The present invention relates to sterile surgical garments and in particular to novel surgical garments and device for detecting the existence of a leak in the sterile barrier of the surgical garments. Background of the Invention

During many medical procedures, particularly surgical and dental procedures, the medical practitioner and patient are separated by a sterile barrier to prevent cross contamination and infection. This sterile barrier generally includes gloves, and may also include sleeves and/or a full sterile gown.

There is presently a high incidence of cross contamination between the medical practitioner and the patient due to breaks in the sterile barrier provided by gloves and gowns. These breaks may occur either from pre-existing manufacturing defects or from small punctures or tears incurred during the surgery or other medical procedure. Because the defects are usually small, they often go undetected for minutes to hours after they occur, especially in a rapidly paced or complex operation. Such a break is usually only noticed after a significant amount of fluid has leaked through the glove or gown. Sometimes, the break will not even be noticed until the end of the procedure when the medical practitioner notices blood on his or her hands or body after disrobing. The delay in detection increases time of exposure and the chances of transmission of an infectious agent from the medical practitioner to the patient, or from the patent to the medical practitioner. This problem is significant because of the potential for bacterial contamination and wound infection. Furthermore, with the increasing risk of A.I.D.S. and hepatitis in the general population, transmission of these viruses is of major concern to both the medical practitioner and patient.

Prior Art

Prior proposals have been made to provide devices to detect breaks in the sterile barrier and to generate alarms, but such prior proposals have not been entirely successful and have not met with wide acceptance.

In United States Patent No. 4,321,925, issued March 30, 1982, it is proposed to provide an electronic detector in the heel of a surgeon's shoe to detect leaks in the surgeon's gloves. Contact members from the electronic detector in the shoe are galvanically connected to the sturgeon's body and to an electrically conductive floor on which the surgeon stands. The operating table is electrically connected to the same conductive floor. Thus, the patient is electrically connected to the floor. Accordingly, if there is a leak in the surgeon's gloves, the surgeon will be electrically connected to the patient, completing the electrical circuit and sounding an alarm. Although this proposal will generate an alarm in the event of a leak in the surgeon's gloves, there are many drawbacks to this proposal. For example, this proposal is limited to use where the floor is electrically conductive. Furthermore, the alarm will not sound unless the conductor in the heel of the shoe is in contact with the floor. This may not be the case at all times, since a surgeon frequently lifts a heel to perform certain procedures. Furthermore, the surgeon may step on bandages or other nonconductive material accidentally dropped on the floor during surgery, which would also prevent sounding of any alarm. Furthermore, the patient must be electrically connected to the alarm circuit, which, may inter ere with electronic patient monitoring devices. In United States Patent No. 4,956,635, issued

September 11, 1990, a method and apparatus for testing the integrity of a personal barrier such as a medical

glove is proposed. In this proposal, an electrical lead from an alarm circuit is connected to a saline solution or to the body of the patient. The surgeon stands on a conductive floor, which is also connected to the alarm circuit by means of an electrical lead. The surgeon is, thus, part of the electrical circuit. Accordingly, if there is a break in the glove, the electrical circuit will be completed when the surgeon touches the patient (or sticks a glove in the saline solution) , sounding the alarm.

This proposal suffers many of the drawbacks of the first proposal. The floor must be electrically conductive, and the surgeon's shoes must make electrical contact with the floor. Thus, for example, the alarm will not sound if the surgeon has stepped on bandages or other nonconductive material accidentally dropped on the floor during surgery. The patient must also be electrically connected to the alarm circuit, which may interfere with electronic patient monitoring devices. In French Patent No. 2.208.300, the alarm circuit is connected to the surgeon's leg by means of a wire. To test the integrity of the glove, the surgeon places his or her gloved hand in a liquid solution, which is also electrically connected to the alarm circuit. Although this proposal eliminates the need for a conductive floor, the integrity of the glove can only be checked at periodic intervals by placing the surgeon's gloved hand in the liquid solution. If the sterility of the liquid solution is compromised during surgery, contamination of the patient could result even in the absence of breaks in the glove. Furthermore, the wire connected to the surgeon's leg will limit the surgeon's mobility during surgery. Objects of the Invention It is an object of the present invention to provide a novel surgical garment and device which overcomes the foregoing drawbacks of the prior art.

It is another object of the present invention to provide a device for detecting the existence of a leak in the sterile barrier of a surgical garment and for generating an alarm in the case of such leak. It is another object of the present invention to provide a medical garment which can be readily incorporated into a leak detection system without the need for a conductive floor.

It is another object of the present invention to provide a medical garment leak detection system which does not require that the patient be a part of the electrical circuit.

It is another object of the present invention to provide a medical garment leak detection system which permits the medical practitioner freedom of movement.

It is another object of the present invention to provide a medical garment leak detection system which does not require that the medical practitioner be part of the electrical circuit. It is another object of the present invention to provide a medical garment leak detection system wherein a leak can be detected without the need for contact of fluid between the medical practitioner and the patient. It is another object of the present invention to provide a medical garment leak detection system which is self-contained.

It is another object of the present invention to provide a medical garment leak detection system which is simple and reliable. Summary of the Invention

In accordance with a preferred embodiment of the present invention, a medical garment adapted to be worn by a medical practitioner during medical procedures is provided having a nonconductive layer and a conductive layer over the nonconductive layer. At least one of these layers is normally substantially moisture

impermeable. Means for electrically connecting the conductive layer to an electrical detection circuit is also provided.

In accordance with another preferred embodiment of the present invention, a system for detecting breaks in a substantially moisture impermeable barrier between a medical practitioner and a patient during medical procedures is provided which includes a medical garment haying a nonconductive layer and a conductive layer over the nonconductive layer, at least one of these layers being normally substantially moisture impermeable. The system also includes means for electrically connecting the conductive layer to an electrical conductor, means for imposing an electrical bias between the conductive layer and the medical practitioner and means for electrically connecting the medical practitioner to the detection means so that, in the event of a break in the substantially moisture impermeable layer, conductive liquids entering the break will permit a detectable flow of electricity between the electrical conductor and the medical practitioner. Means for detecting the flow of electrical current are also provided.

In accordance with still another preferrec ⁵ embodiment of the present invention, a medical garment adapted to be worn by a medical practitioner during medical procedures having a nonconductive layer sandwiched between respective first and second conductive layers is provided. At least one of said layers is normally substantially moisture impermeable. Means for electrically connecting said first and second conductive layers to an electrical detection circuit are also provided. Brief Description of the Drawings

These and other objects and advantages of the present invention will become apparent from the following detailed description and drawings, wherein:

Fig. 1 depicts a system in accordance with a preferred embodiment of the present invention, including a multi-layer glove, a gown having a multi-layer contact panel, electrical conductors and an electrical detection device, in use by a medical practitioner.

Fig. 2 is a diagrammatic cross-sectional view of a portion of a glove constructed in accordance with a preferred embodiment of the present invention, as depicted in Fig. 1, taken along the line 2-2. Fig. 2a is simplified schematic of a gown contact panel and monitor in accordance with a preferred embodiment of the present invention, in partial cross- section and in use by a medical practitioner.

Fig. 2b is simplified schematic of a glove having two conductive layers in accordance with a preferred embodiment of the present invention, in partial cross-section, connected to a monitor by means of electrical conductors and in use by a medical practitioner. Fig. 2c is simplified schematic of a glove having two conductive layers in accordance with a preferred embodiment of the present invention, in partial cross-section, with a directly connected monitor and in use by a medical practitioner. Fig. 3 is a simplified schematic of the system in accordance with a preferred embodiment of the present invention, incorporating both a multi-layer glove and gown contact panel, a portion of which is depicted in diagrammatic cross-section, in use by a medical practitioner.

Fig. 4 is a block diagram of an electrical detection and alarm circuit in accordance with a preferred embodiment of the present invention.

Fig. 5 is a schematic of an electrical detection and alarm circuit in accordance with a preferred embodiment of the present invention.

Detailed Description

Referring now to the drawings in detail, and initially to Figs. 1 and 3 thereof, a system 10 for detecting breaks in a sterile barrier between a medical practitioner 11 and a patient (not shown) during medical procedures is depicted. Typically, this sterile barrier includes two gloves 12 (only one of which is shown) and a sterile, generally disposable, gown 13 comprised of moisture resistant material. Gown 13 includes sleeves 14 and a torso portion 15.

In certain medical procedures, such as dental procedures, a full gown 13 is not necessary. In such cases, the sterile barrier may consist of gloves 12 alone, or gloves 12 along with moisture resistant sleeves 14. For convenience, however, the following primarily describes the invention as embodied in the gloves 12 and gown 13 worn simultaneously, although the principles of the invention are equally applicable to sleeves 14 worn with gloves 12 or gloves 12 worn alone. In accordance with the present invention, gloves 12 are of a novel construction, including at least one non-conductive layer 16 and a conductive layer 17 over the non-conductive layer. Preferably, though not necessarily, the glove also includes an outer layer 18. This multi-layer construction is schematically depicted in cross section in Figs. 2 and 3.

At least one of layers 16, 17 or 18 must be normally substantially moisture impermeable in order to create a substantially moisture impermeable, and sterile, barrier between the medical practitioner and the patient. Preferably, at least non-conductive layer 16 is normally substantially moisture impermeable. In that way, perspiration from the medical practitioner 11 will not come in contact with conductive layer 16 to unintentionally complete an electrical circuit between the body of the medical practitioner 11 and the conductive layer 17 , in the absence of a break in layer

8

16. Layers 17 and 18 are also conveniently substantially moisture impermeable, although this is not essential to the invention.

Preferably, nonconductive layer 16 is composed of latex, which is currently the material used in gloves today. Polyurethane may also be used. The conductive layer 17 is a flexible conductive material, preferably an elastic conductive polymer a few thousand of an inch thick. Latex mixed with graphite is the preferred material. The optional third layer 18 is conveniently an outer layer of latex. Where such a third layer 18 is employed, conductive layer 17 may be simply a layer of graphite sandwiched between layers 16 and 18. A thin film of conductive material, such as aluminum, silver, tin or tin oxide vacuum deposited or sputtered onto the outside of layer 16 or the inside of layer 18 may also serve as the conductive layer 17. These three layers are preferably bonded together to form a glove with about the same thickness as conventional surgical gloves. The cuff of glove 12 also has an exposed contact area 19 for connection of an electrical conductor 20 to conductive layer 17.

The gown 13 used in the present invention preferably is made of a sterile, moisture resistance multi-layered paper, similar to that presently in use. However, the gown 13 in accordance with the present invention also includes a contact panel 21 constructed in a manner similar to glove 12. That is, contact panel 21 preferably includes at least one non-conductive layer 16' and a conductive layer 17' over the non-conductive layer 16'. At least one of these layers is substantially moisture resistant, preferably layer 16'. Preferably, though not necessarily, the contact panel 21 also includes an outer layer 18'. This multi-layer construction is schematically depicted in cross section in Figs. 2a and 3. Non-conductive layer 18' may also be omitted entirely. All layers of contact panel 21 are

preferably bonded together, although this is not essential.

Contact panel 21 may be separate from gown 13, or may be integrally incorporated therein. Furthermore, the moisture resistant material of the gown 13 itself may serve as one of the layers of contact panel 21 as depicted in Fig. 3, such as layer 16'. Preferably, contact panel 21 is positioned in the front torso area 15 of the gown 13, where patient contact is most likely to occur. However, contact panel 21 may also be positioned at other places on the gown 13, or may be integral throughout the entire gown 13, or any part or parts thereof.

In the embodiment whe . sleeves 14 are employed, rather than a full gov,n 13, the contact panel 21 would be positioned in a part of sleeves 14, or integral therewith, in the similar manner to a full gown 13.

Conductive layer 17 of glove 12 (or 17' of contact panel 21) includes a portion 19 (19') left uncovered by layer 18 (18') to permit connection of an electrical conductor 20 (20'), i.e., a wire, to conductive layer 17 (17'). The electrical conductor 20 (20') is attached to portion 19 (19') of conductive layer 17 (17') by means of connection 24. Connection 24 (24') is conveniently an adhesive contact of the type commonly used for E.K.G. monitoring, but may also be a snap connection, adhesive, spring clip, or any other convenient means. The other end of conductor 20 (20') is attached to an electronic monitor 22, the construction and operation of which is described below. Another electrical conductor 23 extends from monitor 22 and is attached to the body of the medical practitioner 11 by means of contact 25, which is conveniently an adhesive contact of the type commonly employed for E.K.G. monitoring.

When so connected, system 10 forms an electrical circuit between conductive layer 17 (17') and the body of the medical practitioner 11. The circuit is incomplete (i.e., open) as long as layer 16 (16') remains moisture impermeable. However, if a defect, such as a hole or tear in layer 16 (or 16') occurs, bodily fluid (i.e., blood, plasma or perspiration) will cross the layer 16 (or 16') . Because bodily fluids are conductive, this fluid will conduct electricity between the conductive layer 17 (or 17') and the body of the medical practitioner 11, thus completing the electrical circuit and permitting current to flow.

Monitor 22 is preferably small, in the range of 2 x 1 x 1/2 cm, and preferably disposable. Monitor 22 may be separate or incorporated into the disposable gown 13 worn in sterile procedures. Conveniently, monitor 22 would be located near the neck-line or front of the gown where it could be easily seen and heard.

Monitor 22 includes a current detection circuit 26 for detecting flow of current and for activating annunciators 27 (i.e., alarms) in the event such current flow is detected.

Monitor 22 measures electrical conductivity between electrodes 24 (24') connected by wires 20 (20') and 23. A low conductivity measurement (approximately less than 2 x 10~ ⁷ Siemens or greater than 5 x 10 ⁶ Ohm) by detection circuit 26 will not activate the alarms 27. Higher conductivity (less resistance) will activate the alarms 27, preferably with pulsing visual and/or auditory signals whose repetition rate is proportional to conductivity (inversely proportional to resistance) . The pulsing is controlled by a variable pulse rate generator 28. A low repetition rate indicates a small compromise in the sterile barrier. A high or increasing rate indicates a significant loss of effectiveness of the sterile barrier.

Monitor 22 includes a battery 29 for powering the current detection circuit 26, for creating a safe, low voltage electrical bias between leads 20 (20') and 23, and for powering alarms 27. Monitor 22 consumes a negligible amount of energy from the battery when it is inactive (in storage, or in use but with an intact and therefore insulating sterile barrier) . Thus, the monitor can be stored "on". The power source should remain viable for two to three years with the monitor in the inactive state.

In operation, when the conductivity exceeds the previously mentioned threshold, the current turns on a transistor Ql (depicted in Fig. 5) in current detector 26, sending power to the variable pulse rate generator 28. Detector 26 is inactive until a sufficient subthreshhold current activates it. A current larger than the activation threshhold causes the alarms to annunciate.

The pulse rate generator 28 is conveniently an integrated circuit (IC) . Pulse rate generator 28 to annunciator driver 31 produces an output of pulses whose repetition rate is proportional to the current between the electrodes arid therefore proportional to the conductivity of the sterile barrier. Annunciator driver 31 contains a high current switch which is suitable for turning on and off the visible and auditory annunciators 27. The visible annunciator is preferably a high efficiency light emitting diode (LED) 33. The auditory annunciator 34 is preferably a high efficiency piezoelectric buzzer. Preferably, the audio frequency oscillator needed to drive the piezoelectric element is contained within the housing of integrated circuit 28. The drive oscillator may also be incorporated within annunciator driver 31. The current detection circuit 26 is conveniently constructed as depicted in Fig. 5. Transistor Ql acts as a switch to power the 7555 IC.

Resistors R3, Rl, the electrodes, R2, and R5 are in parallel with C2 to form a current path from the base of Ql to circuit common. When electrode resistance is less than about 5 Meg ohms, Ql conducts and the collector current charges C3 to an operating voltage of about 2 volts and the voltage at IC pin 3 rises to near the operating voltage. The current in the electrode circuit charges C2 as well. Diode Dl becomes forward biased and supplies current to charge C2 as the electrode resistance falls. It is reversed biased when the monitor is inactive. Oscillation begins when the voltage IC pin 6 reaches 2/3 of the IC operating voltage. The pin 6 voltage depends on electrode resistance and the time required to charge C2. Thus brief episodes of conductivity in the electrode circuit are ignored. When IC pin 6 reaches its threshold voltage the IC changes state, pin 3 changes from about 2 volts to about 0 volts, and C2 discharges through R4 and D2. After about 40 milliseconds, IC pin 2 reaches a lower threshold of 1/3 of the IC operating voltage at which time the IC returns to the initial state, and C2 begins to charge again. During the 40 millisecond alternate state, pin 7 changes from an open condition to a current sink which activates the auditory alarm 34 and visible alarm 33. In modern medical procedures, there are frequently a number of electrical devices for patient monitoring and life support in operation. In order of avoid the potential for accidental shock to the medical practitioner from unintentional contact between such devices and the conductors of the leak detection system 10, a protection circuit 35 is preferably included in the present invention. This protection circuit is comprised of Rl, R2, and Cl, depicted in Figs. 4 and 5, and serves to impede direct current shocks, as well as radio frequency (RF) currents originating from an electrosurgical unit, for example, and passing through the electrode circuit which includes the medical

practitioner. The series impedance offered by Rl, R2, and Cl is preferably approximately 100K ohms at RF frequencies and should be sufficiently high to prevent burns at the electrode sites. The shunting effect of Cl also prevents RF frequency currents from affecting the rest of the circuit.

Referring again to Fig. 1, an exposed, but sterile, conductive test area 36 is preferably positioned at a convenient place on gown 13 and connected by lead 37 to conductor 23. Similarly, glove 12 preferably includes an exposed, but sterile, conductive test area 38 connected to the conductive layer 30. Thus, proper operation of the system can be tested by contacting the conductive test area of glove 12 to the conductive test area 36 prior to commencing the medical procedure.

Except for the placement of the leads, the apparatus of the present invention is used in the same manner as conventional gloves and gowns. The medical practitioner, i.e., a surgeon, attired in non-sterile "scrubs" first washes his or her hands and arms in the usual fashion. He or she then enters the operating room and a pre-packaged, sterile gown constructed in accordance with the present invention is placed onto the surgeon by the sterile scrub nurse and tied in back by the non-sterile circulating nurse.

The non-sterile circulating nurse would then place lead 25 onto the surgeon's neck since the neck is not sterile. Next, the sterile gloves 12 constructed in accordance with present invention are put on the surgeon. At this point the surgeon attaches the appropriate lead 20, which is sterile, to the conductive layer of the gloves 12.

Normally the surgeon then dips his/her hands in a sterile saline solution to wash off gloving powder. With the system of the present invention, this step would also test the integrity of the gloves before the operation started. Finally, the surgeon would tap the

conductive test area 38 on each glove to the exposed conductive test area 36 on the gown, to test the circuit. If the circuit is operational, the alarm will sound. The apparatus and the surgeon are now ready to begin the operation.

As long as the moisture impermeable layer 16 (16') remains intact, the two leads 23 and 20 (20') are insulated from each other and the circuit is incomplete. In the event of a disruption of layer 16 (16') , however, bodily fluid would be free to pass between the surgeon and the conductive layer 17 (17') in the glove 12 or gown contact panel 21, thus completing the circuit and triggering the alarm. At this point the operating room personnel could stop and assess where the leak occurred and remedy it by changing the glove or gown.

It should be noted that leads 20 and 20' may be connected to each other or separate. If leads 20 and 20' are kept separate, a separate detection circuit 26 is required for each lead. The advantage of this approach is that the alarms 27 will be unique to that lead, thus indicating whether the leak occurred in the moisture impermeable layer 16 of glove 12 or moisture resistant layer 16' or the gown contact panel. Separate circuits can also be employed for each of the two gloves 12. This simplifies finding the leak. However, if 20 and 20' are connected together, only a single detection circuit is required, which simplifies construction. However, in this case, location of the leak would need to be done manually. In another embodiment of the invention, depicted schematically in Figs. 2b and 2c, the multilayer medical garment includes at least one nonconductive layer 18a sandwiched between first and second conductive layers, respectively 17 and 17a. For convenience, a glove is described, but the principles of this embodiment apply equally when applied to a contact panel or other medical garment. At least one of these layers must be

normally substantially moisture impermeable, preferably nonconductive layer 18a. Preferably, nonconductive layer 18a is normally substantially moisture impermeable. Advantageously, an outer (or second) nonconductive layer 18 may be included on the outside of conductive layer 17. Also advantageously, an inner (or third) nonconductive layer 16 is included on the inside of conductive layer 17a, between medical practitioner 11 and conductive layer 17a. Preferably, either or both of nonconductive layers 16 and 18 are normally substantially moisture impermeable. Either or both of conductive layers 17 and 17a may be normally subtantially moisture impermeable.

In the two conductive layer embodiment depicted in Figs. 2b and 2c, electrodes 24 and 25 are connected to conductive layers 17 and 17a, respectively, and an electrical bias imposed between them through contacts 24 and 25. In the event of a leakage of fluid between the first and second conductive layers 17 and 17a, the electrical current passes between the first and second conductive layers through the (now breached) nonconductive layer 18a, thus completing the electrical ciruit.

In the two conductive layer embodiment, separate monitors may conveniently be used on each of the left glove, right glove, contact panel, etc. Use of such separate monitors simplifies locating and correcting a leak in the event of an alarm. As depicted in Fig. 2b, contacts 24 and 25 may be connected to monitor 22 by means of conductors 20 and 23. Alternatively, as depicted in Fig. 2c, monitor 22 may be attached directly to each of the left glove, right glove, contact panel, etc. (by clipping it, for instance) , the electrical connection being made by means of contacts 24 and 25, thus elimnating conductors 20 and 24. By eliminating conductors 20 and 24, the construction and use of the system is simplified.

Another advantage of the two conductive layer embodiment is that the medical practitioner 11 is not needed as part of the electrical circuit. Thus, a leak may be detected even if the layer next to the medical practioner (either 17a or 16) is not leaking.

Accordingly, a leak may be detected even in the absence of fluid contact between medical practitioner and patient, and preferably, prior to such contact. In other respects, the operation and use of the two conductive layer embodiment of the invention is substantially the same as the single conductive layer embodiment previously described.

Although a detailed description of certain embodiments of the present invention has been provided, it will be apparent to persons of ordinary skill in the art that various changes and modifications may be made within the scope and spirit of the present invention, and there is no intention of limiting the invention to solely the embodiments shown and described. Rather, the scope of the invention is to be determined with reference to the appended claims.