Patent ID: 12239288

DETAILED DESCRIPTION OF THE INVENTION

The following discussion of the embodiments of the disclosure directed to an apparatus and method for monitoring differential pressure is merely exemplary in nature, and is in no way intended to limit the disclosed devices or their applications or uses. For example, the invention is described in the context of an endoscope, but is anticipated to be useful with tools of many types. In respect of the methods disclosed, the steps presented are exemplary in nature, and thus, steps can be added, removed or reordered without departing from the spirit and scope of the invention.

As discussed above, there is a need for real-time endoscope leak testing during a procedure so that, if a leak is detected, the doctor can terminate the procedure and remove the endoscope from the patient as quickly as practicable. Applicant is not aware of any FDA (Food and Drug Administration) approved devices for leak testing an endoscope during use on patients or any standard for testing endoscopes for leaks during use on patients. Thus, patients are at risk during medical procedures using an endoscope. The apparatus according to the invention uses an innovative means of detecting failure of a tool, such as a medical endoscope, by creating and monitoring a differential pressure to the external atmospheric (ambient) pressure. After the differential pressure is established, any significant change to the fluid/gas pressure inside the endoscope indicates a leak has developed and a cross contamination potential exists, and the monitoring device immediately notifies the person or system operating the tool of the potential problem. The indication can be any form of light, sound, electronic communication or otherwise.

Two main embodiments of the invention are disclosed below. The first embodiment can be a passive device that does not include a built-in means for establishing a pressure differential between the interior of the endoscope and the environment. The passive device must be attached to an external pump which creates the pressure differential. An active version of first embodiment of the device includes an integral internal piston assembly and a power source, and can create the desired pressure differential without the need for connecting to an external pump. Either the passive device or the active device can further be configured to be directly mounted in or on the endoscope, or located remotely from the endoscope and connected by a small tube or hose.

There is shown inFIGS.1A-1Da tool2to which a pressure monitoring control module30according to the invention is mounted. InFIGS.1and6, and all of the following discussion, the tool2is specifically an endoscope. The tool2includes a body4, which is a structural component made of a suitable metal or plastic. The body4is generally tubular and hollow. At a distal end of the body4, meaning the end of the body4which is situated away from the doctor, is affixed a flexible tube6. The tube6is the component of the tool2that is inserted into the patient—for example, down the esophagus toward the stomach. The tube6is much longer than shown in the figures as its detail is not significant to the discussion, other than to point out that the distal end of the tube6is sealed, such as with a lens through which fiber optic elements can illuminate and view, or a video camera element.

The endoscope (tool2) shown inFIG.1is an optical endoscope, with an eyepiece and fiber optics (discussed below) for illumination and viewing. Another type of endoscope, which is increasing in popularity, is a video endoscope (discussed later in reference toFIG.6). In a video endoscope there is no eyepiece; instead, a digital video camera is located at the distal end of the flexible tube6, and digital video images are provided by electrical/electronic connection to an external video processor for display on a display device. The disclosed leak testing technique using the control module30is applicable to both optical and video endoscopes.

At a location near the middle of the body4, an adapter8is provided, where the adapter8is configured for attachment of a light source to provide illumination via light fibers into the body cavity being examined. At a proximal end of the body4, an eyepiece10is provided, where the eyepiece10allows attachment of a video camera or other means of viewing the body cavity via optical fibers that extend all the way to the distal end of the flexible tube6. The tool2also includes a port12configured to accept a biopsy tool (not shown), where the port12provides access to a secondary internal tubular passage (not shown) through which the biopsy tool can be extended to the distal end of the flexible tube6to take a tissue sample from the patient.

The above discussion of the tool2(endoscope) is provided for background information only. The main point is that the body4and the flexible tube6are sealed at both ends and at all other ports, resulting in an internal volume that should be leak-free and airtight at all times. Thus, only exterior surfaces of the tool2should ever be in contact with the patient, and only those exterior surfaces can be and must be sterilized or high-level disinfected before a procedure.

As discussed above, it is undesirable for a leak to develop in the tool2during a patient procedure. However, it can easily be imagined that a leak or puncture could occur, in the flexible tube6for example, during a procedure. It is even more undesirable for a leak to develop and go undetected, as the continued use of the tool2exposes the patient to greater potential cross contamination with material inside the tool2. Until now, doctors had no way to determine if a leak had developed during a procedure. Current devices used to leak test an endoscope are designed to test the instrument prior to cleaning for subsequent use.

The pressure monitoring control module30provides the leak detection capability discussed above. The control module30, shown without the tool2inFIGS.2A-2E, is in fluid communication with the internal volume of the tool2through an outlet port32(FIG.2A) which is releasably coupled to a corresponding pressure port14on the body4of the tool2(FIG.1C). When the control module30is coupled to the tool2, this causes the internal pressures to become equal but unknown relative to the atmospheric pressure outside the tool2and control module30. A pumping device (not shown) is then connected to an accessory port34(FIGS.2A-2C) of the control module30. After the pumping device is activated, the pressure inside the control module30and the tool2is changed to a pressure at the desired difference relative to atmospheric pressure. At this point, a signal is provided to indicate that the desired differential pressure has been established and leak detection capability is operational via pressure monitoring.

The differential pressure of the combined internal volume (of the control module30and the tool2) relative to ambient can be positive or negative. In other words, the combined internal volume can be pressurized slightly, or the combined internal volume can be pumped out to a partial vacuum. In a preferred embodiment, the pressure differential is a partial vacuum in the combined internal volume of the control module30and the tool2, and the pressure difference is about ⅓ of atmospheric pressure. In other words, if the ambient pressure in the procedure room is a standard atmosphere of 14.7 psi, then the absolute pressure in the combined internal volume will be established at about 10 psi (which is about ⅓ less than 14.7). Once the desired pressure differential is established, the pumping device is turned off and the pressure in the combined internal volume should remain at the desired value as long as there are no leaks. The 10 psi is an example and, as explained above, the pressure differential can be any selected value above or below ambient.

By establishing the differential pressure as described above, any leak or puncture in the tool2will immediately be made apparent by a change in the pressure in the combined internal volume. In the example described above, where the combined internal volume of the control module30and the tool2has an initial absolute pressure of 10 psi, if a leak develops in the tool2, the pressure in the control module30will rise from 10 psi to near ambient pressure of 14.7 psi. During pressure monitoring, some slight variation from the 10 psi value is allowable without signaling an alarm, to account for temperature change of the flexible tube6when inserted into the patient, for example. However, any increase in pressure greater than about 10%, or 1 psi, for example, can be considered a definite indication of a leak. The value of the pressure change that triggers an alarm is freely selectable. This pressure monitoring leak detection technique is only effective when a differential pressure is first established, as in the embodiments of the present invention.

Any suitable design for the control module30can be used, as long as the device is airtight and capable of monitoring a change in internal pressure. The control module30as shown inFIGS.2A-2Ehas a case36or bottom portion that is cup-shaped and covered by a top38to form an enclosed housing for components. The interior of the enclosed housing forms a pressure chamber defining the internal volume of the control module30. The accessory port34and the outlet port32extend through the walls of the case36, allowing fluid communication with the pumping device and the tool2, respectively.

The components inside the housing of the first or passive version of the control module30are shown inFIGS.3A and3B. A printed circuit board (PCB)40is positioned in the bottom of the case36. The PCB40is an exemplary representation for any suitable type of processor that can be used in the control module30. Instead of the PCB40, an application specific integrated circuit (ASIC), a general purpose microprocessor, or any other suitable processing or computing device can be used. Mounted on or connected to the PCB40are a battery42, an LED44, an optional wireless charging coil46and a pressure sensor module48. The battery42provides power to the components in the control module30—including the PCB40, the LED44and the pressure sensor module48. The LED44is representative of any suitable visual signal generating device such as an LCD or touchscreen.

The LED44is an indicator that provides communication to the operator through different output states. The LED44is representative of any and all types of outputs that can be desired from the control module30. The outputs can be any modality or combination of modalities: optical (such as by the LED44); audible; wirelessly transmitted; or hard wired. Optical and audible outputs can be provided directly by the control module30. Output signals can also be provided from the control module30to a monitoring system that is in use in the procedure room. That is, the monitoring system in the procedure room would typically have its own built-in data recording system, audible alarms, visible alarms, etc. Outputs from the control module30would be compatible with and usable as inputs to the procedure room monitoring system.

To use the control module30for leak detection by pressure monitoring and/or other monitoring (humidity, moisture, etc.), the control module30is first coupled to the tool2as described above. Then the pumping device is activated to create the differential pressure between the combined internal volume (of the module30and the tool2) and the outside environment, as discussed above. When an acceptable internal pressure (such as 10 psi absolute) is reached, the LED44displays a signal, such as a green light, indicating the acceptable differential pressure. Once set, the LED44will continue to display the signal indicating proper tool pressure. If the sensed pressure changes outside set limits, then the LED44signals an alarm condition indicating a change in pressure and a possible leak in the tool2. As mentioned, the “operative/normal” signal and the “alarm” signal can be displayed by the LED44, produced audibly by the control module30, and/or provided by electronic communication from the control module30to the procedure room monitoring system including a monitor being viewed by the physician performing the procedure.

The pressure sensor module48monitors pressure continuously when the control module30is in operation—first determining when the acceptable pressure differential has been established, and then monitoring the internal pressure to detect changes. In monitoring mode, the control module30allows for some variations in the pressure signal from the pressure sensor module48without setting off the alarm signal. The normal acceptable pressure variations can be due to temperature changes in the tool2when advanced into the patient's body, and slight volume changes caused by bending and unbending of the flexible tube6of the tool2. The control module30triggers the alarm should the pressure change too quickly or outside preset parameters. For example, if the internal pressure climbs from the 10 psi starting value, the alarm can be triggered when the internal pressure reaches a threshold value of 11 psi.

Rate of pressure change is also monitored and can trigger an alarm, where the rate of pressure change detection allows for the possibility of contamination plugging a leak prior to the internal pressure reaching the alarm threshold. For example, if the internal pressure climbs from 10 psi to 10.8 psi within a few seconds, the alarm can be triggered due to the high rate of pressure change, even though the alarm pressure threshold (e.g., 11 psi) is not exceeded because the leak is temporarily plugged by a contaminant.

When a leak is detected and the alarm is triggered, the control module30can be configured to release the differential pressure, so that the interior of the endoscope quickly returns to ambient pressure. Alternately, the control module can not mechanically release the differential pressure, but instead just allow the interior pressure to return to ambient due to the leak. The alarm can be disabled or reset by the operator. Even if the operator decides to immediately discontinue the procedure upon notice of a leak, he or she may not want to continue to hear the alarm signal while removing the endoscope from the patient, so disabling or silencing the alarm is a desirable feature. The operator of the tool2may also determine that it would not be desirable to immediately discontinue the procedure, in which case the ability to silence the alarm is even more essential. Any time a leak is detected while the endoscope is inside a patient, the operator can choose to take immediate remedial action with the patient, or make note of follow-up action or monitoring which is to be undertaken.

The control module30also provides the option to re-establish the pressure differential and restart leak detection monitoring. In this case, the pumping device would again be activated to create the differential pressure between the combined internal volume (of the module30and the tool2) and the outside environment, as discussed above. Upon signaling that the desired differential pressure has been achieved, the procedure can resume with active leak detection monitoring, and the operator can choose to continue or discontinue the procedure based upon how soon a second leak alarm is issued.

Power for the control module30is supplied by the battery42that is rechargeable through the wireless charging coil46when in the presence of an external charging system. In some versions, the control module30could be disposable and the wireless charging coil46would then not be present. The battery42can also be a single-charge disposable type, even if the control module30itself is reusable many times; in this case the charging coil46is not needed. In another version, an external power supply could provide power to the control module30via an electrical cable, and the battery42would not be needed for normal operation while serving as a backup power source.

A check valve or shut-off valve can be provided between the external pumping device and the control module30—near the accessory port34. The check valve or shut-off valve would prevent pressure leakage through the accessory port34after the differential pressure is established and the pumping device is turned off.

Other types of sensors besides the pressure sensor module48can also be included in the control module30. For example, a humidity sensor can be provided inside the control module30, and a baseline humidity level could be measured once the control module30is coupled to the tool2. Then, during the endoscopic procedure, any significant change in humidity level would trigger the alarm signal indicating a potential leak. A moisture sensor can also be provided, either instead of or in addition to the humidity sensor. It is possible that in some circumstances the humidity sensor, or another type of sensor, can detect a change of conditions inside the control module30—indicative of a leak in the tool2—sooner than the pressure sensor module48.

The second version of the first embodiment of the control module30according to the invention is an active embodiment and is shown inFIGS.4A,4B and5. The active device functions identically to the passive device with one exception; an internal piston assembly is added to the active device, thus eliminating the need to connect to an external pumping device as discussed above for the passive device. The addition of the piston assembly in the active device enables the control module30to modify the internal pressure to a level different enough to allow sensing of a leak anywhere within the monitored cavities.

The active version of the control module30has a pump in the form of a piston assembly50that includes a piston52, a compression spring54, a check valve56and a piston cavity58. The piston assembly50is shown in exploded form inFIG.5. The control module30also has a drive assembly60that includes a cam62, a planetary DC motor64and a motor mount66. The motor64rotates an axle68in an axle support70. The cam62is attached to the axle68for rotation by the motor64. When the control module30is commanded to begin and establish the differential pressure, the motor64rotates the axle68(and therefore the cam62) by a quarter turn or a half turn. The non-symmetric form of the cam62presses against the piston52to move the piston52. If the piston52is moved outward (away from the axle68) by the cam62, the volume inside the control module30will increase and the pressure inside the control module30will drop. If the cam62is rotated to allow inward movement of the piston52, the spring54pushes the piston52inward to decrease the volume and increase the pressure inside the control module30. The piston assembly50can be configured to increase or decrease internal pressure by selecting the check function of the check valve56.

The PCB40in the control module30can be provided with one or more communication components to communicate data and track performance of the tool2. These communication components can be optical, wired, wireless and/or any other means of communication between two devices. Thus, the components of the control module30can send and/or receive signals through the communication component(s) to and from a data processing device such as a computer as would be used in an endoscopy procedure room. This includes the ability to log performance of the tool2over a timed interval made retrievable through any of the aforementioned techniques.

While the pressure monitoring control module30has been described above and shown inFIGS.1A-1Das an external tool-mounted configuration, other configurations are possible. In one alternate configuration, the control module30can be miniaturized for integrated mounting inside the tool2, or mounted in an accessory device used with the endoscope. In another configuration, the pressure monitoring control module30can be positioned remotely.

FIG.6is an illustration of a pressure monitoring control module30located remotely from the endoscope tool2and connected to the endoscope by fluid couplings discussed below. InFIG.6, the tool2is a video endoscope of the type described earlier. In a typical video endoscope system, the endoscope (tool2) is connected to a video processor90via an umbilical cord80. The umbilical cord80provides electronic communication from the endoscope tool2to the video processor90. The umbilical cord80can also include one or more fluid passages used for providing sterile water or other fluids to the distal end of the flexible tube6.

At an end opposite the tool2, the umbilical cord80terminates in a plug82, which plugs into a jack92on the video processor90. The video processor90also includes one or more ports94for communication with a separate computer, a video display device, or other electronic device, as understood by those skilled in the art. The ports94can be on an opposite side of the video processor90from the jack92; they are shown on the same side inFIG.6for clarity and simplicity. The video processor90also includes a power cord96for providing electrical power.

The control module30depicted inFIG.6(shown much larger than scale) is the active device ofFIGS.4and5, with its own internal pumping device. A hose84releasably couples the accessory port34of the control module30with the plug82on the end of the umbilical cord80. The differential pressure created by the control module30is communicated to the tool2via the hose84and a continuation of the hose84that is inside the umbilical cord80. The hose84can be very small in diameter, as volume flow rate through the hose84is not an important factor. An inline filter (not shown, seeFIG.8) can be provided in the hose84to prevent contamination of the control module30when using a negative differential. In the embodiment ofFIG.6, the tool2is not encumbered with any additional structural appendages, thus enabling easy manipulation of the tool2by the operator.

In any version, and particularly in the device shown inFIG.6, the control module30can be connected to a procedure room computer system for full two-way electronic communication—including sending signals (ready signal, alarm signal) from the control module30, sending collected data from the control module30, and sending signals from the procedure room computer system to the control module30, such as procedure begin and end signals, silence alarm signal, etc. The two-way communication between the control module30and the procedure room computer system can be facilitated by wireless communication or by wires running along the hose84to the plug82and into the video processor90. The collected data sent from the control module30to the procedure room computer system can include date, start time, stop time, tool ID #, patient identification information, pressure vs. time data, and any other available data. In any of the devices discussed above, the control module30can be constructed to be reusable and/or disposable.

The distance between the video processor90and the tool2as shown inFIG.6is not to scale; the video processor90would be much farther distant from the tool2in relation to the sizes shown; that is, the umbilical cord80in reality is longer than shown inFIG.6. Another configuration of the device shown inFIG.6would incorporate the control module30into the video processor90. This would allow the hose84to be eliminated or greatly reduced in length, and the fluid communication between the control module and the endoscope would be directly through the umbilical cord80and the plug82to the jack92. The control module30could also be integrated into other accessories used with the endoscope.

FIG.7is a flowchart diagram100of a method for monitoring differential pressure in a tool to detect a leak, using the devices illustrated inFIGS.1-6. At step102, the pressure monitoring control module30is connected to the tool2such that an internal volume of the control module30is in fluid communication with an internal volume of the tool2to create a combined internal volume. The control module30can be directly mounted upon the tool2, or the control module30can be located remote from the tool2and connected with the hose80.

At step104, a pressure differential is established between the combined internal volume and the ambient pressure outside the tool2and the module30. If an external pumping device is used, the pumping device can be switched on and off in a normal manner. If the active version of the control module30is used, a start button can be provided on the control module30, or a start signal can be provided from a computer in the procedure room if so connected. At step106, a signal is issued by the control module30indicating that the differential pressure has been established. The signal can be a solid green display of the LED44on the control module30, or an audible tone, or any sort of signal can be communicated to the computer in the procedure room. Also at the step106, the baseline or starting pressure is stored for usage during the monitoring phase. In the example discussed earlier, the baseline pressure after establishing the differential pressure is 10 psi absolute. As discussed, the baseline pressure can be any suitable value that is different from the ambient pressure outside the tool2and control module30—where the internal pressure can be higher or lower than the external pressure.

At step108, the tool2is in use (e.g. an endoscope being used by a physician to perform a procedure on a patient) and the pressure in the combined internal volume is continuously monitored by the control module30using the pressure sensor module48. At decision point110, the control module30monitors both the change in the internal pressure itself and the rate of change of pressure, and can issue an alarm if either of these parameters exceeds a predetermined threshold. For example, a pressure rate of change greater than 0.5 psi/minute can trigger an alarm. Also, if the baseline pressure is 10 psi, then a pressure sensor reading greater than 11 psi (change from baseline>1 psi) can trigger an alarm. The alarm thresholds listed here are merely exemplary. Thresholds can be configured based on the exact type of endoscope being used and procedure being performed. Threshold values can be configured by communication from a procedure room computer to the control module30, or configured directly in the control module30.

When no alarm condition is detected at the decision point110, the process loops back to the step108to continue monitoring internal pressure. When an alarm condition is detected at the decision point110, an alarm is issued at step112indicating a possible leak in the tool2. The alarm can be any combination of a change in the LED44(change of color, a flashing code, etc.), an audible alarm, and/or any signal that can be displayed by a procedure room computer system based on an alarm signal from the control module30. The alarm can be silenced by the tool operator if so desired. The operator may also choose to restart pressure monitoring after an alarm, beginning with re-establishment of the differential pressure.

A second embodiment of the pressure monitoring control module according to the invention is shown inFIGS.8-10B. Referring toFIGS.8and9, a pressure monitoring control module120is located remotely from a tool2(endoscope) and is releasably connected to the endoscope by a disposable or reusable hose122with a filter. The control module120includes a housing124having a front wall configured as a control panel126. One end of the hose122is connected to an outlet port128provided at the lower left in the control panel126and an opposite end of the hose is connected to a pressure port14of the endoscope2. The differential pressure created by the control module120is communicated to the endoscope2via the hose122. The hose122can be very small in diameter, as volume flow rate through the hose is not an important factor.

The control panel126of the control module120is shown in more detail inFIG.9. An ON/OFF push button power switch130provided at the upper left in the control panel126switches electrical power provided to the control module120via a power cord132(FIG.8) at the back of the control module. The power cord132can be plugged into a conventional electrical outlet (not shown) to receive AC power required to energize the components in the housing124. A display panel134is positioned centrally in the control panel126. The display panel134displays messages, such as instructions, status information and alarms, for the operator and can function as an input device used by the operator for operating various functions of the control module120. For example, the display panel134can be a liquid crystal display (LCD) or a light emitting diode (LED) panel and can include a touchscreen capability. To the right of the display panel134is a vertical array of lighted push button switches that can be used by the operator to select operating modes of the control module120when performing the method shown inFIG.7. Actuation of a START switch138initiates the generation of the differential pressure and the monitoring of the pressure in the combined internal volume during a medical procedure using the endoscope2. Actuation of a STOP switch140terminates the method without releasing the differential pressure. Actuation of a RESET switch136during performance of the method restarts the method. Actuation of an OFF switch142terminates the method and releases the differential pressure. In the alternative, actuation of the STOP switch140and/or actuation of the RESET switch142could also release the differential pressure.

FIGS.10A and10Bare a schematic block diagram of the interconnection of the components included in the control module120shown inFIGS.8and9as well as the connections with external components used during performance of the method according to the invention. The views are linked at “A”, “B” and “C”. The external components include an AC power source144that can be a conventional electrical outlet into which the power cord132is plugged. Other external components are the endoscope2with the pressure port (endoscope adapter)14connected to a reusable or disposable connection tube146(FIG.8). The tube146is connected to an outlet end of the hose122through a reusable or disposable filter provided in an optional filter coupling device148(FIG.8). The opposite end of the hose122is connected to the outlet port128.

The internal components of the control module120are positioned inside the housing124(FIG.8). An input of an AC to DC power converter150is connected to the power cord132to receive the AC power. An output of the converter150is connected to provide DC power at a suitable voltage to a microcontroller152and other components of the control module120. The microcontroller152is connected to a microprocessor with memory154that is connected to the display panel134. A battery156is connected to the converter150through a DC power circuit158to provide electrical power when the AC power source144is interrupted or otherwise not available. The circuit158also recharges the battery156from the converter150under control of a battery level circuit160. A constant voltage surge protect circuit162is connected to the converter150to protect the control module components from AC power surges.

The ON/OFF power switch130, the RESET switch136, the START switch138, the STOP switch140and the OFF switch142are inputs to the microcontroller152. A wireless communication circuit164is connected to the microcontroller152for communication with peripheral equipment166such as printers and electronic medical records systems, etc.

A motor control circuit168is connected between the microprocessor154and an electric motor170that drives a pump172. An outlet of the pump172is connected through a solenoid valve174to an inlet of a pressure chamber176. The microprocessor154and the motor control circuit168operate the motor170to cause the pump172to generate a predetermined differential pressure in the pressure chamber176. The motor170can be operated to generate both negative and positive pressure differentials. The microprocessor154controls the solenoid valve174to maintain and release the differential pressure as required by the method. An outlet of the pressure chamber176is connected to the outlet port128. As described above in connection with the first embodiment, sensors are used to detect and report various conditions associated with the pressure chamber176. For example, a pressure sensor178detects the differential pressure in the pressure chamber176, representing the combined internal volume pressure, and sends a pressure signal to the microprocessor154for operating the motor control circuit168and generating alarm signals and messages. A humidity sensor180detects the humidity level in the pressure chamber176, representing the combined internal volume humidity, and sends a humidity signal to the microprocessor154for operating the motor control circuit168and generating alarm signals and messages.

Also connected to the microprocessor154are a pressure relief valve182, an alarm184and at least one hardware connection port186. The pressure relief valve182is operated to relieve the differential pressure at a connection in the fluid communication path between the pump outlet and the outlet port128. The alarm184can generate any one or combination of a visual signal (change of color, a flashing code, etc.), an audible alarm, and/or any signal that can be displayed by a procedure room computer system based on an alarm signal from the microprocessor154. Among the alarm signals are signals based on outputs from the pressure sensor178and the humidity sensor180. The at least one hardware connection port186can be, for example, a USB port in the rear wall of the housing124for communication with a device such as a printer or a computer.

The apparatus and the method disclosed above for monitoring differential pressure fulfill the need for real-time leak detection in endoscopes and other tools. The various embodiments—including active, passive, tool-mounted and remote—offer great flexibility in selecting a control module most suited to a particular application.

While a number of exemplary aspects and embodiments for a pressure differential monitoring leak testing device have been discussed above, those of skill in the art will recognize modifications, permutations, additions and sub-combinations thereof. It is therefore intended that the following appended claims and claims hereafter introduced are interpreted to include all such modifications, permutations, additions and sub-combinations as are within their true spirit and scope.