Electrode assembly and methods of using the same in the respiratory and/or cardiac monitoring of an infant

Abstract

A disposable electrode assembly and method of using the same in the respiratory and/or cardiac monitoring of an infant comprising a pad or very fine open pore polyurethane providing an infant back receiving area of approximately 41/2 inches by 41/2 inches on which a plurality of separate flexible carbon powder impregnated polyvinyl chloride sheet electrodes are affixed in surface-to-surface engagement so as to be intimately contacted by the skin of an infant's back received on said back receiving pad area. The pad has portions converging outwardly from opposite sides of the back receiving area for extending generally beneath the armpits and along the lower edge of the rib cage of an infant where they are held to the sides of the infant's torso by integral pad straps releasably adjustably secured together across the infant's chest above the belly area by Velcro fastener elements. Snap fastener terminal elements are provided for effecting a detachable electrical connection with the leads of the monitoring instrument.

Parent Case Text

This application is a continuation-in-part of co-pending application Ser. No. 440,750 which was filed Feb. 8, 1974 and now abandoned.

Description

This invention relates to infant or new born baby care and more particularly to an improved electrode assembly and method of using the same in the respiratory and/or cardiac monitoring of an infant.

In the care of infants it is frequently necessary to continuously monitor the respiratory and/or heart functions of the infant, usually in conjunction with incubator treatments. The practice heretofore has been to use separate adhesively applied electrodes for purposes of respiratory and/or ECG monitoring. A typical electrode of the type used in practice is disclosed in U.S. Pat. No. 3,713,435. An electrode of this type embodies a central male snap fastener assembly surrounded by a disk of flexible material. The male element of the snap fastener assembly serves as a terminal for connection with the lead of the monitoring equipment. The opposite side of the male snap fastener assembly serves as a receptacle for a conductive paste or electrolyte gel. The corresponding face of the flexible disk is provided with a pressure sensitive adhesive which serves to hold the electrolyte gel into contact with the skin. In operation, usually three of these electrodes are applied to the infant's chest area with the infant being supported in the incubator on his or her back.

While the use of electrodes of this type produce reliable monitoring, this reliability is obtained with the known inconvenience and aggravation experienced by adults when being so monitored. Thus, it is well known that conductive pastes or electrolyte gels are a source of skin irritation and maceration. Likewise, the area of the skin contacted by the pressure sensitive adhesive frequently can become irritated and sore. While these effects can be considered inconveniences and aggravations by adult patients, they often become severe problems when applied to new born babies or infants. The severity of the problem is magnified and multiplied by the frequent attendant need to X-ray the infant's chest undergoing treatment. Since the electrodes are adhered to the infant's chest and contain metal, each one of the three must be removed each time before the X ray is taken and then replaced after the X ray has been completed. This removing and replacing procedure further increases the chances of irritation to the infant's tender skin. There exists a need for a reliable electrode system which will eliminate the problems incident to direct skin contact of gels and adhesives and is either easily and conveniently removable and replaceable for X ray purposes or permit unobstructive X ray picture taking while attached.

An object of the present invention is the provision of a reliable electrode system and method of using the same in the respiratory and/or cardiac monitoring of an infant which will fill the above described need by eliminating the aforesaid disadvantages of present practices. In accordance with the principles of the present invention this objective is obtained by utilizing a plurality of flexible sheet form electrodes, preferably formed of carbon powder loaded polyvinyl chloride, sized and arranged so as to have a maximum contact area with the infant's skin at a location throughout the back area so that such contact can be maintained primarily by the weight of the infant in his or her normally supported position within the incubator. The utilization of flexible sheet form electrodes enables a reliable electrical connection to be effected without the use of conductive pastes or electrolyte gels since electrical resistance to the connection can be minimized by virtue of the greater area of contact of the connection. Utilizing the infant's back as the area of contact also secures many advantages. First, it utilizes a skin area which is normally contacted anyway by virtue of the infant's normal position in the incubator. Thus, skin areas which do not receive normal intimate contact, such as the chest area, are allowed to remain unencumbered. Second, the weight of the infant can be utilized to facilitate a somewhat pressurized contact. Third, by utilizing non-metallic electrodes which extend throughout the back area, the metal leads of the ECG equipment can be peripherally attached to the electrodes, thus making it possible to maintain the torso area free of obstructing metal for X-ray purposes.

It is recognized that flexible sheet form electrodes which eliminate the need for conductive paste or electrolyte gel have long been proposed in the patented literature as, for example, Ruben U.S. Pat. No. 1,973,911 dated Sept. 18, 1934. The single electrode of the Ruben patent is provided with a mucilaginous adhesive to effect securement to the skin, an arrangement which would be unsuitable for infants and would not fill the need for an electrode system which maintains reliable contact without the possibility of skin irritation due to adhesive skin engagement. The patented literature also contains other proposals for the use of flexible sheet form electrodes where skin engagement is maintained by adhesive eliminating means suitable for specific purposes other than infant monitoring. For example, Browner U.S. Pat. No. 3,025,857 dated Mar. 20, 1962, discloses an electrotherapy device in which a plurality of flexible sheet form electrodes are affixed to a flexible wall of a treatment table with certain of the electrodes being carried by straps affixed to the wall by means of which the patient is both strapped to the treatment table and contacted with the electrodes on exposed upwardly facing skin areas. The Browner arrangement thus provides for the selective contraction of the strapped patient's muscles by electrical excitement through the various electrodes. Another specialized use is disclosed in Roman U.S. Pat. No. 3,534,727 dated Oct. 20, 1970. The purpose of the Roman arrangement is to enable monitoring to take place while the patient is physically active. To this end, a plurality of flexible sheet form electrodes are maintained in skin contact by means of a tightly fitting elastic garment. Bolduc U.S. Pat. No. 3,720,209 dated Nov. 25, 1970, discloses the use of a plurality of flexible sheet form electrodes mounted on the upper surface of a flat flexible plate-like base so that an ECG can be taken with the patient simply lying on a treatment table with the base mounted electrodes between the patient and the treatment table.

In filling the aforementioned specific needs incident to infant care, the present invention relies not only upon the use of a plurality of flexible sheet form electrodes but also upon the combination of such electrodes with an effective reliable non-adhesive attaching structure which fulfills the needs specific to infant care. The attaching structure of the present invention and its mode of operation differs in principle from the attaching structures of the prior art discussed above because it neither utilizes a strapped to the table relationship, a tight fitting elastic garment relationship nor a flat plate-like relationship. While these latter relationships may be described or necessary for the particular application to which they relate, they could not be satisfactorily applied to infant care. Strapping the patient down to the treatment table may be regarded as necessary while giving an adult an electric muscle shock treatment but would not be desirable for infants. Likewise, wearing an elastic garment may be required dress for astronauts but is hardly suitable for infants. So also it would be expected that an adult would lie still on a flat pad long enough for an ECG reading, but such conduct cannot be expected in the long term monitoring of an infant.

In accordance with the principles of the present invention, an attaching structure is provided which will maintain a plurality of flexible sheet form electrodes against the back of an infant in such a way as to maintain reliable non-adhesive contact over an extended period of time without strapping the infant to the incubator, without requiring the infant to wear tight fitting elastic garments or to be immobile. The attaching structure embodying these principles includes a pad of soft pliable material, preferably a very fine open pore foamed polyurethane sheet of approximately one-fourth inch thickness, having a back engaging area of approximately 41/2 inches by 41/2 inches to which the plurality of flexible sheet from electrodes are attached substantially throughout, the sides of the back engaging area having portions which converge outwardly thereof so as to pass under the infant's armpits and extend along the lower edge of the infant's rib cage when held against the sides of the infant's torso. Soft pliable quick connect and disconnect strap means, preferably formed integrally of the pad material, is provided between the converging portions to maintain the same against the sides of the infant's torso which, in turn, maintains the electrode carrying back engaging area against the infant's back. The soft pliable strap means extends across the infant's chest above the belly area so that attachment is effected by the application of a soft pliable restraint which is completely unrestrictive to the breathing movements which occur in the belly area of infants.

Another object of the present invention is the provision of a reliable infant long term monitoring electrode assembly of the type described which is sufficiently simple and economical in construction as to be made sterile and disposable after one use.

These and other objects of the present invention will become more apparent during the course of the following detailed description and appended claims.

The invention may best be understood with reference to the accompanying drawings wherein illustrative embodiments are shown.

In the drawings:

FIG. 1 is a perspective view illustrating the manner in which a preferred electrode assembly embodying the principles of the present invention is disposed in attached relation with an infant;

FIG. 2 is a perspective view showing the electrode assembly in attached relation with an infant;

FIG. 3 is a top plan view of the electrode assembly disposed in a flat condition prior to attachment to the infant;

FIG. 4 is an enlarged, fragmentary sectional view taken along the line 4--4 of FIG. 3 illustrating an electrode assembly of modified form embodying the principles of the present invention;

FIG. 5 is a view similar to FIG. 3 illustrating an electrode assembly of modified form embodying the principles of the present invention; and

FIG. 6 is an enlarged fragmentary sectional view taken along the line 6--6 of FIG. 5.

Referring now more particularly to the drawings, there is shown in FIGS. 1-4 thereof a disposable electrode assembly, generally indicated at 10, which, in accordance with the principles of the present invention, is particularly suited for the respiratory and/or cardiac monitoring of infants or new born babies. As best shown in FIG. 3, the electrode assembly comprises a sheet-like pad 12 of soft pliable non-conductive material having an infant back receiving area 14 of approximately 41/2 inches by 41/2 inches. A plurality of separate flexible sheet form electrodes 16, 18, 20 and 22 of conductive particle impregnated plastic material are affixed in surface-to-surface engagement with the pad 12 so as to extend substantially throughout the back receiving area thereof.

The pad 12 also includes integral portions 24 which converge outwardly from opposite sides of the back receiving area 14 thereof for extending generally beneath the armpits and along the lower edge of the rib cage of an infant when the converging side portions are held to the sides of the infant's torso. The converging side portions 24 are arranged to be held to the sides of the infant by appropriate soft pliable strap means which in the preferred embodiment are in the form of a pair of integral strap portions 26. Mounted on the strap portions 26 are cooperating Velcro fastener strips 28 and 30 which serve to releasably adjustably secure the strap portions 26 in a position extending across the chest cage of the infant.

In the embodiment shown in FIGS. 1-4, the pad 12 also includes an infant head receiving and terminal carrying portion 32 extending outwardly from the area 14 in the direction of and beyond an infant's head whose back is received on the back receiving area 14. The electrode assembly 10 also includes terminal means for effecting a detachable electrical connection of each electrode 16, 18, 20 and 22 with a lead of a monitoring machine. In the embodiment shown in FIGS. 1-4, the terminal means includes strips 34, 36, 38 and 40 which are integral with and extend from the peripheries of the electrodes 16, 18, 20 and 22 respectively. The strips extend through openings 42, 44, 46 and 48 respectively, in the pad 12 and are affixed in surface-to-surface engagement with the exterior of the pad in an outwardly extending parallel relation in the direction of the portion 32. The terminal means also includes male snap fastener elements 50, 52, 54, and 56 which are fixedly secured to the free ends of the strips 34, 36, 38 and 40 respectively and the associated pad portion 32.

It will be understood that the pad 12 may be constructed of any soft pliable non-conductive material or composite construction, however, a preferred material is a very fine open pore polyurethane of approximately one-fourth inch thickness. A pore size of 100 PPI is preferred. As to the size of the back engaging area 14, it will be understood that a measure of variation from the exact 41/2 .times. 41/2 dimension previously stated is clearly within the purview of the present invention. Basically, it is desirable to make the area be as large as possible to increase the electrical contact area and hence minimize the resistance of the connector On the other hand, it is desirable to make the area as small as possible to accommodate the smallest size infant encountered.

Commensurate with this view, a 4 inch by 3 inch dimension of the area is desirable and, of course, the term "approximately" contemplates a slightly lower dimension as well as dimensions above the exact 41/2 .times. 41/2 dimension specified. Moreover, it will be appreciated that a variation in the dimension across the back is more restricted than the dimension normal thereto in order to achieve the proper functioning to the converging portions 24.

The electrodes can be of any desired electrically conductive flexible material, the preferred material shown being carbon powder impregnated polyvinyl chloride. While cooperating Velcro fastener elements 28 and 30 are preferred, other fastening elements or assemblies may be utilized. Likewise, while male snap fastener elements made of metal are preferred as a terminal construction, other types of terminals may be utilized, including simple wires.

The electrodes are preferably relatively thin, the preferred thickness shown being 0.030 inches. The shape of the electrodes and the number of electrodes provided can be varied. It is preferred that they be of generally equal size extending over as much of the back receiving area 14 as possible but at least 50% of the area. In the preferred embodiment shown, there are four electrodes of generally equal square configuration (approximately 2 inches by 1-15/16 inches for the 41/2 inch .times. 41/2 inch size and 11/2 inches by 11/2 inches for the 4 inch .times. 31/2 inch size) extending over approximately 80% of the back receiving area 14.

With the above in mind, it will be understood that the terms "pad of soft pliable material" and "flexible sheet form electrodes" are not limited to the preferred embodiments specifically described above but comprehend other types of constructions. For example, the pad and electrodes could be formed of woven or knitted material with the electrodes being provided by electrically conductive yarns (e.g., carbon powder loaded resin or metallic coated thread) positioned in the fabric to engage the infant's back by the weaving or knitting operation. Other arrangements will readily occur to those skilled in the art.

In practicing the present method, the electrode assembly 10 is first placed in a generally flat condition, as shown in FIG. 1, on the upper surface of the incubator with the exterior surface of the pad 12 engaging the upper surface of the incubator and the exposed surfaces of the electrodes 16, 18, 20 and 22 facing upwardly. Next, the leads of the monitoring instrument are detachably connected with the snap fastener terminal elements 50, 52, 54 and 56. Next, the infant is placed in the incubator in a position such that his or her back rests upon the electrodes 16, 18, 20 and 22 and the infant's head rests upon the pad portion 32, as is shown in FIG. 1. Next, the strap portions 26 are brought up around the infant's chest and the cooperating Velcro fastening elements 28 and 30 are brought into engagement. FIG. 2 illustrates the operative position of the assembly 10 when applied to the infant.

In summary, the method of the present invention involves the steps of positioning the infant's back into skin engagement with a plurality of generally coplanar flexible sheet form electrodes substantially throughout the back area of the infant while flexibly retaining the electrodes in a generally fixed relation with respect to one another within said generally coplanar relationship, applying a slight flexible retaining pressure along the infant's sides generally between the lower edge portion of the rib cage and the armpits and across the infant's chest above the belly area to the aforesaid flexible retention of the electrodes to maintain the aforesaid skin engagement between the infant's back and the electrodes, and utilizing the skin engagement of the electrodes with the infant's back to establish a circuit for the electrical signals thus captured to a monitoring device. The monitoring device may be of any well-known construction capable of providing an indication of the infant's respiration and/or ECG based upon the electrical signals conveyed thereto through the established circuit.

Normally, the skin engagement is effected with the electrodes in a dry condition, however, it is within the contemplation of the present invention to place a small quantity of water (e.g., a drop or a few drops) upon the skin engaging surface of the electrodes before positioning the infant's back into skin engagement therewith. The water is preferably sterilized water to eliminate any possibility of irritation.

With the four electrode assembly shown, it will be understood that one of the electrodes, such as the electrode 22, constitutes the ground electrode. Normally, only two of the other three electrodes, in addition to the ground electrode, would be operable at any one time. The provision of the four electrodes enables the operator to achieve a conventional Lead I reading, as by utilizing electrodes 16 and 18 along with the ground electrode 22; a conventional Lead II reading, as by utilizing electrode 18 and electrode 20 along with the ground electrode 22; or conventional Lead III reading, as by utilizing electrodes 16 and 20 along with the ground 22.

It will be understood that the electrical signals which are thus captured by the use of the present electrode assembly 10 are suitable for either respiratory monitoring or cardiac monitoring or both. In accordance with known practices, the signals captured which are suitable for respiratory monitoring are the variations in the electrical resistance of the infant's thorax due to breathing, while the signals captured which are suitable for ECG monitoring are the electrical signals which trigger the heart beat. Circuitry suitable to provide appropriate output monitoring signals corresponding to each type of captured signal is also well-known.

The provision of the head receiving and terminal carrying pad portion 32 is preferred since it serves to present the terminals which are connected with the leads of the monitoring instrument in the controlled manner which is spaced from the infant. With this arrangement, X rays can be taken with the assembly 10 attached to the infant since the electrical wires of the leads of the instrument are maintained out of contact with the infant and there are no metallic materials embodied in the assembly 10 which would obstruct an X ray picture when taken with the device applied to the infant.

It will be understood that while the provision of the pad portion 32 is preferred, it is within the contemplation of the present invention to eliminate the portion 32 from the pad. A modification of this type is illustrated in FIGS. 5 and 6. Since the embodiment of FIGS. 5 and 6 varies from that of the preferred embodiment of FIGS. 1-4 solely in the elimination of the pad portion 32 and the specific configuration of the terminal means, corresponding elements of the assembly illustrated in FIGS. 5 and 6 are designated by corresponding prime numerals which do not require further detailed description. Suffice it to say that the electrode assembly 10' includes terminal means in which the electrodes 16', 18', 20' and 22' are provided with integral triangular portions or strips 58, 60, 62 and 64 which extend in affixed surface-to-surface engagement with the associated converging side pad portions 24. These terminal electrode portions have small snap fastener elements 66, 68, 70 and 72 respectively fixed thereto. As best shown in FIG. 6, the pad adjacent each snap fastener element is preferably apertured, as indicated at 74, to receive the lead connection therein. In this embodiment the exterior surface portion of each snap fastener element on the electrode side of the pad is provided with electrical insulation in order to prevent metal-to-infant skin contact. Such insulation can be provided in any suitable manner, such as making the snap fastener portions of a non-metallic material, by applying insulating tape thereto, or by plastic coating the snap fastener portions, as indicated in FIG. 6.

It thus will be seen that the objects of this invention have been fully and effectively accomplished. It will be realized, however, that the foregoing preferred specific embodiments have been shown and described for the purpose of illustrating the functional and structural principles of this invention and are subject to change without departure from such principles. Therefore, this invention includes all modifications encompassed within the spirit and scope of the following claims.

Claims

What is claimed is

1. A disposable electrode assembly for use in respiratory and/or cardiac monitoring of an infant comprising a sheet-like pad of soft pliable non-conductive material having an infant back receiving area of approximately 41/2 inches by 41/2 inches, a plurality of separate flexible sheet form electrodes extending substantially throughout the back receiving area of said pad so as to be intimately contacted by the skin of an infant's back received on said back receiving pad area, said pad having portions converging outwardly from opposite sides of said back receiving area for extending generally beneath the armpits and along the lower edge of the rib cage of an infant when said converging side portions are held to the sides of the infant's torso, strap means of soft pliable material for extending across the chest cage of the infant centrally between said converging side portions, means for releasably adjustably securing said strap means in the aforesaid extending relation to thereby hold said converging side portions against the sides of the infant's torso so that said flexible sheet-form electrodes are maintained in skin contact with the infant's back without relative surface-to-surface movement therebetween when the infant moves to either side from a normal back supported position or is moved into a front supported position, and terminal means for effecting a detachable electrical connection of said electrodes with the leads of a monitoring instrument.

2. A disposable electrode assembly as defined in claim 1 wherein said electrodes are affixed in surface-to-surface engagement with said pad and are formed of conductive particle impregnated plastic material.

3. A disposable electrode assembly as defined in claim 2 wherein said conductive particle impregnated plastic material comprises carbon powder impregnated in polyvinyl chloride.

4. A disposable electrode assembly as defined in claim 3 wherein said pad is formed of a sheet of very fine open pore foamed plastic material.

5. A disposable electrode assembly as defined in claim 4 wherein said foamed plastic material is polyurethane.

6. A disposable electrode assembly as defined in claim 4 wherein said strap means includes an integral strap portion extending centrally outwardly from each converging pad portion.

7. A disposable electrode assembly as defined in claim 6 wherein said releasable adjustable strap securing means comprises cooperating Velcro fastening strips on each strap portion.

8. A disposable electrode assembly as defined in claim 4 wherein said terminal means includes an integral portion on each electrode extending outwardly from said back receiving area in surface-to-surface engagement with said pad and a male snap fastener element of conductive material secured to each integral electrode portion.

9. A disposable electrode assembly as defined in claim 4 wherein said plurality of electrodes include four electrodes arranged in quadrant fashion within said back receiving area.

10. A disposable electrode assembly as defined in claim 9 wherein said pad includes an integral infant head and terminal carrying portion extending from said back receiving area in a direction toward and beyond the head of an infant whose back is received on said back receiving portion, said terminal means including an integral strip extending from the periphery of each electrode through said pad and in surface-to-surface engagement with the exterior surface thereof to a position adjacent the free end of said integral infant head receiving and terminal carrying pad portion and a male snap fastener element of conductive material secured between the end of each integral electrode strip and the associated pad free end portion.

11. A disposable electrode assembly as defined in claim 9 wherein said terminal means includes an integral portion on each electrode extending along the associated converging side portion of said pad and a male snap fastener element of conductive material secured to each integral electrode portion.

12. A method of monitoring the respiration and/or ECG of an infant which comprises the steps of positioning the infant's back into skin engagement with a plurality of generally coplanar flexible sheet form electrodes substantially throughout the back area of the infant while flexibly retaining the electrodes in a generally fixed relation with respect to one another within said generally coplanar relationship, applying a slight flexible retaining pressure along the infant's sides generally between the lower edge portion of the rib cage and the armpits and across the infant's chest above the belly area to the aforesaid flexible retention of the electrodes to maintain the aforesaid skin engagement between the infant's back and the electrodes, and utilizing the skin engagement of the electrodes with the infant's back to establish a circuit for the change in resistance in the infant's thorax and/or the electrical activity of the infant's heart to a monitoring device capable of providing an indication of the infant's respiration and/or ECG based upon the electrical signals conveyed thereto through the established circuit.

13. A method as defined in claim 12 wherein a small quantity of water is placed upon the skin engaging surface of the electrodes before positioning the infant's back into skin engagement therewith.