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Description  |
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TECHNICAL FIELD
The present invention relates in general to computer monitoring of the
exact position of an endoscope, sound alarms as set, and record events
occurring during the procedure.
BACKGROUND OF THE INVENTION
Numerous endoscopes are now being used to examine and operate upon various
parts of a patient. An endoscope called the Resectoscope has made a most
distressing operation called Open Prostatectomy into the finest of all
surgeries because it is painless and minimises blood loss. The above
statement is qualified `when done well` because complications can occur
and make this into the worst of all surgeries.
The diseased prostate obstructs the patients urinary passage just as it
leaves the urinary bladder. In this surgery called `Trans Urethral
Resection of the Prostate` the prostate is cut into pieces under vision
and removed through the said resectoscope.
The prostate gland lies within three boundries namely the bladder neck
above, the verumontanum below, and its outer boundery being its capsule.
Resecting (cutting) within these limits is safe but if any cutting is done
beyond these limits then dangerous complications can occur. Such
complications occur when a trainee surgeon operates or if a large prostate
is removed by a less experienced surgeon. Reasons for this are that only
the operating surgeon can see through the endoscope and recognizing the
safe limits becomes difficult especially when the field of vision is
obscured by heavy bleeding.
Displaying the prostate on the computer screen and continuous display of
the cutting element of its every move will enable the senior surgeon to
know exactly what the trainee is doing.
Another important thing is that the gland needs to be removed completely.
Any remaining tissue can grow and cause obstruction later. In this
invention as soon as the prostatic capsule is reached this is marked and
displayed on the computer screen in color. In the end one look at the
screen will show the surgeon if any tissue has been left behind.
Serious complications occur if one perforates the prostatic capsule. Many
blood vessels are present here and when cut into causes much bleeding and
possible shock from blood loss. Also if a large vein is cut then the
irrigating fluid enters the blood circulation through the cut vein causing
hyponatremia (dilution hence reduction of sodium content of blood). The
patient then looses consciousness and goes into shock.
The commonest way this happens is as follows: The surgeon cuts away the
prostate from bladder neck to a distance of say 2 centimeters and reaches
prostatic capsule here. Then when he begins cutting from this point beyond
for another 2 centimeters inadvertantly he cuts an area where capsule has
already been reached. The present invention will prevent this by an alarm.
One of the most distressing complications occur when resection is done
beyond the verumontanum. The result is damage to the external urethral
sphincter causing incontinence. Inability to control urine keeps him
continuously wet. The present invention alerts the physician and this
complication can now be avoided.
The computer starts timing the surgery and displays the time. When a
capsule perforation occurs by mistake this event can be marked and the
time interval between this occurrence and the end of surgery is important
because the longer this `perforation time` the greater the amount of
irrigation fluid can leak outside the prostate and into the blood stream.
This time is recorded.
It is possible to record an operation using a video camera but using this
is cumbersome because of size and it is expensive. We will now be able to
record events occuring during the said procedure in a cheap computer disc
and display it whenever desired. Such reliable documentation of what the
physician did will become important in the future.
DISCLOSURE OF INVENTION
During examination and surgery using an endoscope, the instrument is moved
in and out of the body cavity. The cutting element of the said endoscope
is also being moved in and out in relation to the endoscope sheath.
Movement of the whole instrument also takes place in the circular plane.
All these movements must be monitored in relation to landmarks in the
examining organ. Once this is done then alarms can be set as warning
whenever the predetermined landmarks are transgressed. In an endoscope
where cutting is done the most important time to monitor is when the
cutting current is switched on and the cutting element is moved to cut
tissue that comes in contact with it. It is during this time that if
preset boundaries are transgressed that alarms are to be sounded and if
necessary switch off the cutting current.
In order to accomplish this above mentioned objects movement of the said
endoscope in its various planes must be converted by a transducer to
something that the computer will be able to receive, understand and act
according to information received. Movement can thus be converted by using
transducers like resistance, capacitance, inductance, current, voltage,
light intensity, frequency rate, or time of reflected frequency.
Changing resistance with change in position of the endoscope was selected
in the present model. Movement in three planes need to be monitored in
this instance: 1. In and out plane. 2. The position of the cutting element
in relation to the endoscope sheath. 3. Circular plane. Thus three
potentiometers are used. Each varies resistance when movement occurs in
its particular plane. Change of resistance and current due to movement is
fed to an analog to digital converter (ADC) chip. This converts analog
variations to ditital numbers. This is connected to the computer central
processing unit (CPU) through a buffer chip. By programing the computer
acts as programed upon receiving information.
BRIEF DESCRIPTION OF DRAWINGS
The above mentioned purposes and descriptions of the invention will be
clear by reference to the following drawings wherein:
FIG. 1 is a view of the bladder, prostate, and urethra.
FIG. 2 is a view of the endoscope with additions necessary for the
invention.
FIG. 3 is a view of the endoscope and in schematic form the wiring from the
added components.
FIG. 4 is a view of the game input port of the Apple IIe computer.
FIG. 5 is to show how the prostate is to be represented in graphic form.
FIG. 6 is a view of the prostate opened out to enable graphic
representation.
FIG. 7 shows the endoscope sheath and cutting element in relation to the
graphic representation of the prostate.
FIG. 8 is to show how the cutting of the prostate is represented in graphic
form.
FIG. 9 shows representation of alarm when cutting is about to be performed
beyond safe limits.
FIG. 10 shows alarm when cutting is about to be performed in an area where
the safe limit has already been reached.
FIG. 11 shows the circuit diagram of the computer interface and the Apple
IIe Game Input Port.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Discussion will be in the following order:
1. Description of prostate.
2. Description of endoscope.
3. Movements of endoscope.
4. Interfacing the endoscope to computer.
5. Computer programing.
Referring to FIG. 1 the urinary bladder 1 is seen. Below this is the
prostate gland 2 and this leads to the rest of the urinary passage called
the urethra 3.
We are interested in the prostate 2. The upper limit of the prostate 2 is
the bladder neck 4. Through the center of the prostate 2 passes the
prostatic urethra 5. In disease the prostate 2 enlarges and compreses the
prostatic urethra 5 as shown in this diagram. The lower end of the
prostate 2 is marked by the veru 7 (more fully called the verumontanum).
This is the most important landmark not only because it marks the lower
limit of the prostate 2 but also because it indicates the level of the
external urethral sphincter 8. Surrounding the prostate 2, like an orange
skin, is the prostatic capsule 6.
The endoscope in FIG. 2 is called resectoscope and is available from many
sources. This one is manufactured by Statham Instruments Inc., 2330
Statham Blvd, Oxnard, Calif. 93030. Its two main parts are the
resectoscope sheath 9 and the working element 10.
The working element 10 consists of a fixed part 11 and a moving part 14.
The fixed part 11 helps to support the telescope 12 and provides and inlet
13 for irrigating fluid which when flowing keeps the operative field
clear. The part that is movable 14 holds the cutting element 15 and has a
socket 16 which connects to an external source (not shown) of high
frequency current that is used to cut tissue and stop bleeding by
coagulation. This movable part 14 also has a thumb grip 17 to push the
cutting loop 15 forward and a spring 18 (U.S. Pat. No. 3,835,842) to bring
the loop 15 back to its resting position.
Movements of the resectoscope shown in FIG. 2 are three. One is in an `in
and out` direction. Second is the movement of the cutting loop 15 `in and
out` of the resectoscope sheath 9. The third movement is movement of the
whole endoscope in a `circular plane`. This is to be able to inspect and
operate upon the organ all round starting from say the 1 O'clock position
round in a clockwise direction to the 12 O'clock position.
Transducers are used to convert the above mentioned movements to digital
data. In this particular model three potentiometers 19, 24, 27 each having
a resistance of 0 to 150,000 ohms are used--one potentiometer for each of
the above mentioned movements. As described below the body of each
potentiometer is fixed to one part and the rotary moving contact of the
potentiometer is fixed so that rotation of the moving contact occurs when
the above mentioned movement occurs.
The first potentiometer 19 varies resistance with the `in and out` movement
of the endoscope. The body of the potentiometer 19 is fixed to one arm 20
and the moving contact to the other arm 21. Each arm 20, and 21 are equal
in length to ensure linearity of resistance with distance travelled. The
distal arm 20 is connected to a ring 22 with a ball and socket joint 23.
This ring is fixed to the patients body (not shown) with adhesive tape.
For the second movement another potentiometer 24 is used. The body of this
potemtiometer 24 is fixed to the moving part 14 of the working element 10
by a plate 25. The rotating contact of the potentiometer 24 is connected
to the non moving part 11 of the working element 10 by two hinged flat
metal pieces 26 and 26a. As the cutting loop 15 is moved in and out the
resistance of the potentiometer 24 changes.
The third potentiometer 27 varies resistance with circular motion. To the
resectoscope sheath 9 is attached a ring with teeth 28. This ring 28 is
fixed to the resectoscope sheath flange 29. This ring moves round with
circular movement of the resectoscope. Between this ring 28 and the
resectoscope sheath flange 29 is a plate 30 that extends downward. There
is a space between the ring 28 and the flange 29 so that this plate 30
does not move when the resectoscope moves in a circular plane, but always
hangs down due to gravity. From this plate 30 are four spacers 35 that
hold another plate 34 which is fixed to the body 33 of the potentiometer
27. To the moving part 32 of potentiometer 27 is fixed a toothed ring 31.
This ring's teeth are enmeshed with the teeth of ring 28 which is above.
This assembly hangs down always due to gravity but with the circular
movement of the resectoscope the resistance of potentiometer 27 changes
proportionately.
To interface with a computer analog signals have to be converted to digital
numbers. Analog to digital converter (ADC) chips are readily available.
Since most personal computers have ADC already built in, this is used in
the present model. Such ADC are used to play games with joystick, paddles
and push buttons.
The computer used is an Apple Computer, model IIe obtainable from Apple
Computer Inc., 20525 Mariani Ave., Cupertino, Calif. 95014. Analog to
digital conversion in the computer is accomplished by using a special
integrated circuit chip IC NE 558 Quad Timer. Each game control (GC) input
is part of an analog to digital conversion circuit that allows an analog
resistance value to be converted (by software) to a digital quantity the
IIe can handle. The resistor forms part of a simple `R C` (resistor
capacitor) circuit that sets the time constant of the IC NE 558 timer.
When this timer is reset, by accessing GCRESET ($C070) bit 7 of each G C
(game control) I/O (input/output) memory location becomes high (1) but
will eventually become low (0) when the timer `times out`, that is, the
period of time equal to the time constant for each of the four "R C"
circuits has elapsed. (page 338, Inside the Apple IIe by Gary B. Little,
published by Brady Communication Co., Inc., Bowie, Md., 20715).
The Apple IIe has four ADC (analog to digital converter) connected to the
game port which are similar in concept to a dual slope ADC (analog to
digital converter). A fixed 5 volt is connected to one end of a variable
resistance. The output of the variable resistance has current which varies
inversely with the resistance. This incoming current charges a capacitor
until the charge becomes equal to a reference charge stored in a second
capacitor. The amount of time for the input capacitor to become fully
charged is proportional to the setting of the resistor in the game paddle
or other device. There is a subroutine in the monitor which begins the
sampling process and then checks the status of the ADC (analog to digital
converter) every 10.8 microseconds. If the external resistance is near
zero, the ADC is triggered very rapidly. With a maximum resistance of
150,000 ohms it can take up to 256 test periods or 256 .times.10.8=2.76
milliseconds to determine the setting. (page 246-247 Apple Thesaurus by
Aaron Filler, published by Datamost, 20660 Nordhoff St., Chatsworth,
Calif., 91311--6152).
FIG. 3 shows in a schematic form wiring from the said resectoscope
potentiometers to the computer game control port FIG. 4. A +5 volts is
supplied from 40 and is connected via wire 39 to one terminal 44, 48, 46
of each potentiometer. Potentiometer 19 transduces `in and out` movement
of the resectoscope and output of variaton is taken from 47 and goes out
via wire 37 to connection 41 which is input of GC0 (Game control input
number 0). Similarly output of potentiometer 24 which varies with movement
of the cutting loop 15 is taken from terminal 45 via wire 38 to GC1 (game
control number 1) input 42. Potentiometer 27 is for rotary movement and
terminal 49 is connected to GC2 (game control number 2) input 43 via wire
36.
The method of displaying the prostate on the computer screen is shown in
FIG. 5 and FIG. 6. The prostate is shown as if it has been cut open from
the 12 O'clock position to its center and opened out in the form of a
rectangle. The left side is 50, 51 and the right side 52, 53. The opened
prostate as a rectangle is shown in FIG. 6. The visible part is the inside
surface of the prostate 2. This inside surface is the prostatic urethra 5.
The capsule 6 or outer boundary is deep to the surface.
FIG. 7 shows the prostate 2 opened out as a rectangle. The resectoscope
sheath 9 and cutting loop 15 are also seen. The said loop 15 and sheath 9
are seen on the computer screen to move up and down as it is moved by the
surgeon. The loop 15 and sheath 9 together move sideways on the screen as
it is rotated in a circular plane by the operating surgeon. In addition
the loop 15 is shown to move in and out of the resectoscope sheath 9
exactly as it occurs during the surgery. The circle 54 becomes colored
pink when the cutting current is about to be switched on by a foot switch
and during the time it is on. To enable this, the switch PB0 (FIG. 11) 61,
is coupled to the cutting current left foot switch (not shown) so that
when this switch is depressed PB0 61 is first activated, FIG. 8 54, then
as this switch is further depressed the cutting current switch is
activated. As shown in FIG. 8 a part of the prostate being cut 55. The
color deep to it changes to pink 56. To the left of this an additional
slice of prostate was removed hence its color changed to green 57. Again
from the left of this part 57 to the left edge, prostatic capsule 6 has
been reached hence it is all given the final color of purple 58.
While cutting into the prostate 2 the capsule 6 can be easily recognized.
As a slice of prostate is cut and casule has been reached in that part, a
push button PB1 (FIG. 11) 62, coupled to a right foot switch, is switched
on momentarily by the surgeon. This colors that part of the prostate
purple on the computer screen indicating that in this portion capsule has
been reached.
In FIG. 10 the distal half of the prostate is being resected. The cutting
loop 15 is in a place where capsule has already been reached 59 and the
cutting current is about to be switched on 54. Here there ia a danger of
cutting the capsule and perforating it hence the alarm 60 sounds to alert
the surgeon.
In FIG. 9 the resectoscope loop 15 is beyond the veru 7 and the cutting
current foot switch is depressed activating switch PB0 61 first. The alarm
60 sounds alerting the surgeon before he further depresses the foot switch
to activate the cutting current. Similarly the alarm will sound if the
cutting loop 15 is above the bladder neck 6, the upper safe limit, and the
cutting current is about to be switched on (not shown).
Computer software specifics vary with each type of computer. In general the
computer is programed to do the following: First bladder 1, prostate 2,
and urethra 3 are drawn on the screen as in FIG. 1. Then the prostate 2 is
shown to open out to form a rectangle FIG. 5 and FIG. 6. The bladder 2 and
urethra 3 disappear leaving a rectangle as in FIG. 7.
High resolution graphics is used. From shape tables in memory shapes of the
end of the resectoscope sheath 9 and the end of the resectoscope cutting
loop 15 are loaded. According to variations of current at computer input
GC0, FIG. 11 37, these two shapes namely sheath 9 and loop 15 move
together up and down on the screen. Combined readings from input GC0+GC1
37, 38 move the loop 15 in and out of the sheath 9. Sideways movement
occur with variations to input GC2 36.
The upper limit of the rectangle is redrawn by bringing the loop 15 to the
level of the bladder neck 4 and pressing right foot switch activating PB1.
Similarly the lower limit is set by bringing the loop to the level of the
veru 7 and again activating PB1 62. The upper and lower limits are set and
assigned to variables in the computer. Setting these limits is followed by
reading the surgery starting time. A seperate plug in card called Business
Card has a clock. Time is read from this. This is obtainable from Street
Electronics Corp., 1140 Mark Ave., Kartinteria, Calif. 93013. It is
plugged in one of the plug in slots in the Apple IIe computer.
Digital data converted from inputs GC0 37, GC1 38, and GC2 36 are obtained
by variables assigned to computer commands PDL(0), PDL(1), and PDL(2)
respectively. These readings then help to move the sheath 9 and loop 15 as
described.
Push button switch PB0 61 is coupled to the left foot switch that switches
the cutting current. As soon as this switch PB0 61 is activated the
position of the cutting edge of the loop 15 is read. Then three things are
checked. Is this above the bladder neck 4, or is it below the veru 7, or
is it in an area of capsule 6? If the answer is yes then an audible alarm
sounds. If necessary it is easy to deactivate the cutting current. If the
answer is no then the color over the area where this loop 15 moves is
changed. A two dimensional array is formed representing plot positions of
the area occupied by the prostate on the computer screen. When PB0 is
activated and the loop 15 is moved, the position of the cutting edge of
the loop 15 is read from PDL(0)+PDL(1) which gives the X axis position and
from PDL(2) which gives the Y axis postion. While cutting switch PB0 is
depressed wherever the loop 15 moves the color is changed. The number of
this color is stored in the above mentioned array. When cutting is done
over the same area again then the color is changed to the next color.
Colors available are black, pink, green, blue, and purple. Begining color
is black. Then when the first cut is made the area traversed by the loop
15 becomes pink. After the second cut over the same area color changes to
green. The third cut makes it blue. If another cut is made over the same
area it becomes pink. Thus between the first and final colors three colors
come in sequence--pink, green, blue, pink, green, blue, etc. When the
capsule 6 is reached PB1 62 is depressed. This causes the color to change
to the final color--purple. All this time numbers for colors are changed
and stored in the array. The final color of purple holds special
significance because when the cutting curent PB0 is on, one of the three
things the computer checks is whether the location where the loop 15
traverses has the final color purple. If the answer is yes then the alarm
sounds alerting the surgeon that the loop 15 is over capsule and cutting
can cause perforation. At the end of the one look at the computer screen
will tell whether all prostate has been completely removed or not. Purple
color occupying the whole area indicates complete removal.
One of the computer subroutines is to read the X axis, Y axis, and color
numbers at the location occupied by the loop 15 cutting edge. These
numbers are stored in a sequential access file. This is to make a
permenant record of events occurring during the surgery. Upper and lower
limit positions will also be saved. Replay will be done by recalling these
numbers and moving the loop 15 according to location indicated by the
position numbers and color will change according to the color number.
Thus, according to this invention the endoscopic examining and treatment
procedures will become much safer.
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