Abstract:
An external automatic defibrillator including an attachment device that can be externally attached and carried by a patient, an identification device for detecting an abnormal event in the cardiac activity, which can be treated by an electric shock, as well as a defibrillator allowing to exert a shock upon the patient after having detected the abnormal event. In order to ensure reliable functioning over a longer period of time, the identification device is configured so that the identification device can detect an abnormal event in an interval of not more than 90 seconds or one minute.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to an automatic external defibrillation device, having an attachment device for external placement on and wear by a patient, having an identification arrangement for detecting an abnormal event in connection with a cardiac activity which is treatable by electric shock, and having a defibrillation arrangement for applying a shock to a patient after the abnormal event has been detected. 
     2. Discussion of Related Art 
     An automatic external defibrillation device of this type is disclosed in German Patent Reference DE 689 27 898 T2. An attachment device with an upper body harness or clothing for wearing it, by which an electrode arrangement can be attached to the body of the patient, is provided with this known defibrillation device. A monitoring arrangement is also provided, including at least one monitoring unit on the harness, by which a chest movement during breathing can be detected. A difficulty in connection with such portable automatic external defibrillation devices is in always providing sufficient electrical power for shock treatment. 
     A similar portable defibrillator, by which the cardiac activity is analyzed and it is determined whether defibrillation is required, is taught by U.S. Pat. No. 4,576,170. 
     A further portable external defibrillation device is disclosed in United States Patent Application Publication 2003/0004547 A1. The object here is to design the electrodes employed for an extended wearing period. 
     SUMMARY OF THE INVENTION 
     One object of this invention is to provide an automatic external defibrillation device of the type mentioned above, but with an increase in functional dependability. 
     This object is attained by characteristics of this invention as taught in this specification and in the claims. The identification arrangement is designed for detecting an abnormal event within a period of time of at most 90 seconds, or within a minute after the appearance of the event. 
     The short duration of the period of time for detecting the abnormal event is based on a rapid identification and assures a rapid decision, whether a defibrillation pulse, or sequence of pulses, is required and should be delivered. It has been shown that the shorter the time between ventricular fibrillation and the shock, the less power is required for the shock. The relatively small amount of power for the shock is easier on the heart but it is not necessary to store as much power in the power supply, in particular the battery, for assuring sufficient power for shocking. Thus, it is advantageous if the detection of an abnormal event and treatment take place within one minute. 
     The further steps are of advantage in connection with gentle treatment and a power-saving operation, so that within this period of time it is possible for the identification arrangement to send an identification signal to the defibrillation device, which can automatically deliver a shock. 
     Also, steps contribute to the dependable identification of events to be treated, wherein reference data are specified in the identification arrangement for identifying the abnormal event, and an evaluation arrangement is provided, by which the abnormal event can be detected from the patient data regarding the cardiac activity supplied by the identification arrangement, wherein suitable evaluating algorithms in the identification arrangement are made a basis. 
     In this case, an adjustment to the characteristics and requirements of a respective patient can be provided if the reference data is provided in a patient-specific manner. Here, the patient-specific reference data can be preset by a physician and/or calculated as a function of the respective history in the identification arrangement by specific algorithms. 
     Dependable data acquisition and evaluation is also supported if an additional sensor arrangement is provided, by which additional information regarding the patient and/or the operational state of the defibrillation device can be made available to the identification arrangement. It is, for example, thus possible to include the actual behavior of the patient and/or to check the positionally-correct application of the electrodes or sensors, and also to monitor the status of the identification arrangement, the defibrillation device and/or the power supply. 
     Here, advantageous embodiments include that the additional sensor arrangement has at least one movement sensor and/or at least one position sensor, by which a movement or the position of the body can be detected. If during this it is found that the patient moves, the detection of an abnormal event, for example by an EKG, can be discarded as erroneous and a new measurement can be taken. If another person externally moves the body of the patient there would be endangerment by a shock. If, for example, the upper body of the patient is vertical, the detection of an abnormal event could be erroneous, or the patient could fall over after a shock and become injured. In such situations, better differentiations and treatment methods are achieved by the additional information. 
     In this connection, with advantageous design variations the movement sensor and/or the position sensor can have at least one acceleration sensor. 
     If the additional sensor arrangement has a strain gauge, it is, for example, possible to dependably detect breathing movements by a suitable algorithm and to include them in the evaluation for detecting an abnormal event. 
     Furthermore, strong identification criteria for a decision whether a shock should be triggered can be obtained if the additional sensor arrangement has sensors for detecting the neurological state of the patient, sensors for detecting the blinking reflex and/or sensors for detecting eye movement, and if a voice output and/or voice input unit for verbal information from or to a remote control station is provided. The identification arrangement can be designed for detecting and evaluating movements or movement patterns following a request for movement made to the patient and/or for the evaluation of verbal signals from the patient. The identification arrangement can be designed to perform a calibration on the basis of a position and/or movement state of the patient, and the identification arrangement can be designed so that in defined positions of the patient the triggering of the shock is prioritized, or can only be triggered in defined positions. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       This invention is explained in view of exemplary embodiments, making reference to the drawings, wherein: 
         FIG. 1  is a schematic view of a defibrillation device; and 
         FIG. 2  shows an exemplary embodiment of an analysis and progress control device. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  shows an automatic external defibrillation device, which can be permanently placed on the body of a patient in danger of a fatal heart attack and can be worn until the risk falls below a defined threshold. 
     The mobile defibrillation device, held on the body of a patient by a wearing device  20 , has an electronic component  10 , a defibrillator component  11 , a triggering component  12 , a monitoring component  12  and a registration component  14 . 
     The wearing device  20  has, for example, at least one shoulder strap  21  and at least one belt  22  in the form of a chest and/or waist belt. A power supply  30  for the electronic component  10  is maintained on the wearing device  20 , in which case the design can be such that the electronic component  10  is placed in a housing together with the power supply  30 . Also, actuator electrodes  40 , in particular the patient electrodes, as well as further sensors of an additional sensor arrangement  42 , if provided, are maintained on the wearing device  20 . In this case, the patient electrodes can simultaneously contain sensor units  41 , for example in order to perform impedance measurements, and it is possible to detect EKG signals by suitable electrodes, which can also be integrated into the patient electrodes and can be evaluated by the electronic component  10 , in a known manner. 
     Besides an electronic control and power device, in particular for the defibrillator component  11 , the electronic component  10  also has a switching component with an identification arrangement for detecting an abnormal event in connection with the cardiac activity of the patient, in which case a computing unit containing suitable algorithms and associated memory devices is provided. The memory device is a part of the registration component  14 , which can be designed with a radio module for transmitting and receiving patient data, or data processed in the electronic module  10 , to a remote control station. The identification arrangement can have an evaluation arrangement for detecting, from patient data regarding the cardiac activity of the patient, and possibly additional information obtained from an additional sensor arrangement, an abnormal event in the cardiac activity by a comparison with reference data. The reference data, matched to the respective patient, can be stored from the start, and/or can be determined in accordance with a history of the event, possibly adapted, and suitably stored. The patient data are obtained by suitable sensors and are supplied to the identification arrangement via connecting elements and, when required, an identification signal is transmitted by it to the defibrillation device for automatically triggering a shock when needed. Also, previously known patient data, which relate to special, individual characteristics of the patient, can be stored in the electronic component  10 , in particular in the identification arrangement, for using them for the detection and evaluation of an abnormal event in the cardiac activity, and to include them in the decision regarding the triggering of a defibrillation shock. 
     The additional information can, for example, contain movement data or position data regarding the patient, or respiratory activities of the patient, or combinations of these and further data, so that the assurance of detecting the abnormal event can be increased, for example by determining definite movements or movement patterns or, in case of unfavorable conditions, the issue of the identification signal to the defibrillation device can be stopped, or prevented. For example, the additional sensor arrangement  42  has at least one movement sensor and/or at least one position sensor, which are advantageously designed as acceleration sensors, in particular 3D-acceleration sensors, which are advantageously applied at the hip or to the front of the chest. A stretchable tape, with a conductivity that can be changed, and an appropriate algorithm, for example, are suitable for detecting pulmonary activities. 
     By employing a plurality of movement sensors, it is possible to obtain a more accurate picture of the body activities, and thus to provide a better distinction between active and passive movements. This can occur by evaluating a difference signal, for example, by which movement components acting as common-mode signals from the outside can be recognized as passive movements. Also, placement of the sensors in the appropriately embodied wearing device  20  close to the extremities, for example, can be used for better identifying movements when seated, for example. 
     In one embodiment of the defibrillation device, there is a voice output and/or input device for voice information from or to a remote control station. With this, the system with the defibrillation device can request the patient to make defined movements and/or changes in body position in case of a questionable signal evaluation. If as a result the system registers a movement or defined characteristic movement patterns, which are identified by the identification arrangement, for example by a comparison with stored movements, or movement patterns, it is possible to assume that a patient is conscious and shows bodily activities, and a shock can be prevented, or a suitable situation can be awaited. With this design, in a further embodiment the patient is requested via the voice input to assume defined body positions and that in these defined body positions a calibration of the system, in particular of the identification arrangement, is performed. In a further embodiment, prior to assuming defined body positions which favor a shock indication, for example lying during sleep, the patient tells this to the defibrillation device via an input unit, so that the signal evaluation can be modified, for example by a change of weight factors in the computer evaluation of the signals. 
     In a further embodiment, the patient can actively suppress the administration of a shock by pushing operating keys. The preparation of a shock can be signaled by various signals, such as optical, acoustic, and tactile. 
     In a further embodiment additional sensors are provided, by which it is possible to draw conclusions regarding the neurological state of the patient. For example, the further additional sensors are designed for the generation of evoked potentials, which are generated by signal sources designed for this and are detected via sensor elements. In a further embodiment, checking a blinking reflex and/or eye movements by further additional sensors, wherein in one embodiment can be an electro-oculogram. 
     An example for an analysis and progress control device for checking whether a shock should be triggered and whether a shock is possibly required is represented in  FIG. 2 . The control is represented by the use of action diagrams, divided into an area EKGA for EKG analysis, a movement analysis AB and a system control device ST. 
     In the EKG analysis EKGA, a check is made in a step E 1  starting from an initial point, whether ventricular fibrillation (VF) exists. If in a step E 2  it is decided that there is no ventricular fibrillation, a return to step E 1  for the analysis of the ventricular fibrillation is made. If it is decided in this step E 2  that a ventricular fibrillation has been detected, in a step B 1  an evaluation of the movement/position data is performed in the area of the movement analysis BA and a time-measuring device or timer is started for a defined length of time. If in a succeeding step B 2  of the movement analysis BA the end of the period of time is determined, a transition is made to a step S 2  in the area of the system control device ST for preparing a shock. If it is determined in step B 2 , that the length of time has not yet expired, a check is made in the area of the movement analysis BA in a succeeding step B 3  whether an action by the patient has been identified, which the patient had been previously requested to perform in a step S 1 , for example acoustically, for example via the above mentioned voice input, visually or by tactile means. If in step B 3  an action had been unequivocally detected, a return is made to step B 1  of a ventricular fibrillation analysis. If an action is not unequivocally determined in step B 3 , a determination is made in a further step B 4  of the movement analysis whether or not an action is possible. If an action is possible, a transition is made to step S 1  in the area of the system control device ST for requesting the action. If it is determined in step B 4  that no action can be detected, or is possible, a transition is made to step S 2  in the area of the system control device ST for making preparations for a shock. If it is determined in a succeeding step S 3  in the area of the system control device ST that the user has terminated the shock preparation, for example by inputting appropriate first information, as discussed above, a return is made to the step E 1  of ventricular fibrillation analysis in the area EKGA of the EKG analysis. If no termination is detected in step S 3 , a transition is made to a step E 3  of a further background analysis of the ventricular fibrillation in the area EKGA of the EKG analysis. If it is determined in a successive step E 4  that ventricular fibrillation no longer exists, a return is made to step E 1  of ventricular fibrillation analysis. If it is determined in step E 4  that ventricular fibrillation continues to exist, a shock is triggered in a step S 4  in the area of the system control device ST. After that, a transition is made to an end point, after which further activities, such as analyses and checks, can be performed. 
     In other words, the progress of an analysis by a combination of an EKG and a movement analysis corresponding to the action diagrams in accordance with  FIG. 2  can be represented as follows. 
     a) Request to Perform the Action 
     The patient is requested, for example visually, acoustically or in a tactile manner, to perform a bodily action, which can be based on a previously specified movement pattern, for example. The incoming transition then includes making a switch from the appropriate decision node B 4 , provided that an action is possible, to step S 1  of the request to perform an action. The resulting transition is that a switch is made from step S 1  to step B 1  of evaluating the movement/position data and starting the timer. 
     b) Evaluating the Movement/Position Data and Starting the Timer 
     In case there is a request made of the patient to show a bodily action, the timer is started for a defined length of time, a time window, in which the action must take place. In this case, incoming transitions are that a switch is made from the decision node E 2  to the evaluation, movement/position data, starting the timer, in step B 1 , provided, that ventricular fibrillation had been detected. Furthermore, a switch is made from the step of requesting the performance of an action to step B 1  of evaluating the movement/position data and starting the timer. The incoming transition here is the shift from step B 1  to the decision node B 2 . 
     c) Shock 
     A shock is applied here, and the analysis is freshly started thereafter. An incoming transition here is the switch from the decision node E 4  to step S 4 , provided that ventricular fibrillation still exists. An outgoing transition includes the switch from step S 4  shock to the end point. 
     d) Shock Preparation 
     Part of a shock preparation are the notice to the patient and the surroundings by visual, acoustical and/or tactile signals, charging of the capacitor unit of the defibrillator and dispensing of a gel in the defibrillator electrodes. Incoming transitions here are a switch from the decision node B 4  for shock preparation in accordance with step S 2 , provided no actions are noted, and from the decision node B 2  for shock preparation in step S 2 , provided that the length of time has ended. An outgoing transition includes the shift from shock preparation in step S 2  to the decision node S 3 . 
     e) VF-Analysis 
     Here, an EKG analysis is performed with the goal of detecting ventricular fibrillation. Incoming transitions here are the switch from the initial point to the VF-analysis in step E 1 , the switch from the decision node E 2  back to the VF-analysis, provided that an action by the patient had been unequivocably detected, the switch from the decision node S 3  to the VF-analysis E 1 , provided a termination by the user exists, and the switch from the decision node E 4  to the VF-analysis E 1 , provided ventricular fibrillation no longer exists. An outgoing transition includes a shift made from step E 1  of the VF-analysis to the decision node E 2 . 
     f) Further Background Analysis VF 
     The VF background analysis in step E 3  continues permanently, even if movement data etc., are evaluated. This analysis is used as a permanent safeguard that a rhythm requiring a shock continues to be present. Here, the incoming transition is the shift from the decision node S 3  to the further background analysis in accordance with step E 3 , provided that no termination was performed by the patient. The outgoing transition here is the shift from the further background analysis E 3  to the decision node E 4 . 
     In one embodiment of the defibrillation device, the identification arrangement is designed for rapid evaluation and identification of an abnormal event in the cardiac activity, and the defibrillation device is designed for a correspondingly rapid reaction and issuance of a defibrillation pulse. The above mentioned measures are used for rapid and dependable evaluation and identification, in particular, the identification lies within a time period which is shorter than 2 minutes, preferably less than 90 seconds, and even better lies below 1 minute. It has been shown that the shorter the time from the appearance of ventricular fibrillation to the shock is, the less energy is required for the shock. This is easy on the patient, and also does not require as much power, so that the power supply can assure sufficient shocking power over a longer period of time.