Surgery: kinesitherapy – Kinesitherapy – Exercising appliance
Reexamination Certificate
1999-05-20
2001-11-06
Kamm, William E. (Department: 3762)
Surgery: kinesitherapy
Kinesitherapy
Exercising appliance
C607S042000
Reexamination Certificate
active
06312399
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates generally to the field of cardiopulmonary resuscitation and artificial ventilation. In particular, the present invention relates to devices and methods for increasing cardiopulmonary circulation during cardiopulmonary resuscitation procedures involving.
Worldwide, sudden cardiac arrest is a major cause of death and is the result of a variety of circumstances, including heart disease and significant trauma. In the event of a cardiac arrest, several measures have been deemed to be essential in order to improve a patient's chance of survival. These measures must be taken as soon as possible to at least partially restore the patient's respiration and blood circulation. One common technique, developed approximately 30 years ago, is an external chest compression technique generally referred to as cardiopulmonary resuscitation (CPR). CPR techniques have remained largely unchanged over the past two decades. With traditional CPR, pressure is applied to a patient's chest to increase intrathoracic pressure. An increase in intrathoracic pressure induces blood movement from the region of the heart and lungs towards the peripheral arteries. Such pressure partially restores the patient's circulation.
Traditional CPR is performed by active compressing the chest by direct application of an external pressure to the chest. This phase of CPR is typically referred to as the compression phase. After active compression, the chest is allowed to expand by its natural elasticity which causes expansion of the patient's chest wall. This phase is often referred to as the relaxation or decompression phase. Such expansion of the chest allows some blood to enter the cardiac chambers of the heart. The procedure as described, however, is insufficient to ventilate the patient. Consequently, conventional CPR also requires periodic ventilation of the patient. This is commonly accomplished by a mouth-to-mouth technique or by using positive pressure devices, such as a self-inflating bag which delivers air through a mask, an endotracheal tube, or other artificial airway.
In order to increase cardiopulmonary circulation induced by chest compression, a technique referred to as active compression-decompression (ACD) has been developed. According to ACD techniques, the active compression phase of traditional CPR is enhanced by pressing an applicator body against the patient's chest to compress the chest. Such an applicator body is able to distribute an applied force substantially evenly over a portion of the patient's chest. More importantly, however, the applicator body is sealed against the patient's chest so that it may be lifted to actively expand the patient's chest during the relaxation or decompression phase. The resultant negative intrathoracic pressure induces venous blood to flow into the heart and lungs from the peripheral venous vasculature of the patient. Devices and methods for performing ACD to the patient are described in U.S. Pat. Nos. 5,454,779 and 5,645,552, the complete disclosures of which are herein incorporated by reference.
Another successful technique for increasing cardiopulmonary circulation is by impeding air flow into a patient's lungs during the relaxation or decompression phase. By impeding the air flow during the relaxation or decompression phase, the magnitude and duration of negative intrathoracic pressure is increased. In this way, the amount of venous blood flow into the heart and lungs is increased. As a result, cardiopulmonary circulation is increased. Devices and methods for impeding or occluding the patient's airway during the relaxation or decompression phase are described in U.S. Pat. Nos. 5,551,420 and 5,692,498 and co-pending U.S. application Ser. No. 08/950,702, filed Oct. 15, 1997. The complete disclosures of all these references are herein incorporated by reference.
The above techniques have proven to be extremely useful in enhancing traditional CPR procedures. As such, it would be desirable to provide still further techniques to enhance venous blood flow into the heart and lungs of a patient from the peripheral venous vasculature during both conventional and alternative CPR techniques. It would be particularly desirable to provide techniques which would enhance oxygenation and increase the total blood return to the chest during the relaxation or decompression phase of CPR.
SUMMARY OF THE INVENTION
The invention provides methods and devices for increasing cardiopulmonary circulation when performing cardiopulmonary resuscitation. The methods and devices may be used in connection with most generally accepted CPR methods. In one exemplary method, a patient's chest is actively compressed during the compression phase of CPR. At least some of the respiratory muscles, and particularly the inspiratory muscles, are then stimulated to contract during the relaxation or decompression phase to increase the magnitude and prolong the duration of negative intrathoracic pressure during the relaxation or decompression phase, i.e., respiratory muscle stimulation increases the duration and degree that the intrathoracic pressure is below or negative with respect to the pressure in the peripheral venous vasculature. By enhancing the amount of venous blood flow to the heart and lungs, cardiopulmonary circulation is increased.
Among the respiratory muscles that may be stimulated to contract are the diaphragm and the chest wall muscles, including the intercostal muscles. The respiratory muscles may be stimulated to contract in a variety of ways. For example, the diaphragm may be stimulated to contract by supplying electrical current or a magnetic field to various nerves or muscle bundles which when stimulated cause the diaphragm to contract. Similar techniques may be used to stimulate the chest wall muscles to contract. A variety of pulse trains, pulse widths, pulse frequencies and pulse waveforms may be used for stimulation. Further, the electrode location and timing of pulse delivery may be varied. In one particular aspect, an electrical current gradient or a magnetic field is provided to directly or indirectly stimulate the phrenic nerve.
To electrically stimulate the inspiratory motor nerves, electrodes are preferably placed on the lateral surface of the neck over the motor point for the phrenic nerve, on the chest surface just lateral to the lower sternum to deliver current to the phrenic nerves just as they enter the diaphragm, on the upper chest just anterior to the axillae to stimulate the thoracic nerves, in the oral pharyngeal region of the throat, or on the larynx itself. However, it will be appreciated that other electrode sites may be employed. For example, in one embodiment the respiratory muscles are stimulated by a transcutaneous electrical impulse delivered along the lower antero-lat margin of the rib cage. In one embodiment, inspiration is induced by stimulating inspiratory muscles using one or more electrodes attached to an endotracheal tube or pharyngeal tube.
A variety of other techniques may be applied to further enhance the amount of venous blood flow into the heart and lungs during the chest relaxation or decompression phase of CPR. For example, the chest may be actively lifted during the relaxation or decompression phase to increase the amount and extent of negative intrathoracic pressure. In another technique, air flow to the lungs may be periodically occluded during at least a portion of the relaxation or decompression phase. Such occlusion may be accomplished by placing an impedance valve into the patient's airway, with the impedance valve being set to open after experiencing a predetermined threshold negative intrathoracic pressure.
In one particular aspect of the method, respiratory gases are periodically supplied to the patient's lungs to ventilate the patient. In another aspect, a metronome is provided to assist the rescuer in performing regular chest compressions.
In still another aspect, the respiratory muscles are stimulated only during certain
Benditt David G.
Lurie Keith G.
Patterson Robert
Voeckel Wolfgang
Zielinski Todd M.
CPRx LLC
Kamm William E.
Townsend and Townsend / and Crew LLP
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