Surgery – Instruments – External pressure applicator
Reexamination Certificate
2001-08-14
2004-01-27
Robert, Eduardo C. (Department: 3732)
Surgery
Instruments
External pressure applicator
C606S203000, C600S498000, C600S499000, C356S425000
Reexamination Certificate
active
06682547
ABSTRACT:
BACKGROUND
The use of an inflatable cuff to occlude blood flow into a subject's limb, thereby providing a bloodless surgical field in the portion of the limb distal to the cuff over a period of time suitably long for the performance of a surgical procedure, is well known in surgical practice. Tourniquet systems typically include an inflatable cuff for encircling a limb at a selected location and a tourniquet instrument for maintaining the pressure in the cuff near a selected pressure. Such tourniquet instruments of the prior art typically contain, or connect to, a source of pressurized gas and include a pressure regulating mechanism for controlling and maintaining the pressure of the gas supplied to the tourniquet cuff near the selected pressure. Typically a variety of cuff sizes are provided so that a cuff that overlaps itself when encircling the limb may be selected, thereby ensuring that pressure is applied to the limb around its entire circumference. Cuffs are also provided in a variety of shapes, widths, materials, configurations and other physical characteristics as required for different types of patients, limb locations, and surgical procedures.
Some types of tourniquet cuffs of the prior art have relatively complex physical characteristics aimed at safely and effectively occluding blood flow without regard to the cost of manufacture and although relatively effective cannot be manufactured at low cost, especially in small volumes. Other types of prior-art cuffs have simplified physical characteristics that reduce the cost of manufacture but that may not result in the safe and reliable occlusion of blood flow. No low cost, commercially available tourniquet cuff is known in the prior art that allows identification of the type and physical characteristics of the cuff by a tourniquet instrument to which the cuff has been pneumatically connected.
Modern prior art tourniquet instruments employ digital electronic technology in the regulation of pressure and in the detection of certain hazardous conditions. However the selected pressure for the tourniquet cuff is often based on the surgeon's estimate of the minimum pressure required to safely occlude blood flow past the cuff. This minimum safe pressure is affected by the physical characteristics of the cuff, and so providing a convenient and reliable means of identifying certain physical characteristics of the cuff (such as length, width, and type) may be useful for a variety of functions. For example, if a wide cuff is being used, the instrument may display instructions to the surgeon to select a lower tourniquet pressure setting to reduce the chance of pressure related injury while still stopping blood flow effectively. Identification of the cuff also allows optimization of various operation parameters and hazard warning criteria of the tourniquet system. For example if a pediatric cuff is in use, the maximum allowable pressure supplied by the instrument may be reduced accordingly.
If the cuff type can be identified, a record may be kept more easily and more accurately for inventory control and optimization purposes. Such a record may also be used (in combination with recording of other parameters such as pressure used) to aid in establishing safer practice guidelines for the use of surgical tourniquets. Finally, a tourniquet system having automatic cuff identification enables sale or lease of the instrument to a user on a per-use basis or in connection with the purchase of specified quantities of the matching cuffs. A variety of related functions are enabled by an automatic cuff identification feature. For example if an inappropriate cuff is connected, the system may be programmed to warn the user and record the event, but function normally. The cuff identification and recording ability enables the system to be programmed to function with an inappropriate cuff up to a specified number of times only (with associated warnings), then subsequently be disabled unless an appropriate cuff is used.
In many cases, cuffs are color coded to indicate size. For example the ‘Comforter™ Disposable Gel Cuff’ sold by DePuy Orthopaedics Inc. has a color dot on the outer packaging label corresponding to the cuff size, but no indication of cuff size on the cuff itself. In several other types of tourniquet cuff (for example ‘Zimmer ATS Disposable Tourniquet Cuffs’, Zimmer Patient Care, Dover, Ohio), components permanently attached to the cuff (such as edge trim and/or tie ribbon) are made of a selected color of material corresponding to the cuff size. These identification means are solely visual and interpretable by the user who is familiar with the color coding scheme. No communication to the instrument is established and therefore no automatic recording, display of information, or adjustment of instrument operating parameters relative to the cuff type can be done.
In U.S. Pat. No. 4,605,010, McEwen describes a tourniquet cuff that includes an electrical means for identifying remotely the physical characteristics of the cuff, as well as for remotely determining the circumference of the limb encircled by the cuff. To permit remote identification of cuff type, the McEwen '010 cuff includes electrically conductive components within the cuff structure, and requires an electrical connection as well as a pneumatic connection between the tourniquet cuff and the tourniquet instrument. Thus electrical power and an electrically conductive pathway are necessarily present within the cuff, in close proximity to the patient's limb encircled by the cuff. This can present a hazard to the patient under some circumstances. Also, inclusion of electrical components within the tourniquet cuff increases the cost and complexity of manufacture of such cuffs. The prior art tourniquet cuff described by McEwen '010 also includes means for allowing a connected tourniquet instrument to remotely determine the circumference of the limb encircled by the cuff. This permits the tourniquet pressure setting to be adjusted, based on the relationship between the physical characteristics of the remotely identified cuff and the remotely identified circumference of the limb encircled by the cuff. No other tourniquet systems in the prior art known to the inventors of the current invention establish a connection other than a pneumatic connection between the cuff and the instrument, such that information about the cuff can be received by the instrument.
Certain tourniquet cuffs of the prior art, known commonly as disposable tourniquet cuffs, are designed and manufactured specifically for use in a sterile surgical field. In many cases such disposable tourniquet cuffs are sterilized after manufacture, are supplied as sterile products, and are discarded after one surgical procedure has been completed. Other tourniquet cuffs of the prior art, known commonly as reusable cuffs, are designed and manufactured for use in multiple surgical procedures. Such prior art reusable cuffs are generally supplied as non-sterile products, and are intended to be thoroughly cleaned and inspected before each surgical procedure. These non-sterile, reusable tourniquet cuffs of the prior art are discarded if inspection before use results in the detection of excessive wear, physical deterioration, or contamination.
The most commonly used cuffs in the prior art typically include three layers of material and a stiffener (Zimmer ATS Disposable Tourniquet Cuffs, Zimmer Patient Care, Dover, Ohio). The inner and outer layers are typically woven nylon coated on one side with thermoplastic polyurethane, the middle layer is plain thermoplastic polyurethane sheet, and the stiffener is made of high density polyethylene sheet. When encircling the patient's limb in use, the inner layer lies against the skin. All three layers are die cut to a particular shape defining the length and width of the cuff, and all have the same perimeter. In a first sub-assembly operation, a port made of thermoplastic material is bonded to the middle layer, creating a gas passageway through the layer that a pneumatic h
Glinz Kenneth L.
Inkpen Kevin Bryant
Jameson Michael
McEwen James Allen
Comstock David
ipsolom llp
Robert Eduardo C.
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