GB1603726A

GB1603726A - Direct transcutaneous derivation of patient biological parameters

Info

Publication number: GB1603726A
Application number: GB20923/78A
Authority: GB
Original assignee: F Hoffmann La Roche AG
Current assignee: F Hoffmann La Roche AG
Priority date: 1977-05-31
Filing date: 1978-05-19
Publication date: 1981-11-25
Also published as: DE2823307A1; JPS53148884A; FR2392650A1; NL7805403A

Description

(54) IMPROVEMENTS IN OR RELATING TO DIRECT TRANSCUTANEOUS DERIVATION OF PATIENT BIOLOGICAL PARAMETERS (71) We, F. HOFFMANN-LA ROCHE & CO. AKTIEN GESELLSCHAFT, a Swiss Company, of 124--184 Grenzacherstrasse, Basle, Switzerland, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to electrode arrangements for direct transcutaneous derivation of patient biological parameters, devices incorporating such arrangements and methods of use thereof.

Transcutaneous electrodes are used for long term monitoring of electrophysiological phenomenon because they are easily retained for long periods, provide a good signal and are amenable to attachment to difficult areas. One of the more common uses is for detecting the fetal electrocardiogram (ECG) and other heart beat signals during labor, where an electrode must be placed easily, remain firmly attached and be atraumatic, especially on removal.

The prior art teaches the use of several types of electrodes for transcutaneous monitoring, including standard injection needles, practically all of which are administered to the patient substantially perpendicular to the skin, thus risking the danger of for example too deep a puncture.

To facilitate holding the transcutaneous electrode in place, especially in fetal.

monitoring, several adaptations have been proposed and/or used, including the surgical clip arrangement of Hon (Instrumentation of Fetal Heart Rate and Fetal Electrocardiography III. Fetal ECG Electrodes: Further Observations, Obstet.

Gyn. 30:281,1967); the fish-hook type arrangement of La Croix (United States Patent Specification No. 3,580,242); the double and single spiral arrangements of Ruttgers and Hon (United States Patent Specifications Nos. 3,750,650 and RE 28,990, respectively); and the barbed, straight needle arrangement of Junge (German Utility Model Registration No. 74.19264).

The surgical clip and spiral electrodes are traumatic (the latter primarily from the torque created on application) and must be inserted ( and in the case of the surgical clip also removed) with a special tool, placing the surgeon's hand well away from the presenting part, and thus losing the "feel" of the situation, reducing physician confidence, and adding a possibility for error in placement. Since the physician is trained to palpate (that is feel) and use this modality to a great extent, this loss can be rather disconcerning.

The fish-hook electrode is also traumatic, especially on removal. The barbed needle electrode is significantly smaller than the others and offers a better opportunity for "feel", but its rough edges, that is the multiplicity of little barbs, also tend to cause trauma. Moreover, application thereof is difficult in the absence of an applicator tool, with the electrode often slipping away from the entry site when force is applied to effect skin penetration.

It is, therefore, a principle objective of this invention to provide a transcutaneous electrode arrangement which enables the aforementioned drawbacks of the prior art arrangements to be overcome or at least mitigates, namely to provide a transcutaneous electrode arrangement which can be small, and easily placed, thus while retaining the "feel" of the situation, relatively atraumatic and remaining firmly attached, yet is able to be conveniently and easily removed when desired.

In accordance with one aspect of the present invention there is provided an electrode arrangement suitable for use in direct transcutaneous derivation of patient biological parameters, such as the ECG of an unborn fetus, in which the active electrode element has a tuberous pin configuration with at least one tuberosity arranged along the length thereof for enabling relatively atraumatic attachment and removal of the electrode respectively to and from a patient.

According to a second, aspect of the present invention there is provided in combination with an electrode arrangement for derivation of patient biological parameters in accordance with the first aspect, an applicator comprising a main elongate member of rigid material, one end of which is longitudinally divided to form a pair of opposing arms which are normally separate in a first orientation to define a space therebetween and which are constructed to be urged into a closed second orientation in which the facing surfaces thereof cooperate and a locking part displaceable along at least a portion of the elongated member in the vicinity of the divided end thereof, which locking part in a retracted first position permits the arms to assume the first orientation and in an engaging second position urges the arms into the second orientation, the arms, at least on the facing surfaces thereof, being configured to cooperate with a predetermined portion of the electrode body so as to enable the latter to be locked between the arms when assuming the second orientation under the urging of the locking part and to be released when the arms are permitted by the locking part to assume the first orientation.

According to a third aspect of the present invention there is provided in combination with an electrode arrangement according to the first aspect, a locking applicator arrangement comprising an elongate main member of rigid material and having one end thereof longitudinally split to form a pair of opposed cooperating arms normally spaced apart to define a channel therebetween, each arm having a recess of predetermined configuration located in opposition to one another, and a displaceable locking part mounted on the main member proximate the one end thereof for movement toward and away from the one end in order respectively to decrease and increase the dimension of the channel and thereby effect respectively a locked and unlocked orientation, the one end of the main member being constructed to cooperate with a predeterminably configured base portion of the electrode arrangement to facilitate application thereof to a monitor site.

There are disclosed herein electrode/applicator combinations which allow relatively atraumatic transcutaneous insertion while retaining a sense of "feel" of i llf-effort and an electrode similarly c on removal, and not critical to the form of removal. In contrast, it is well known, as example, that spiral electrodes must be carefully unscrewed and the skin clip carefully separated to prevent severe trauma. As may be expected, too, trauma caused by the barbed arrangements can hardly be avoided.

The transcutaneous electrode of the present invention may comprise a means to insert a metal or other electrically conductive substance into the skin. This may comprise an appropriately rigid pin having a tuberosity (i.e. a rounded prominence) or preferably multiple tuberosities to hold it in place. The skin tension will prevent easy backward displacement by closing around the tuberosities, but the non-barbed, nonpinching nature thereof allows easy, atraumatic insertion and removal.

This active electrode element preferably extends from a base member which also has mounted thereto a reference electrode element (indifferent plate). This latter element may be situated, for example, on a portion of the base opposing the active element to complete the bipolar arrangement.

In at least one electrode embodiment herein described, the stem or pin electrode element may be bent, thus giving rise to a curved form of transcutaneous electrode which can provide even better "feel" and easier insertion.

Various insertion means (i.e. applicators) are provided which allow the desired sense of "feel". Such may, for example, take the form of a relatively flexible elongated member resembling an open-ended wrench.

the electrode is received into a notched and bevelled end thereof and is held firmly in place, not only by the cooperative design of the electrode body and the engaging end of the applicator, but also by drawing and holding the connector wire(s) leading to the electrode tight against the shaft of the member and/or by securing the wire(s) in a fork-like notch provided at the opposite end thereof. The tips of the physician's fingers are used to guide the member, and the flexibility thereof promotes the much desired sense of "feel. Most importantly perhaps is the fact that the applicator enables the electrode to be stably maintained during application to the patient, while allowing the physician's finger tip(s) to make direct contact with the electrode body during as well as prior to application. The electrode is intended preferably to be inserted so that the pin or stem constituting the active electrode element lies substantially parallel to the patient's skin surface. This orientation of insertion can be facilitated by the above mentioned curved-stem electrode which resembles a surgical needle.

In another applicator embodiment, the tuberous stem or pin electrode is held in a finger tip flexible mold, having an orifice therein through which the electrode protrudes. The orifice is dimensioned to enable the electrode to be held in place firmly by the finger for easy placement, and yet allow the electrode to be easily released once engagement with the patient has taken place.

An especially preferred embodiment of applicator disclosed herein involves a locking arrangement on an elongated cylindrical or flat main member, in which the electrode is received at the one end of the applicator and locked thereon by a slidable or rotatable locking part, there to be securely retained until release is desired, which is effected by moving the locking part to a retracting position.

An arrangement for maintaining electrode sterility prior to actual application to the patient is also disclosed^, which comprises a cover or canopy made of, for example, light sterile latex, which surrounds the tuberous active electrode element until the moment the electrode is applied. By placing the electrode arrangement against the tissue and applying pressure the cover and then the tissue is punctured, providing protection from contamination of the engaging electrode element up to the moment of actual puncture of the skin at the desired site, and limiting contamination only to the actual site of puncture.

For a better understanding of the invention and to show how the same may be put into effect, reference will now be made by way of example, to the accompanying drawings, in which: Fig. 1 illustrates in an enlarged sectional side view a first electrode according to the invention, employing an active electrode element having a single tuberosity; Fig. 2B illustrates in an enlarged, breakaway, partially sectional side view another embodiment of electrode according to the invention, employing an active electrode element having, however, multiple tuberosities; Fig. 2A illustrates in an enlarged, breakaway, partially sectional side view yet another embodiment of electrode according to the invention, in which the singletuberosity active electrode element is bent or curved to facilitate the application thereof to the patient; Fig. 2C illustrates in an enlarged breakaway side view still another embodiment of electrode according to the invention, employing the multiple tuberosity active electrode element of Fig. 2B in a curved configuration similar to that of Fig. 2 ; Fig. 2D illustrates in an enlarged breakaway side view, another embodiment of electrode according to the invention, in which the active electrode element has a smooth-threaded, screw-like configuration; Figs. 3A-3B show respectively in a cross-sectional side and a top view a first embodiment of electrode applicator, taking the form of an elongated, flexible member resembling an open-ended wrench, with the electrode of Fig. 1 received thereon and ready for application; Fig. 4 illustrates the electrode/applicator arrangement of Figs. 3A and 3B about to be applied by the physician's hand to the fetal scalp at the opening of the cervix; Fig. 5 illustrates in perspective view a second embodiment of applicator, in the form of a flexible finger-tip arrangement; Figs. 6A and 6B illustrate diagrammatically in side views the tuberous pin electrode of Fig. 1 in a sterile embodiment respectively prior to and at completion of application into a patient; Figs. 7A-7C illustrate respectively in bottom and left end and right end views another applicator embodiment, taking the form of a locking applicator arrangement; Fig. 7D is a sideview of the locking applicator of Fig. 7A with, however, the locking mechanism removed for clarity; Figs. 8A and 8B illustrate diagrammatically in side and end views respectively a version of the locking applicator of Fig. 7 having, however, a flat configuration; Figs. 9A and 9B illustrate in plan and side views respectively another version of the locking applicator of Fig. 7, having for the most part the flat configuration of the applicator of Fig. 8 with, however, the electrode receiving end having a cylindrica} configuration; and Fig. 9C is a cross-section of the applicator of Fig. 9A taken along the line 9C-9C.

With reference to the Figures, it is pointed out that the illustrations are not necessarily drawn to scale, but rather are exaggerated somewhat for ease of illustration and understanding.

Referring to Fig. 1, there is illustrated in an enlarged sectional side view a first embodiment of electrode for the direct transcutaneous derivation of biopotentials, such as the ECG of an unborn fetus. The depicted electrode comprises a base 1 of electrically insulating material such as nylon, a pin-like but tuberous active electrode element 2 and a reference electrode element (indifferent plate) 3. A pair of electrical leads 4 completes the electrode, which leads are connected to the active and reference electrode elements respectively.

The base 1 has at least a first portion la, preferably of substantially cylindrical shape, and may, as indicated in Fig. 1, have a second portion Ih located atop the cylindrical portion la and preferably integral therewith, which toP portion is preferably also of substantially cylindrical shape and coaxial with base portion la, but possessing a larger cross-sectional diameter.

The pin-like active electrode element 2 illustrated in Fig. 1 protrudes from the end of cylindrical base portion la and has at least a single exposed tuberosity along the length thereof, in this case proximate the free end. Active electrode element 2 is here depicted in a straight configuration and having a pointed free end. Active element 2 is arranged to extend from the lower end of cylindrical base portion la substantially along the longitudinal axis ofthe fatter. The lead 4 to active element 2 makes contact at the embedded end of the latter safely within the interior of the base 1.

The actual dimension and curvature of the tuberosity(s) of active element 2 are based upon the ability of the interior tissue tension to assist in retaining the electrode following application, tempered, however, by the desire of requiring only a small application force to administer the electrode to the patient.

Active element 2 may, in place of the straight pin-like configuration depicted in Fig. 1, take on a curve form, such as that shown in Fig. 2A, in which the active element, while at least initially projecting outward from the base substantially along the longitudinal axis of cylindrical base portion la, has its free end arranged to form an angle relative to the initially projecting portion thereof (i.e. at the point it breaks surface with the base 1) of less than 1800 and preferably in the vicinity of 90 , although the precise angle is not critical.

The curvature of the active element 2 facilitates application of the electrode to the patient in the preferred orientation in which the active element is inserted into the patient's skin substantially parallel to the skin surface.

Also, active element 2 preferably may, in lieu of the single tuberosity con iguration depicted in Figs. 1 and 2A, be provided along its exposed portion, either in actuality or effectively, with multiple tuberosities, such as are illustrated in Figs. 2B, 2C and 2D.

Fig. 2B in particular illustrates a multipletuberosity, straight-pin configuration 2b, in which the first tuberosity is located proximate the pointed free end of active element 2b and the final tuberosity is spaced somewhat from the surface of the base portion of la bearing the active electrode element. The various tuberosities define largely symmetical, smooth indentations therebetween which facilitate maintaining the attached electrode in place following application, and yet such an active electrode element design enables relatively easy atraumatic removal when desired.

While the actual size and curvature of the individual tuberosities are predetermined in dependence on the internal tissue tension, for ease of application the tuberosity located proximate the free end may be somewhat smaller in size then the others.

Moreover, the tuberosities may continue to increase in size away from the free end of active element 2, and thereby define as a result an ever-increasing force needed for additional penetration into the patient's tissue.

Fig. 2C illustrates in particular the preferred curved-pin configuration of Fig.

2A with multiple tuberosities such as that shown in Fig. 2B. This combination provides in one and the same electrode the advantages regarding insertion and placement thereof associated to the Fig. 2A configuration with the atraumatic placement-retaining advantages of the Fig.

2B configuration.

Fig. 2D illustrates what may be described as at least one substantially continuous tuberosity or a series of tuberosities forming a more or less continuous, smooth, threadlike (helical) configuration along the shaft 2d, which also has a pointed free-end. Such an arrangement possesses the placementretaining capability of say the configuration according to Fig. 2B and provides in addition thereto the capability of being screwed into or out of the epidermus of the patient, as and if desired, to further reduce the possibility of any trauma, as well as providing a convenient means for governing the extent of penetration into the patient's tissue. It is to be understood that the active electrode element 2d of Fig. 2D may also take on a curved configuration similar to that of Fig. 2C, and thereby retain the above-indicated advantages in combination with the earlier-mentioned advantages of a curved configuration.

Figs. 1, 2A and 2B illustrate further that the reference electrode element 3 may be configured and located on base 1 in various different embodiments, and may in connection therewith take the form of a film or band of electrically conductive material or instead a plate or disc. For example, in Fig. 1, reference element 3 is shown in the form of a thin plate or disc-like configuration situated atop the top flat; portion lb of the base and covering all or only part of this flat top. The lead 4 associated to the reference electrode 3 is connected to the latter on the underside thereof, preferably near the center region.

Fig. 2A, on the other hand, shows a base portion la without top portion ib, in which the top surface of cylindrical base portion la is concave, in order to facilitate the fit of the electrode with the fingertip of the person administering the electrode to the patient. The reference electrode element a, as shown, covers this concave surface.

Looking to Fig. 2B, there is again depicted a base 1 arrangement comprising only the cylindrical first portion la.

However, in this instance reference electrode element 3, rather than being mounted on the end of the cylindrical base portion la or lb opposite the active element 2, instead takes the form of a ring configuration 3b mounted around the circumference of cylindrical base portion la so as to have its operative surface preferably flush with the side of the base. In such a configuration, the associated electrical lead 4 may be connected on the inside ring surface of element 3b.

In general, the relative size of the electrode embodiments depicted herein are on the order of or smaller than the aforementioned Junge electrode, preferably less than 5 mm in length for the exposed portion of the active electrode element and 2-3 mm in cylindrical length for the base.

In all cases, active and reference electrode elements 2 and 3 are metallic or otherwise electrically conductive and mutually insulated from one another by the base material.

Various arrangements of the electrical leads 4 are depicted in Figs. 1, 2A and 2B which primarily accommodate the design and structure of the base 1. While the illustrated arrangements are considered preferred configurations, it is to be understood that other suitable and convenient lead arrangements are within the scope of this invention.

More particularly, the electrical lead configuration of Fig. 1 is intended to facilitate the application to the patient of the electrode depicted with the electrode applicator illustrated in Figs. 3A and 3B, as will be more particularly discussed hereinafter. In this configuration of Fig. 1, it is to be noted that not only do the leads make electrical contact with the active and reference electrode elements well within the interior of the base material, but that the leads run through the base interior to exit proximate the junction of first cylindrical base portion la and top base portion lb.

Figs. 2A and 2B also show the leads 4 to be exiting from the side of the base 1 and make electrical contact with the active and reference electrode elements well within the interior of the base material. Fig. 2B in particular illustrates the reference electrode lead making contact with the cylindrical reference element 3b on the inside surface thereof.

Figs. 3A and 3B illustrate respectively in side section and top views a first embodiment of finger-operable applicator for use, in particular, in connection with the electrode embodiment depicted in Fig. 1.

The applicator of Figs. 3A and 3B is a flexible, elongated member 10 having the appearance of an open-ended wrench, with a fork-shaped first end 11 constituting the electrode receiving end and the other end 12, also fork-shaped, employed as the electrode wire or lead receiving end. The electrode receiving end 11 comprises a pair of relatively thick, blunted tines which define a space therebetween dimensioned to closely cooperate with the cross-sectional diameter of the electrode cylindrical base portion la. The wire-receiving end 12 of applicator 10 has, on the other end, a pair of slender and somewhat rounded tines which define a substantially parallel-walled narrow channel having a width dimension intended to closely cooperate with the cross-sectional dimension of the electrode lead(s) 4.

Figs. 3A and 3B show the electrode of Fig. 1 properly received unto the elongated member 10 and stabilized for ready application to the patient's skin. The illustrated straight-pin, single-tuberosity electrode projects in a direction substantially perpendicular to the longitudinal direction of the applicator. The electrical lead(s) extend along the length of the applicator to be tucked into the slit at the wire receiving end 12, there to be pulled taut, if desired, by the physician prior to application and permitting a proper amount of tension to remain exerted upon the electrode lead(s) in order to facilitate the electrode being securely held in place within the channel of the electrode receiving end 11. The tautness of the lead(s) can be maintained merely by the physician 5 grasp of the applicator during the approach to and application of the electrode into the patient's tissue.

Fig. 4 illustrates the electrode arrangement of Figs. 3A and 3B as the electrode is about to be applied by the physician to the fetal scalp at me opemng of the cervix, as is apparent. The elongated structure of applicator 10 conveniently cooperates with the extended forefinger of the physician's hand, wherein the wire receiving end 12, and therefore the lead(s), are firmly clasped between the thumb, and palm and other fingers. Such an arrangement provides to the physician the necessary stability of the electrode during placement as well as permits the physician the desired direct feel of the situation, thus maintaining physician confidence particularly in applications of the electrode involving difficult circumstances, such as are depicted in Fig. 4 in reaching the unborn fetus as early as possible during the birth process.

The base structure 1 of the electrode may be further adapted to facilitate cooperative engagement with the applicator of Figs. 3A and 3B. In this regard, reference is made to Fig. 1 in which there is provided in the base a pair of oppositely-disposed, transverselyrunning grooves Ic having a cross-sectional dimension approximating the thickness of the elongated applicator 10. Such an engaging arrangement further enables the electrode to be securely maintained in position during the approach to and application into the intended tissue area of the patient. The grooves Ic may also be continued fully around the base to form a concentric groove about base portion la.

Such is illustrated for example by the groove Ic in the base of the electrode depicted in Fig. 2C.

Alternatively, the cylindrical base portion la may be provided with a pair of opositely-disposed, longitudinally-running flat sides for engagement with the applicator of Figs. 3A and 3B. Such would provide a precise orientation of the electrode, as would, or course, be the case also with the oppositely-disposed grooves 1 C of Fig. 1. A precise orientation would be desirable in regard to the possible asymmetrical aspects of the electrode, in particular the point of exit of the leads from the base portion and even more particularly with regard to the active electrode element having the curved electrode configuration depicted in Figs. 2A and 2C.

Turning now to Fig. 5, illustrated therein is a second embodiment of applicator, taking the form of a finger-tip arrangement 20 of resilient material by which there is constituted on the one hand an alternate means of applying the tuberous pin electrode to say the fetal scalp and on the other hand additional feel of the situation is obtained. The applicator of Fig. 5 closely resembles a finger cot configuration and is to be worn over the end digit(s) of the finger 22 (most likely the index finger). Along the side of the flexible finger-tip applicator 20 there is provided at least one orifice or aperture 21 proximate the closed end thereof, which orifice(s) is substantially circular in shape and dimensioned to closely cooperate with that of the cylindrical base portion la of the electrode of say Figs. 2A and 2B.

Such an applicator particularly provides the physician with good feel of the situation " roughout the approach to the monitor sget and application of the electrode. The electrode configuration depicted in Fig. 5 is that of Fig. 2A, including the concave structure of the top or back end of the base, which particularly permits the physician to exert a guidance of and force upon the electrode against the wall of the orifice of the finger-tip applicator to enable the electrode to be retained in the ready position while approaching the monitor site.

It is envisioned that the electrode may be assembled on the finger-tip applicator in such a way as to have the lead wires run along the interior of the applicator and along the index finger, then to be grasped, under tension if desired, between the thumb, palm and other fingers. Moreover, it is envisioned that this applicator may be loose enough on the finger to enable the easy extraction of the finger from the applicator, leaving the latter behind along with the electrode, particularly in the case of monitoring the unborn fetus. In this latter regard, it is pointed out that the particular embodiment of electrode employed may be that depicted in Fig. 1 (as demonstrated by the dashed line 23 in Fig. 5), in which the top portion lb of the base 1 would, of course, securely maintain the electrode in and protruding from orifice 21.

Figs. 6A and 6B diagrammatically illustrate in side views the tuberous pin electrode of Fig. 1 in a sterile embodiment, respectively prior to and at the completion of application to the monitor site. Mounted on the cylindrical base portion la, e.g.

secured by suitable adhesive, is a sterile covering or canopy 30 (here shown to be transparent for conveni show the left end and right end views of the applicator of Fig. 7A, while Fig. 7D illustrates the main member of the applicator without the locking portion, and in the open or unlocked orientation.

The locking applicator of Figs. 7A-7D comprises an elongated, cylindrically shaped main member 50, one end of which is divided into a pair of arms 51a and 51b which define a slot or channel 52 therebetween. Arranged on elongated main member 50 is a displaceable locking part 53, which is intended to interact with the operative, i.e. locking, end 50a of the applicator. Main member 50 and displaceable locking member 53 are composed of relatively rigid material such as polyethylene. Member 50 is constructed to have the arms 51a and 51b normally opening away from one another somewhat.

Arms 51a and 51b have opposing recesses 55a, 55b in the surfaces thereof facing one another. Preferably, recesses 55a and 55b are substantially rectangular in shape (cross-section) for cooperating or mating with the base portion of the electrode to be received on the applicator for delivery to the patient. It is to be understood, however, that the actual shape of recesses 55a and 55b may take any suitable form, so long as they along with the rest of the operative portions of the arms 51a and 51b are shaped and dimensioned to cooperate with the intended base portion of the electrode.

As particularly illustrated in Fig. 7B, both elongated main member 50 and locking member 53 are cylindrical in configuration, although member 50 could instead have a flat configuration, such as is illustrated for example in Figs. 8A and 8B. The applicator arrangement of Figs. 7A-7B is particularly adapted for receiving the body structure illustrated in Fig. 2C. This electrode is received at the locking end of the applicator such that the cylindrical base portion of the former would be coaxial with main member 50. In this regard, the front tooth-like portions 56a, 56b, of the arms 51a, 51b engage the recess lc of the base portion of the electrode of Fig. 2C.

The remainder of the elongated member 50 is provided with a series of elongated window openings 57, preferably four in number, which run parallel to the longitudinal axis of member 50, and also a hexagonally shaped distal or remote end piece 58. The window openings 57 serve on the one hand as shock absorbers, particularly in the case where an electrode of the type depicted in Fig. 2D is used, in which the window openings prevent excessive driving torque from being applied to the electrode. On the other hand, the window openings permit light from an endoscope to illuminate the presenting part of the patient, as will be particularly appreciated in connection with the monitoring of the unborn fetus through the cervix. The hexagonal shape of end piece 58 facilitates the generation of torque to be applied to the electrode, as needed, for application thereof to the patient. End piece 58 also is provided with a slot or recess 59 in which may be conveniently tucked the electrode lead(s) until disengagement is desired.

Although Figs. 7A and 7B depict the locking member 53 in the form of a sliding cylindrical sleeve, which slides into its locking forward position to bias the arms 51a, 51b, together in a closely cooperating position, and slides back away from the locking end of the member 50 to its retracted position for enabling disengagement of the electrode from the applicator, it is to be understood that the relationship of locking member 53 and main member 50 may be such as to have the locking member rotatably threaded on the main member for rotation into and out of, the locking position. It is to be noted further that member 50 is tubular and thus may provide an internal path for the leads to extend away from the locking end.

Figs. 8A and 8B show a flat configuration of the locking applicator depicted in Figs.

7A-7D, in which main member 50 and its locking end arms 51a, 51b have essentially a rectangular cross-section. Moreover, in this embodiment, the locking member 53 preferably takes on a substantially rectangular cross-sectional configuration.

Figs. 8A and 8B show locking member 53 in the retracted or unlocked position so as to define the full channel 52 between the arms 51a, Sib. As before, the applicator depicted in Figs. 8A and 8B is particularly adapted for engagement with an electrode base such as that illustrated in Fig. 2C, only this time, due to the flat structure of the main member 50, the orientation of the electrode in the assembled position on the locking applicator is such as to have the operative end thereof facing perpendicular to the longitudinal direction of main member 50.

In this regard, the thickness dimension of maili member 50, in particular its associated arms 51a, 51b, is such as to cooperate with the width dimension of the recess lc in the base portion of the electrode shown in Fig.

2C.

The locking applicator of Figs. 8A and 8B operates in essentially the same manner as that of the applicator of Figs. 7A-7D, wherein the electrode body is inserted between the arms 51a and 51b so as to engage the recesses 55a and 55b and teeth 56a and 56b accordingly. Therefollowing, the locking member 53 is moved longitudinally along main member 50 toward the locking end 50a, and thereby biasing the arms 51a and Slb toward one another and thus effecting the engagement with the intended electrode body portion.

Because of the friction between the arms and the locking member, the latter maintains its position unless positively urged backward along the main member 50 towards the retracting position. Fig. 8A shows, moreover, a representative one of possible a number of limit stops 61 by which It is intended that the locking member 53 be prevented from progressing too far along the shaft of main member 50 away from the locking end portion 50a.

Figs 9A-9C illustrate a further embodiment of the locking applicator, in which for the most part the main member 50 assumes a rectangular cross-sectional configuration except for the free-end portion of the locking arms 51a, 51b. The free-end portions of arms 51a, 51b assume instead a cylindrical configuration 51a', 51b'.

As is particularly illustrated in this embodiment, arms 51a, 51b are provided with respective locking ears 60a and 60b which are intended for engagement with locking member 53 to hold the latter securely in the locking position. In this instance, locking member 53 takes on a hollow rectangular configuration with a pair of slots on opposing sides thereof which are intended to cooperate with locking ears 60a, 60b. Figs. 9A and 9B each illustrate the applicator in the locked mode where the electrode (not shown) is secured between the cylindrically shaped free ends of the arms 51a, 51b. Here again, the actual specific shape of the locking end portion of this applicator cooperates with the design of the rear portion of the electrode.

Main member 50 is provided with a flat paddle-shaped portion 62 at the end remote from the locking end portion, which serves the dual purposes of preventing locking member 53 from sliding off the shaft of main member 50 and also to present a pair of flat broad surfaces for easy grasping of the applicator by the physician, particularly in the event a certain amount of torque is desired in the application of the electrode to the patient. It is to be noted, moreover, particularly in Fig. 9B, that the shaft of main member 50 is bent substantially in the middle portion thereof to facilitate the approach to the patient, particularly in such difficult situations as the approach to the unborn fetus by way of the vagina and cervix. As before in the case of the locking applicator of Fig. 7D, a slot or recess 59 is provided in the end portion of 50b of main member 50 for convenient insertion of the electrode lead(s) while approaching the monitor site.

It is to be understood that it is within the scope of this invention for the locking applicator to also take the form of a tubular main member 50 with however the operative (locking) end portion thereof having a flat configuration similar to that of Figs. 8A and 8B. In this regard the locking mechanism 53 may take either the tubular form depicted in Fig. 7A or the form of Fig.

9C, as desired.

There has been disclosed herein a disposable electrode for direct transcutaneous derivation of patient biopotentials, such as the ECG of an unborn fetus, the active electrode element of which has a tuberous pin configuration with at least one tuberosity arranged along its length for enabling atraumatic attachment to and removal from the patient. The active electrode element may be of curved and multi-tuberous configuration for particularly facilitating application and firm attachment thereof substantially parallel to the skin surface. Several embodiments of disposable applicator are disclosed by which the sense of feel of the effort of and during application is retained. These include a flexible member elongated for easy grasping by the hand and having one end thereof designed to cooperatively engage'the electrode for stability yet permit the physician's finger to remain in contact with the electrode and a locking applicator arrangement which includes a displaceable locking piece enabling the electrode to firmly remain upon the applicator as the former is administered to the patient.

WHAT WE CLAIM IS: 1. An electrode arrangement suitable for use in direct transcutaneous derivation of patient diological parameters, such as the ECG of an unborn fetus, in which the active electrode element has a tuberous pin configuration with at least one tuberosity arranged along the length thereof for enabling relatively atraumatic attachment and removal of the electrode respectively to and from a patient.

2. An electrode arrangement according to Claim 1, which comprises: (a) a base of electrically insulating material, (b) an active electrode element extending from the base, the extending portion thereof having along its length at least one tuberosity, (c) a reference electrode element mounted on the base and spaced from the active electrode element, and (d) means for electrically connecting the active and reference electrode elements to a biopotential monitor.

3. An electrode arrangement according to Claim 2, wherein the base has at least a first

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. toward the locking end 50a, and thereby biasing the arms 51a and Slb toward one another and thus effecting the engagement with the intended electrode body portion. Because of the friction between the arms and the locking member, the latter maintains its position unless positively urged backward along the main member 50 towards the retracting position. Fig. 8A shows, moreover, a representative one of possible a number of limit stops 61 by which It is intended that the locking member 53 be prevented from progressing too far along the shaft of main member 50 away from the locking end portion 50a. Figs 9A-9C illustrate a further embodiment of the locking applicator, in which for the most part the main member 50 assumes a rectangular cross-sectional configuration except for the free-end portion of the locking arms 51a, 51b. The free-end portions of arms 51a, 51b assume instead a cylindrical configuration 51a', 51b'. As is particularly illustrated in this embodiment, arms 51a, 51b are provided with respective locking ears 60a and 60b which are intended for engagement with locking member 53 to hold the latter securely in the locking position. In this instance, locking member 53 takes on a hollow rectangular configuration with a pair of slots on opposing sides thereof which are intended to cooperate with locking ears 60a, 60b. Figs. 9A and 9B each illustrate the applicator in the locked mode where the electrode (not shown) is secured between the cylindrically shaped free ends of the arms 51a, 51b. Here again, the actual specific shape of the locking end portion of this applicator cooperates with the design of the rear portion of the electrode. Main member 50 is provided with a flat paddle-shaped portion 62 at the end remote from the locking end portion, which serves the dual purposes of preventing locking member 53 from sliding off the shaft of main member 50 and also to present a pair of flat broad surfaces for easy grasping of the applicator by the physician, particularly in the event a certain amount of torque is desired in the application of the electrode to the patient. It is to be noted, moreover, particularly in Fig. 9B, that the shaft of main member 50 is bent substantially in the middle portion thereof to facilitate the approach to the patient, particularly in such difficult situations as the approach to the unborn fetus by way of the vagina and cervix. As before in the case of the locking applicator of Fig. 7D, a slot or recess 59 is provided in the end portion of 50b of main member 50 for convenient insertion of the electrode lead(s) while approaching the monitor site. It is to be understood that it is within the scope of this invention for the locking applicator to also take the form of a tubular main member 50 with however the operative (locking) end portion thereof having a flat configuration similar to that of Figs. 8A and 8B. In this regard the locking mechanism 53 may take either the tubular form depicted in Fig. 7A or the form of Fig. 9C, as desired. There has been disclosed herein a disposable electrode for direct transcutaneous derivation of patient biopotentials, such as the ECG of an unborn fetus, the active electrode element of which has a tuberous pin configuration with at least one tuberosity arranged along its length for enabling atraumatic attachment to and removal from the patient. The active electrode element may be of curved and multi-tuberous configuration for particularly facilitating application and firm attachment thereof substantially parallel to the skin surface. Several embodiments of disposable applicator are disclosed by which the sense of feel of the effort of and during application is retained. These include a flexible member elongated for easy grasping by the hand and having one end thereof designed to cooperatively engage'the electrode for stability yet permit the physician's finger to remain in contact with the electrode and a locking applicator arrangement which includes a displaceable locking piece enabling the electrode to firmly remain upon the applicator as the former is administered to the patient. WHAT WE CLAIM IS:

1. An electrode arrangement suitable for use in direct transcutaneous derivation of patient diological parameters, such as the ECG of an unborn fetus, in which the active electrode element has a tuberous pin configuration with at least one tuberosity arranged along the length thereof for enabling relatively atraumatic attachment and removal of the electrode respectively to and from a patient.

portion of substantially cylindrical shape and wherein the active electrode element projects outwardly from one end of the cylindrical first portion at least initially in a direction substantially parallel to the longitudinal direction of the latter.

4. An electrode arrangement according to Claim 2, wherein the active electrode element has a substantially straight pin-like configuration with a tuberosity proximate the free end thereof and having a substantially pointed free end.

5. An electrode arrangement according to Claim 2, wherein the active electrode element has an overall curved configuration with a tuberosity located proximate the free end thereof and having a substantially pointed free end.

6. An electrode arrangement according to Claim 5, wherein the curved configuration of the active electrode element is such that the free end thereof forms an angle of less than 1800 with respect to the other end of the exposed portion thereof.

7. An electrode arrangement according to Claim 2 or 3, wherein the active electrode element has a plurality of tuberosities of predetermined size relative to one another distributed along the length thereof.

8. An electrode arrangement according to Claim 7, wherein the tuberosities are distributed substantially equidistant from one another.

9. An electrode arrangement according to Claim 7, wherein the active electrode element has a plurality of tuberosities at least a predetermined one of which is of different sizes from the remainder.

10. An electrode arrangement according to any one of Claims 2 to 9, wherein the reference electrode element is a film of electrically conductive material covering a portion of the exterior of the base.

11. An electrode arrangement according to any one of Claims 2 to 10, wherein the base is substantially cylindrical in shape with the active electrode element projecting out one end thereof and with the reference electrode element covering at least a portion of the other end thereof.

12. An electrode arrangement according to, Claim 11, wherein the other end of the base is concave.

13. An electrode arrangement according to Claim 10, wherein the base is substantially cylindrical in shape and the reference electrode element is in the form of a band of electrically conductive material arranged around the circumference of the base.

14. An electrode arrangement according to Claim 3, wherein the base has a discshaped second portion arranged to communicate with the other end of the cylindrical first portion, the disc-shaped second portion having a cross-sectional diameter greater than the cylindrical first portion.

15. An electrode arrangement according to Claim 14, which further comprises a flexible elongate applicator having a forksha~ped first end with a pair of blunted tines defining a space therebetween which is dimensioned to cooperate with the cylindrical first portion of the base.

16. An electrode arrangement according to Claim 15, wherein the substantially cylindrically shaped first portion of the base has a pair of longitudinally running opposing flat sides to facilitate engagement of the electrode with the first end of the applicator.

17. An electrode arrangement according to Claim 15, wherein the applicator is substantially flat and has opposing broad surfaces, and wherein the substantially cylindrical first portion of the base has a pair of opposing transversely running grooves to facilitate engagement. of the electrode arrangement with the first end of the applicator.

18. An electrode arrangement according to Claim 17, wherein the grooves comprise respective portions of a concentric recess about the circumference of the cylindrical first portion.

19. An electrode arrangement according to Claim 15, wherein the electrical connecting means includes at least one wire extending from the latter and wherein the applicator has a fork-shaped second end with a pair of blunted tines defining a space therebetween dimensioned to the diameter of the at least one wire to facilitate maintaining engagement of the electrode with the first end of the applicator.

20. An electrode arrangement according to Claim 3, which further comprises an applicator of resilient material configured substantially in the form of a finger cot to be worn over the end of a finger of the hand, the applicator having an orifice therein proximate the closed end thereof of cooperating shape and dimension(s) to the electrode to facilitate the placement thereof at a monitor site.

2f. An electrode arrangement according to any one of Claims 2 to 20, which further compnses a canopy secured to the base and covering the active electrode element, the canopy being composed of a readily deformable, perforatable material, forming a shield about the active electrode element, the arrangement of the canopy being such as to preserve the sterility of the active element up to the moment of actual application of the electrode to a monitor site.

22. An electrode arrangement according to any one of Claims 2 to 21, wherein the at least one tuberosity is a substantially continuous helical configuration which extends along the length of the active electrode element in a smooth-threaded fashion.

23. An electrode arrangement according to Claim 22, wherein the active electrode element has an overall curved configuration and a substantially pointed free end..

24. An electrode arrangement according to Claim 3 or any one of Claims 7 to 23 when appended to Claim 3, wherein the substantially cylindrically shaped first portion of the base has at least one transversely running recess.

25. An electrode arrangement according to Claim 2, wherein the active electrode element has an overall curved configuration having a plurality of tuberosities located along the length thereof and a substantially pointed free end.

26. An electrode arrangement according to Claim 25, wherein the tuberosities are predeterminably sized and spaced apart relative to one another.

27. An electrode arrangement according to Claim 25 or 26, wherein the curved configuration of the active electrode element is such that the free end thereof forms an angle of less than 180C with respect to the other end of the exposed portion thereof.

28. In combination with an electrode arrangement for derivation of patient biological parameters in accordance with Claim 1, an applicator comprising a main elongate member of rigid material, one end of which is longitudinally divided to form a pair of opposing arms which are normally separate in a first orientation to define a space therebetween and which are constructed to be urged into a closed second orientation in which the facing surfaces thereof cooperate, and a locking part displaceable along at least a portion of the elongated member in the vicinity of the divided end thereof, which locking part in a retracted first position permits the arms to assume the first orientation and in an engaging second position urges the arms into the second orientation, the arms, at least on the facing surfaces thereof, being configured to cooperate with a predetermined portion of the electrode body so as to enable the latter to be locked between the arms when assuming the second orientation under the urging of the locking part and to be released when the arms are permitted by the locking part to assume the first orientation.

29. A combination according to Claim 28, wherein the elongate member at least at the divided end thereof is substantially cylindrical in shape.

2. A combination according to Claim 29, wherein the electrode when locked into the applicator assumes an orientation extending along the longitudinal direction of the applicator.

31. A combination according to Claim 28, 29 or 30, where the locking part is substantially cylindrical in shape and is linearly slidable along the elongate member.

32. A combination according to Claim 28, 29 or 30, wherein the locking part is substantially cylindrical in shape and is rotatably threaded on the elongated member.

33. A combination according to any one of Claims 28 to 32 wherein the elongate member includes at least one limit stop to restrict the longitudinal movement of the locking part along the main member.

34. A combination according to Claim 33, wherein the limit stop is arranged on the main member beyond the space to restrict the locking part from movement in the direction away from the divided end.

35. A combination according to Claim 29 or 30, wherein the elongate member, except for a portion of the opposing arms, has a substantially flat configuration, in which the connected end portions of the arms also assume a substantially flat configuration but the free-end portions assume a cylindrical configuration.

36. A combination according to Claim 35, wherein the locking part operates on the substantially flat portion of the arms to effect the second orientation of the cylindrical configuration portion of the arms.

37. A combination according to Claim 36, wherein the locking part has a substantially rectangular cross-section.

38. A combination according to Claim 37, wherein the elongate member has a pair of locking ears located on opposite sides and the locking part has a pair of apertures on opposite sides thereof for engagement with the locking ears when the locking part assumes the second position.

39. A combination according to Claim 35, 36, 37 or 38, wherein the end portion of the elongate member opposite the divided end widens into a paddie-shaped configuration providing a pair of broad surfaces facilitating guidance of the electrode up to and during application thereof to the monitor target.

40. A combination according to Claim 38, wherein the elongate member is substantially flat and the cooperation between the engaging portion of the elongated member and the electrode is such as to provide the electrode with an orientation which is perpendicular to the longitudinal direction of the elongated member.

41. A combination according to Claim 40, wherein the locking part is linearly slidable along the elongate member.

42. A combination according to Claim 40, wherein the locking part is rotatably threaded on the elongate member.

43. In combination with an electrode arrangement according to Claim 1, having a base portion of predetermined configuration, a locking applicator arrangement comprising an elongate main member of rigid material and having one end thereof longitudinally split to form a pair of opposed cooperating arms normally spaced apart to define a channel therebetween, each arm having a recess of predetermined configuration located in opposition to one another, and a displaceable locking part mounted on the main member proximate the one end thereof for movement toward and away from the one end in order respectively to decrease and increase the dimension of the channel and thereby effect respectively a locked and unlocked orientation, the one end of the main member being constructed to cooperate with the predeterminably configured base portion of the electrode arrangement to facilitate application thereof to a monitor site.

44. A combination according to Claim 43, wherein the electrode arrangement comprises a base and wherein the base of the electrode arrangement is composed of an electrically insulating material having a substantially cylindrical first portion with at least one transversely running groove therein.

45. A combination according to Claim 44, wherein the main member is substantially flat and the cooperative engagement of the one end thereof with the electrode arrangement is such that the longitudinal axis of the former is oriented substantially perpendicular to the longitudinal axis of the cylindrical first portion of the base.

46. A combination according to Claim 44, wherein the main member is tubular and the cooperating arrangement of the one end thereof with the electrode arrangement is such that the longitudinal axis of the former is oriented substantially parallel to the longitudinal axis of the substantially cylindrical first portion of the base.

47. A combination according to Claim 43, which further comprises at least one limit stop arranged on the main member beyond the channel defined by the opposing arms to restrict the movement of the displaceable locking part away from the one end.

48. A method of direct transcutaneous derivation of patient biological parameters, such as the ECG of an unborn fetus, which comprises the use of an active electrode element having a tuberous pin configuration with at least one tuberosity arranged along the length thereof for enabling relatively atraumatic attachment and removal of the electrode respectively to and from a patient.

49. A method of direct transcutaneous derivation of patient biological parameters, such as the ECG of an unborn foetus, which comprises the use of an electrode arrangement or combination in accordance with any one of Claims 2 to 47.

SO. An electrode arrangement substantially as hereinbefore descnedwith reference to, and as shown in, Figures I, 6A and 6B of the accompanying drawings.

Si. An electrode arrangement substantially as hereinbefore described with reference to, and as shown in, Figure 2A of the accompanying drawings.

52. An electrode arrangement substantially as hereinbefore described with reference to, and as shown in, Figure 2B of the accompanying drawings.

53. An electrode arrangement substantially as hereinbefore described with reference to, and as shown in, Figure 2C of the accompanying drawings.

54. An electrode arrangement substantially as hereinbefore described with reference to, and as shown in, Figure 2D of the accompanying drawings.

55. An electrode and applicator combination substantially as hereinbefore described with reference to, and as shown in, Figures 3A, 3B and 4 of the accompanying drawings.

56. An electrode and applicator combination, substantially as hereinbefore described with reference to, and as shown in, Figure 5 of the accompanying drawings.

57. An electrode and applicator combination, substantially as hereinbefore described with reference to, and as shown in, Figures 7A, 7B, 7C and 7D of the accompanying drawings.