Patent Application
20080147023
The present invention relates to surgical systems and methods. More particularly, the present invention relates to systems and methods for controlling fluid flow. Even more particularly, embodiments of the present invention relate to systems and methods for controlling the flow of fluid entering from the bottom of an aspiration chamber in a surgical system.
The human eye can suffer a number of maladies causing mild deterioration to complete loss of vision. While contact lenses and eyeglasses can compensate for some ailments, ophthalmic surgery is required for others. Generally, ophthalmic surgery is classified into posterior segment procedures, such as vitreoretinal surgery, anterior segment procedures, such as cataract surgery, and combined anterior and posterior segment procedures.
The surgical instrumentation used for ophthalmic surgery can be specialized for posterior segment procedures or anterior segment procedures or support both. In any case, the surgical instrumentation often requires the use of associated consumables such as surgical cassettes, fluid bottles/bags, tubing, hand piece tips and other consumables.
A surgical cassette can provide a variety of functions depending on the procedure and surgical instrumentation. For example, surgical cassettes for cataract surgeries help manage irrigation and aspiration flows into and out of a surgical site. Surgical cassettes provide an interface between surgical instrumentation and the patient, delivering pressurized infusion and aspiration flows into and out of the eye. For a typical Venturi based aspiration system, the fluid is first extracted from a patient eye into an aspiration chamber, and then removed from the aspiration chamber into a drain bag.
The aspiration chamber can serve many functions. For example, the aspiration chamber can function as a sensing chamber for a continuous level sensing, which provides volumetric and aspiration flow information to the surgical console. The aspiration fluid generally enters the aspiration chamber from the top. Due to dripping, the aspiration fluid entering from the top of the aspiration chamber unavoidably causes disturbance to the fluid surface and consequently affects the continuous level sensing. Moreover, when the fluid port is at the top of the chamber, not all of the fluid can be used for reflux procedures. Consequently, new solutions are needed to minimize the disturbance to the liquid/air surface in the aspiration chamber and to make more fluid available for reflux. Previously, to conduct a reflux procedure a mechanical force is applied to the aspiration line to force the liquid out of the handpiece. The forced backflow of liquid (i.e., the aspiration fluid travels in the opposite direction to its normal movement) may or may not successfully unblock or unclogged the handpiece. Moreover, because the aspiration port is positioned at the top of the aspiration chamber, the forced out liquid is not necessarily replaced by more liquid. Therefore, a new solution is needed to make the reflux operation sustainable. Embodiments of the invention disclosed herein can address these needs and more.
Embodiments of the present invention provide a new system, apparatus, and method for controlling the flow of aspiration fluid in a surgical cassette. When the aspiration fluid enters the aspiration chamber of the surgical cassette, the disturbance to the liquid/air surface must be minimized so as to facilitate the many functions of the aspiration chamber. For example, through a continuous level sensing the aspiration chamber functions as a sensing chamber and provides volumetric and aspiration flow information to the surgical console. The aspiration chamber also functions as a fluid reservoir for sustained reflux and priming.
Embodiments of the invention address these needs by placing the aspiration port at or close to the bottom of the aspiration chamber. When the aspiration fluid enters the aspiration chamber from below the fluid surface (e.g., from a port located at the bottom or on a sidewall close to the bottom), it does not create disturbance at the liquid/air interface and thus minimizes any effect on the continuous level sensing. Also, since the aspiration port is placed at or very close to the bottom of the aspiration chamber, the liquid inside the chamber can be fully used.
Embodiments of the present invention provide many advantages over prior art systems and methods of aspiration flow control in surgical cassettes. For example, by placing the aspiration port at the bottom of the aspiration chamber, it eliminates the disturbances to the fluid surface when the aspiration fluid enters the aspiration chamber. As a result, it minimizes the noise introduced to the continuous level sensing and improves the signal to noise ratio, which leads to more accurate and reliable data needed to determine the fluid to air ratio changes over time and flow rate of aspiration fluid into and out of the aspiration chamber.
Another advantage provided by embodiments of the invention is directed to the reflux and priming of the aspiration line. In embodiments where the aspiration port is positioned at the bottom of the aspiration chamber, the liquid in the chamber can be fully used for reflux and priming. This makes it possible for sustained reflux and pushing priming.
A more complete understanding of the present invention and the advantages thereof may be acquired by referring to the following description, taken in conjunction with the accompanying drawings in which like reference numbers indicate like features and wherein:
Preferred embodiments of the invention are illustrated in the FIGURES, like numerals being used to refer to like and corresponding parts of the various drawings.
Surgical console 100 also includes a connection panel 120 used to connect various tools and consumables to surgical console 100. Connection panel 120 can include, for example, a coagulation connector, connectors for various hand pieces, and a cassette receiver 125. Surgical console 100 can also include a variety of user friendly features, such as a foot pedal control (e.g., stored behind panel 130) and other features.
In operation, a cassette (not shown) can be placed in cassette receiver 125. A clamp in surgical console 100 clamps the cassette in place to minimize movement of the cassette during use. The clamp can clamp the top and bottom of the cassette, the sides of the cassette or otherwise clamp the cassette.
Surgical console interface section 170 can face the console during use and provide an interface for fluid flow channels (e.g., flow channel 177 for the peristaltic pump provided by an elastomeric pump membrane), valves (e.g., infusion/aspiration valves), and other features to manage fluid flow. Cassette 150 can also attach to a fluid bag (not shown) to collect fluids during a procedure.
Surgical cassette 150, according to various embodiments of the present invention, includes chambers to hold fluids for aspiration and infusion. For example, chamber cartridge 180 can include two chambers 181 and 182. A third chamber 185 can be internal to cassette 150 on the opposite side of cassette 150 from chamber cartridge 180 (e.g., at the side of cassette 150 indicated by 190). In one embodiment, chambers 181 and 182 are infusion chambers and chamber 185 is an aspiration chamber. Valve seals 187/188 can be formed of separate pieces or a single piece of an elastomeric material and can return to approximately their original shapes when the forces applied by the actuators are removed. Different valves in cassette 150 can have the same or different configurations to control the flow through the cassette.
The surgical cassette is held in place by a clamp having a bottom rail 314 and a top rail (not shown). Each rail can have outer clamping fingers (e.g., clamp finger 324) that contact the cassette in corresponding clamping zones and inner clamping fingers to locate the cassette during insertion and push the cassette out of cassette receiver during release. A release button 326 is pressed to initiate release of the cassette from the clamp. Cassette receiver 325, according to one embodiment, can include linear light sources to project light into the walls of the cassette chambers and sensor arrays to detect the light refracted through the chamber (or reflected from the chamber wall). Each linear light source can include a plurality of light sources vertically arranged (i.e., to project light along vertically spaced transmission paths) and positioned to project light into a wall of the cassette. For example, linear light source 332 can project light into the walls of the aspiration chamber 185. Respective linear sensor arrays can receive light refracted through the chamber or reflected at the chamber surface. Each sensor array can include vertically arranged portions to receive light through the wall of the cassette chamber. The vertically arranged portions can be, for example, pixel sensors, separate sensors or other mechanisms for sensing illumination.
As described in U.S. patent application Ser. No. 11/477,032, entitled “System and Method of Non-Invasive Continuous Level Sensing,” filed Jun. 28, 2006, which is hereby fully incorporated by reference herein, the level and hence volume of fluid in a chamber can be determined by projecting light into the wall of the cassette and evaluating the light pattern detected by the corresponding linear sensor array. By tracking the change in volume over time, the volumetric or mass flow rate of fluid into/out of the chamber can be determined. As noted above, the flow rate of fluid into a chamber can be regulated by a vacuum source, e.g. a Venturi Pump in the surgical console.
The configuration of
Surgical system 500 can further include surgical cassette 522 inserted into surgical console 502. Surgical cassette 522 can include a fluid chamber 524, such as an infusion chamber or aspiration chamber that can act as a fluid reservoir for surgical instrumentation. Fluid from a hand piece 576 is led to a valve chamber 528 via an inlet flow passage 530 and from valve chamber 528 to fluid chamber 524 via an outlet flow passage 532. The flow rate of fluid flowing from the hand piece 676 to fluid chamber 524 is controlled by the pneumatic pressure/vacuum source 556.
Controller 508 can implement various control schemes known or developed in the art to generate signals to control the pneumatic pressure/vacuum source 556 based on a comparison of a measured flow rate and a setpoint flow rate. In one embodiment, chamber 524 is an aspiration chamber connected to a venturi-based pressure/vacuum system, 556 which works in concert with controller 508 to supply suction pressure to the aspiration chamber. In this case, aspiration chamber is connected to a handpiece via an aspiration line. Aspiration fluid is extracted by suction from a surgical site via the handpiece and sent to the aspiration chamber through the aspiration line.
In one embodiment, aspiration chamber 624 is connected to a venturi-based pressure/vacuum system 608 through port 636. In one embodiment, pressure/vacuum system 608 resides in surgical console. In one embedment, pressure/vacuum system 608 provides aspiration pressure or vacuum. One example of a venturi-based vacuum system is the ACCURUS® system from Alcon Laboratories, Inc. In conjunction with an aspiration pressure system, a controller such as controller 608 as described above with reference to
Previously, the aspiration chamber is fitted with an aspiration port on the top. When the aspiration fluid extracted from the surgical site enters into the aspiration chamber through the aspiration port, it drips from the top and causes disturbance to the fluid surface in the aspiration chamber. To eliminate this problem and minimize the disturbance to the liquid/air surface, aspiration chamber 624 is designed to have an aspiration port 632 located at the bottom of aspirating chamber 624, allowing aspiration fluid 620 from aspiration line 602 to enter aspiration chamber 624 from below the surface of fluid 620. This bottom-entry configuration eliminates dripping and thus the disturbance to the continuous level sensing function described above with reference to
In one embodiment, aspiration port 632 is positioned close to the bottom (e.g., on a sidewall) of aspiration chamber 624. When aspiration fluid 620 enters aspiration chamber 624, it again enters from below the fluid surface and does not affect the continuous level sensing. As a result, it minimizes the noise introduced to the continuous level sensing, allowing aspiration chamber 624 to provide more accurate and reliable data needed to determine the fluid to air ratio changes over time.
Having the aspiration fluid entry located at or close to the bottom of an aspiration chamber has additional advantages. For example, since the aspiration port is placed at or very close to the bottom of the aspiration chamber, the liquid inside the chamber can be fully used. More particularly, the aspiration chamber also functions as a fluid reservoir for sustained reflux and push priming, where the liquid inside the aspiration chamber is pressurized and pushed towards the hand piece to replace the air volume in the aspiration line. Reflux can be achieved by pressurizing the aspiration volume. Since aspiration port 632 is arranged to be at or close to the bottom, air is not introduced into aspiration line 602 during reflux. Priming aspiration line 602 can be similarly done with ease due to the bottom-entry design of aspiration chamber 624.
Furthermore, in some cases, hand piece 601 may be blocked (e.g., due to tissue or other extracted solid materials in aspiration fluid 620) or become restrictive (e.g., due to down scaling). In one embodiment, a control scheme as described below, can be implemented to flush out aspiration fluid 620 via hand piece 601.
For example, the flow rate can be adjusted based on whether the flow rate is outside of some range about the setpoint. Moreover, the controller can be programmed to perform a flushing operation. For example, if a command or signal is received by the controller indicating a need or desire to flush the aspiration line, the controller can signal the vacuum or similar pressure system connected to the aspiration chamber to increase the air volume inside the aspiration chamber, forcing the fluid out of the aspiration chamber through the aspiration port located at or near the bottom of the aspiration chamber. A push priming operation for the aspiration chamber can be conducted in a similar manner by increasing the air volume inside the aspiration chamber. Since the aspiration port is located at or near the bottom of the aspiration chamber, priming the aspiration line or tube can be easy and efficient as only a minimal amount of fluid is necessary.
While the present invention has been described with reference to particular embodiments, it should be understood that the embodiments are illustrative and that the scope of the invention is not limited to these embodiments. Many variations, modifications, additions and improvements to the embodiments described above are possible. It is contemplated that these variations, modifications, additions and improvements fall within the scope of the invention as detailed in the following claims.
