News Column

"Defibrillator Display Including CPR Depth Information" in Patent Application Approval Process

August 21, 2014



By a News Reporter-Staff News Editor at Politics & Government Week -- A patent application by the inventors Johnson, Guy R. (Gloucester, MA); Silver, Annemarie (Bedford, MA); Freeman, Gary A. (Newton Center, MA), filed on April 1, 2014, was made available online on August 7, 2014, according to news reporting originating from Washington, D.C., by VerticalNews correspondents.

This patent application is assigned to ZOLL Medical Corporation.

The following quote was obtained by the news editors from the background information supplied by the inventors: "The heart relies on an organized sequence of electrical impulses to beat effectively. Deviations from this normal sequence are known as 'arrhythmia.' Certain medical devices include signal processing software that analyzes electrocardiography (ECG) signals acquired from a medical patient (e.g., a victim at a scene of an emergency) to determine when a cardiac arrhythmia such as ventricular fibrillation (VF) or shockable ventricular tachycardia (VT) exists. These devices include automated external defibrillators (AEDs), ECG rhythm classifiers, and ventricular arrhythmia detectors. An AED is a defibrillator--a device that delivers controlled electrical shock to a patient--while being relatively easy to use, such as by providing verbal prompts to a provider of care to 'talk' the provider through a process of evaluating a patient for, attaching the patient to, and activating, AED therapy. Certain of the medical devices just discussed are also capable of recognizing the two distinct cardiac waveforms: VT and VF.

"VT is a tachydysrhythmia that originates from a ventricular ectopic focus, characterized by a rate that is typically greater than 120 beats per minute and wide QRS complexes. VT may be monomorphic (typically regular rhythm originating from a single focus with identical QRS complexes) or polymorphic (unstable, may be irregular rhythm, with varying QRS complexes). An example rhythm for an unstable VT is illustrated in FIG. 1A. Depending on the rate and the length of time that the VT has been sustained, a heart in the VT state may or may not produce a pulse (i.e., pulsatile movement of blood through the circulatory system). The cardiac activity in the VT state still has some sense of organization (note that the 'loops' are all basically the same size and shape). If there is no pulse associated with this VT rhythm, then the VT is considered to be unstable and a life threatening condition. An unstable VT can be treated with an electrical shock or defibrillation.

"Supraventricular tachycardia (SVT) is a rapid heartbeat that begins above the heart's lower chambers (the ventricles). SVT is an abnormally fast heart rhythm that begins in one of the upper chambers of the heart (atria), a component of the heart's electrical conduction system called the atrioventricular (AV) node, or both. Although SVT is rarely life-threatening, its symptoms, which include a feeling of a racing heart, fluttering or pounding in the chest or extra heartbeats (palpitations), or dizziness can be uncomfortable.

"VF is usually an immediate life threat. VF is a pulseless arrhythmia with irregular and chaotic electrical activity and ventricular contraction in which the heart immediately loses its ability to function as a pump. VF is the primary cause of sudden cardiac death (SCD). An example rhythm for VF is illustrated in FIG. 1B. This waveform does not have a pulse associated with it. There is no organization to this rhythm (note the irregular size and shape of the loops). The pumping part of the heart is quivering like a bag of worms, and it is highly unlikely that this activity will move any blood. The corrective action for this rhythm is to defibrillate the heart using an electrical charge.

"A normal heart beat wave starts at the sinoatrial node (SA node) and progresses toward the far lower corner of the left ventricle. A massive electrical shock to the heart can correct the VF and unstable VT rhythms. This massive electrical shock can force all the cardiac cells in the heart to depolarize at the same time. Subsequently, all of the cardiac cells go into a short resting period. The hope is that the sinoatrial node (SA node) will recover from this shock before any of the other cells, and that the resulting rhythm will be a pulse-producing rhythm, if not normal sinus rhythm.

"Many AEDs implement algorithms to recognize the VT and VF waveforms by performing ECG analyses at specific times during a rescue event of a patient using defibrillation and cardio-pulmonary resuscitation (CPR). The first ECG analysis is usually initiated within a few seconds after the defibrillation electrodes are attached to the patient. Subsequent ECG analyses may or may not be initiated, based upon the results of the first analysis. Typically, if the first analysis detects a shockable rhythm, the rescuer is advised to deliver a defibrillation shock. Following the shock delivery, a second analysis can be initiated automatically to determine whether the defibrillation treatment was successful or not (i.e., the shockable ECG rhythm has been converted to a normal or other non-shockable rhythm). If this second analysis detects the continuing presence of a shockable arrhythmia, the AED advises the user to deliver a second defibrillation treatment. A third ECG analysis may then be executed to determine whether the second shock was or was not effective. If a shockable rhythm persists, the rescuer is then advised to deliver a third defibrillation treatment.

"Following the third defibrillator shock or when any of the analyses described above detects a non-shockable rhythm, treatment protocols recommended by the American Heart Association and European Resuscitation Council require the rescuer to check the patient's pulse or to evaluate the patient for signs of circulation. If no pulse or signs of circulation are present, the rescuer can be directed to perform CPR on the victim for a period of one or more minutes. The CPR includes rescue breathing and chest compressions. Following this period of CPR, the AED reinitiates a series of up to three additional ECG analyses interspersed with appropriate defibrillation treatments as described above. The sequence of three ECG analyses/defibrillation shocks followed by 1-3 minutes of CPR, continues in a repetitive fashion for as long as the AED's power is turned on and the patient is connected to the AED device. Typically, the AED provides audio prompts to inform the rescuer when analyses are about to begin, what the analysis results were, and when to start and stop the delivery of CPR.

"Many studies have reported that the temporary discontinuation or excessive pausing of precordial compression can significantly reduce the recovery rate of spontaneous circulation and 24-hour survival rate for victims. Thus, it is useful to recognize abnormal heart rhythms during chest compressions. There is recent clinical evidence showing that performing chest compressions before defibrillating the patient under some circumstances can be beneficial. Specifically, it is clinically beneficial to treat a patient with chest compressions before defibrillation if the response times of the medical emergency system result in a delay of more than four minutes, such that the patient is in cardiac arrest for more than four minutes. Chest compression artifact rejection can employ spectral analysis of the ECG, defibrillation success prediction, and therapeutic decision-making typically specify a set of parameters in the ECG frequency spectrum to be detected. For example, U.S. Pat. No. 5,683,424 compares a centroid or a median frequency or a peak power frequency from a calculated frequency spectrum of the ECG to thresholds to determine if a defibrillating shock is necessary.

"Unfortunately, existing AEDs require batteries able to deliver large amounts of current due to the charging requirements of defibrillator high voltage capacitors. This results in batteries that are excessive in both size and weight that limit both their portability, convenience, and in the case of external, wearable defibrillators such as the LifeVest (ZOLL Medical, Chelmsford, Mass.) their wearability and comfort. In addition, batteries continue to be the least reliable element of the AEDs currently manufactured, with regular recalls resulting from manufacturing defects as well as normal end-of-life degradation that always occurs with batteries, but are particularly troublesome for life-saving equipment."

In addition to the background information obtained for this patent application, VerticalNews journalists also obtained the inventors' summary information for this patent application: "This document describes systems and techniques that may be used to provide information about patient status and/or CPR administration during administration of CPR to a patient. The systems and techniques described herein aim to identify the most important data and to display the information in an efficient and effective manner to a rescuer. The data displayed to the rescuer can include information about the quality of the CPR administered by the rescuer, including, for example, CPR chest compression depth. The data displayed to the rescuer can also include information about the patient status. The data about the patient and CPR is presented graphically and/or textually in a manner that improves the ability of a rescuer to quickly understand the state of a patient and to make clinical decisions that will benefit the patient.

"This document describes systems and techniques for automatically determining a target chest compression depth based on measured physiological parameters of a patient. In some examples, the target compression depth can be provided to a rescuer as a guide for administration of chest compressions and the system can modify the target compression depth by a fraction of an inch.

"In certain implementations, such systems and technique may provide one or more advantages. For example, patient care may be improved when a rescuer can easily view well-formatted information in a single location. Also, rescuers may be able to modify their administration of CPR (e.g., modify the compression depth) to be more effective because the system has determined whether a different depth is likely to be more effective based on measured parameters and presented relevant data to the rescuer in an understandable manner.

"In one implementation, a method for providing adaptive Cardiopulmonary Resuscitation (CPR) treatment to a person in need of emergency assistance includes obtaining, by a portable computing unit, values for depths of a plurality of the chest compressions. The method also includes obtaining, by the portable computing unit, information about a physiological parameter of the person. The method also includes providing, at a first rate, periodic feedback to a user about chest compressions performed by the user based at least in part on the values for the depths of the plurality of the chest compressions and a target compression depth, and periodically determining, at a second rate that is slower than the first rate, whether to adjust the target compression depth based at least in part on the information about the physiological parameter of the person, so that multiple instances of feedback about chest compressions performed by the user are provided to the user for each instance of determining whether to adjust the target compression depth.

"Embodiments can include one or more of the following.

"The method can include providing information about a target CPR compression depth to the user.

"The periodic feedback to a user about chest compressions performed by the user can include feedback to the user about the compression depth.

"Providing the periodic feedback to the user about chest compressions can include displaying on a graphical display screen of a defibrillator, an indication of the values for the depths of one or more of the plurality of the chest compressions and an indication of the target compression depth.

"Providing the periodic feedback to the user about chest compressions can include displaying on a graphical display screen of a defibrillator, a graphical representation of the depths of one or more of the plurality of the chest compressions and an indication of the target compression depth.

"Providing the periodic feedback to the user about chest compressions can include displaying on a graphical display screen of a defibrillator, a graph having a visual indicia representing the target compression depth and visual indicia representing the values for the depths of one or more of the plurality of the chest compression displayed above or below the visual indicia representing the target compression depth.

"Providing the periodic feedback to the user about chest compressions can include displaying on a graphical display screen of a defibrillator, a graph having a bar representing the target compression depth and additional bars representing depths of one or more of the plurality of chest compressions.

"Compressions that are deeper than the target compression depth can be displayed below the bar representing the target compression depth and compressions that are more shallow than the target compression depth can be displayed above the bar representing the target compression depth.

"Providing the periodic feedback to a user about chest compressions can include displaying an icon that indicates whether the chest compressions are being performed properly.

"The method can also include receiving information about the patient's heart activity and displaying on a graphical display, with the feedback about chest compressions, an electrocardiogram of the patient.

"Displaying the electrocardiogram can include moving an electrocardiogram trace laterally across the display.

"The periodic feedback to the user about chest compressions can include a bar graph that displays the depth of the plurality of the chest compressions and an indicator of the target compression depth.

"Lengths of bars in the bar graph can represent compression depths.

"Obtaining information regarding depths of a plurality of the chest compressions can include obtaining data regarding chest compressions performed on the patient comprises from an accelerometer that is positioned to move in coordination with the patient's breastbone.

"The portable computing unit can be integrated with a portable defibrillator.

"The portable computing unit can be a touchscreen tablet computer.

"The method can also include displaying a graphical representation of the information about the physiological parameter of the person.

"The method can also include displaying a graphical representation of the information about the physiological parameter including a time varying graph of the physiological parameter.

"The method can also include displaying a graphical representation of the information about the physiological parameter including trend data associated with a trend in values of the physiological parameter.

"The method can also include determining a trend in the obtained information about the physiological parameter of the person and displaying a graphical representation of the determined trend.

"Displaying the graphical representation of the determined trend can include providing multiple arrows showing potential trend directions and providing a visual indicia associated with one of the multiple arrows, the visual indicia being indicative of a direction of the determined trend.

"The first rate can be a per compression rate and the second rate can be a time period of between 10 seconds and one minute.

"The first rate can be a rate of 5 seconds or less and the second rate can be a rate of 10 seconds or greater.

"In some additional aspects, an external defibrillator includes one or more sensors arranged to contact a patient and obtain measurements regarding chest compressions performed on the patient. The defibrillator also includes one or more additional sensors arranged to contact a patient and obtain measurements regarding a physiological parameter of the patient. The defibrillator also includes a video display screen for displaying, at a first rate, periodic feedback to a user about chest compressions performed by the user based at least in part in the values for the depths of the plurality of the chest compressions and a target compression depth. The defibrillator also includes a processor connected to memory that stores computer instructions for periodically determining, at a second rate that is slower than the first rate, whether to adjust the target compression depth based at least in part on the information about the physiological parameter of the person, so that multiple instances of feedback about chest compressions performed by the user are provided to the user for each instance of determining whether to adjust the target compression depth.

"Other features and advantages will be apparent from the description and drawings, and from the claims.

DESCRIPTION OF DRAWINGS

"FIG. 1A is a magnitude versus time plot of a ventricular tachycardia (VT) rhythm.

"FIG. 1B is a magnitude versus time plot of a ventricular fibrillation (VF) rhythm.

"FIG. 2 is a diagram of one implementation including an automatic electronic defibrillator (AED) and a multiple lead electrocardiograph (ECG) device.

"FIG. 2A is a diagram of the AED of FIG. 2.

"FIGS. 3A and 3B are examples of ECG analysis and charging cycles.

"FIG. 4A is a flow chart showing actions taken to charge a defibrillation device during chest compressions associated with a CPR interval.

"FIG. 4B is a flow chart showing actions taken to charge a defibrillation device using different current levels that are selected based on the likelihood of a shockable rhythm being observed.

"FIG. 4C is a flow chart showing actions taken to adaptively charge a defibrillation device using different current levels based on the likelihood of a shockable rhythm being observed.

"FIG. 4D is a flow chart showing actions taken to adaptively charge a defibrillation device to a level selected based on ECG analysis.

"FIG. 5A is a diagram of and ECG signal.

"FIG. 5B is a diagram of a CPR acceleration signal showing strong cross-correlation with the ECG signal.

"FIG. 6A is a diagram of and ECG signal.

"FIG. 6B is a diagram of a CPR acceleration signal showing low cross-correlation with the ECG signal.

"FIG. 7 is a diagram of a defibrillation device with a display.

"FIG. 8A is a flow chart showing actions taken to modify information presented on a display of a defibrillation device based on the detection of CPR chest compressions.

"FIGS. 8B-8E show screenshots showing exemplary information presented on a defibrillator display.

"FIG. 9A is a flow chart showing actions taken to provide an indication of CPR quality on a display of a defibrillator device.

"FIGS. 9B and 9C are screenshots showing exemplary information presented on a defibrillator display.

"FIG. 10A is a flow chart showing actions taken to provide a release indicator.

"FIGS. 10B and 10C are screenshots showing exemplary information presented on a defibrillator display.

"FIG. 11 is a screenshot showing exemplary information presented on a defibrillator display.

"FIG. 12A is a screenshot showing exemplary information presented on a defibrillator display.

"FIG. 12B is a screenshot showing exemplary information presented on a defibrillator display.

"FIG. 13 is a flow chart showing actions taken to adjust a target compression depth by a fraction of an inch.

"FIG. 14 is a flow chart showing actions taken to adjust a target compression depth and provide feedback on CPR quality to a rescuer.

"FIG. 15A is a screenshot showing exemplary information presented on a defibrillator display.

"FIG. 15B is a screenshot showing exemplary information presented on a defibrillator display."

URL and more information on this patent application, see: Johnson, Guy R.; Silver, Annemarie; Freeman, Gary A. Defibrillator Display Including CPR Depth Information. Filed April 1, 2014 and posted August 7, 2014. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=1732&p=35&f=G&l=50&d=PG01&S1=20140731.PD.&OS=PD/20140731&RS=PD/20140731

Keywords for this news article include: ZOLL Medical Corporation.

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


For more stories covering the world of technology, please see HispanicBusiness' Tech Channel



Source: Politics & Government Week


Story Tools






HispanicBusiness.com Facebook Linkedin Twitter RSS Feed Email Alerts & Newsletters