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Description  |
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FIELD OF THE INVENTION
This invention relates to the automatic maintenance of glucose level in a
diabetic within predetermined limits and, more particularly, to control
apparatus for monitoring the body's sugar level during a given period, and
if need be, for injecting suitable doses of insulin to suppress any excess
amount of glucose -- all without any involvement by the diabetic.
BACKGROUND OF THE INVENTION
As is well known and understood, throughout the history of diabetic
control, the classic approach has been to provide insulin injections on a
regular timed basis. In particular, the control is such that the level of
glucose in the blood fluctuates from a low level, just after an insulin
injection, to a very high level, just before a second injection is made.
Strict time schedules are observed for the necessary injections, but even
when the schedules are strictly adhered to, the complaints are legion as
to the need to follow this type of control regimen.
SUMMARY OF THE INVENTION
As will become clear hereinafter, the control apparatus of the present
invention automatically provides the necessary insulin injection without
the need for any involvement by the diabetic. As will be seen, control
apparatus operates internally of the body to automatically react urine
from the kidneys with Benedict's Solution, and to employ a light emitter
-- photocell arrangement to indicate the glucose level in accordance with
the amount of light passing the mixture. In response to the signal
developed by the photocell, a valve is opened to inject a measured amount
of insulin into a major artery, so as to maintain the level of glucose
substantially constant. As will be described, such measurement and control
is had whenever the person urinates, and because of the frequencies
thereof and the relative time lapses therebetween, the apparatus of the
invention is able to monitor the glucose level several times a day,
thereby controlling it to within a small range. Both the Benedict's
Solution and the insulin are stored in reservoirs which are surgically
implanted within the diabetic, and with the pH level of the insulin raised
so as to extend its stability over longer periods of time. Both reservoirs
are situated within the body in a position so that they can be recharged
for reuse.
In accordance with the operation of the invention, various stages
contribute to the overall regulation of glucose level. In order of
operation, the sequence employs: (1) an activation stage, wherein the
apparatus is triggered into action; (2) a filter stage, wherein materials
capable of undesirably influencing a determination of glucose level are
filtered out; (3) the Benedict's Solution injecting stage, wherein the
solution is added to the urine for the monitoring of glucose; (4) the
testing stage, wherein the light passing the mixture and impinging the
photocell is converted to an electronic control signal to regulate the
amount of insulin to be injected; and (5) the insulin injection stage,
wherein the amount of insulin injected into the bloodstream is regulated.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other features of the present invention will be more clearly
understood from a consideration of the following description taken in
connection with the accompanying drawings in which:
FIG. 1 is a flowchart illustrating the sequence of events in the operation
of the control apparatus;
FIG. 2 illustrates the activation stage;
FIG. 3 shows a combined filter stage, a Benedict's Solution injecting stage
and a test system stage according to the invention;
FIG. 4 illustrates one arrangement for the testing stage electronic control
system; and
FIG. 5 shows the insulin injection stage.
DETAILED DESCRIPTION OF THE DRAWINGS
Before considering a detailed description of the various stages which
comprise the control apparatus of the invention, it will first be
understood that the apparatus to be described operates with active
mechanical controls, the process beginning with the initial operation via
the activation stage 10 of FIG. 1. Here the control apparatus includes a
small microswitch which is momentarily activated by the passage of urine
-- for example, through the ureter tube located after the bladder. The
filter stage 12, however, is located in the ureter tube before the bladder
and serves to separate out all material present in the urine which is
larger than the glucose complexes. The tripping of the switch brings into
operation the Benedict's Solution injection stage 14, where the filtrate
is mixed with Benedict's Solution, the effect being to darken the glucose
complexes present. The treated solution then passes to the testing stage
16, wherein a photocell is opposed to a light emitting source, in
accordance with which the signal generated indicates the extent of glucose
present and the amount of insulin to be injected as a control, as a
function of the light which passes. That is, as the glucose level rises
and falls, the transparency of the mixture decreases and increases,
respectively, thereby controlling the light passing through and impinging
onto the photocell -- with the constraints on the electronic circuitry
included within the testing stage 16 being such that should the photocell
detect a minimum amount of light, a control signal would be developed to
direct the injection of a maximum dosage of insulin, and vice versa. Once
the amount of glucose present has thus been determined, the control signal
representative thereof is coupled to the insulin injection stage 18 so as
to regulate the injection of insulin into a major artery. Here, a
microvalve is operated by the signal control to permit insulin to flow
into the artery for a predetermined time interval, with the entire
operation being then terminated by the closing of this microvalve after
the insulin has thus been injected. This terminates the operation, until
the microswitch in the activation stage 10 is triggered again by the flow
of urine, in making a further glucose measurement.
Referring now more particularly to the activation stage of FIG. 2, it will
be understood that the function of the activation stage is to initiate the
sequence of events which ultimately results in the injection of insulin
into the bloodstream to supress high levels of glucose. Due to the nature
of the urine fluid to be tested, and because of the fact that urination is
what activates the entire mechanism, the activation station is placed in
an area where it is directly exposed to periodic urinary flow -- the
urinary tract most suitable being directly after the bladder, in the
ureter. The activation stage 10 is encompassed within an elastic material
22, chosen with a mind towards minimizing the possibility of rejection by
the body -- and a material such as Dacron might be used. By using an
elastic material, the walls of the stage 10 can move within the areas of
the body organs, whereas using a non-rejection type material permits it to
be implanted in the area where the section of the ureter will be removed.
A pair of electrical contacts 24, 26 are incorporated at the sides of the
implanted stage 10, being separated by a gap 28, encased in order to
prevent against the urine acting as an electrolyte to form an electrical
connection between the contacts 24, 26. A pair of cable connections 30, 32
couple to the contacts 24, 26 to complete an electrical circuit when the
contacts are closed under the flow of urine. More particularly, included
within the implanted activation stage 10 is an inverted cup body 34
arranged to catch the flow of urine entering the activation stage from the
direction indicated by the arrow I, and exiting in the direction indicated
by the arrow O.sub.1. In response to the pressure force exerted on the cup
by the urinary flow, the cup 34 will pivot so as to force the contact 24
across the gap 28 to connect to the contact 26, and thus close the
circuit. In order to lessen any strain upon the contact 24, the cup 34
could be perforated to allow some urine to pass through in the direction
of the arrow O.sub.1, and thereby reduce much of the force that would
otherwise be exerted upon the contact 24. Also, a large cross-sectional
area of the cup 34 is arranged to force against the contact 24, so as to
maintain integrity of operation over the years of expected use of the
invention. Additionally, as a design feature, the cable connections 30, 32
are made to the contacts 24, 26 through hermetic openings so as to reduce
any urinary fluid from penetrating outside the vessel walls 22. To reduce
the possibility of the urine from corroding the insulation at the cable
connections 30, 32, some form of resistant plastic (e.g. polyurethane)
might be employed. In one embodiment of the invention, the distance 36 in
FIG. 2 was fabricated to be approximately 1 inch in length, the distance
38 was fabricated to be approximately 0.5 inches, the dimension 40 was
selected to be 0.375 inches and the dimension 42 was selected as 0.09375
inches.
Referring to the filter stage 12 of FIG. 3, it will be appreciated that the
function of the filter stage is to isolate a usable portion of urine for
testing by separating out urine components larger in size than the glucose
complexes. From its output, the filtrate moves through the activation
stage 10 into the Benedict's Solution stage 14 and the testing stage 16
where the actual glucose measurement takes place. In FIG. 3, therefore, it
will be seen that the housing 44, -- again constructed of an elastic
composition (and of Dacron or similar material so as to prevent rejection
by the body) -- encompasses a series of cup collectors 46, 48 arranged in
an aerodynamic cone configuration 29 to capture the urine as it flows in
the direction indicated by the arrow I.sub.2 towards the direction
indicated by the arrow O.sub.2. From the cup collectors 46, 48, the urine
flows through a plurality of filters 50, 52, 54, each of increasing
fineness, and suspended by a plurality of supports 56, 58 provided as an
integral portion of the interior unit of the housing 44.
It is important to prolong the life of the filter stage 12 that it be
located in an area where the urine flow is constant, rather than as where
the flow is periodic or under pressure in nature -- for example, as the
urine flow would be if the filter stage were positioned in the ureter
located directly after the bladder. Thus, the location of the filter stage
12, according to the invention, should be before the bladder, but after
the kidney, along the vessel known as the ureter before the bladder
penetration. (Then, it is only the filtered urine which operates the
activation stage 10.) It will also be noted that stress problems are not
as acute with the filter stage 12 as with the activation stage 10 because
the filter stage 12 has no moving parts subject to failure.
Also shown in FIG. 3 is the Benedict's Solution injecting stage 14. As
shown, there is included a reservoir 60 for storing the Benedict's
Solution until required by the system after the activation stage 10 has
engaged the entire apparatus. At the lower portion of the reservoir 60 is
a one-way valve 62, which is normally closed to the flow of solution from
the reservoir 60, but which, however, is opened for a short time interval
(less than one second) by the operation of a small magnetic control 63 to
permit the solution to mix with the filtrate for the subsequent testing to
occur. Reference numeral 64 identifies an elastic tube which leads from
reservoir 60 to the surface of the skin 68 through which the supply of
Benedict's Solution is replaced at regular intervals. At the surface of
the skin, in the area indicated by reference notation 66, will be seen the
tube 64 as it reaches the skin surface 68. In accordance with the
invention, the location on the surface of the skin 68 above the point
where the tube 64 extends is marked with a dye visible under ultraviolet
light to indicate the location for recharging reservoir 60 through
injection of fresh solution. A second one-way valve 70 is also included,
through which a hypodermic administering agent, for example, may penetrate
in injecting fresh solution into the reservoir 60 in charging the device,
and which prevents any fluid from flowing back into the tube 64.
In one design of the invention, the end of the tube 64 extending towards
the surface of the skin 68 is widened at its end so as to fit flush
against the skin interior to enable suturing to the interior of the skin
wall. The reservoir 60 is constructed of elastic material so as to permit
an outward movement during its filling and an inward contraction during
the time the solution is added to the filtrate in serving to force the
solution through the oneway valve 62. For ease of construction, the
Benedict's Solution injecting stage 14 could be located at the same
location as the filter stage 12 -- as shown, at the ureter before the
bladder penetration. As with the activation stage 10 and the filter stage
12, the material of which the Benedict's Solution reservoir 60 is
fabricated is selected of a material which will be accepted by the body,
and not rejected by it.
The testing stage 16 of the control apparatus incorporates a test system
(76 in FIG. 3) and the electronic circuitry (FIG. 4) which directs the
entire operation, from activating the apparatus to injecting the insulin.
Referring to FIG. 3, the test system 76 incorporates two reservoirs 80, 82
subsequent to the Benedict's Solution injecting stage 14, into which the
treated filtrate is forced to flow through constructed regions 84 so as to
facilitate the identification of any glucose present. Each of these
reservoirs 80, 82 have associated with it a combination light-emitting
diode and photocell arrangement, in accordance with the operation of
which, the light from the diode diffuses through the treated filtrate to
be incident upon the photocell. As will be readily understood, the
intensity of the light impinging the photocell is dependent upon the color
of the mixture -- which in turn is related to the concentration of the
glucose level. In particular, as Benedict's Solution changes color in the
presence of a glucose complex, the degree of color change depends upon the
relative concentration of that glucose complex in the urine being
analyzed. In particular, the signal level developed by the photocell as
the emitted light passes the admixture would be a maximum in the absence
of glucose and would progressively decrease as the amount of glucose
present becomes greater.
The electronic circuitry of FIG. 4, in part, translates the molar
concentration of glucose present into the amount of insulin needed to be
injected into the blood. In its operation, the electronic circuitry serves
to direct the insertion of a predetermined amount of insulin for a given
signal level from the photocell, and directs that the amount of insulin
injected be accordingly reduced as the signal level from the photocell
increases.
As will be understood, upon the activation of the system, when the switch
contacts 24, 26 of FIG. 2 are closed, there is a resulting closure of the
switch S (FIG. 4) to energize the multivibrators 90, 92. This provides an
output control signal for the Benedict's Solution injecting stage magnet
63 at terminal 94 of some one second duration and a like output control
signal at terminal 96 to energize the light emitting diode. During the
time the light emitting diode is energized, the signal from the photocell
P couples through an operational amplifier 98 in providing the output
control signal at terminal 100 for controlling a valve opening at the
insulin injecting stage for a time determined by the resistance setting of
potentiometer 102, which is individually set to satisfy the diabetic needs
of the individual being served. It additionally goes without saying that
the duration of the output signal at terminal 100 will be proportional to
the density of glucose in the urine such that the combination of the
glucose complex present and the resistance setting of potentiometer 102
will regulate the amount of insulin injected as befits the individual's
needs at any instant of time.
In one construction of the control apparatus, the signal developed at
terminal 94 is employed to not only activate the light emitting diode, but
to de-activate the activation stage 10 of FIG. 2 (by opening the closed
circuit formed between cable connections 30, 32) so as to make the
activation stage operate as a momentary switch. When the insulin injection
is completed, the apparatus becomes recycled to its initial, quiescent
condition, until the activation stage is once again set in motion by
urinary flow to re-establish the operational sequence. In the system of
FIG. 4, it will be appreciated that the electronic circuitry is powered by
batteries 106, 108 of a kind commonly used in pacemaker technology. While
applicant does not wish to be limited in his choice of component values,
the following have proved useful in one embodiment of the invention, in
which ten 1.4 volt batteries were employed in energizing the electronics.
Resistor R1 . . . 5.1 ohms
Resistor R2 . . . 5.6 ohms
Resistor R3 . . . 10 ohms
Resistor R4 . . . 1 kilohm
Resistor R5 . . . 68 kilohms
Resistor R6 . . . 100 ohms
Resistor R7 . . . 100 kilohms
Resistor R8 . . . 10 kilohms
Resistor R9 . . . 150 kilohms
Resistor R10 . . . 10 kilohms
Resistor R11 . . . 100 kilohms
Resistor R12 . . . 1 kilohm
Resistor R13 . . . 1 kilohm
Resistor R14 . . . 10 kilohms
Resistor R15 . . . 150 kilohms
Resistor R16 . . . 10 kilohms
Resistor R17 . . . 1 kilohm
Resistor R18 . . . 1 kilohm
Resistor R19 . . . 100 kilohms
Capacitor C3 . . . 20 microfarads
Capacitor C4 . . . 1 microfarad
Capacitor C5 . . . 1.6 microfarads
Capacitor C6 . . . 1 microfarad
Capacitor C7 . . . 1.6 microfarads
Transistors T1-T11. 2N1605
Operational Amplifier 98 . . . RCA Type CA3004
in addition, the light emitting diode employed was selected such that the
emitted light would be sensitive to the particular range of colors that
might be assumed by the Benedict's Solution mixture. The photocell P
selected had an imput of 0.08-9 milliamperes, such that a current signal
of 9 milliamperes is generated when the testing stage indicates a clear
urine specimen, i.e., without glucose present. On the other hand, where
the Benedict's Solution mixture was saturated with glucose, so that
minimum light was registered by the photocell, then the photocell would
provide an output current of 0.08 milliamperes.
As was previously mentioned, potentiometer 102 is pre-set in order to match
the individual with his possible dosage needs of insulin during the day.
This resistance is, in actuality, set with regard to the values employed
for capacitors C1 and C2 -- in particular, the maximum time during which
the insulin injecting stage will be active is given by the expression 1.2
RC, wherein R represents the resistance value for the potentiometer 102
and C represents the capacitance values for capacitors C1 and C2. If it is
assumed, for example, that 1cc of insulin is to be injected over a two
second interval, then 1.2 RC would equal 2 seconds, and RC would equal
1.7. If the capacitance values for capacitors C1 and C2 were each selected
to be 1 microfarad each, then the resistance value for potentiometer 102
for this person would be 1.7 ohms, a value readily available in variable
resistance design.
As with the stages previously described, certain design considerations must
be observed in order to maintain the integrity of the testing stage
operation. One area of concern is to prevent any fluid from infiltrating
the structure of the light emitting diode -- photocell arrangement and
causing a possible failure of the testing system. Thus, in an actual
design for surgical implantation, the photocell and light emitting diode
should be hermetically sealed, and with a sealant able to withstand
exposure to any urinary flow. The testing stage, because of the design
employed, will be understood as being a part of the actual filter stage
and Benedict's Solution injecting stage construction, as implicit in its
illustration as part of FIG. 3. In other words, the testing stage is
located within the filter stage housing in the ureter, prior to the
bladder.
The insulin injecting stage 18 of FIG. 5 is similar in construction to the
Benedict's Solution injecting stage 14 of FIG. 3, in its usage of an
elastic reservoir 110 to store a fluid, which is permitted to exit via
means of a one-way valve 112 controlled by energization of a small magnet
114. Similarly, the reservoir 110 is provided with a second one-way valve
116 which permits fluid -- in this case insulin -- to be injected into the
reservoir 110 while at the same time, not permitting any to flow in an
opposite direction. A tube 118 extends from the reservoir 110 to the
surface of the skin where an arrangement analogous to that with the
Benedict's Solution injection could be utilized -- that is, the employment
of an identifying mark visible under ultraviolet light through which an
attending physician could provide an insulin injection to recharge the
reservoir. A second tube 120, directs the insulin to be injected into the
flow of blood in an artery, preferably, the aorta from whence it can
quickly flow to all areas of the body. The cable connection 122 couples
the electrical control signal from output terminal 100 of FIG. 4 to
activate the magnetic control 114 in regulating the injection of insulin
in accordance with the duration of the control signal applied. A pair of
reservoirs 110, 111 are shown in FIG. 5, both of which will be understood
to be similarly constructed. The dimensions 130, 132 and 134 were selected
to be 0.5 inches, 0.75 inches and 2.25 inches, respectively.
As far as the insulin storage in reservoir 110 is concerned, recent
advances have been noted in insulin preparation research to the point that
it is possible to store insulin at body temperatures for up to twelve
months without it losing more than 60% of its starting strength by raising
the pH level of the insulin employed. If it is assumed that the Benedict's
Solution injection stage will be activated on the average of 5 times per
day, and that a capacity of 30cc of Benedict's Solution could be stored,
then by establishing the physical dimensions and component selection of
the electronic components employed, it would be possible to design the
Benedict's Solution construction to retain sufficient solution for a 30
test supply before a need for recharging. It should be clearly apparent
that once the implantation is completed, the diabetic condition is
monitored and regulated automatically, without any need for daily
injections or changes in prescribed diet.
In connection with the implantation of the insulin injecting stage 18, it
will first be recognized that the pressures exerted on the aorta due to
the reservoir charging may result in some form of fatigue within the
system of the body's metabolism. In order to inhibit this, a sheath
fitting placed around the aorta would permit expansion of the reservoir
110 without any pressing against the aorta itself. Care must also be taken
to insure that the insulin will continue to flow through the valve 120
even though there be a slight imperfection or break in the penetration
into the aorta.
In considering the invention, it has been determined that the electronic
circuitry of the control apparatus should be located in an area of
comparative proximity to the stages located near the aorta and in the
ureters. The most convenient place for the electronics will thus be seen
to be in the abdominal cavity. The battery system to energize the
electronics should, also, be located as nearly as possible to the
electronic circuitry employed. For the components listed previously, two
packs of five batteries in series were employed in providing the
appropriate energization. Furthermore, the wiring employed to couple
signals between stages and the electronics with as little hindrance as
possible and yet able to withstand the constant material stresses while
maintaining integrity for the life of the instrument are readily available
in the field of pacemaker technology and can be utilized equally as well
with the apparatus described herein.
While there has been described what is considered to be a preferred
embodiment of the present invention, it will be readily understood that
changes may be made by those skilled in the art without departing from the
scope of the teachings herein. For at least such reason, therefore, this
invention should be read in light of the claims appended hereto.
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