Surgery: light – thermal – and electrical application – Light – thermal – and electrical application – Thermal applicators
Reexamination Certificate
2001-10-11
2004-03-02
Gibson, Roy D. (Department: 3739)
Surgery: light, thermal, and electrical application
Light, thermal, and electrical application
Thermal applicators
C607S096000, C607S112000
Reexamination Certificate
active
06699267
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the selective raising and/or lowering of patient temperatures, and more particularly, to systems and methods for controlling a patient's temperature via the circulation of heated/cooled fluid through one or more pads contacting a patient.
BACKGROUND OF THE INVENTION
The use of contact pad systems for selectively cooling and/or heating bodily tissue is known. In such systems a fluid, e.g. water or air, is circulated through one or more pads to affect surface-to-surface thermal energy exchange with a patient. One highly effective contact pad and related system is disclosed in U.S. Pat. No. 6,197,045, hereby incorporated by reference in its entirety. As noted in the '045 patent, the ability to establish and maintain intimate pad-to-patient contact is often of key importance to fully realizing medical efficacies with contact pad systems.
In this later regard, the effect of temperature on the human body has been well documented. Elevated temperatures, or hyperthermia, may be harmful to the brain under normal conditions, and even more importantly, during periods of physical stress, such as illness or surgery. Conversely, lower body temperatures, or mild hypothermia, may offer some degree of neuroprotection. Moderate to severe hypothermia tends to be more detrimental to the body, particularly the cardiovascular system.
Temperature management, or thermoregulation, can be viewed in two different ways. The first aspect of temperature management includes treating abnormal body temperatures, i.e. cooling the body for elevated temperatures, or warming the body for lowered temperatures. The second aspect of thermoregulation is an evolving treatment that employs techniques that physically control a patient's temperature to provide a physiological benefit, such as cooling a stroke patient to gain some degree of neuroprotection.
Hypothermia may occur for a variety of reasons, including exposure to cold environments, brain injury, or complex surgical procedures. During surgery, a patient typically experiences mild hypothermia as a result of the effect of general anesthesia on the body's thermoregulatory system and prolonged exposure of internal organs. Mild hypothermia in the medical or the surgical patient has been thought to prolong the time to extubation, contribute to coagulopathies, increase the chance of infection, and increase cardiac demand as a result of shivering.
Hyperthermia may occur as a result of systemic inflammatory response, sepsis, stroke, or other brain injury. While the mechanism of the effect of the hyperthermia on the brain is not clearly understood, there is evidence to indicate that even mild increases in temperature may contribute to neurological deficits. Hyperthermia also increases the metabolic rate and may deplete energy stores in the body.
In view of the foregoing, it may be appreciated that recognized medical applications for contact pad systems are ever-increasing. By way of example, cooling pad systems may be utilized in early therapy to reduce neurological damage incurred by stroke and head trauma patients. Additional applications include selective patient heating/cooling during surgical procedures such as cardiopulmonary bypass operations.
As these and other medical applications have evolved, the present inventors have recognized the desirability of enhancing the predictability, responsivity, flexibility and portability of thermal exchange pad systems. More particularly, while known heating/cooling contact pad systems have proven effective for many applications, the present inventors have recognized that additional performance objectives and potential applications can be realized via the implementation of further improved control systems and associated control methodologies.
SUMMARY OF THE INVENTION
In particular, one objective of the present invention is to provide an improved patient temperature control system and method that provides rapid heating/cooling capabilities via one or more interconnectable contact pads while also yielding size, weight and operating efficiencies.
Another objective of the present invention is to provide an improved patient temperature control system and method that offers high thermal exchange reliability while accommodating application flexibility via the interconnectability of either one or a plurality of contact pads.
An additional objective of the present invention is to provide an improved patient temperature control system and method that facilitates ready set-up and portability.
A further objective of the present invention is to provide an improved patient temperature control system that yields enhanced wear and performance of one or more interconnectable contact pads.
Yet a further objective of the present invention is to provide an improved patient temperature control system and method that enhances patient comfort.
One or more of the above objectives and additional advantages may be realized by utilizing the temperature control system features and associated methods disclosed hereinbelow. The system features may include at least one heat exchanger for affecting at least one of heating and cooling a fluid, a circulating pump for circulating the fluid through the heat exchanger, and at least one interconnectable patient contact pad to affect heat transfer therebetween. For purposes hereof, the term “contact pad” refers to any type of pad through which fluid may be flowed from an input port to an output port and which is otherwise adapted to contact a patient to affect heating or cooling.
In one aspect, the inventive system may also include at least a first fluid reservoir, or “make-up fluid reservoir”, fluidly interconnectable with the contact pad(s). The first fluid reservoir may be utilized to contain fluid that is removable from the reservoir to fill/circulate through the pad(s) during use. In conjunction with this aspect, the system may be defined so that, during normal heating/cooling operations, fluid is circulatable through the pad(s) and the heat exchanger(s) by the circulating pump substantially free from passage through the first fluid reservoir. By virtue of this arrangement, rapid fluid temperature changes may be achieved in the system since only the circulated fluid is temperature controlled (e.g., not any additional fluid remaining within the first fluid reservoir during fluid circulation). Relatedly, reduced heat exchanger requirements may be realized. Further, flexibility may be maintained by containing a fluid volume in the first reservoir that is sufficient for filling a plurality of interconnectable contact pads.
Preferably, the system also comprises a second fluid reservoir, or “circulating fluid reservoir”, through which fluid is circulated during normal heating/cooling operations. In that regard, the first and second reservoirs may be directly, fluidly interconnected so that fluid may be removed from and flowed back into the first fluid reservoir via passage through the second fluid reservoir. Further, the heat exchanger, circulating pump and first and second fluid reservoirs may be supportably located within a common housing, wherein the system is substantially self-contained to facilitate portable use.
More particularly, all or at least a portion of the first fluid reservoir may be physically located above the second fluid reservoir to provide for gravity fluid flow from the first reservoir to the second reservoir. Relatedly, the top of the first reservoir may be maintained at substantially atmospheric pressure (e.g. via a vent having a semi-permeable filter), wherein gas may be removed from/passed into the system. Further, a sensor may be provided at the second fluid reservoir for sensing the amount of fluid contained by the second reservoir, wherein a user output may be provided if/when the fluid amount drops below a predetermined amount.
For example, the sensor may provide an output signal to a controller (e.g. a microprocessor), wherein the controller transmits a signal to a user out put (e.g. a display and/or audible o
Ellingboe Bruce
Voorhees Marc
Gibson Roy D.
Marsh & Fischmann & Breyfogle LLP
Medivance Incorporated
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