator 12 notifies the rescuer that charging is complete using one or more output devices 34A - 34N (hereinafter 34), such as a display screen, an audible sound generator, a voice synthesizer, or an indicator light, and instructs the rescuer to stand clear and not touch the patient 10.
  • the defibrillator 12 then delivers the defibrillating shock to the patient.
  • the microprocessor 26 may activate an output device 34 that informs the rescuer that defibrillator 12 is ready to deliver a defibrillation shock to patient 10 and instructs the rescuer to activate the switch by manually operating an input device 30, such as by pressing a "shock" button.
  • microprocessor 26 may also modulate the electrical pulse delivered to patient 10.
  • Microprocessor 26 may , for example, regulate the shape of the waveform of the electrical pulse and the duration of the pulse.
  • microprocessor 26 may evaluate the efficacy of an administered defibrillation shock.
  • microprocessor 26 may store and retrieve data from memory 36. Memory 36 stores instructions that direct the operation of microprocessor 26.
  • memory 36 stores information about patient 10 and defibrillator 12.
  • memory 36 may store the ECG of patient 10, information about the number of shocks delivered to patient 10, the energy delivered per shock, the timing of shocks and the patient response to shocks.
  • motion detection systems are found in commercially available AEDs such as those available under the trademarks LIFEPAK 500 and LIFEPAK CR Plus from Medtronic Emergency Response Systems. Inc. of Redmond Washington. Examples of motion detection systems are described in detail in U.S. Patents 5,247,939 and
  • patient impedance data are collected and successive impedance values are compared to a predetermined threshold. If the last two values exceeded the threshold, then excessive motion is determined to be present.
  • patient impedance values are compared to predetermined upper and lower limits, and the time in which they exceed these limits is noted. Excessive motion is determined to be present if the impedance signal undergoes relatively large variations for a short time, or smaller variations for a longer time.
  • the AED will perform analysis of ECG data such as an ECG analysis to see if the patient has a heart rhythm that calls for defibrillation therapy (such as, for example, the Shock Advisory SystemTM analysis used in the LIFEPAK CR Plus and LlFEPAK 500 defibrillators), or any other ECG analysis (such as, for example, a VF waveform analysis which evaluates the likelihood that a defibrillation shock will be effective), or a combination of such ECG analyses.
  • an ECG analysis starts, an internal timer is also started (block 1). Concurrent with the ECG analysis, data is collected for motion analysis (block 2).
  • This data may be patient impedance, and motion detection may be determined by data analysis such as that discussed above, to determine if excessive motion is present, (block 3). if no excessive motion is determined to be present, the device continues the ongoing ECG analysis (block 4). If excessive motion is determined to be present, and the internal timer has not yet exceeded a predetermined elapsed time T 0 , the device enters into a "motion alert" condition and interrupts or ceases the ECG analysis (block 5). The device then prompts the rescuer to stop motion (block 6).
  • an audible voiced prompt such as "Motion detected, stop motion", or “Motion detected, do not touch patient”, or ''Analyzing interrupted, stop all motion.” if the rescuer had been performing CPR, this prompt will alert him to take his hands off the patient.
  • data for motion analysis continues to be collected (block 7), and a determination of the presence or absence of excessive motion is made (block 8). if excessive motion is no longer present; then the device continues on to the step of block 9, where the interrupted ECGanalysis is restarted.
  • the ECG analysis may be started again from the beginning, or it may be picked up where it had left off at block 5. Once the internal timer has exceeded a predetermined elapsed time to, the device will start or continue the ECG analysis regardless of the presence of motion.
  • the time period to is preferably short enough to minimize the delay in therapy (for example, less than 30 seconds), and long enough that the user has an opportunity to address any motion conditions that are easily addressable (for example, 5 seconds to stop
  • the time period to may be preset. Alternatively, it may be configured at a desired value upon initial setup of the defibrillator device, or in other embodiments, it may be configurable as desired (via the user interface, for example or via a reprogramming of the defibrillator) at any point in the operational life of the defibrillator.
  • the defibrillator may be equipped with a user input mechanism so that, if a user wants to override the automatic restart of the ECG analysis after the pre-programmed delay, the defibrillator may be instructed to not continue ECG analysis after a time T 0 but instead to wait, either for an extended time period of a preset length, or until further input from the user is received by the defibrillator.
  • This may be useful in cases where, for example, a user is making a deliberate choice to cause motion sufficient to interfere with accurate ECG analysis (for example, where a user is moving a patient to another location, or choosing to administer a therapy that causes motion).
  • the user input may be accomplished through, for example, a user interface that includes a button to be pressed to indicate the override choice.
  • ECG analysis will begin to proceed again when the motion detection condition is cleared or at the end of the aforementioned period of time T 0 whichever occurs first.
  • the pause in ECG analysis resulting from the motion detection condition will not last longer than the aforementioned period of time. This will provide a defibrillator which prompts the user to halt actions that may result in ECG artifact, and which can be quickly addressed, such as halting chest compressions.
  • ECG analysis will proceed after the aforementioned period has transpired regardless of whether or not motion detection persists; ECG analysis will not be delayed indefinitely.
  • the completion of ECG analysis will allow the rescuer to proceed with either CPR or a defibrillation shock, both of which may be immediately beneficial to the patient in many circumstances.
  • the described embodiment of a motion detection system will allow ECG analysis to proceed after the short period of delay.

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Abstract

L'invention concerne un dispositif médical permettant d'analyser l'ECG d'un patient, p. ex. défibrillateur externe, et qui est utilisé selon le procédé suivant, lequel comporte les étapes consistant à. (a) déterminer si le patient est en mouvement; (b) s'il est établi que le patient est en mouvement, indiquer que le patient est en mouvement; (c) après avoir fourni l'indication, déterminer si le patient est en mouvement, et, le cas échéant, commencer l'analyse ECG après l'écoulement d'un temps T0. Le temps écoulé T0 est mesuré à partir d'un point dans le temps antérieur au début de l'étape (a). Le procédé comporte de plus les étapes consistant à: collecter des données d'ECG du patient, et lancer l'analyse des données d'ECG avant l'étape (b). L'étape (b) comporte en outre l'étape consistant à interrompre l'analyse d'ECG lancée précédemment. Le procédé comporte de plus l'étape consistant à faire démarrer une minuterie quand l'analyse d'ECG commence, afin de mesurer le temps écoulé.
PCT/US2006/060362 2005-10-31 2006-10-30 Systeme de detection de mouvement pour defibrillateur externe WO2007053820A1 (fr)

Applications Claiming Priority (2)

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US73242005P 2005-10-31 2005-10-31
US60/732,420 2005-10-31

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4610254A (en) * 1984-03-08 1986-09-09 Physio-Control Corporation Interactive portable defibrillator
EP0551746A2 (fr) * 1992-01-10 1993-07-21 Physio-Control Corporation Détection de mouvement entre une électrode et un patient et rétablissement rapide des limites
WO2004091719A2 (fr) * 2003-04-11 2004-10-28 Cardiac Pacemakers, Inc. Discrimination de l'arythmie au moyen de parametres multiples

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4610254A (en) * 1984-03-08 1986-09-09 Physio-Control Corporation Interactive portable defibrillator
EP0551746A2 (fr) * 1992-01-10 1993-07-21 Physio-Control Corporation Détection de mouvement entre une électrode et un patient et rétablissement rapide des limites
WO2004091719A2 (fr) * 2003-04-11 2004-10-28 Cardiac Pacemakers, Inc. Discrimination de l'arythmie au moyen de parametres multiples

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