External cardiac resuscitation devices (e.g., defibrillators) deliver current pulses to a patient through a pair of electrodes that are typically adhesively secured to the chest of the patient. Each electrode is connected to the resuscitation device by an electrical cable and at least one electrical connector. Often, two electrical cables and two electrical connectors are used. One cable extends from a first connector at the defibrillator to a second connector in the vicinity of the patient. A second cable, which is typically supplied as an integral part of the electrode, makes the connection from the second connector to the electrode. The two defibrillation electrodes are typically disposable, and come sealed within a package. To reduce the time required to deliver defibrillation therapy, the electrodes are often connected to the defibrillator ahead of time.
For a variety of reasons, the prior art has suggested providing an electrical connection between the electrodes within the interior of the electrode package used with cardiac resuscitation devices. One approach (U.S. Pat. No. 5,579,919) has been to provide an electrical connection between the gel layers of the electrodes, e.g., by adhering the two electrodes to an electrically conductive release liner. The purpose for this connection has been to determine the integrity of the electrode (e.g., whether the gel layers remain moist and properly functioning). The resistance across the two electrodes is monitored, and a rise in resistance is indicative of electrode failure.
Another reason for providing an electrical connection between the electrodes has been to provide a way for the electronics of the defibrillator to determine the state of the rescue effort, and take desired action. It has been suggested (U.S. Pat. No. 5,700,281, U.S. Pat. No. 5,817,151) that a metal strip be connected between the current-spreading layers, and the strip positioned so that when the package is opened the strip is torn to break the connection. That permits the electronics monitoring the short circuit formed by the electrode cables and the metal strip to detect that the strip has been severed, and learn that the electrodes have been removed from the package.
Similarly, a frangible electrical connective link (41, FIG. 16) has been provided (U.S. Pat. No. 7,801,605) between the electrodes, with the frangible link being mechanically connected to the housing of the defibrillator so that when the electrodes are removed from their packaging, or from their normal storage location, the frangible link is broken, and electronics onboard the defibrillator automatically turns on power to the defibrillator.
The present assignee introduced a product in which an additional electrical lead was connected within the package to each of the electrical therapy leads, and the additional electrical leads were brought to a connector installed at the periphery of the package. The connector included a shorting conductor that electrically connected the two additional leads together. The shorting conductor was configured so that when the package was opened according to instructions, the shorting conductor was withdrawn from the connector and remained with the discarded packaging. The electrical connection between the two therapy leads provided by the additional leads and the shorting connector was used to periodically test the integrity of the cables and connectors providing the electrical connection between the defibrillator and the packaged electrodes. But the additional leads were connected to the therapy leads short of the location at which the therapy leads were connected to the current-spreading layer, and so the testing was unable to test the entirety of the connection between the defibrillator and the current-spreading layers. And, furthermore, it was discovered in use of the product that the electrode package could possibly be opened incorrectly in a manner that would not result in the shorting connector being withdrawn, thus leaving the possibility that the electrodes might be applied with the shorting connector still in place.