BACKGROUND OF THE INVENTION
The present invention relates generally to thermal coverings, more specifically, to thermal coverings adapted to reduce the incidence of hypothermia. As such, the invention is particularly well suited in medical environments for use as a surgical drape, gown, or blanket. The invention is also suitable for campers, rescue workers, and the like for use in emergency, rescue, and survival conditions. Other uses of course would be evident to those skilled in the art.
In many emergency situations, it is critical for a patient to receive prompt and proper attention to his/her injuries in order to avoid exacerbating those injuries that may have already occurred. Often, the first rescuers to arrive on the scene are emergency medical staff who are responsible for preparing the patient for transportation to the nearest medical facility where the individual's injuries are to be treated. Depending upon the particular circumstances surrounding the patient's injuries and the location of an accident scene, these rescuers may typically be emergency medical squads who are employed with either a fire department, a local hospital, a law enforcement agency, rescue patrols and the like. In most situations, the patient is transported to the most appropriate medical facility by a ground ambulance, but air ambulances are also employed when circumstances dictate that this would be most efficient.
One of the many concerns of certified rescue workers during their preliminary treatment of a patient is to provide, to the extent possible, the most comfortable surroundings for the individual. This can both place the patient at ease and can be vital to the success or failure of initial medical treatment, particularly in instances where weather conditions are severe or where the patient is in shock. For instance, rescues that take place in cold or wet weather conditions, such as those often encountered by ski patrols, require that the patient be adequately insulated from the cold to avoid further reduction in body temperature, while rescues occurring in windy or rainy climates require that the patient be covered with a material repellant to these elements. Therefore, it is vital that the emergency rescue personnel be adequately equipped so that they can quickly and properly adapt to the specific situation at hand.
The patient may remain at the medical facility and require continued thermal protection to provide heat to his/her body. In addition, the patient may be required to undergo a surgical procedure. It is well known that a patient under general anesthesia undergoes several physiological changes that inhibit the body's normal thermo-regulatory capabilities. General anesthesia depresses the function of thermoregulating centers in the hypothalamus, thus resulting in the body's diminished ability to self-regulate body temperature. Infusion of intravenous fluid may contribute to cooling body temperature during surgery because such intravenous fluids absorb heat from the body when they are at a temperature below body temperature. Inspiration of dry anesthesia gases during surgery may also contribute to body temperature cooling during surgery because the dry gas both absorbs heat from the body and because of the cooling action created when water from the body is absorbed by the dry gas. Moreover, during surgery the body cavity may be exposed, which increases the effective surface area of the body and also cools body parts that are normally not exposed to the environment. The incidence of hypothermia occurring after surgery has been estimated to be as great as 60% to 90%.
To prevent hypothermia from occurring in many situations, including rescue, emergency surgery, and/or many elective surgeries, it is necessary to provide active heating to the patient. As such, to minimize any potential complication in the description detailed in this disclosure, the remainder of the disclosure will refer to coverings for use in surgical settings. This is meant to serve as a simplification of the disclosure only and is not intended to exclude other thermal coverings including those more appropriately adapted for use in emergency, survival, or rescue situations.
- SUMMARY OF THE INVENTION
One requirement appropriate for use in a surgical setting is that the heating system or method used to heat the patient during surgery be capable of maintaining a sterile surgical field. Another important requirement for any active heating system or method is that it delivers sufficient heat to the body to lessen the likelihood of the onset of hypothermia. Although many devices exist that may be used to provide heat or to provide a sterile environment, none of these devices are capable of utilizing thermogenic materials contained within the covering to generate heat without requiring a rupturable membrane or continued circulation of the thermogenic material.
Objects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.
The present invention provides a chemically activated thermal covering that has two main components. The first component is a thermogenic system which is associated with the second component, a carrier containing or otherwise supporting the thermogenic system. The thermogenic system contains at least one, and often more than one compartment which contains a first reagent. The first reagent is maintained at a first pressure. The system also contains an actuator for controllably isolating a second reagent from the first reagent. The second reagent is maintained at a second pressure which is higher than that of the first reagent. A channel, and often a plurality of such channels are provided for connecting the compartment or compartments to the actuator. In some embodiments, a plurality of individually controllable actuators are provided. Each actuator controls a bank of such channels and compartments. In any event, the system works upon the principle that the pressure differential between the first and second reagents draws the second reagent into the compartment where the first reagent is located thereby initiating the thermal reaction. The carrier portion of the system typically is fashioned into a foldable, conformable, generally planar carrier material for carrying the thermogenic system in the form of a covering including a nonwoven fabric and/or a film material. The covering may be in numerous forms, including a surgical drape or a blanket.
In another aspect, the present invention the second reagent is contained within a dedicated reservoir. The reservoir may be volumetrically changeable and may include an expandable bladder. The second reagent may be obtained from an environment within which the covering is located, including utilizing the oxygen contained within the air itself and as such may not include a dedicated reservoir component. In some embodiments the compartments containing the first reagent may be maintained under a vacuum until the actuator is actuated at which time the second reagent is drawn into the compartment initiating the thermal reaction.
In yet another aspect of the present invention the compartments and channels of the thermogenic system may be configured as a plurality of compartments and channels thereby forming at least one conduit system. As such, each conduit system may contain at least one channel leading to a plurality of compartments. The channels and/or compartments may be made of reversibly collapsible materials, be formed from a film or other fluid tight substrate, and may be formed from aspects of the carrier material itself. Moreover, the thermogenic system may include a bank of independently controllable actuators each capable of introducing a second reagent into a conduit system containing a channel connected to a compartment containing the first reagent. The thermogenic system may be affixed to an exterior surface of the carrier, may be internal to the carrier or may have internal as well as external components.
- BRIEF DESCRIPTION OF THE FIGURES
In still another aspect of the present invention, the thermal covering may include the first reagent impregnated within a foam or other sponge-like material. Embodiments of the thermal covering according to the invention are described below in greater detail with reference to the appended figures. As such, these and other objects are achieved by the apparatus disclosed and claimed herein.
FIG. 1 is a plan view of an embodiment of a thermal covering according to the present invention;
FIG. 2 is a cross-sectional view of another embodiment of a thermal covering according to the present invention;
- DETAILED DESCRIPTION OF THE INVENTION
FIG. 3 is a cross-sectional view of still another embodiment of a thermal covering according to the present invention.
Reference will now be made in detail to one or more examples of the invention depicted in the FIGs. Each example is provided by way of explanation of the invention, and not meant as a limitation of the invention. For example, features illustrated or described as part of one embodiment may be used with another embodiment to yield still a different embodiment.
Other modifications and variations to the described embodiments are also contemplated within the scope and spirit of the invention.
As such, turning in detail to FIG. 1, a chemically activated thermal covering 10 in accordance with the present invention is depicted. The chemically activated thermal covering 10 is generally configured to be in the form of a flat, foldable, conformable, relatively planar material. In the FIG. 1 embodiment, it may be seen that in one of its simplest forms the covering 10 comprises a thermogenic system 12 associated with a carrier 14 of some type, such as a sheet material.
Such a structure in the form of the covering 10 may be provided with edges 16 as shown on FIG. 1. The thermogenic system 12 comprises a plurality of interconnected compartments 18 affixed to or otherwise carried by the carrier 14. The location of the compartments 18 may be on either side of; on both sides of; and in some embodiments even within the structure of the carrier 14 itself. In any event, the compartments are each interconnected one to another via tubing or channels 20. The tubing may actually be constructed of a tubing material, however, channels or passages created within the material comprising the carrier 14 are contemplated as well. For ease of description, dedicated tubing, passages, or channels are referred to as channels 20, and the compartments 18 together with the channels 20 are referred to as a conduit system 22.
Within each compartment 18 may be found some quantity of a first reagent 24. The first reagent would be capable of generating heat or otherwise exhibiting thermogenic properties when exposed to a second reagent 26. In many embodiments the second reagent 26 may comprise a fluid. The fluid itself may comprise a gas such as air or a liquid such as water. In other embodiments more complex arrangements of additional reagents may be used.
Specific reagents capable of forming such a thermogenic reaction are known in the art and as such are not individually identified herein. Moreover, though the description is drawn to the creation of an exothermic reaction, reagents capable of inducing a cooling effect may also be selected. It should be understood that the reagents selected should be chosen so that the desired effect heating or cooling effect is induced. For ease of description, the remainder of the disclosure addresses a heating effect though the claims are drawn to both heating and cooling.
In any event, the second reagent 26 must be kept separate from the first reagent 24 until such time that the exothermic reaction designed to provide heat to the patient is desired. One such construction provides a reservoir 28 that may be placed in fluid communication with the conduit system 22. Once the second reagent 26 is introduced into the conduit system 22, the reaction may progress from compartment to compartment via the channels, or otherwise, depending upon the actual design of delivery of the second reagent 26 to the first reagent 24.
The principle behind the operation of the present invention is that the second reagent 26 is drawn into the conduit system 22 by a pressure differential maintained between the conduit system 22 and the reservoir 28. To accommodate this, the conduit system 22 is maintained under a lower pressure with respect to the reservoir 28. In some instances this lower pressure may actually be a vacuum, that is, a pressure less than 1 atmosphere. Under most normal surgical and emergency conditions a slight vacuum would be sufficient, however the covering 10 may also be used in an environment that may differ from 1 atmosphere. Examples of this might be at high altitudes where pressures are lower than 1 atmosphere, and within a decompression chamber or a hyperbaric oxygen therapy chamber where pressures are higher than 1 atmosphere. Therefore it is important to note that the conduit system 22 is at a lower pressure with respect to the reservoir at the time when the reaction is initiated.
As stated, until such time that it is desirous for the reaction to take place, the reservoir 28 must be separately maintained or otherwise isolated from the conduit system 22. As such an actuator 30 of some form is provided that when actuated enables flow of the second reagent into the conduit system 22. The actuator 30 may be located anywhere on or otherwise associated with the covering 10, such as at an edge 16. The form that the actuator 30 takes may vary based upon the system design; some embodiments may be, but are not limited to: providing a rupturable membrane or valve between the reservoir and the remainder of the system, keeping a physical separation between the conduit system 22 and the reservoir 28 until such time that the reaction is desired, as well as other possibilities. In any form, the actuator serves the purpose of keeping the reagents separate from one another until such time that it is desired to initiate the exothermic reaction. Once actuation occurs, the second reagent 26 is drawn into the conduit system 22 through the channels 20 and into the compartments 18 due to the pressure differential, thereby reacting with the first reagent 24, generating the exothermic reaction and heating the patient.
In certain embodiments, connecting the reservoir 28 containing the second reagent 26 to the conduit system 22 does not alter the fact that the thermogenic system 12 remains a closed system. As such, a sufficient quantity of reagent 26 should be contained within the reservoir 28 to enable a complete reaction to occur within the thermogenic system 12 once the reagent 26 is introduced into the conduit system 22. One construction capable of enabling fluid flow from the reservoir 28 to the conduit system 22 within such a closed system is to provide the reservoir with some way with which to change its volume. Some possible methods suitable to accomplish this include but are not limited to providing a collapsible reservoir, a syringe-type reservoir having a plunger or other moveable component that accommodates a volumetric change in the reservoir 28, or a bladder within the reservoir that expands to fill the void left within the reservoir 28 as the reagent 26 is drawn into the conduit system 22.
In certain embodiments, the reservoir 28 may comprise the external environment within which the covering 10 itself is located. An example of this is when the second reagent 26 comprises oxygen contained within air. Actuation of the actuator 30 would allow air to be drawn into the conduit system 22. As such, it should be understood that the reservoir 28 may not exist as a specific component within the thermogenic system 12, but may comprise the external environment itself. In other embodiments, the reservoir 28 may be attached to the system 12 coincident with manufacture or may be provided as a separate component attached only when it is desirous for the reaction to be initiated.
A number of possibilities exist that enable the conduit system 22 to be maintained at a lower pressure with respect to the reservoir 28. The conduit system 22 could simply be kept at a negative pressure by placing it under a vacuum. Alternatively, the conduit system 22 could be made of a reversibly collapsible material so that the compartments 18 and/or the channels 20 are initially in a collapsed condition and would expand upon transfer of reagent 26 from the reservoir 28 through the actuator 30. This could be handled by maintaining the conduit system 22 in a collapsed state until the pressure in the thermogenic system 12 is equalized. Equalization occurs when the second reagent 26 is drawn into the conduit system 22 at which time all or part of the conduit system 22 returns to an uncollapsed state. One possible embodiment of such a conduit system may comprise channels that are made of soft rubberized or flexible tubing such as surgical tubing.
Looking to FIG. 2, a cross section of an alternative embodiment is depicted. In this embodiment the reservoirs 18 are contained within an interior aspect of the covering 14. Moreover, a large quantity of compartments 18 may be provided. This embodiment may best be described as being reminiscent of a material commonly referred to as “bubble-pack.” Bubble-pack typically consists of two layers of a thin plastic material, such as polyethylene or vinyl formed with periodic bubbles between the layers. In this embodiment, the covering 14 may comprise a multilayer construct having a first layer 32 and a second layer 34. Between the two layers 32, 34 are situated reservoirs 18 and channels 20 together forming the conduit system 22. One manner with which to form the reservoirs 18 is to utilize film layers 36 to create them in the same manner as one would form bubble-pack. The use of film 36 to create bubble-pack would be understood by those skilled in the art and no further description is considered necessary to address the formation of reservoirs 18.
As in the FIG. 1 embodiment described above, a quantity of the first reagent 24 would be contained within the compartments 18. The channel 20 may simply comprise a void space within the covering 14 to connect to the reservoirs 18. The channel 20 is depicted in FIG. 2 as being vertically offset from the reservoirs 18 for clarity. It should be understood that the channel 20 may also tangentially impinge upon the reservoirs 18 so as to eliminate the vertical sections of channel 20 depicted in FIG. 2. Moreover, since FIG. 2 is a cross sectional view it is not readily apparent that a plurality of such channels 20 may be provided. Any number of such channels 20 may be independently controlled by the use of individual actuators 30, as shown in FIG. 1, thereby forming a bank of individually controllable reactions. A foam 38, sponge-like material, or other spacer as depicted in FIG. 2 may be provided as well. Though such a material is not necessary, it may provide added insulative effects to the covering 10 among other things.
In fact, FIG. 3 depicts an alternative embodiment of a carrier 10. In this embodiment, a foam 38 is impregnated with the first reagent 24. Upon actuation, the second reagent 26 is introduced into the conduit system through the channel or channels 20. An embodiment, such as that shown in FIG. 3 eliminates the need for dedicated compartments. In essence the entire covering may be made to encase and act as the thermogenic system.
In any of the embodiments, the carrier 14 may comprise clothlike, liquid-impervious, barrier material, which itself possesses a unique balance of performance characteristics and features making the material suitable for use in forming surgical drapes, thermal blankets, as well as other emergency thermal coverings. The carrier 14 may be a woven material, a nonwoven material or combinations of the same. In some embodiments a single layer nonwoven material, a laminate of like materials, a laminate of nonwoven polymers combined with film layers or any combination may be provided. In the event that a laminate is selected, the individual layers of the laminate comprising the carrier 14 may themselves be laminated, bonded or attached together by known means, including thermal-mechanical bonding, ultrasonic bonding, adhesives, stitching and the like.
In use, for example in a surgical setting, the thermal covering 10 may be provided in the configuration of a sterile surgical-thermal drape of a nonwoven laminate as described above. Medical personnel would remove the drape from its packaging and then place it on the desired patient surface so that the thermal effect is transferred to the patient. The reagents are allowed to intermix by initiating the reaction in a manner that prevents the sterile drape from contacting any unsterilized surface or objects so as to maintain the sterility of the drape. After this has been done, surgical procedures may then be performed on exposed portions of the patient or through a fenestration in the drape (not explicitly shown) without risking inadvertent contamination of medical instruments or devices by contact with the drape. One skilled in the art will recognize that the specific description of the surgical drape is exemplary and other embodiments may incorporate additional features such as fenestration reinforcement materials, pouches, clips, tape, as well as other features found on various embodiments of surgical drapes.
Accordingly, while this invention has been described by reference to certain specific embodiments and examples, it will be understood that this invention is capable of further modifications. This application is, therefore, intended to cover any variations, uses or adaptations of the invention following the general principles thereof, and including such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and fall within the limits of the appended claims.