Implantable Bio-data Monitoring Method And Apparatus

Abstract

A system for monitoring a condition of a body function or organ or device implanted within a body includes a sensor or transducer responsive to that condition or a change in it connected to a signal means capable of producing an audible, visual or heat signal of variable intensity indication to control the energization of the signal means from a source of energy. The sensor and signal means and the source of energy may be implanted within the body with the signal means sufficiently near the surface of the skin so that its energized state may be detected from outside the body.

Description

BACKGROUND OF THE INVENTION

This invention relates to the art of obtaining information about internal conditions in bodies. More specifically, it relates to devices which can be implanted within bodies and provide extracorporeal indications of internal conditions.

Obtaining information from inside the body without opening the skin has been a problem since the beginning of the art of healing. Historically, medical practitioners have been able to learn much from such factors as patient's skin color, his temperatures, respiration and heart beat. They could look into his mouth, ears and eyes. The normal or abnormal fluids or solids given up by the body could be examined. In addition, the body could be probed with the hands and fingers.

Beyond this many clinical and laboratory instruments have aided greatly in the diagnosis and treatment of many diseases and conditions. Such instruments range from the simple stethescope, thermometer, etc. to complex machines for inducing or measuring ionizing radiation, ultrasonic pulses and electrical currents. Most of these instruments and methods have been extracorporeal, and in many cases are not always capable of obtaining all the data required. In some cases, data is obtained by a surgical exploration and direct visual examination. In other cases, instruments are temporarily induced into the body to obtain samples of blood or other matter or to make related measurements.

When the need for the data is on a one time only basis or is only very rarely required, the above type of data acquisition technique may be adequate. However, when the need for obtaining data is permanent or very frequent, many of the procedures would become intolerable to the patient and/or to the doctor.

Work has been done to perfect means whereby wires and tubes can be maintained permanently through the skin. However, the use of this so-called percutaneous "hardwire" telemetry to sensors within the body carries too high a risk of infection for routine use. In addition, there is often the problem, particularly encountered in connection with laboratory animals, of having the wires protruding through the skin torn out.

Some work has been done in implanting various kinds of sensing devices within the body and deriving information therefrom. However, these have been relatively complicated systems for use in laboratories and very frequently are intended to be implanting only for short periods of time. Many conditions and diseases which are to be monitored and cared for adequately or to warn a patient or a physician exist where a more or less permanent implant of a telemetering or communications system is desirable. The criteria for such systems would include that there be a suitable power source, that it be of small size and weight, that it be reliable and capable of surviving within the body. Other criteria would require such means to have a long life, provide a reliable signal and that no damage be done to the body. Further, it would be desirable that such implants be economical to assure the widest possible use and that it not interfere or that it interfere as little as possible with a patient's conduct of his normal life.

Reference is made herein to the device described in my co-pending application Ser. No. 741,117, filed June 27, 1968, now issued as U.S. Pat. 3,527,220 in which a signaling device is shown in conjunction with an implantable pump for the administration of drugs and the like and actuated by means external to the body.

Therefore, in accordance with this invention, there is provided a signal system capable of implantation within a body which is small in size, reliable in operation and capable of long survival.

It is an object of this invention to provide a method for indicating a condition inside a body.

It is another object of this invention to provide a signaling system implantable within a body which may be arranged to provide readily ascertainable indications of a condition or change in condition within a body.

It is a further object of this invention to provide a signaling system implantable within a body which may be arranged to provide indications of a series of changes in an internal condition.

It is still a further object of this invention to provide a signaling system implantable within a body which is capable of providing information about the condition of a body function or organ or of another device implanted within the body.

These and other objects of the invention are achieved by providing a signaling system including a sensor responsive to an internal condition and connected to a signaling means located near the surface of the body so that an indication of a change in condition produced by the signaling means will be transmitted through the skin and sensed externally and which also includes a source of energy which may be either implanted or external to the body.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention itself is set forth in the claims forming a part of this application. For purposes of illustration various embodiments of the invention are described and shown in the drawings in which:

FIG. 1 is a block diagram illustration of an implantable signaling system in accordance with the invention;

FIG. 2 is a block diagram illustration of another embodiment of a signaling system in accordance with the invention;

FIG. 3 is a block diagram illustration of still another embodiment of a signaling system in accordance with the invention;

FIG. 4 is a block diagram illustration of one form of the embodiment of the invention illustrated in FIG. 1;

FIG. 5 is a block diagram illustration of another embodiment of the invention;

FIG. 6 is a block diagram illustration of another form of the embodiment of the invention illustrated in FIG. 1;

FIG. 7 is a block diagram illustration of another embodiment of the invention illustrated in FIG. 1;

FIG. 8 is a block diagram illustration of another embodiment of the invention;

FIG. 9 is a schematic illustration of the electrical circuit of an embodiment of the invention;

FIG. 10 is a schematic illustration of the electrical circuit of another embodiment of the invention; and

FIG. 11 is a schematic illustration of the electrical circuit of still another embodiment of the invention.

An illustration of the general organization of a signaling system in accordance with the invention is shown in FIG. 1. In this figure, a signaling means 2 capable of producing an audible, visual or heat signal is implanted in the body, preferably at a point just below the surface of the skin 4. The signal means is selected to produce a signal of variable intensity. By "variable intensity" is meant a condition of the signal means which ranges from the condition of being completely off, i.e., not energized to the condition where it is on or producing signals in response to the output of the sensor. Intended to be encompassed within this meaning is the situation where the signal is going from off to on repeatedly within a time of interval so that information about a condition may be ascertained from the number of times it is on or the interval between on times. Thus, if a visual signal is used, the frequency at which light appears and is detected may be a source of information about a condition.

The precise location is not critical but the factors to be considered in locating this device include the ability of the skin and other body tissue to transmit the signal. Therefore, in order to achieve optimum output from the signaling means, it is desirable to locate it as close to the surface of the skin as possible.

If the signal means selected develops a visual or light indication, then such light emitting means may take the form of a so-called light-emitting diode which is currently on the market. Such diodes are made of gallium arsenide phosphide. These diodes require a forward bias of about 11/2to 2 volts. They are less than a tenth of an inch in diameter and have an overall length of about an eighth of an inch. They are rated at 50 feet-Lamberts brightness at a forward bias of 1.65 volts and a forward current rating of 50 milliamperes. It has been found that the region of peak transparency of the skin is in the 750 to 1,250 millimicron range. This region is just above the visible spectrum in the infrared range so that the particular diode suggested represents a good compromise if its wavelength is in the 600 to 700 millimicron range; that is, near the range of peak skin transparency. When this device is used, rich red color appears on the surface of the skin which the eye may easily detect.

It may be desirable to use light-emitting diodes producing more light in the visible range, as, for instance, when a series of such light signals are implanted to provide information about different levels of changing or changeable conditions inside the body. Devices for this purpose that are presently available are diodes capable of emitting green and amber lights.

If an audible signal producing device is desired, a vibrating crystal or ceramic element energized in the audio range by an exiting coil may be used and, when energized, will produce a signal which may be detected by microphones external to the body.

A suitable heat signal may be provided by the use of an appropriate electric heating element, the output of which may be measured by a temperature sensitive device external to the body. When such an element is used, it should be operated at temperatures which will avoid discomfort to the host body and damage to surrounding tissue.

A signaling system in addition to the signal 2 would also include a source of energy 6 and sensing means such as a sensor or transducer 8. The source of energy 6 may be itself implanted within the body or may include elements both implanted and external to the body. The implantable sensor 8 may take any number of forms depending upon the condition it is decided to monitor. Generally speaking, the thing being monitored may be a body organ or fluid or may be some other device implanted within the body such as an artificial organ, a pump or a valve. Conse-quently, the sensor may be a device responsive to changes in pressure, temperature, volume, flow rate, conductivity, motion, position or the condition of an electrical circuit. When connected to the signaling means 2 in the series arrangement shown in FIG. 1, this sensor will control the flow of electrical energy to the signaling means causing it to be energized or de-energized or energized at various levels.

By way of specific illustration the sensor 8 can take the form of a pressure sensitive device placed in the outlet of an implanted pump operating within the body. The sensor could be responsive to a decrease or an increase in the pressure of the fluid being pumped to provide a signal which may be ascertained externally so that corrective action can be taken if necessary. Alternatively, the sensor could be a switch mounted on the rotor of the pump and operated to a closed position if the pump should cease operation to provide the desired indication. In still another application, the sensor could be a pressure sensitive device measuring blood pressure and providing an indication if the pressure either falls or rises above predetermined values.

When implanted, all portions of the system which are implanted should include two forms of protection, one designated by the number 50 to protect the system itself from the harmful action of any body fluids and to protect the body by electrically insulating the system from the body and the other to insure that there is no harmful interaction with the materials from which the elements are formed with body tissue or fluids. A suitable outer coating for the elements of the system and any connecting wires may be made of a silicon rubber, such as "Silastic," manufactured by the Dow Corning Company. Where this material is applied over the signaling means 2 it should be in a transparent form in the event a visual signal is used in order not to impair the effectiveness of the signaling means. A suitable inner coating may be "Dacron" or "Teflon" or an epoxy which have been found to be compatible with body tissues and fluids. If such materials are to be in contact with the blood or the blood stream, they should be non-thrombogenic.

Appropriate anchoring devices such as wings or tabs of a fibrous or net like material can be molded on the elements of the system. It has been found that body tissue will grow through these anchoring devices to secure an implanted device in position.

It is contemplated that the signal produced may be used in either an analogue or digital fashion. That is, it can be used to derive representations of a series of changes in a condition or to derive a signal which merely indicates that the condition is in one state or the other. FIG. 2 illustrates an embodiment of an analogue device wherein three signal means, 2, 2' and 2 ", are connected in parallel between the source 6 and the sensor 8. Thus, if the sensor 8 is a temperature sensitive resistor, such as a thermistor, the signal means 2, 2' and 2" can be connected in the circuit to be energized at various levels of output from the sensor 8 and thus provide a more proportional or analogue signal representative of the change in condition. If the signal means selected produce their signals at the same level of applied voltage, they may be arranged to respond to various changes in the condition being sensed by connecting weighted resistors intermediate the means and the sensor. The resistor having a value of R may be connected between signal means 2" and the sensor 8 while resistors having values of R/2 and R/4 may be connected between the sensor and the signal means 2' and 2 respectively. Alternatively, signal means producing signals at different voltage levels may be used.

FIG. 3 is an illustration of another embodiment of the analogue form of the invention. In this embodiment a single signal means 2 is used in cooperation with a signal evaluator 10 external to the body. Thus, if the signal is an audible signal, the signal evaluator may be constituted by a suitable audio pickup, such as a microphone, the output of which is supplied to an appropriate indicating meter having a calibrated scale. Likewise, if the signal means 2 produces a visual or heat signal, the signal evaluator 10 may constitute a light sensitive element, the output of which is supplied to an appropriate calibrated instrument.

In FIG. 4 the embodiment illustrated is one in which the source of energy is not implanted completely within the body, but rather comprises a first element, namely, an energy transmitter 12 external to the body and a second element, an energy receiver 14, implanted within the body and interconnected to the signal means 2,. When this arrangement is used, it would not be necessary to implant a source of energy such as a battery within the body and have the problem of opening up the body to implant new batteries or finding ways to recharge the battery within the body.

FIG. 6 illustrates one form the embodiment of FIG. 4 may take. In this form, the energy transmitter 12 includes a signal generator 16 producing electrical signals of radio frequency which are supplied to a transmitting coil 18 and received by the receiver 14 inside the body.

FIG. 7 illustrates another form of this embodiment of the invention. In this figure, the energy transmitter constitutes a light source 20 external to the body while the energy receiver comprises a plurality of photovoltaic cells 22. When the light source 20 is energized, a voltage produced by the photovoltaic cells 22 will be available to energize the signal means 2. Using this arrangement and the form illustrated in FIGS. 5 and 6, the implanted signaling system can be interrogated as desired by bringing the external energy source in proximity to the implanted energy receiver to provide energy for the excitation of the signal means if the sensor 8 has responded to the presence or absence of the condition, as determined by its design.

If it is desired to implant a battery energy source within the body but at the same time it is desired to conserve the battery so as to reduce the frequency of its replacement or recharging, the embodiment shown in FIG. 5 has a particular utility. In this form, a battery 24 and normally opened switch 26 are implanted and connected in the series circuit with the implantable sensor 8 and signal means 2. The switch may include a magnetic element responsive to the presence of a magnetic field produced by a switch actuator 28 external to the body. Using this form of the invention when it is desired to sample the condition, the switch actuator 28 may be brought in proximity to the switch 26 actuating or closing the circuit and permitting the output of the sensor 8 to control the energization of the signal means 2.

Under certain circumstances it may be desirable to obtain a relatively high degree of precision in monitoring the condition selected. For this purpose the embodiment of FIG. 8 may be used. Included in this embodiment is a switch 29 capable of closing a circuit to the sensor 8, or to a calibrated standard 30, or shorting both of these elements and closing a circuit directly to the signal means 2. As with the embodiment of FIG. 5, the implantable switch 29 may be actuated by a means external to the body so as to selectively connect the sensor 8 to the calibrated standard in circuit with the signal means 2 and by this means provide a reference to which the output of the signal means in response to the condition of the sensor may be compared. By operating the switch 29 to short the sensor 8 and standard 30 the signal means will be connected directly to the source of energy. In this way a greater resolution of measurement may be obtained. Thus, when directly connected to the source, the signal means will be at its highest level of intensity, and when connected to the sensor, it will be at an intermediate value, and when connected to the standard, it will be at a lower value. Additionally, this arrangement affords the opportunity to test the elements in the circuit. If the signal means does not function at all, the switch may be operated to its various positions to sequentially connect the signal means to the sensor, standard or directly to the source as an aid in identifying a particular component which may have failed.

It should be understood that various combinations of the apparatus illustrated in these figures may be made. Thus, a source of energy may be internal or external. If internal, it may include a battery, fuel cell or a radioactive isotope fueled source from which electrical energy may be derived by heat or direct conversion. If external, it may comprise an inductive or radiative generator, means coupling energy into the circuit or a source of light. Any one of these may be combined with any type of sensor and with any type of signal means using audible, visual or heat producing indications or be of the binary or analogue variety. Alternatively, a mechanical source of energy such as a wound spring can be provided to actuate an audible signal device.

FIGS. 9, 10 and 11 illustrate schematically various embodiments of the invention. In FIG. 9, the source of energy includes a rotatable magnet 32 selected to have a strength such that when it is rotated in proximity to the coil 34 a current will flow in the coil. The sensor in this form comprises a normally open switch 36 and the signal means is a light-emitting diode 38. The switch 36 may be a pressure closable switch or may be closed in response to the rotation or lack of it of a pump rotor or the like and when closed will complete a circuit through the diode 37 to the diode 38. The diode, when sufficient forward voltage is applied thereacross, will emit light in the visible or near infrared ranges.

In FIG. 10, the energy source is a transformer 40 wherein the primary 42 is external to the body while the secondary is implanted within the body. The circuit also may include a protective diode 46 to prevent application of reverse voltage of the light-emitting diode 38.

The circuit of FIG. 11 is a series circuit including a battery 47 and a normally opened switch 48. The switch 48 may be of the magnetically operated type and closed by bringing a magnet to the vicinity of the implanted circuit.

While various embodiments of the invention have been described and illustrated, these are intended only as examples.

Claims

What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. A method of indicating a condition inside a body comprising the steps of: implanting sensing means sensitive to such a condition; implanting light emitting means inside the body at a distance whereby said light emitting means, when energized, will be detectable through the skin of the body; interconnecting said sensing means and said light emitting means; providing a source of energy for said light emitting means so that said light emitting means will be energized in response to the change in the condition in the body sensed by said sensing means; sensing the condition within the body with said sensing means; emitting light from said light emitting means through the skin of the body when said light emitting means is energized in response to a change in the condition in the body sensed by said sensing means; and detecting from outside the body the light emitted from said light emitting means.

2. The method of claim 1 including the step of implanting switch means in the body and interconnecting said switch means between said sensing means and said light emitting means and the further step of actuating said switch means to permit energization of said light emitting means.

3. The method of claim 1 including the step of implanting said source of energy for said light emitting means in the body.

4. The method of claim 1 wherein said step of providing a source of energy comprises implanting an energy receiver in the body and the steps of bringing an energy transmitter external to the body in proximity to said energy receiver and activating said energy transmitter to cause energy to be transmitted to said energy receiver.

5. The method of claim 1 including the step of implanting switch means in the body and interconnecting said switch means between said sensing means and said light emitting means and the further steps of providing external actuating means and actuating said switch means by said actuating means when it is desired to sample the condition within the body.

6. The method of claim 1 including the step of implanting at least one additional light emitting means in the body and interconnecting said additional light emitting means to said sensing means to provide at least one additional indication of changes in the condition within the body.

7. A bio-data transmission system having a portion thereof implantable within a body comprising means adapted to be implanted within the body for emitting light signals in response to different sensed conditions within the body, sensing means adapted to be implanted within the body and connected in circuit with said light emitting signal means to control the level and interval of excitation of said light emitting signal means, a source of energy having at least one portion thereof adapted to be implanted within the body and operatively connected to said signal means and said sensor, and protective coating means coating said sensing means, said signal means and the portion of said source of energy that is adapted to be implanted within the body to protect said signal means, said sensing means and said portion of said energy source from harmful action of the body.

8. The bio-data transmission system of claim 7 wherein said light emitting signal means comprises means for providing an indication of a discrete change in a condition within the body.

9. The bio-data transmission system of claim 7 including a light signal receiver locatable outside the body responsive to the light emitted outside the body from said light emitting signal means.

10. The bio-data transmission system of claim 7 wherein said light emitting signal means comprises means for providing an indication of change throughout a range of a condition in the body.

11. The bio-data transmission system of claim 10 wherein said light emitting signal means comprises a plurality of signal devices connected in parallel with the output of said sensor.

12. The bio-data transmission system of claim 11 wherein said light emitting signal means comprises light emitting elements capable of emitting light of different colors.

13. The bio-data transmission system of claim 7 wherein said source of energy comprises an energy receiver adapted to be implanted within the body and an energy transmitter capable of being located exterior to the body to transmit energy to said energy receiver.

14. The bio-data transmission system of claim 13 wherein said energy receiver comprises a receiving coil and said energy transmitter comprises a radio frequency signal generator and a transmitting coil operatively connected to said radio frequency signal generator.

15. The bio-data transmission system of claim 13 wherein said energy transmitter comprises a light source and said energy receiver comprises at least one photovoltaic cell adapted to be implanted within the body.

16. The bio-data transmission system of claim 7 wherein said source of energy comprises a battery adapted to be implanted within the body.

17. The bio-data transmission system of claim 16 including a switch adapted to be implanted within the body connected in electrical circuit with said light emitting signal means, said sensing means and said battery.

18. The bio-data transmission system of claim 7 including a calibrated standard adapted to be implanted within the body and a switch adapted to be implanted within the body and to alternatively connecting either said calibrated standard or said sensing means to said light emitting means.