Surgery: light – thermal – and electrical application – Light – thermal – and electrical application – Thermal applicators
Reexamination Certificate
2000-12-15
2002-12-24
Nasser, Robert L. (Department: 3736)
Surgery: light, thermal, and electrical application
Light, thermal, and electrical application
Thermal applicators
C607S113000
Reexamination Certificate
active
06497721
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates to the selective modification and control of a patient's body temperature, and to the regulation of the temperature of a fluid that is to be delivered to a specific target location within a body structure. More particularly, the invention provides methods and apparatus for treating or inducing hypothermia or hyperthermia by inserting a catheter into a blood vessel of the patient and selectively transferring heat to or from blood flowing through the vessel, and for altering the temperature of a fluid that is to be delivered to the target location while the fluid is within the patient.
The present invention further relates to the selective modification and control of whole body temperature and the temperature of selected target regions of the body such as the brain. More particularly, the invention is directed to methods and apparatus for lowering the temperature of the brain by using heat transfer regions of a heat transfer catheter to cool fluids in contact with, or circulating in, around, or leading to the brain region to provide regional hypothermia and temperature control.
BACKGROUND OF THE INVENTION
Under ordinary circumstances, the thermal regulatory system of the human body maintains a near constant temperature of about 37° C. (98.6° F.). Heat lost to the environment is precisely balanced by internal heat produced within the body.
Hypothermia is a condition of abnormally low body temperature generally characterized by a core body temperature of 35° C. or less, and may be further clinically defined according to its severity. For example, a body core temperature within the range of 32° C. to 35° C. may be described as mild hypothermia, 30° C. to 32° C. as moderate, 24° C. to 30° C. as severe, and a body temperature of less than 24° C. may constitute profound hypothermia. Although the above ranges may provide a useful basis for discussion, they are not absolutes and definitions vary widely as indicated in the medical literature.
Hyperthermia may be defined as a condition of abnormally high body temperature, and may be the result from exposure to a hot environment or surroundings, overexertion, or fever. Body core temperatures may range from 38° C. to 41° C. due to conditions such as fever, and may be substantially higher in cases of exposure and overexertion. Like hypothermia, hyperthermia is a serious condition that can be fatal.
Although both hypothermia and hyperthermia may be harmful and require treatment in some case, in other cases hyperthermia or hypothermia, and particularly hypothermia, may be therapeutic or otherwise advantageous, and therefore may be intentionally induced. For example, periods of cardiac arrest in the setting of myocardial infarction and heart surgery can produce brain damage or other nerve damage. Hypothermia is recognized in the medical community as an accepted neuroprotectant during cardiovascular surgery and therefore a patient is often kept in a state of induced hypothermia during cardiovascular surgery. Likewise, hypothermia is sometimes induced as a neuroprotectant during neurosurgery. Hypothermia may also be beneficial in other situations, for example, for victims of head trauma, spinal trauma, brain attack (also sometimes called stroke), spinal surgery or surgery where blood flow may be interrupted or compromised to the brain or spinal cord such as aneurysm repair, as well as other types of surgery where neuroprotection is desirable.
Neural tissue, that is all tissue of the nervous system such as the brain or spinal cord, is particularly subject to damage by vascular disease processes including, but not limited to ischemic or hemorrhagic stroke, blood deprivation for any reason, including cardiac arrest, intracerebral hemorrhage and head trauma In each of these instances, damage to brain tissue may occur because of ischemia, pressure, edema or other processes resulting in a loss of cerebral function and permanent neurological deficits. Lowering the brain temperature may confer neuroprotection through several mechanisms including the blunting of post-insult elevation of neurotransmitters such as glutamate, reduction of cerebral metabolic rate, moderation of intracellular calcium, prevention of intracellular protein synthesis inhibition, and reduction of free radical formation as well as other enzymatic cascades and even genetic responses. Thus intentionally induced hypothermia may prevent some of the damage to brain or other neurological tissue during surgery or as a result of stroke, intracerebral hemorrhage and trauma.
Treatment of stroke in particular is a possibly therapeutic use of intentionally induced hypothermia. Stroke (sometimes called brain attack) is a severely debilitating and complex disease that results from the blockage (ischemic stroke) or rupture (hemorrhagic stroke) of a blood vessel within or leading to the brain region. During a stroke, brain cells are damaged either by a lack of oxygen or by increased pressure. These events can eventually result in death and necrosis of brain tissue. In general, at least one goal in the therapeutic intervention for stroke is to preserve the function of as much brain tissue as possible. However, current medical treatment for stroke is largely supportive in nature. Newer treatments, for example clot-dissolving drugs, are available but may be only suitable for treatment of ischemic strokes and must generally be used shortly (within several hours) of the initial stroke symptoms to avoid side effects related to bleeding within the brain. In practice, it has been difficult to treat strokes within this time window since patients often do not arrive at a medical facility until several hours after the onset of a stroke. As a result, most strokes are not aggressively treated with medical therapy. A treatment to prolong this time window, and to protect brain cells from death, would have a profound impact on patient care.
Experimental studies of ischemia have shown reduction in infarcted brain tissue volume in animals treated with hypothermia during or shortly after a stroke or ischemic insult. It is therefore believed that the application of hypothermia to a patient who is suffering or has recently suffered a stroke may be beneficial.
Despite the acceptance of hypothermia as a neuroprotectant, it has not been widely used outside of the surgical setting. Additionally, most current practices attempt to provide hypothermia to the brain by inducing whole body hypothermia through systemic treatment. However, whole body hypothermia presents numerous difficulties and is cumbersome to implement in a patient who is not under general anesthesia. Lowering the systemic temperature of a patient not only takes a significant amount of time, but also subjects the patient to deleterious effects of hypothermia including cardiac arrhythmias, coagulation problems, increased susceptibility to infections, and problems of discomfort such as profound shivering.
Control of the body's temperature, for example, to maintain normothermia (usually 37° C.), is often desirable. For example, in a patient under general anesthesia, the body's normal temperature regulating mechanisms may not be fully functioning, and the anesthesiologist may be required to artificially control the patient's body temperature. Similarly, a patient may lose an extraordinary amount of heat to the environment, for example, during major surgery, and the patient's unaided body may not be able to generate sufficient heat to compensate for the heat lost. A device and method for controlling body temperature, for example by adding heat to maintain normothermia, would be desirable.
Particularly in the surgical setting, it has sometimes been the case that blood or other fluid was heated or cooled outside a patient's body and introduced into the body to heat or cool the body or some target location within the body. However, heating or cooling fluids outside of the patient may be cumbersome and require elaborate equipment. For example, in surgery, the temperature of a
Dineen Michael T.
Ginsburg, incapacited Robert
Machold Timothy R.
Buyan Robert D.
Nasser Robert L.
Radiant Medical Inc.
Stout, Uxa, Buyan & Mullins, LLPO
LandOfFree
Method and apparatus for regional and whole body temperature... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus for regional and whole body temperature..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for regional and whole body temperature... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2995941