Surgery: light – thermal – and electrical application – Light – thermal – and electrical application – Electrical therapeutic systems
Reexamination Certificate
2000-06-23
2004-02-17
Evanisko, George R. (Department: 3762)
Surgery: light, thermal, and electrical application
Light, thermal, and electrical application
Electrical therapeutic systems
Reexamination Certificate
active
06694187
ABSTRACT:
FIELD OF THE INVENTION
The present disclosure relates to an external defibrillator instruction system and method. More particularly, the disclosure relates to an external defibrillator system and method which provides details as to the patient's condition to the attending technician during no shock situations.
BACKGROUND OF THE INVENTION
Defibrillators supply pulses of electricity to a patient's heart to convert ventricular arrhythmias, such as ventricular fibrillation and ventricular tachycardia, to normal heart rhythms through the processes of defibrillations and cardioversion, respectively. There arc two main classifications of defibrillators: external and implanted. Implanted defibrillators are surgically implanted into patients who have a high likelihood of needing electrotherapy in the future. Implanted defibrillators typically monitor the patient's heart activity and automatically supply electro-therapeutic pulses directly to the patient's heart when indicated. Thus, implanted defibrillators permit the patient to function in a somewhat normal fashion away from the watchful eye of medical personnel.
External defibrillators send electrical pulses to the patient's heart through electrodes which are applied to the patient's torso. External defibrillators are useful in the emergency room, emergency medical vehicles, and in other situations where there may be an unanticipated need to provide electrotherapy to a patient on short notice. The advantage of external defibrillators is that they may be used on a patient as needed, and then subsequently moved to be used with another patient.
External defibrillators can be broken down into two further categories: those for use by skilled medical personnel, and those for use by non-medical, yet properly trained, personnel. In the latter category, the defibrillators are often arranged as what is known as automatic external defibrillators (AEDs). With such “automatic” external defibrillators, the attending technician normally is provided with instructions produced by the defibrillator which advise the technician as to whether a shock should be delivered and when. Normally, such defibrillators primarily instruct the technician with a “no shock” message and a “shock” message. These messages typically are conveyed to the technician through a display on the device and/or with a voice prompt transmitted by the device.
Typically, automatic external defibrillators distinguish between ventricular fibrillation, ventricular tachycardia, asystole, and electromechanical dissociation/pulseless electrical activity to determine whether a shock should be administered. When ventricular fibrillation or ventricular tachycardia is detected, it is generally advisable to administer cardiopulmonary resuscitation (CPR) to the patient, secure the patient's airway, hyperventilate the patient with 100% oxygen, and defibrillate (i.e., shock) the patient up to several times (e.g., three times). When asystole or electromechanical dissociation is determined, CPR is generally advisable, although no shock should be delivered to the patient.
Although conventional automatic external defibrillators normally can determine which cardiac rhythms are appropriate for defibrillation and which rhythms are not and instruct the technician accordingly, the no shock messages provided by conventional automatic external defibrillators do not differentiate between asystole where there is no useful or detectable cardiac activity, and other non-shockable rhythms where the patient has an effective heart activity, such as normal sinus rhythm found in healthy individuals. As is known by those in the medical field, these rhythms indicate quite different patient conditions.
Because conventional automatic defibrillators do not communicate the distinct situations of asystole and normal sinus rhythm, their use is potentially hazardous in that it may cause an inappropriate response on the part of the technician. For instance, if the patient has effective heart activity, continued CPR on that patient is ill-advised. Such a situation could delay the transfer of the device to another patient in need of defibrillation. In addition, the technician may be tempted to deliver a further shock to the patient despite resumption of normal heart function, particularly where the technician is not highly trained. Where the patient has been in asystole for a prolonged period of time, it similarly is unnecessary for the technician to continue CPR in that the likelihood of the patient being revived is remote.
From the foregoing, it can be appreciated that it would desirable to have an external defibrillator which not only distinguishes between asystole and normal sinus rhythm, but which also communicates which of these conditions is present to the technician when no shock is advised for the patient.
SUMMARY OF THE INVENTION
The present disclosure relates to a method for instructing a user as to how to treat a patient with a defibrillator. The method comprises analyzing electrocardiogram data of the patient to determine whether a shockable condition exists, distinguishing between normal heart function and asystole where no shock is advisable, and communicating to the user that the patient is in asystole where an asystole condition is detected. Through this method, the attending technician is notified not only that a shock is not advised, but whether the shock is not advised due to an asystole condition.
In view of the above method, the present disclosure also relates to an external defibrillator which comprises logic configured to analyze electrocardiogram data of the patient to determine whether a shockable condition exists, logic configured to distinguish between normal heart function and asystole where no shock is advisable, and logic configured to communicate to the user that the patient is in asystole where an asystole condition is detected.
The features and advantages of the invention will become apparent upon reading the following specification, when taken in conjunction with the accompanying drawings.
REFERENCES:
patent: 5163429 (1992-11-01), Cohen
patent: 5381803 (1995-01-01), Herleikson et al.
patent: 5391187 (1995-02-01), Freeman
patent: 5735879 (1998-04-01), Gilner et al.
patent: 5836993 (1998-11-01), Cole
patent: 6304773 (2001-10-01), Taylor et al.
patent: 6356785 (2002-03-01), Snyder et al.
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