TEMPERATURE CONTROLLED CABINET
SYSTEM AND METHOD FOR HEATING
ITEMS TO DESIRED TEMPERATURES
CROSS-REFERENCE TO RELATED 5
APPLICATIONS
This application claims priority from U.S. Provisional Patent Application Serial No. 60/158,507, entitled "Temperature Controlled Cabinet System and Method for Heating Items to Desired Temperatures", and filed Oct. 8, 1999. The disclosure of the above-mentioned provisional application is incorporated herein by reference in its entirety.
BACKGROUND OF THE INVENTION
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1. Technical Field
The present invention pertains to systems for heating medical items. In particular, the present invention pertains to a system for heating and maintaining medical solution containers (e.g., bags or bottles containing saline or intra- 20 venous (IV) solutions, antibiotics or other drugs, blood, etc.) or other medical items (e.g., instruments, blankets, etc.) at desired temperatures by providing an even distribution of heat to the medical items placed within the system.
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2. Discussion of Related Art
Generally, various items are required to be heated prior to utilization in a medical procedure to prevent thermal shock and injury to a patient. These items typically include intravenous solution, surgical instruments, bottles and blankets. 30 In order to provide the necessary heated items for use in medical procedures, medical personnel may utilize several types of warming systems to heat items toward their operational temperatures. For example, ovens may be disposed within operating rooms to heat items to desired tempera- 35 tures. Further, U.S. Pat. No. 4,419,568 (Van Overloop) discloses a wet dressings heater having a base with side walls defining a cavity, and an insert connected to the base and defining at least one recess in the cavity for receiving wet dressings. A heater has an electrical heating element in 40 close proximity to the insert recess for heating the wet dressings, while the temperature of the heating element is controlled in a desired temperature range for those wet dressings.
U.S. Pat. No. 4,495,402 (Burdick et al) discloses a 45 warmer for heating wet dressings and other articles disposed within a heating and storage compartment. The articles are arranged within the compartment in stacked relation and disposed on a plate that is supplied with thermal energy from a heater. The plate includes a center aperture whereby a first 50 thermal sensor is disposed in the aperture in contact with a bottommost article. Control circuitry is disposed beneath the plate to control the heater to maintain temperature ofthe bottommost article at a desired level based on the temperatures sensed by the first thermal sensor and a second thermal 55 sensor responsive to heater temperature.
U.S. Pat. No. 5,408,576 (Bishop) discloses an intravenous fluid warmer having a cabinet structure to accommodate a plurality of intravenous fluid bags. A temperature sensor and pad of heating filaments are disposed within the cabinet 60 structure, whereby the temperature sensor enables automatic temperature regulation of the pad of heating filaments to heat the intravenous fluid bags. The heating filaments are covered by a rubber layer to prevent melting of the bags during heating. A temperature indicator disposed on the 65 cabinet structure permits a user to ascertain when a desired temperature is attained, whereby an intravenous fluid bag is
removed from the intravenous fluid warmer via an opening defined in a side of the cabinet structure.
U.S. Pat. No. 5,986,239 (Corrigan, III et al.) discloses a conductive warmer for flexible plastic bags. The warmer includes a heat-conducting member of thermally conductive material having a plurality of fins which are parallel and spaced apart to define a plurality of bag-receiving compartments. The fins are connected to a back portion of the heat-conducting member to which a heating element is attached in a heat-exchanging relationship. The heating element conducts heat through the back portion and fins of the heat-conducting member to the bags.
In addition, the related art provides warming systems for other types of items. For example, U.S. Pat. No. 4,605,840 (Koopman) discloses a horizontal holding cabinet for prepared food, wherein the cabinet has a plurality of drawercontaining modules arranged side-by-side to each other. Each module has a heating element and an integral water reservoir and is capable of being independently heated and humidified. The modules each further include a drawer receiving cavity having an open front adapted to receive a drawer frame. The cavity bottom wall is provided with one or more heating elements, whereby the module walls conduct heat to heat the cavity. A temperature thermostat is mounted on the undersurface of the cavity bottom wall to sense cavity temperature and is further connected to a thermostatic controller that controls the heating elements in accordance with a desired temperature.
The warming systems described above suffer from several disadvantages. In particular, ovens typically do not have a high degree of accuracy or control, thereby enabling use of items having temperatures incompatible with a medical procedure and possibly causing injury to a patient. Further, the Burdick et al and Bishop warmers employ heaters that generally contact a particular portion of an article being heated, thereby heating articles in an uneven manner and enabling formation of hot spots. Moreover, the Burdick et al, Bishop, Corrigan, III et al and Van Overloop warming systems heat items simultaneously to only a single desired temperature rendering them incompatible for applications requiring various items to be heated to different temperature ranges. These systems further employ a heating element covering a substantial portion of a conducting member, thereby increasing system costs and power usage. The above described systems typically have heating area dimensions specifically configured to accommodate particular items and, therefore, are limited with respect to the types of items that may be heated by those systems. The Koopman system employs heating elements disposed within a housing cavity and not in direct contact with the surface supporting an item. This typically requires the system to heat the cavity, thereby providing increased heating time for an item to attain a particular temperature. In addition, the above-described warming systems do not provide a selectively configurable structure for partitioning system compartments to facilitate a relatively even heat distribution for additional or varying items placed therein.
The present invention overcomes the aforementioned problems and provides several advantages. For example, the present invention warming system distributes heat evenly to one or more medical items of varying shapes and sizes, thereby ensuring relatively uniform heating of items with enhanced temperature control. Further, since medical items are supported within system compartments on a heating plate, the medical items are not in direct contact with a heater, thereby avoiding creation of "hot spots". Moreover, the present invention reduces costs by utilizing a single
common controller to simultaneously control each heater within system compartments, and provides versatility since each compartment heater may be individually controlled to enable the system to heat medical items contained within different compartments to the same or different desired 5 temperatures. In addition, a warming system rack structure of the present invention provides even heat distribution and enhanced temperature regulation of individual medical items contained within the receptacles. Since most hospital personnel are unaware of the temperature of a particular 10 medical item prior to use, the rack structure provides a fairly high degree of control of that temperature.
OBJECTS AND SUMMARY OF THE
INVENTION 15
Accordingly, it is an object of the present invention to heat a medical item to a desired temperature by uniformly distributing heat about the medical item, thereby avoiding creation of "hot spots" and "cold spots".
It is another object of the present invention to simulta- 20 neously maintain various items at different desired temperatures for use in medical procedures.
Yet another object of the present invention is to simultaneously maintain various items at different desired temperatures for use in medical procedures via a temperature control 25 system including heating compartments individually controlled by a common controller, wherein each heating compartment is maintained at a desired temperature.
Still another object of the present invention is to evenly 3Q distribute heat about a medical item within a heating compartment of the system by conducting heat through a heating plate that at least partially surrounds the medical item.
A further object of the present invention is to provide a collapsible rack structure within a system heating compart- 35 ment to partition that compartment and facilitate a uniform distribution of heat to additional or varying items.
The aforesaid objects may be achieved individually and in combination, and it is not intended that the present invention be construed as requiring two or more of the objects to be 40 combined unless expressly required by the claims attached hereto.
According to the present invention, a temperature control system includes a cabinet or system housing having an interior partitioned into individual heating compartments for 45 containing medical items. Each compartment includes a heating assembly having a generally U-shaped heating plate with thermally conductive bottom and side walls, a heater, a temperature sensor and a temperature cut-out switch. The heater is typically disposed beneath the bottom wall of the 50 heating plate and applies heat to the heating plate to heat medical items placed thereon. The U-shaped configuration of the heating plate ensures even distribution of heat applied to one or more medical items placed within the heating compartment. The system further includes a controller in 55 communication with the heater and temperature sensor of each heating assembly, wherein the controller controls heating of each compartment based upon a user selected desired or set point temperature associated with that compartment. A collapsible rack structure may additionally be disposed 60 within one or more compartments to form individual receptacles in those compartments for receiving and heating medical items placed therein.
The above and still further objects, features and advantages of the present invention will become apparent upon 65 consideration of the following detailed description of specific embodiments thereof, particularly when taken in con
junction with the accompanying drawings, wherein like reference numerals in the various figures are utilized to designate like components.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a view in perspective of a temperature controlled cabinet system in accordance with the present invention.
FIG. 2 is an exploded perspective view of a cabinet or housing of the system of FIG. 1.
FIG. 3 is a view in perspective of a heating assembly of the system of FIG. 1.
FIG. 4 is a view in plan of the underside of a heating plate of the heating assembly of FIG. 3.
FIG. 5 is an electrical schematic diagram of an exemplary control circuit of the system of FIG. 1.
FIG. 6 is a view in perspective of an alternative cabinet or housing for the system of FIG. 1.
FIG. la is a view in elevation of the system of FIG. 1 including collapsible rack structures for containing medical items, the rack structures being illustrated in fully and partially collapsed states.
FIG. lb is a view in elevation of the system of FIG. la with the rack structures in fully and partially expanded states.
DETAILED DESCRIPTION OF THE
PREFERRED EMBODIMENTS
A temperature controlled cabinet system for heating and maintaining medical solution containers (e.g., bags or bottles containing saline or intravenous (IV) solutions, antibiotics or other drugs, blood, etc.) or other medical items (e.g., instruments) at desired temperatures is illustrated in FIG. 1. Specifically, temperature controlled cabinet system 502a includes a cabinet or system housing 504a having a shelf 506 partitioning the cabinet interior into upper and lower compartments 524, 526, respectively. Each compartment includes a respective heating assembly 508(1),508(2) for receiving medical items placed within that compartment and heating the medical items to a desired temperature. Cabinet 504a is generally in the form of a rectangular box and includes top and bottom walls 510, 512, side walls 514, 516, a front door 528, a front wall 518 disposed above the door, and rear wall 520. The cabinet walls and door are each substantially rectangular and collectively define a cabinet interior. Rollers or casters 519 are attached to the cabinet bottom wall with each caster disposed toward a corresponding cabinet bottom wall corner to enable the system to be transportable. The casters or rollers may be of any quantity, may be implemented by any conventional or other types of rollers or wheel-type structures, and may be disposed at any locations on the cabinet. Further, the cabinet may be constructed of electro-galvanized steel or other suitably sturdy material, and may be of any size or shape. However, by way of example only, the cabinet system has an approximate height of thirty-six inches. It is to be understood that the terms "top", "bottom", "side", "front", "rear", "horizontal", "vertical", "upper", "lower", "up", "down", "height", "length", "width", "depth" and the like are used herein merely to describe points of reference and do not limit the present invention to any specific orientation or configuration.
Compartments 524 and 526 are generally disposed in vertical alignment within the cabinet interior. Heating assembly 508(1) is disposed on shelf 506 within compartment 524, while heating assembly 508(2) is disposed on
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