Transurethral irrigation pressure controller

The invention corresponds to a device used in conjunction with a resectoscope in endoscopic surgical operations which includes a housing, pumping means, means for controlling, measuring and displaying the speed of said pumping means in order to make corrections in the inflow and outflow rate of irrigating fluid from the patient thereby maintaining a constant distention of the bladder. The device also includes a plurality of audio-visual alarms that alert the operating physician to any abnormal condition.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to an apparatus, to be used in conjunction with a 
resectoscope, capable of providing constant distention of the patient's 
bladder. 
2. Description of the Prior Art 
Endoscopic surgical operations to correct prostatic and urinary bladder 
pathology are now performed with a resectoscope. The resectoscope has an 
inlet that is connected to an irrigating fluid storage that is placed 
between 60 and 90 cm above the operating table level and an outlet 
connected to a suction chamber maintaining 10 to 50 cm of Hg of pressure. 
The operating physician has to guess how much distention and pressure the 
bladder has and interrupt the operation if dangerous limits are approached 
as time goes by. The Iglesias type of continuous irrigation resectoscope 
is currently being used as described above but there has not been an 
apparatus capable of monitoring and controlling the inflow and outflow of 
irrigating fluid to the patient's bladder and correcting for urine and 
blood produced. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to invention to provide an 
apparatus capable of monitoring and controlling the outflow and inflow of 
fluid to the patient's bladder, through a resectoscope, thereby 
maintaining a constant distention of the bladder. 
It is another object of the present invention to improve the visibility 
inside a patient's bladder undergoing an endoscopic surgical operation by 
constantly irrigating said bladder. 
It is yet another object of the present invention to provide an apparatus 
capable of detecting dangerous over distention of the bladder and calling 
it to the attention of the operating physician. 
Still another object of this invention is to provide an apparatus for 
irrigation during all diagnostic and manipulative endoscopic procedures. 
The invention also comprises such other objects, advantages and 
capabilities as will later more fully appear and which are inherently 
possessed by the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to the drawings wherein like reference characters designate like 
or corresponding parts throughout the several views, the device is 
generally designated by the numeral 12. The device 12 has a plurality of 
hangers 42 holding interconnected, as shown in FIGS. 1 and 2, irrigation 
fluid bags 44, 46, 48 and 50. The number of bags not being critical but it 
is convenient to be able to replace empty bags without interrupting the 
operation. Interconnecting tubing 60 interconnects the bag outlets 52. 
Outlet 52 of fluid bag 50 is connected to outlet pump tube 64 which is 
connected to outlet pump 16. The tubes or conduit means used are of a 
substantially flexible material, such as rubber. The outlet peristaltic 
pump 16 on side 18 of housing 14 is connected to outlet tube 67 through 
which the irrigating fluid is caused to pass. The irrigating fluid is 
forced through outlet tube 67 to the patient's bladder by means of a 
simultaneous irrigation and suction resectoscope (of the Iglesias type 
such as the one manufactured by Karl Storz K G, Tuttlingen, W. Germany 
that is inserted in the patient's urethra. This type of resectoscope has 
two connections: one for the irrigating fluid coming into the patient's 
bladder and another one for the fluid being extracted from the bladder 
which also carries blood, urine and other organic materials. The 
continuous irrigation resectoscope is a well known medical instrument that 
allows the physician to see where he is operating by improving the 
visibility inside the bladder and prostatic urethra that is clouded by 
bleeding. Outlet tube 67 is connected to said first connection in the 
resectoscope for the fluid coming into the patient. Inlet tube 22 is 
connected to the second connection in said resectoscope on one end and the 
other end of the inlet tube 22 is connected to inlet pump 72. The output 
of outlet pump 16 and the input of inlet pump 72 are connected by priming 
line 74 which is connected, via two "T" connectors, to outlet pump tube 64 
and inlet tube 22 as shown in FIG. 1. The main purpose for priming line 74 
is to eject all trapped air when the device 12 is initialized. Priming 
line 74 is provided with a shut off clamp 75 that impedes any further 
transmission of fluid once all the air has been eliminated. 
Sensing device connecting tube 90 connects inlet pump 72 to fluid condenser 
23 where the irrigating fluid is deposited. Sensing device 70, which is 
immersed in said deposited fluid, contains the necessary instruments for 
the measurement of the concentration of urine and blood in the irrigation 
fluid as diluent, as it is discussed with more detail below. Any commonly 
used method for measuring the concentration of blood and urine may be 
used. The preferred embodiment takes advantage of the different electrical 
conductivity coefficients of the blood and urine to make this measurement. 
Once the concentration of these substances in the diluent is computed, the 
flow rate for inlet pump 72 is increased to take into consideration these 
segregations or hemorrhages. The other methods for measuring the 
concentration of urine and blood are: absorbance at a definite wavelength, 
refractive index or any other characteristic corresponding to the blood 
and urine. The measurements are always made with respect to the pure 
irrigating fluid as the base reference. 
Having described the path of the irrigating fluids through the apparatus, 
the following paragraphs will describe how this is accomplished in terms 
of block diagrams. Each block represents a group of known electrical or 
mechanical components providing the function described herein. These 
functions are well known by those skilled in the art. 
Referring to FIG. 2, we have the sensing and controlling circuitry 
generally referred to as 1. Microprocessor 2 is a conventional device such 
as the Motorola's 6801, Intel's 8080, etc., and it is used to provide the 
necessary decision making capability that can also be provided with 
special function hardware circuitry. Program memory 3 contains the 
instructions required for the different operations and these instructions 
are usually fixed. Consequently, program memory 3 will not be changed 
frequently and can be implemented with a Read Only Memory (ROM) such as 
the one that comes with 6801 device. Temporary memory 4 will contain data 
acquired in real time that will change from time to time and, 
consequently, it is recorded in a storage device capable of being updated 
periodically. In the preferred embodiment, the random access memory inside 
the 6801 device is being used. However, it is possible to use any random 
access memory device to implement the functions of program memory 3 and 
temporary memory 4. 
Output signals from microprocessor 2 are fed to motor interface 5 which 
actually contains two similar motor interface circuits. One circuit is 
connected to outlet pump variable speed motor 7 and the other circuit is 
connected to inlet pump variable speed motor 6. Each one of these motors 
engages to a coupling 8 which drives the peristaltic pumps 16 and 72. 
These peristaltic pumps have the characteristic that the fluid going 
through them never touches the pumps, therefore contamination is avoided. 
The rotational speed of the pumps 16 and 72 is being measured by shaft 
speed sensor 9 and its output is fed to conditioning amplifier 10. 
Conditioning amplifier 10 is an interface intended to harmonize the output 
waveform coming out of the shaft speed sensor 9 with that required by the 
input channel of microprocessor 2, which in the preferred embodiment 
corresponds to TTL logic levels. In sum, both pumps 16 and 72 can be 
controlled and monitored by the microprocessor 2. 
A pressure transducer 11 is connected, via a "T" connector 13, to outlet 
tube 22. The output of transducer 11 is fed to linear conditioning 
amplifier 15 which acts as an interface circuit for analog multiplexer 17. 
The pressure transducer 11 measures the pressure inside the bladder as it 
is transmitted through the resectoscope by virtue of Pascal's hydrostatic 
principle wherein the pressure in a liquid is transmitted equally 
throughout the body of the liquid. Inlet pump 72 will have to be stopped 
before a pressure measurement is taken. The operator may also want to stop 
outlet pump 16 when taking the pressure measurement thereby avoiding 
further distention of the bladder. 
Analog multiplexer 17 is shown in FIG. 2 connected to sensing device 70 via 
linear conditioning amplifier 15. The multiplexer 17 is not critical since 
the inputs from cell 19 and transducer 11, after being conditioned by 
amplifiers 15, may be fed to two analog to digital converters 21. However, 
good engineering economics judgment calls for the use of a less expensive 
multiplexer 17 that in turn is connected to one A/D converter 21. The 
output from converter 21 is then fed to microprocessor 2. A contamination 
detection cell is immersed in the outflowing irrigation fluid collected by 
fluid condenser 23 which is just a large enough reservoir that smooths out 
the pulsating action from the pumps. In the preferred embodiment the 
contamination detection cell inside sensing device 70 measures the 
electrical conductivity of the outflowing irrigating fluid to determine 
the amount of urine and blood dissolved therein. It is basically a 
conductivity cell having two plates and a constant current source. The 
voltage drop across the plates varies depending upon the conductivity of 
the fluid, which is a function of the blood and urine contamination. The 
information is then transmitted to microprocessor 2, as stated above, and 
compared to pre-set limits stored in memory 3 or 4. When the blood 
contamination reaches a preset limit, an alarm is triggered by 
microprocessor 2 and a visual and/or audio indication is activated to call 
the user's attention. FIG. 1 shows excessive contamination indicator 35 on 
the front panel of the apparatus 12. 
Other alarm indicators are provided to insure the proper operation of the 
device 12, as shown in FIG. 1. System fault indicator 33 is activated when 
a number of self-imposed tests are not passed by microprocessor 2. The 
pump failure indicator 34 is activated when the pumps don't operate when 
they are supposed to or when one of the pump's speed exceeds the speed of 
the other pump by more than a certain percentage, around 25% in the 
preferred embodiment. Finally, the excessive pressure indicator 36 is 
activated when the pressure of the bladder reaches a pre-determined level 
that is considered dangerous. Preferably, these pre-set alarm limits are 
set inside the machine to avoid inadvertent errors by operators. An 
audible alarm 43 is activated when any of the alarm indicators 33, 34, 35 
or 36 is turned on. The audible alarm 43 may be inhibited with alarm 
inhibit switch 45. 
There are three 3-digit readout displays 37, 38 and 39 in device 12; as 
shown in FIG. 1. Each readout display is used to provide two variables and 
readout 39 provides, additionally, two pre-set threshold constants: one 
for the bleeding factor and the other one for the pressure inside the 
bladder. In the preferred embodiment, the readout displays are 
seven-segment LED readouts connected with the pertinent encoder/decoder 
circuitry to microprocessor 2 as shown in FIG. 2. For each one of the 
three displays there is a switch, 76, 77 and 78, refer to FIG. 1, that 
selects which one of the two variables is being displayed. Inlet/outlet 
flow readout display 37 shows the information sent by shaft speed sensor 9 
to microprocessor 2. Distention/Volume readout display 38 provides the 
total volume of irrigating liquid, as computed by microprocessor 2, that 
has flowed through the resectoscope if switch 77 is pressed down. If 
switch 77 selects "Distention" (up), then readout 37 will display the 
volume of irrigating fluid inside the patient's bladder plus the blood and 
urine produced. Distention is computed by microprocessor 2 by subtracting 
the total volume pumped in by inlet pump 72 from the total volume pumped 
out by outlet pump 16. The third readout 39 supplies the bleeding factor 
or the bladder pressure, which are variables that need to be closely 
monitored by the operating physician. Like with the other two readouts, a 
switch 78 selects which variable is being displayed. There is an 
additional switch associated with readout 39 and this is pushbutton switch 
79 which causes microprocessor 2 to display the pre-set threshold figures 
that it has in storage for the bleeding factor and for the pressure of the 
bladder. If one or more of these threshold figures is exceeded, the above 
mentioned alarm circuit is activated. 
As shown in FIG. 1, a three position mode control switch 29 is provided. 
The manual mode is used for bypassing microprocessor 2 in order to 
activate the pumps manually operating inlet pump switch 47 and outlet pump 
switch 49, to prime the tubing and eject the air out. Once this is done, 
priming line 74 is closed by means of a clamp 75. The standby mode allows 
the user to input the values for variables like desired distention, flow 
rate, bleeding factor threshold and pressure threshold. The values for 
said variables are changed by using the proper level select switch for 
increasing 53 or decreasing 54 inlet or outlet flow rate, increasing 55 or 
decreasing 56 distention, for increasing 57 or decreasing 58 bleeding 
factor, pressure or its pre-set thresholds. Finally, the automatic mode 
gives control to microprocessor 2 and the device 12 starts pumping the 
irrigation fluid inside the patient's bladder until the desired distention 
is achieved. 
A power supply circuitry is also provided, as shown in block diagram form 
in FIG. 2, to supply the appropriate voltages to the other circuits of the 
present invention. The power supply 40 is well known in the art, its 
construction and operation being described in a multitude of references. 
The power supply 40 is connected by electric cable 26 to the public 
network when power switch 41 is on. 
It is believed the foregoing description conveys the best understanding of 
the objects and advantages of the present invention. Different embodiments 
may be made of the invention herein described without departing from the 
inventive concept of this invention. It is to be understood that all 
matter disclosed herein is to be interpreted merely as illustrative, and 
not in a limiting sense, except as set forth in the following appended 
claims.