Surgery: kinesitherapy – Kinesitherapy – Device with applicator having specific movement
Reexamination Certificate
2000-12-01
2003-04-08
Pothier, Denise M. (Department: 3764)
Surgery: kinesitherapy
Kinesitherapy
Device with applicator having specific movement
C601S151000
Reexamination Certificate
active
06544202
ABSTRACT:
FIELD OF THE INVENTION
The invention is related to an apparatus and method for periodically producing an adaptable pressure waveform in a pneumatic sleeve applied to a limb of a human patient in order to help prevent deep vein thrombosis (DVT) or to treat lymphedema in the patient.
BACKGROUND OF THE INVENTION
Limb compression systems of the prior art apply and release pressure on a patient's extremity to augment venous blood flow and help prevent deep vein thrombosis (DVT) or to treat lymphedema. Limb compression systems of the prior art typically include: a source of pressurized gas; one or more pneumatic sleeves for attaching to one or both of the lower limbs of a patient; and an instrument connected to the source of pressurized gas and connected to the sleeves by means of pneumatic tubing, for controlling the inflation and deflation of the sleeves and their periods of inflation and deflation. In U.S. Pat. No. 3,892,229 Taylor et al. describe an early example of one general type of limb compression system of the prior art known as an intermittent limb compression system; such systems apply pressure intermittently to each limb by inflating and deflating a single-bladder sleeve attached to the limb. In U.S. Pat. No. 4,013,069 Hasty describes an example of a second general type of limb compression system of the prior art, known as a sequential limb compression system; such systems apply pressure sequentially along the length of the limb by means of a multiple-bladder sleeve or multiple sleeves attached to the same limb which are inflated and deflated at different times. Certain intermittent and sequential limb compression systems of the prior art are designed to inflate and are deflate sleeves on both limbs either simultaneously or alternately, while others are designed for use on one limb only.
The primary purpose of most of the limb compression systems of the prior art is to prevent or, reduce the risk of DVT. Such limb compression systems are used to minimize venous stasis during and immediately following surgery, as well as during long periods of immobility. DVT may lead to pulmonary embolism (PE), a serious hazard for surgical and trauma patients. For example, patients over forty years of age who are undergoing hip or knee surgery, or major abdominal surgery, are at particular risk of DVT. When DVT leads to PE, this complication can result in death, with an estimated 200,000 such deaths occurring in the United States annually. To help prevent DVT and thus PE, the use of pneumatic limb compression systems of both intermittent and sequential types, used either alone or combined with anticoagulant drug therapy, have been developed in the prior art and are commonly used at present.
A purpose of other limb compression systems of the prior art is to treat chronic edema, including lymphedema. Lymphedema refers to the condition of fluid accumulation in a limb. Secondary lymphedema can be a result of trauma or surgical complications. Limb compression therapy using limb compression systems of the prior art has been demonstrated to be of significant value in treating lymphedema.
Systems of the prior art have not been capable of producing a desired pressure waveform in a pneumatic sleeve attached to a limb. This is a significant limitation, as the inventors of the present invention have inferred from the recent clinical literature that applied pressure waveforms having differing shapes produce significantly different changes to venous blood flow. In the clinical literature, the use of a wide range of devices and non-standardized techniques by clinicians to indicate changes in venous flow and venous stasis, either subjectively or quantitatively, has been reported. For example, devices employing Doppler ultrasound, photo-plethysmography, impedance plethysmography, contrast venography, oximetry and de-oximetry have all been used for such purposes in the prior art. Such changes, when detected, then may or may hot have been taken into consideration in the manual adjustment of prior-art systems. For example, Tumey et al. in U.S. Pat. No. 5,443,440 describe apparatus including a sensor for determining whether patients have venous blood flow problems prior to setting parameters and use. However, a significant limitation of many prior-art limb compression systems is that such systems have not incorporated a standardized physiologic transducer and measurement algorithm which provides an indication of the change in venous blood flow produced as a result of the application of a pressure waveform to by means of the sleeve of the system. As a result, these prior-art systems cannot automatically adapt or change the pressure waveform applied to the limb, nor can they permit an operator to manually adapt or change the pressure waveform, in response to changes in venous blood flow, in order to improve the effectiveness of the therapy.
In many sequential limb compression systems of the prior art, such as the one described by Hasty in U.S. Pat. No. 4,013,069, elapsed times are pre-set to initiate the sequential pressurization of each of the multiple-chamber sleeves, or each of the multiple sleeves. This has been a significant limitation and has produced a sub-optimal augmentation of venous blood flow by such sequential limb compression systems, but has been necessary because these prior-art systems have not been capable of producing desired pressure waveforms in multiple-bladder sleeves and multiple sleeves, and have thus not been capable of using a selected parameter of the pressure waveform in one sleeve or bladder of a multiple-bladder sleeve to trigger the pressurization of another sleeve or bladder using the desired pressure waveform for that sleeve or bladder.
Many limb compression systems of the prior art are not capable of producing a desired pressure waveform in a pneumatic sleeve attached to a limb either because they do not directly measure the pneumatic pressure in the sleeve at any instant, or because they do not generate a signal indicative of the pressure suitable for permitting a feedback control system to produce the desired pressure waveform. In the prior art, for example, pressure gauges have been connected to inflatable bladders to provide visual indications of bladder pressure to operators, but such apparatus did not generate a signal suitable for controlling the production of a waveform and the apparatus was considered to be expensive, inconvenient and unnecessary.
Some limb compression systems of the prior art attempt to prevent hazardous over-pressurization by limiting the maximum pressure level produced in the sleeve without actually displaying or measuring the sleeve pressure. For example, in U.S. Pat. No. 4,841,956 Gardner et al. describe a limb compression system in which sleeve pressure is not measured, but in which the peak pressure level is limited by limiting the time period during which inflating gas flows into the sleeve. In such a system the maximum pressure actually produced in the sleeve is dependent on variables such as the flow resistance of the tubing, the design and pneumatic volume of the sleeve, and the pressure of the gas during the inflating time period. Other systems, such as that of Arkans in U.S. Pat. No. 4,396,010, use a preset pressure switch in the instrument to limit the maximum pneumatic pressure level.
In a limb compression system described by Cariapa et al. in U.S. Pat. No. 5,437,610, a pressure sensor is connected to a fluid-filled bladder within a pneumatic sleeve, but the sensor/bladder combination is adapted to measure the static pressure of the limb against the uninflated sleeve, and could not be used or adapted to produce any one of a wide range of desired pneumatic pressure waveforms in the sleeve.
Some limb compression systems known in the prior art attempt to estimate sleeve pressure in an inexpensive and convenient manner, based on a variety of apparatus and methods. These systems do not measure pressure directly in the pneumatic sleeve applied to the limb but instead estimate sleeve pressure indirectly and remotely from the sleeve. F
Jameson Michael
McEwen James Allen
Ipsolon LLP
Pothier Denise M.
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