WO2000016693A1

WO2000016693A1 - Marker system for surgical implements

Info

Publication number: WO2000016693A1
Application number: PCT/NL1999/000579
Authority: WO
Inventors: Willem Dekker; Jan Saeys; Maarten Willem Dekker
Original assignee: Jadap International B.V.
Priority date: 1998-09-18
Filing date: 1999-09-16
Publication date: 2000-03-30
Also published as: NL1010128C1

Abstract

A detection system searches for surgical requisites which have to be removed from the area of operations (1) before a wound is closed. Surgical requisites, which have been left behind, can be traced by means of an electromagnetic field or by X-ray investigation if they are provided with a detectable metal loop (22). A detection system is provided with a generator (13) and an antenna (11) for generating a high frequency electromagnetic field to detect the location of the field if disturbance is caused by the metal loop (22).

Description

MARKER SYSTEM FOR SURGICAL IMPLEMENTS

The invention relates to a detection system for the exclusive and/or repeated detection respectively of operational wound gauze or any other surgical requisites, materials or pieces of equipment that should be removed from an area of operations before the wound is being closed/

The detection of metal objects or of objects, which partly consist of metal, and are usually undesirably and often completely or partly invisibly left behind in the body of human beings or animals after they have undergone an operation, can be performed in various known ways. The aim of the invention is, however, to perform this detection, before the wound is being closed again. The requirements of detection at this early stage are different from a process, when an X- ray-investigation can quietly be executed afterwards, because an area of operations has got to be left and closed quickly. The detection afterwards of any materials left behind demands a second operation, if indeed any materials have undesirably been left behind in the area of operations.

Usually in hospitals the Alara-principle is being followed, which means, that the patient, during his or her stay in hospital, will be exposed as little as possible to (harmful) radiation. Therefore X-ray-investigation to any materials that have undesirably been left behind is not advisable and should be avoided at any time, as much as possible.

A procedure already known e.g. is to connect a battery-fed marker to surgical objects, or even to mark them to this end with radioactive materials, or either paramagnetic or ferromagnetic materials in powder form are being applied. In all these cases considerable disadvantages are experienced, such as the exposure to radioactive radiation or their signalisation is too low; in short; the present procedures are either potentially harmful, or they offer insufficient certainty about the presence of surgical materials left behind.

According to the invention, however, a procedure is presented to take such a combination of measures, that a preventive signalisation of any materials left behind in the area of operations is effective, so that the necessity of re-operation again afterwards will be avoided.

This is obtained by an effective interaction between the object, equipped in advance with the desired signal-release-material, and the proper detection apparatus. According to the invention this is obtained by the following combination of measures:

a. a wound gauze, which on or along its surface has at least been provided with a detectable tuned metal loop and/or a metal strip, of such a size, that it remains recognisable in an X-ray photograph. b. other surgical requisites, materials or pieces of equipment, that have been inside or outside at least fitted with a detectable tuned metal loop and/or strip; c. a detection apparatus, provided with a generator and an antenna, which generates a high frequency electromagnetic field; which electromagnetic field can be adjusted at liberty in order to determine the precise location of the wound gauze, which field, as a result of the presence of the gauze according to a., is being disturbed in its range and thus generates the required detection-impulse; d. a separate detection-receiver apparatus if necessary, in the event the transmitter according to c. generates a pulsating electromagnetic field and detection-receiving will then occur in between the pulses.

The particularity also is here the specific tuning given in advance to the metal loop or the metal strip respectively, so that objects, which have not been so tuned, such as wire stitches or metal staples cannot emit a detection signal.

Whereas a metal in wound gauze will remain visible on an X-ray photograph, which will also be the case if wound gauze has been provided with a metal loop and/or metal strip, the fast and preventive detection of the tuned metal loop in the wound gauze before the operation wound is closed, has appeared to be a most important progress now that the signal function does away with the previous insufficient attempts to solve the problem.

The required source of energy does no longer need to be received from the detectable object such as a battery attached to it, but it can now easily be generated outside the area of operations without any discomfort or harm to the animal or human patient subjected thereto.

In all cases the detection system aimed at can in itself consist of a combination of measures to be taken, resulting from the chosen signal processing procedure successively: metal strip detection by means of the amplitude disturbance of the high frequency field (hysteresis effect); metal strip detection by means of a phase shift of electric current and voltage, which occurs in the resonance circuit of an oscillator; - metal loop detection by means of measurable energy absorption of the metal loop in the high frequency electromagnetic field; a detection of the coupling through of the high frequency signal of a transmitter coil to receiver coil by means of a resonance circuit or loop in the wound gauze or other surgical requisites, materials or pieces of equipment, in such a way that the generated signal in the receiver coil can be detected.

For antenna field detection by using a loop, the fact has to be taken into account, that the operation table itself consists of metal and contains constructive loops, so that preference should be given to the generation of a relatively small antenna field which allows a precise location of any object left behind undesirably. After the first removal of an object, repeated scanning may be required, as it is technically difficult to determine the presence of one or more signalling objects still in the area of operations.

In order to localise e.g. a wound gauze with a strip of metal or a metal alloy, for a first localisation, a relatively large field will be covered by means of a physically large antenna will be covered, and the whole body of a patient can be scanned at once. For the precise localisation subsequently, a physically smaller antenna is reverted to, so that the transmitted field decreases in range.

If a handheld scanner is used, the source of energy can be either a battery-fed scanner, or a connection to the mains, and/or the possibility of the inductive feeding of the scanner on a feeding station. In practise, the factors handiness, usefulness and sterilisation have to be taken into account as well.

Instead of a handheld scanner, energy provision for a fixed scanner may be easier, because in this case the mains can be used directly. As soon as wound gauze or any other surgical requisites have been detected, a handheld scanner can be used for a more precise localisation of any materials that were left behind. As an alarm signal while scanning if an object was left behind in the area of operations, either a visual (LED) or an acoustic signal may be applied, or a combination of both. If the alarm is generated in the scanner itself, the housing of the scanner will have to be adapted regarding the visual readability or the acoustical audibility of the signal. If the handheld scanner sends the alarm by means of radio waves to a base station, the transmitter in the scanner has to be adapted in such a way, that the applied frequency is admissible in respect of the other machinery in the operation room, also care should be taken, that the scanner meets the sterilisation requirements.

Regarding size and form of the antenna to be used, the choice depends on the desired detection distance. For practical considerations, three different ranges of electromagnetic field could e.g. be applied, which would require three different antenna surfaces. Based on various considerations the choice will also depend on requirements, put forward by the specialists (surgeons).

The frequency applied for this system varies between 50 kHz and 200 kHz for the method referred to under f., g. and h., as described in the patent claims. For the system according to the method referred to under e., a sweep frequency is used, which frequency field varies between two given values. These values are below 100 kHz. The frequency of the sweep (time-interval, between the highest and lowest frequency) ranges between 5 Hz and 50 Hz.

The invention will be illustrated hereafter by means of the drawing of a preferred embodiment.

FigJ schematically shows an outline of a so-called static detection;

Fig.2 schematically shows an outline of a so-called dynamic detection;

FigJ schematically shows an outline of wound gauze located within the field of an antenna; Fig.4 schematically shows an outline of a block diagram for a detection according to the invention with acoustical or visual signals, and

Fig.5 schematically shows an example of a possible method of integration of a loop or a strip in wound gauze.

In Fig. 1 the area of operations 1 is shown, inside of which the three wound gauzes 2,3 and 4 are located which have been left behind and which are to be detected by a static antenna 5. This static antenna 5 can e.g. be built into an apparatus which is provided with to be placed above the operation wound of a patient. In Fig.2 an area of operations is shown as in Fig. 1, inside of which the three wound gauzes 2, 3 and 4 are located, which can be detected by moving e.g. a handheld dynamic antenna 6, from position A to position B, so that signal impulses can be received. The dynamic antenna 6 here allows the precise localisation of wound gauze or other object to be detected.

In Fig. 3 a schematic position of wound gauze is shown, at the moment of its entrance into the antenna field. It is presumed, that wound gauze 7 has been provided with a metal loop or a metal strip not shown in the picture; in the latter case preferably a strip of a metal alloy such as it is e.g. applied in anti-shoplifting systems, and which has been completely integrated in wound gauze 7. Wound gauze 7 is located in the area of operations inside the body of the patient and also within the spherical field 8 of antenna 9. This wound gauze 7 functions as signal emitter within the antenna field of this detection antenna 9. The generation of a relatively large antenna field has other limitations as well, because of the presence in the operation room of many other closed metal loops in the immediate vicinity of the patient's body, e.g. in the form of (parts of) closed table frames etc. Taken this into account, a handheld scanner offers, because it generates a smaller antenna field, the immediate possibility for an even more precise localisation, so that in the end the signal emitter can be located - as here is wound gauze 7 - with a precision of a few millimetres.

It is e.g. also possible to scan the whole body of the patient on the operation table at once by means of a relatively large antenna field. Through the registration of a number of signal impulses at different locations, subsequent by a more precise localisation can be obtained. This will be realised by using a hand scanner with a considerably smaller antenna surface.

The block diagram for a handheld scanner in Fig. 4 contains a detection antenna 1 1 , a generator

13 for the generation of the electromagnetic field, and also a transmitter-receiver 12 to separate the transmitted signal from the received signal. In block 14, the obtained impulse signal, e.g. of wound gauze, is amplified, filtered, and detected, whereafter the signal is passed on to a combination of an analogous/digital converter and processing unit 15 for the digital signal. At the outlet of the converter/unit 15 either an acoustic signal 16 (peep) and/or a visible signal 17

(LED) can be given according to the desire of the user. Subsequently, the power supply unit 18 will feed this. The handheld scanner, which can also be equipped according to this block diagram, uses either a battery 18, or a wire to the mains 18. In Fig. 5, wound gauze 19 is shown with a metal strip 20, and also another wound gauze 21 with a metal loop 22. In case of the metal loop 22, this can be integrally woven in the wound gauze or it can be applied in any other suitable way by means of non-toxic glue or by folding loop 22 directly into the gauze. There is wound gauze known already provided with means making its detection possible; the application of the detectable material to wound gauze and/or surgical requisites/instruments etc. does not form part of the invention here, so that a further description of it can be left out.

According to the invention the detection-system will preferably be performed as a so-called hand held scanner. In a prototype of a hand scanner, according to the invention, its specification can be as follows: power, to be specified, field strength, to be specified, loop: diameter, depending on the type of wound gauze, maximal area: thickness minimum 0J mm, maximum 2 mm; strip size: length depending on wound gauze, width minimum 1 mm, maximum

5 mm, thickness maximum 1 mm; number of strips: minimum 1 per wound gauze.

Metal material has been worked into the wound gauze which will not be suitable for reuse.

For environmental considerations the metal may possibly after its use be separated from the gauze. This technology of separating wound gauze from the metal worked into it, does not form part of this invention.

The detection apparatus should be switched on after the operation and before the closing of the wound. As soon as it has been ascertained that no wound gauze or other surgical requisites have been left behind, the apparatus can be immediately switched off again. So, it will be prevented that the electromagnetic field may affect other machinery or devices, present in the (operation) room that are sensitive to it. The electronics of the detection apparatus has to be caged in completely (cage of Faraday).

Claims

CONCLUSIONS

1. Detection system for the exclusive and repeated detection respectively of one or more operational wound gauzes or other surgical requisites or pieces of equipment which should be removed from the area of operations before the wound is closed, consisting of a combination of:

a. a wound gauze, which at least has been provided at or through its surface with a detectable tuned metal loop and/or metal strip, of such a size, that it remains still recognisable on a X-ray photograph;

b. any surgical requisites of pieces of equipment each of which have at least been fitted inside or outside with a detectable tuned metal loop and/or metal strip in them or onto them;

c. a detection apparatus provided with a generator and an antenna generating a high- frequency electromagnetic field, which electromagnetic field can be adjusted at liberty in order to determine the precise location of the wound gauze; which field, as a result of the presence of the gauze according to a., is being disturbed in its range, and thus yields the required detection- impulse.

d. a separate detection-receiver apparatus, if necessary, if the transmitter according to c. generates a pulsating electromagnetic field and the detection-receiving will then occur in between the pulses.

2. Detection system according to claim 1., characterized in that for the detection of wound gauze or any other surgical requisites or materials a combination of the following procedures is applied:

e. metal-strip detection by means of the amplitude disturbance of the high frequency field

(hysteresis effect);

f. metal-strip detection by means of a phase shift of electric current and voltage, which occurs in the resonance circuit of an oscillator; g. metal-loop detection by means of measurable energy absorption of the metal loop in the high frequency electromagnetic field;

h. coupling through detection of the high frequency signal of a transmitter coil to receiver coil by means of a resonance loop in the wound gauze or other surgical requisites or pieces of equipment, in such a way, that the generation of a signal will result in the detection of the resonance circuit.

3. Handheld scanner to be used with the detection system according to any one of the preceding claims 1-2, characterized in that one or more of the above mentioned facilities c-g inclusive, are provided within the housing of the scanner and are also provided with means to generate a visible or audible alarm signal at the presence of one or more pieces of wound gauze or other medical equipment inside the operation wound.

4. Fixed scanner to be used for the detection system according to any of the preceding claims 1- 2, characterized in that one or more of the above mentioned facilities c-g inclusive, are situated within the system limits of the scanner and are provided with means to generate a visible and/or audible alarm signal at the presence of one or more wound gauze's according to la., or any other surgical requisites, materials, or pieces of equipment according to l b. in the area of operations.

5. Wound gauze and/or any other surgical requisites, materials or pieces of equipment for use with the detection system according to any one of the preceding claims 1 -4, characterized in that the piece of metal is present in form of a closed loop (flat as foil and/or woven like cord and/or like thread).

6. Wound gauze and/or any other surgical requisites, materials or pieces of equipment for use with the detection system, according to one of the preceding claims 1-4, characterized in that the piece of metal is present in the form of laminated metal provided with an insulation layer in between the sheets.

7. Wound gauze and/or any other surgical requisites, materials or pieces of equipment for use with the detection system according to any one of the preceding claims 1 -4, characterized in that the metal strip consists of an alloy which may potentially be magnetised.

8. Apparatus fitted with facilities according to any one of the preceding claims 1-2, and provided with a visible and/or audible alarm to be used for the exclusively detecting a wound gauze and/or any other surgical requisites, materials or pieces of equipment, left behind in the area of operations.