The present invention relates to temperature regulation of the human body, in particular, to the use of heat pipes in garments, blankets and pads to warm or cool the human body for activities in extreme temperature environments and for treatment of medical conditions.
The need to regulate body temperature exists where human activities are conducted in extreme temperature environments. Very cold environments are encountered by undersea divers, inhabitants of polar regions, pilots, mountain climbers and snow skiers, as well as by individuals who work in more pedestrian cold environments such as refrigerated containers. Very hot environments are encountered by those in diverse occupations such fire fighters, foundry workers and armored tank drivers.
The need for body temperature regulation also exists in the treatment of medical conditions. Individuals with impaired body temperature regulation systems, such as the elderly, stroke patients, and patients with spinal cord injuries or multiple sclerosis, may be subject to chronic hypothermia or hyperthermia. Victims of exposure, as well as patients having fever, dehydration, infection, and drug reactions may suffer temporarily from hypothermia or hyperthermia, and may require treatment including body temperature regulation.
Deliberate inducement of whole body hyperthermia has been found to be useful as a treatment for cancer, and has met with success. However, side effects range from fatigue to occasional mortality. Injury to temperature-sensitive body parts, such as the liver, has also been associated with whole body hypothermia. Because of these side effects, and the high labor costs associated with monitoring such treatment, regional, rather than whole body, hypothermia has found favor in the treatment of cancer. Inducement of regional or localized hyperthermia has, thus, also been used in the treatment of cancer, as well as in the treatment of joint diseases, such as capsulitis, tendinitis and lower back pain.
Various means have been developed to warm and cool the human body to achieve body temperature regulation needed for such activities and medical treatments. Cold suits, such as the garment shown by Jennings, U.S. Pat. No. 3,289,748, include circulating fluid systems powered by a pump or other means for circulating. See also, Macdonald et al, U.S. Pat. No. 4,807,447. In the garment of Jennings, serpentine tubes extend along the arms and legs of the wearer and converge at inlet and outlet manifolds. Cold suits, however, have the disadvantage of being heavy and are typically restrictive, causing exhaustion and cardiopulmonary distress in the wearer.
Hyperthermia blankets are also known wherein a single phase fluid loop winds back and forth through the blanket from inlet to outlet to cool the user. A chiller attached to the outlet of the fluid loop discharges heat from the hyperthermia blanket. Such blanket systems, however, have problems maintaining a constant blanket temperature throughout, and are heavy due to the weight of the circulating fluid. A blanket including heat pipes provides more uniform heating, as shown by Sgroi, U.S. Pat. No. 4,094,357. In the blanket of Sgroi, the heat pipes converge at one side of the blanket to be cooled by a refrigeration device or, alternatively, heated by a thermal energy source.
Suits and blankets having circulating fluid loops in similar configurations may also be used to provide heat to persons suffering from hypothermia. See, Macdonald et al and Sgroi. However, the same general disadvantages of weight, restriction of movement, and resulting exhaustion are present. Electric blankets are also well-known but often provide uneven heating, and subject the user to low-level electromagnetic radiation. Nonetheless, whether used for heating or cooling, such suits and blankets generally disadvantageously require external connections and/or require external power sources.
Numerous devices have been developed for regional, therapeutic heat transfer. Jones, U.S. Pat. No. 4,706,672 discloses a passive thermal transfer device in which metal fibers woven into a mesh act as a heat sink to draw heat from an afflicted area for dissipation. Golden, U.S. Pat. No. 4,962,761 discloses a thermal bandage to heat or cool an area of the skin, wherein a circulating fluid is used to carry heat to or from the afflicted part. However, the need continues to exists for improved means for applying heat to specific areas of the human body for the treatment of disease which will avoid damage to adjacent tissues and structures.