Surgery: light – thermal – and electrical application – Light – thermal – and electrical application – Electrical therapeutic systems
Reexamination Certificate
2000-04-07
2002-08-20
Schaetzle, Kennedy (Department: 3762)
Surgery: light, thermal, and electrical application
Light, thermal, and electrical application
Electrical therapeutic systems
C607S060000, C607S059000, C607S027000
Reexamination Certificate
active
06438417
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to medical equipment and in particular to a defibrillator having wireless communications for transferring information to and from the defibrillator in a wireless network.
One frequent consequence of heart disease is the development of cardiac arrest associated with a heart arrhythmia such as ventricular fibrillation. Ventricular fibrillation may be treated by delivering an electrical shock to the patient's heart through the use of a defibrillator. Cardiopulmonary resuscitation (CPR) is commonly used to maintain life support for victims of cardiac arrest until a defibrillator can be deployed to treat the arrhythmia.
The chances of surviving a cardiac arrest decrease rapidly over the time following the arrest. Quick response to a cardiac arrest by performing CPR and by administering a defibrillating shock is therefore of critical importance. The American Heart Association's “Chain of Survival” recites the following steps:
1. Early access to emergency care, such as by activating an emergency medical system (EMS);
2. Early CPR initiated by a bystander or other first responder using basic life support (BLS) techniques to help the patient survive until more advanced care arrives;
3. Early defibrillation; and
4. Early advanced cardiac care. The benefits of this approach are discussed in more detail in Cummins, et al. “Improving Survival From Sudden Cardiac Arrest: the ‘Chain of Survival’ Concept,” 83 Circulation 1832-47 (May 1991).
EMS providers are playing an active role in implementing the Chain of Survival concept. Tiered EMS systems are emerging in many geographical areas and are typically divided between first responders, BLS (basic life support) providers, and ACLS (advanced cardiac life support) providers. First responders and BLS providers, often called EMT(B) or EMT-basic, the front line personnel who are first to reach a are now being trained and authorized to use automatic external defibrillators (AEDs) to provide early defibrillation.
AEDs deliver a high-amplitude current impulse to the heart in order to restore normal rhythm and contractile function in the patients who are experiencing ventricular fibrillation (VF) or ventricular tachycardia (VT) that is not accompanied by a palpable pulse. AEDs differ from manual defibrillators in that AEDs can automatically analyze the electrocardiogram (ECG) rhythm to determine if defibrillation is necessary. In nearly all AED designs, the first responder is prompted to press a shock button to deliver the defibrillation shock to the patient. Paramedic defibrillators often combine the AED and manual functions into one unit to allow for use by personnel with differing levels of training.
AEDs are designed to be used primarily by first responders who may not be trained in ACLS techniques. In the pre-hospital setting, these first responders may include emergency medical technicians trained in defibrillation (EMT-Ds), police officers, flight attendants, security personnel, occupational health nurses, and firefighters. AEDs can also be used in areas of the hospital where personnel trained in ACLS are not readily available. In such cases, it may be desirable to provide a defibrillator which operates in an AED mode but with manual functions such as cardiac monitoring disabled.
In more recent AED designs such as the Heartstream Forerunner® defibrillator, the AED functions have been logically grouped into step
1
, “power on”; step
2
, “analyze”; and step
3
, “shock.” More sophisticated audio prompts have been added in addition to the visual prompts provided by the LCD display. The transition from step
1
to step
2
may be initiated by the defibrillator, such as upon detection of patient contact between the defibrillation electrodes to begin the ECG analysis as soon as possible. Proceeding from step
2
to step
3
according to the AED personality requires the user to press a shock button upon recognition of a shockable rhythm by the ECG analysis. In this way, the AED personality is commonly understood to mean semi-automatic rather than fully automatic defibrillation.
In many EMS systems, the next link in the Chain of Survival is provided with the arrival of ACLS trained paramedics equipped with full featured defibrillators/cardiac monitors (“paramedic defibrillators”). Alternatively, if no ACLS trained personnel are available, the patient is directly transported to a hospital emergency department where ACLS care can be provided. In either case, a handoff of the patient takes place between the first responder and subsequent ACLS personnel.
As part of the handoff process, medical information obtained at the scene and stored within the defibrillator must be transferred along with the patient regarding what has taken place during treatment. Commonly referred to as a code summary or an event summary, such information typically may include an ECG strip as well as markers for such events as the time of initial cardiac arrest, initiation of CPR, administration of drugs, delivery of defibrillation shocks, and so on. In addition, an audio recording (“voice strip”) that documents the verbal remarks of the first responders is often provided. Such medical information contained in the event summary should be as complete and accurate as possible to ensure continuity of care and to enable the attending physician to provide the most appropriate follow-up care to the patient. It is desirable that the medical information stored in the event summary have the ability travel alongside the patient during the various handoffs along the Chain of Survival.
The event summary may also be used by the first responder to aid in the generation of incident reports. Such incident reports often must be filed according to the requirements of the local EMS system, both for quality control and documentation. The event summary may be down-loaded or transferred to a host computer running data management software that provides for displaying, analyzing, and playing back the medical information from the event summary in a meaningful manner to reconstruct the events that took place during the emergency treatment of the patient.
Prior art defibrillators provided documentation using hard copy devices such as built-in printers to produce the ECG strip. Event markers, such as the time each defibrillation shock is administered, could be marked on the edge of the paper ECG strip. An audio recording was typically provided using a built-in audio cassette recorder. Because the ECG strip was not stored but simply printed on a paper tape, retaining a copy of the ECG strip solely for report generation was impractical.
More recent AED designs such as the Heartstream Forerunner® defibrillator record the event summary information digitally on a removable storage medium in the form of a PCMCIA memory card. A method for gathering event data is discussed in U.S. Pat. No. 5,549,115, “Method and Apparatus for Gathering Event Data Using A Removable Data Storage Medium and Clock”, issued Aug. 27, 1996, to Morgan et al., and assigned to Heartstream, Inc. The information contained on the PCMCIA card is transferred by physically removing the PCMCIA card from the defibrillator and plugging it into another device such as a card reader connected to a host computer which up-loads the information to the data management software. Other AED designs provide for transferring the information via a wired connection such as an RS-232 serial link to the host computer.
Manually transferring memory cards along with the patient during a handoff from the first responder to an ACLS provider is not practical for a number of reasons. Memory cards are easily lost and may not be compatible with the defibrillator belonging to the ACLS personnel. After the handoff, the event summary stored on the memory card is then unavailable for the first responder to generate incident reports since the memory card has since been transported with patient.
Various methods for transmitting ECG information gathered remotely via telemetry back to an ECG monitor are discussed in U.S. Pat
Andrews Jonathan N.
Arand Patricia A.
Brink Gregory D.
Burton David L.
Forman Nancy H.
Koninklijke PHilips Electronics N.V.
Schaetzle Kennedy
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