Patent Description:
The subject disclosure relates to gas delivery systems for use with surgical access devices, and more particularly, to a system and method for controlling the performance of a pneumatically sealed trocar used in endoscopic or laparoscopic surgical procedures.

Pneumatically sealed trocars such as those disclosed for example in commonly assigned <CIT> and <CIT> can be operated via an electro-mechanical control system. Such control systems are disclosed for example in commonly assigned <CIT>, <CIT>, and <CIT>. These systems function to create and maintain a pneumatic or gaseous seal within the trocar that creates a defined pressure gradient for minimally-invasive laparoscopic or endoscopic surgeries. Those skilled in the art of those surgeries (such as a surgeon or nurse) may choose to pressurize (insufflate) a surgical cavity to a particular pressure in order to better enable visualization of the anatomy and other benefits of insufflation.

When operating a pneumatically sealed trocar via an electro-mechanical control system, it can be advantageous to modulate pneumatic power supplied to the trocar in order to vary its performance behavior and/or characteristics. Design and manufacturing differences may allow for variations in the pneumatic power required to seal a pneumatically-sealed trocar. This can be affected by design, manufacturing variability, area of the seal required (i.e., a <NUM> trocar versus a <NUM> trocar), efficiency, resistance, and other factors.

The pneumatic power required to seal a pneumatically-sealed trocar is also dependent on the magnitude of the pressure gradient maintained by the pneumatic seal. For example, a surgical team might choose to insufflate a patient to <NUM> mmHg, requiring the pneumatic seal in a pneumatically-sealed trocar to maintain a gradient between <NUM> mmHg and ambient pressure (<NUM> mmHg). The power required to maintain this seal (gradient) is larger than the power required to maintain a gradient between <NUM> mmHg and <NUM> mmHg, for example.

Furthermore, during normal operation of a pneumatically-sealed trocar, regular disturbances or perturbations can be expected. These can include, but are not limited to physiology-driven changes to the insufflated cavity (e.g., from breathing or muscle movement), exterior forces applied to the insufflated cavity (from a surgeon or surgical instrument pressing against the cavity), or from passage of instruments or specimens through the seal of the pneumatically-sealed trocar.

Therefore, an electro-mechanical control system operating a pneumatically sealed trocar should be able to modulate power supplied to that trocar in real-time to respond to those disturbances and maintain the seal and pressure gradient as specified. The control system disclosed in <CIT> includes an electro-mechanical control valve that modulates pneumatic power supplied to the trocar. In that system, a pump (typically driven by AC or alternating current) oversupplies the pneumatic circuit with pressure and gas flow. The pneumatic power that is supplied to the pneumatically-sealed trocar is modulated by an embedded control system that adjusts the electro-mechanical valve.

Those skilled in the art of systems or pneumatics engineering will appreciate the design of the pneumatic circuitry, and the role this valve plays as an "H" or "by-pass" valve. The AC driven pump in that system embodiment supplies a constant power output, and the position of the electro-mechanical valve controls the percentage of that power that reaches the pneumatically-sealed trocar and the percentage that is recycled back to the vacuum intake of the pump.

Those skilled in the art will readily appreciate that there are advantages to using a DC-based control system over an AC-based system for the pneumatic control of a pneumatically-sealed trocar, including improved energy efficiency. Therefore, it would be beneficial to provide a control system that is configured to modulate the pneumatic power supplied to a pneumatically-sealed trocar in real-time via a DC driven pump, rather than an AC driven pump.

<CIT> discloses a device for irrigation and/or insufflation during endoscopic surgery/procedures in a body cavity, comprising a first fluid pump device to deliver fluid to the body cavity, a second fluid pump device to move fluid from the body cavity, a control unit connected to the first and/or second fluid pump device, a blood pressure measuring device, wherein the control unit to derives a control signal based on a signal from the blood pressure measuring device, and sends the control signal to the first fluid and/or second fluid pump device, wherein the control signal is derived by processing the signal from the blood pressure measuring device using a correlation factor in the device, dependent on the relationship between a blood pressure measurement signal, and a perfusion pressure of the body cavity, wherein the first and/or second fluid pump device controls the pressure in the body cavity based on the control unit's control signal.

<CIT> discloses an irrigation system for use in endoscopic procedures for maintaining and controlling flow of irrigation fluid to an internal body irrigation site. The system includes a tubing set comprising inflow and outflow lines and a cassette, and an fluid control module comprising a race and a pumping mechanism that squeezes the inflow line of the tubing set against the race to pump fluid to the irrigation site. The cassette includes a through opening exposing a portion of the inflow line to the race and pumping mechanism so that the cassette merely holds the inflow line in alignment with the pumping mechanism but is not required to resist the compressive force of the pumping mechanism. The cassette may include a second through opening exposing a portion of the outflow line to a valve mechanism to regulate pressure independently of the pump mechanism, and rib-or-groove alignment mechanism to align the inflow line with the pumping mechanism and the outflow line with the valve mechanism.

<CIT> discloses an apparatus for supplying liquid to a body cavity during an endoscopic procedure that includes a feedback loop-controlled liquid supply device inherently capable of supplying liquid at a substantially constant pressure substantially independent of the flow rate of liquid delivered by the liquid supply device within a relatively wide range of flow rate. Also disclosed are a disposable plastic pump cassette having an inflow pump in a housing, and an operative cannula. The surgical procedure is performed with continuous control over the body cavity pressure, regardless of the outflow flow rate.

<CIT> discloses a pressure and a vision regulation method and device for irrigation of a body cavity, in which method an inflow liquid pump pressurizes the irrigation liquid in a feed line and in which an outflow device or an external suction source drains the irrigation liquid from the body cavity through a tubing into a waste container and in which a control unit controls either the inflow liquid pump only or both the inflow liquid pump and the outflow device depending on an inflow irrigation liquid pressure from a pressure sensor, where the first control unit compares the inflow irrigation liquid pressure and flow with pressures calculated to correspond to pressure in the body cavity for the respective flow for a nominal surgical site and that a matching between the calculated values and the inflow irrigation liquid pressures is made by altering the effect of either the inflow liquid pump only or the inflow liquid pump and/or the outflow device and/or the shut off valve.

The present invention is defined by the subject matter of the independent claims. Methods of surgery or treatment are not claimed. The subject invention is directed to a new and useful system for controlling the performance range of a pneumatically sealed trocar during an endoscopic or laparoscopic surgical procedure. In an embodiment of the subject invention, the system includes a controller for delivering variable DC voltage to a DC motor, a DC motor operatively connected to the controller for driving a pump operatively connected to a pneumatically sealed trocar, a pump driven by the DC motor for circulating pressurized gas through the pneumatically sealed trocar, and a sensor for sensing pressure and/or flow parameters between the pump and the trocar to provide a feedback control signal to the controller so that the controller can vary the voltage delivered to the DC motor to affect the output pressure and flow of the pump. Preferably the system further includes an AC input voltage source and an AC-DC converter for supplying DC voltage to the controller.

In another embodiment of the subject invention, the system includes a controller for delivering variable DC voltage to at least one DC motor, at least one DC motor operatively connected to the controller for driving at least one pump operatively connected to a pneumatically sealed trocar, at least one pump driven by the DC motor for circulating pressurized gas through the pneumatically sealed trocar, and at least one sensor for sensing pressure and/or flow parameters between the at least one pump and the pneumatically sealed trocar to provide at least one feedback control signal to the controller so that the controller can vary the voltage delivered to the at least one DC motor to affect the output pressure and flow of the at least one pump during an endoscopic or laparoscopic surgical procedure.

The at least one sensor includes a first sensor for sensing positive pressure and flow parameters between the at least one pump and an inlet port of the pneumatically sealed trocar to provide a first feedback control signal to the controller and a second sensor for sensing negative pressure and/or flow parameters between the at least one pump and an outlet port of the pneumatically sealed trocar to provide a second feedback control signal to the controller.

In another embodiment, the at least one DC motor includes at least a first DC motor for driving at least one positive pressure pump connected to the pneumatically sealed trocar and at least a second DC motor for driving at least one negative pressure pump connected to the pneumatically sealed trocar. In this embodiment, the at least one sensor includes a first sensor for sensing positive pressure and/or flow parameters between the positive pressure pump and an inlet port of the pneumatically sealed trocar to provide a first feedback control signal to the controller and a second sensor for sensing negative pressure and/or flow parameters between the negative pressure pump and the outlet port of the pneumatically sealed trocar to provide a second feedback control signal to the controller.

In another embodiment of the disclosure, the at least one pump includes at least first and second pumps that are arranged in parallel and are driven by the at least one DC motor. It is envisioned that controller could be adapted and configured to control the first and second pumps at the same or different output levels to meet different system requirements.

In yet another embodiment of the invention, the at least one DC motor and the AC-to-DC converter are replaced by at least one brushless stepper motor, at least one motor driver, and a pulse generator, which function together as a type of DC controller, though technically the performance output is not controlled solely by modulating supplied DC voltage. The mechanical and pneumatic outputs of the components in this embodiment are controlled precisely by electrical signal modulation, as in the DC motor embodiments described previously. However, in this case rather than modulating DC voltage, electrical pulses controlled from a pulse generator are varied and supplied to a motor driver that drives a brushless stepper motor.

More particularly, electrical pulses of varying strength and length may be used to control precise rotation of the stepper motor by movements of a magnetic field generated by magnets in the motor. This will allow for precision control of motor behavior as well as accurate and repeatable start/stop behavior.

The disclosure is also directed to a method for controlling the performance range of a pneumatically sealed trocar. The method includes the steps of providing a pump for circulating pressurized gas through a pneumatically sealed trocar, driving the pump by way of a DC motor, and controlling the voltage delivered to the DC motor based upon sensed parameters of gas flowing between the pump and the pneumatically sealed trocar to affect the output pressure and flow of the pump during a laparoscopic surgical procedure. The method also preferably includes the step of sensing pressure and/or flow parameters of the gas flowing between the pump and the pneumatically sealed trocar.

These and other features of the control system and method and the way in which it is employed will become more readily apparent to those having ordinary skill in the art from the following enabling description of the preferred embodiments of the subject invention taken in conjunction with the several drawings described below.

So that those skilled in the art will readily understand how to use the control system and method of the disclosure without undue experimentation, preferred embodiments thereof will be described in detail herein below with reference to the figures wherein:.

Referring to the drawings wherein like reference numerals identify similar features or aspects of the embodiments of the subject invention, there is illustrated in <FIG> a system for controlling the performance range of a pneumatically sealed trocar during an endoscopic or laparoscopic surgical procedure, which is constructed in accordance with a preferred embodiment of the subject invention and designated generally by reference numeral <NUM>.

Referring to <FIG>, the system <NUM> includes a controller <NUM> for delivering variable DC voltage to a DC motor <NUM>. The DC motor <NUM> is operatively connected to the controller <NUM> for driving a positive pressure pump <NUM> that is operatively connected to a pneumatically sealed trocar <NUM>. The pump <NUM> is driven by the DC motor <NUM> to circulate pressurized gas through the pneumatically sealed trocar <NUM>. A first sensor <NUM> is provided for sensing positive pressure and/or flow parameters between the pump <NUM> and an inlet port of the pneumatically sealed trocar <NUM> to provide a first feedback control signal to the controller <NUM>.

A second sensor <NUM> is provided for sensing negative pressure and/or flow parameters between the pump <NUM> and an outlet port of the pneumatically sealed trocar <NUM> to provide a second feedback control signal to the controller <NUM>. The first and second feedback control signals enable the controller <NUM> to vary the voltage delivered to the DC motor <NUM> to affect the output pressure and/or flow of the pump <NUM>. The system <NUM> further includes an AC input voltage source <NUM> and an AC-DC converter <NUM> for supplying DC voltage to the controller <NUM>.

Referring to <FIG>, there is illustrated another embodiment of the control system of the disclosure, which is designated generally by reference numeral <NUM>. System <NUM> differs from system <NUM> in that it includes a first DC motor <NUM> for driving a positive pressure pump <NUM> connected to a pneumatically sealed trocar <NUM> and a second DC motor <NUM> for driving a negative pressure pump <NUM> connected to the pneumatically sealed trocar <NUM>. The system <NUM> further includes a first sensor <NUM> for sensing positive pressure and/or flow parameters between the positive pressure pump <NUM> and an inlet port of the pneumatically sealed trocar <NUM> to provide a first feedback control signal to a controller <NUM> and a second sensor <NUM> for sensing negative pressure and/or return flow parameters between the negative pressure pump <NUM> and the outlet port of the pneumatically sealed trocar <NUM> to provide a second feedback control signal to the controller <NUM>. As in the previous embodiment of <FIG>, the system <NUM> further includes an AC input voltage source <NUM> and an AC-DC converter <NUM> for supplying DC voltage to the controller <NUM>.

Referring now to <FIG>, there is illustrated a modified version of the control system <NUM> shown in <FIG>. Here, the system <NUM> includes two positive pressure pumps 114a and 114b, driven by respective DC motors 112a and 112b. These pumps and motors are arranged or otherwise stacked in parallel to increase the pneumatic power capabilities of the system <NUM>, and provide additional control options to improve system efficiency. Moreover, by placing two DC driven pumps in parallel, twice the pneumatic output can be supplied. In this instance, the controller or CPU <NUM> controls the performance output of one or both of the pumps, depending upon the system demands.

For example, if the two pumps 114a, 114b each have a <NUM>/min capacity and they are combined in parallel, and the operating range of the system <NUM> always requires between <NUM>-<NUM>/min, the first pump 114a could always be controlled to <NUM>% of its output (i.e., <NUM>/min), while the output of the second pump 114b could be variably controlled to between <NUM>-<NUM>/min, in order to achieve the system requirement.

Alternatively, both DC driven pumps 114a, 114b could be controlled to the same output level. For example, to achieve an <NUM>/min output, both pumps 114a, 114b would be controlled to a <NUM>/min output. Or, to achieve <NUM>/min output, the two pumps 114a, 114b could be controlled to different levels. For example, pump 114a could be controlled to <NUM>/min and pump 114b could be controlled to <NUM>/min.

In each of these alternate embodiments with multiple motors and pumps, a larger DC power supply would be required (e.g., 24V to supply two 12V motors) and the CPU <NUM> will be responsible for dividing and regulating the voltage supplied between the two motors 112a, 112b as specified, which in turn, will control the output of their respective pumps 114a, 114b. While this embodiment of <FIG> has been shown and described as having two DC driven positive pressure pumps stacked together in a parallel relationship, it is envisioned that more than two pumps or similar or varying capacity can be arranged in this manner to further increase and diversify the operational capabilities of the control system disclosed herein.

Referring to <FIG>, there is illustrated another version of the control system <NUM> shown in <FIG>. In this embodiment of the subject invention, the DC motor <NUM> and the AC-to-DC converter <NUM> shown in <FIG> are replaced by a brushless stepper motor <NUM>, a motor driver <NUM>, and a pulse generator <NUM>. Those skilled in the art might classify this embodiment as a type of DC controller, though technically the performance output is not controlled solely by modulating supplied DC voltage. Nevertheless, those skilled in the art will appreciate the similarities of this embodiment of the invention to other types of DC-controlled systems.

The mechanical and pneumatic outputs of the components in this embodiment are controlled precisely by electrical signal modulation, as in the DC motor embodiments described previously. However, in this case rather than modulating DC voltage, electrical pulses controlled from pulse generator <NUM> are varied and supplied to motor driver <NUM> that drives the brushless stepper motor <NUM>. More particularly, electrical pulses of varying strength and length are used to control precise rotation of the stepper motor <NUM> by precise movements of a magnetic field generated by magnets in the motor. This allows for precision control of motor behavior as well as accurate and repeatable start/stop behavior. Those skilled in the art will appreciate that gear-like geometry of a stepper motor also enables a control system that verifies the number of "steps" of the gear as part of its embedded controls, which may allow for simpler design of the feedback loop to control pneumatic performance of the system by alleviating the need for at least one separate sensor (such as sensor <NUM> or <NUM>).

While the embodiment of <FIG> has been shown and described as having one motor driver <NUM>, one stepper motor <NUM> and one positive pressure pump <NUM>, it is envisioned and well within the subject disclosure, that groupings of these three components (<NUM>, <NUM>, <NUM>) can be arranged in a parallel relationship as shown for example in <FIG>, to further increase and diversify the operational capabilities of the control system <NUM> disclosed herein. More particularly, as shown in <FIG>, the controller <NUM> can be configured to deliver variable pulse signals supplied by pulse generator <NUM> to a first grouping of components including motor driver 132a, stepper motor 130a and positive pressure pump 114a, as well as a second parallel grouping of components including motor driver 132b, stepper motor 130b and positive pressure pump 114b. It is envisioned that controller <NUM> would be configures to deliver the same or different strength or duration variable pulses to the parallel sets of components to meet system requirements.

Referring now in general to the various embodiments of the subject invention described herein, those skilled in the art of embedded system controls will know of several methods of supplying, modulating, and controlling a component or system behavior by varying voltage supplied to a DC component like a pump. The required components may include, but are not limited to, a power supply converter or battery, a potentiometer (which varies circuit resistance to control voltage supplied to the DC component), a computer board (e.g., Arduino or the like), a permanent magnet motor, and others.

The power supply converter or battery is used to supply the DC component with direct current (DC) rather than supplying alternating current (AC), which is supplied normally by power outlets and grids. Controlling the voltage supplied to the DC component will vary its performance output. For example, a 12V DC motor will output more power when supplied with 10V than it would when supplied with 6V. This control is frequently achieved via a loop controller in which a sensor measuring performance output (or some related metric) communicates with the computer board, which is programmed with a response. The computer board will trigger a change to the variable power supplied to the motor when the data from the sensor requires such change.

The method of the disclosure and apparatus of the subject invention modulates pneumatic power supplied to a pneumatically-sealed trocar in real-time via control of the pneumatic output of a DC driven pump. In the system <NUM> of <FIG>, the control loop is designed around three main components: a CPU control board <NUM>, a motor <NUM> that drives the pump <NUM>, and a sensor <NUM>. In this preferred embodiment, the system <NUM> consists of a transformer <NUM> that converts the AC current from the wall (outlet supply) to DC. Alternatively, you could have a battery that charges from the AC current and directly provides DC power. The available power supply must meet or exceed the rating of the powered component (for example, DC power supply must be 12V to fully power a 12V motor). After being converted, the CPU modulates how much voltage is supplied to the motor <NUM>.

Varying the voltage to the motor <NUM> will directly affect the pressure and flow output of the pump <NUM>, which is recorded by sensor <NUM> that loops back to the CPU <NUM>, informing the CPU of the system performance and guiding how to respond to continue control and modulation of the system <NUM> as required. Alternatively, the CPU <NUM> could modulate voltage supply to the motor <NUM> to vary and control vacuum pressure and gas flow using data from the negative pressure sensor <NUM>.

The CPU <NUM> could control a component like a potentiometer to modulate DC voltage supplied to the motor <NUM>. However, potentiometers can add an additional component to the design and waste heat and energy from efficiency loss. A preferred embodiment could use pulse width modulation (PWM) to control voltage supply to the motor <NUM>. This control method modulates pulses of the same magnitude voltage over variable time periods to produce an "effective" level of voltage supply. For example, PWM control of a 12V power supply would control longer duration pulses to create an "average" supply of 10V, whereas PWM control of that same 12V power supply would control shorter duration pulses to create an "average" supply of 4V. These pulses are modulated by timed control of transistors which can be turned on and off by the CPU <NUM>.

This method can be more precise and more efficient than the use of a potentiometer. Those skilled in the art will know of other ways to control and vary precise power delivery aside from using PWM. An alternate embodiment could independently control pressure and vacuum supplied to a pneumatically-sealed trocar via two independent DC pumps, as shown in <FIG>. This embodiment involves controlling one pump <NUM> to provide positive pressure and flow to the pneumatically-sealed trocar <NUM> and a separate pump <NUM> to provide a balancing negative pressure and return flow away from the trocar <NUM>. This embodiment would allow for separate, real-time, independent control over the pressure flow and return/vacuum flow which could allow for a new paradigm of granular performance control. In this embodiment, both pumps would be open to ambient and their performance would not be affected or limited by a single, closed-loop pneumatic circuit.

Whereas in the previous embodiment of <FIG> (and the system disclosed in <CIT>) the single pump pressurizes one side of the pneumatic circuit and applies suction to the other side of the circuit to create a balanced flow on both sides, this alternate embodiment shown in <FIG> would allow for the system <NUM> to control the pressure and return flows to different flow rates. This system enables the electro-mechanical control to use an additional control lever over the performance of the pneumatically-sealed trocar <NUM>. It is posited that small-scale adjustments (perhaps on the order of <NUM>/min) to change the balance of the pressure flow versus the vacuum/return flow could allow for tighter control of pneumatic performance of the trocar <NUM>.

For example, if the loop controller has a small, positive control deviation (the difference between measured performance and targeted performance in an embedded control system) then the CPU <NUM> could call for a <NUM>/min increase to the pressure pump <NUM> or a <NUM>/min decrease to the suction pump <NUM> to balance performance, whereas previously it was impossible to create an imbalance between those two flow rates. This embodiment would require the pressure pump <NUM> to be open to ambient for its intake, and the vacuum/suction pump <NUM> to be open to ambient for exhaust. It is envisioned that the open intake to the pressure pump <NUM> and the open exhaust from the vacuum pump <NUM> would be filtered through a suitable filtration device or element.

Those skilled in the art will readily appreciate that there are a number of advantages to using a DC-based control system instead of an AC-based system for the pneumatic control of a pneumatically-sealed trocar. A DC-based control system is more energy efficient than an AC-based system. An AC pump needs to be oversized in order to fully encompass the operating range of the electro-mechanical control system. The nature of AC components is that they are always fully "on", meaning that full power is required whenever the device is run.

In a DC-based system, the pump(s) need only be powered to the exact level that is required. For example, if a system has an operating range up to <NUM>/min, but a use scenario only requires an output of <NUM>/min, the AC-based embodiment requires the single AC pump to be outputting <NUM>/min (with <NUM>/min diverted away), while the DC-based embodiment could power the DC pump only to a level that outputs <NUM>/min. Not only is this arrangement more energy efficient, it reduces heat and sound generated by the moving mechanical components. As a result, it may be possible to reduce or eliminate insulating components in the design.

In addition, it may allow for fewer components, as the valve/sensors to divert flow from the AC pump output are no longer required. Fewer components allow for simpler development processes and qualification testing and will result in a cost-savings both for cost of goods and development. Furthermore, the use of a DC-based control system will not be subject to the effects that power frequency has on AC motors and pumps, whereby different power grids around the world supply power at different frequencies (typically either <NUM> or <NUM>). When powering an AC motor or pump, the output performance is slightly altered by the frequency, whereas a DC motor or pump can produce the same behavior no matter the frequency.

Claim 1:
A system (<NUM>) configured to control the performance range of a pneumatically sealed trocar (<NUM>), comprising:
a) a controller (<NUM>) configured to deliver variable DC voltage to at least one DC motor (<NUM>);
b) at least one DC motor (<NUM>) operatively connected to the controller (<NUM>) for driving at least one pump operatively connected to a pneumatically sealed trocar (<NUM>);
c) at least one pump (<NUM>) driven by the DC motor (<NUM>) for circulating pressurized gas through the pneumatically sealed trocar (<NUM>); and
d) at least one sensor (<NUM>, <NUM>) configured to sense pressure and/or flow parameters between the at least one pump (<NUM>) and the pneumatically sealed trocar (<NUM>) to provide at least one feedback control signal to the controller (<NUM>) so that the controller (<NUM>) can vary the voltage delivered to the at least one DC motor (<NUM>) to affect the output pressure and/or flow of the at least one pump during a surgical procedure,
wherein the at least one sensor (<NUM>, <NUM>) includes a first sensor (<NUM>) configured to sense positive pressure and flow parameters between the at least one pump (<NUM>) and an inlet port of the pneumatically sealed trocar (<NUM>) to provide a first feedback control signal to the controller (<NUM>) and a second sensor (<NUM>) configured to sense negative pressure and/or flow parameters between the at least one pump (<NUM>) and an outlet port of the pneumatically sealed trocar (<NUM>) to provide a second feedback control signal to the controller (<NUM>),
characterised in that the at least one pump (<NUM>) is a single pump that is configured to pressurize one side of the pneumatic circuit and apply suction to the other side of the circuit.