Abstract:
A control system for a surgical system that includes an irrigation fluid flow sensing capability. The sensing capability may be placed in the control console or in the handpiece. Irrigation flow measurements provided by the sensing capability allows the control system to vary irrigation pressure and/or flow, aspiration pressure and/or flow and power supplied to the handpiece more accurately than prior art sensors that monitor aspiration flow.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates generally to the field of microsurgery and more particularly to a control system for an ophthalmic surgery system. 
     The human eye in its simplest terms functions to provide vision by transmitting light through a clear outer portion called the cornea, and focusing the image by way of the lens onto the retina. The quality of the focused image depends on many factors including the size and shape of the eye, and the transparency of the cornea and lens. 
     When age or disease causes the lens to become less transparent, vision deteriorates because of the diminished light which can be transmitted to the retina. This deficiency in the lens of the eye is medically known as a cataract. An accepted treatment for this condition is surgical removal of the lens and replacement of the lens function by an artificial intraocular lens (IOL). 
     In the United States, the majority of cataractous lenses are removed by a surgical technique called phacoemulsification. During this procedure, a thin phacoemulsification cutting tip is inserted into the diseased lens and vibrated ultrasonically. The vibrating cutting tip liquifies or emulsifies the lens so that the lens may be aspirated out of the eye. The diseased lens, once removed, is replaced by an artificial lens. 
     A typical ultrasonic surgical device suitable for ophthalmic procedures consists of an ultrasonically driven handpiece, an attached cutting tip, and irrigating sleeve and an electronic control console. The handpiece assembly is attached to the control console by an electric cable and flexible tubings. Through the electric cable, the console varies the power level transmitted by the handpiece to the attached cutting tip and the flexible tubings supply irrigation fluid to and draw aspiration fluid from the eye through the handpiece assembly. 
     The operative part of the handpiece is a centrally located, hollow resonating bar or horn directly attached to a set of piezoelectric crystals. The crystals supply the required ultrasonic vibration needed to drive both the horn and the attached cutting tip during phacoemulsification and are controlled by the console. The crystal/horn assembly is suspended within the hollow body or shell of the handpiece by flexible mountings. The handpiece body terminates in a reduced diameter portion or nosecone at the body&#39;s distal end. The nosecone is externally threaded to accept the irrigation sleeve. Likewise, the horn bore is internally threaded at its distal end to receive the external threads of the cutting tip. The irrigation sleeve also has an internally threaded bore that is screwed onto the external threads of the nosecone. The cutting tip is adjusted so that the tip projects only a predetermined amount past the open end of the irrigating sleeve. Ultrasonic handpieces and cutting tips are more fully described in U.S. Pat. Nos. 3,589,363; 4,223,676; 4,246,902; 4,493,694; 4,515,583; 4,589,415; 4,609,368; 4,869,715; 4,922,902; 4,989,583; 5,154,694 and 5,359,996, the entire contents of which are incorporated herein by reference. 
     In use, the ends of the cutting tip and irrigating sleeve are inserted into a small incision of predetermined width in the cornea, sclera, or other location. The cutting tip is ultrasonically vibrated along its longitudinal axis within the irrigating sleeve by the crystal-driven ultrasonic horn, thereby emulsifying the selected tissue in situ. The hollow bore of the cutting tip communicates with the bore in the horn that in turn communicates with the aspiration line from the handpiece to the console. A reduced pressure or vacuum source in the console draws or aspirates the emulsified tissue from the eye through the open end of the cutting tip, the cutting tip and horn bores and the aspiration line and into a collection device. The aspiration of emulsified tissue is aided by a saline flushing solution or irrigant that is injected into the surgical site through the small annular gap between the inside surface of the irrigating sleeve and the cutting tip. 
     The preferred surgical technique is to make the incision into the anterior chamber of the eye as small as possible in order to reduce the risk of induced astigmatism. These small incisions result in a very tight wounds that squeeze the irrigating sleeve tightly against the vibrating tip. Friction between the irrigating sleeve and the vibrating tip generates heat, but the risk of the tip overheating and causing a burn to the tissue is reduces by the cooling effect of the aspirated fluid flowing inside the tip. When the tip becomes occluded with tissue, this aspiration flow can be reduced or eliminated, allowing the tip to heat up. 
     Prior art devices have used sensors that detect large rises in aspiration vacuum, and predict occlusions based on vacuum rise. Based on this sensed occlusion, power to the handpiece may be reduced and/or irrigation and aspiration flows can be increased. See U.S. Pat. Nos. 5,591,127, 5,700,240 and 5,766,146 (Barwick, Jr., et al.), the entire contents of which being incorporated herein by reference. Increased vacuum levels in the aspiration line, however, do not necessarily indicate that the flow of cooling fluid around the tip has been cut off. Even with the tightest incisions, some irrigating fluid will leak out between the wound and the outside of the irrigating sleeve. The wound leakage also provides addition cooling flow to the incision site, and measuring rises in aspiration vacuum alone does not necessarily indicate that a potential for a corneal burn exists. Therefore, power to the handpiece may be interrupted prematurely. 
     Therefore, a need continues to exist for a control system for a surgical handpiece that utilizes a better indication of fluid flow at the tip for the control of ultrasonic power levels. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention improves upon the prior art by providing a control system for a surgical system that includes an irrigation fluid flow sensing capability. The sensing capability may be placed in the control console or in the handpiece. Irrigation flow measurements provided by the sensing capability allows the control system to vary irrigation pressure and/or flow, aspiration pressure and/or flow and power supplied to the handpiece more accurately than prior art sensors that monitor aspiration flow. 
     Accordingly, one objective of the present invention is to provide a surgical console control system. 
     Another objective of the present invention is to provide a surgical console control system having an irrigation flow sensing capability. 
     Another objective of the present invention is to provide a surgical console control system that provides more accurate control of the handpiece operating parameters. 
     Another objective of the present invention is to provide a surgical console control system that provides more accurate control of the infusion operating parameters. 
     Another objective of the present invention is to provide a surgical console control system that provides more accurate control of the aspiration operating parameters. 
     These and other advantages and objectives of the present invention will become apparent from the detailed description and claims that follow. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a block diagram of a first embodiment of a control system that can be used with the present invention showing the flow sensor in the instrument. 
     FIG. 2 is a block diagram of a second embodiment of a control system that can be used with the present invention showing the flow sensor in the handpiece. 
     FIG. 3 is a block diagram of a third embodiment of a control system that can be used with the present invention showing the flow sensor in the instrument and pressurized infusion control of the infusion source. 
     FIG. 4 is a block diagram of a fourth embodiment of a control system that can be used with the present invention showing the flow sensor in the handpiece and pressurized infusion control of the infusion source. 
     FIG. 5 is a block diagram of a fifth embodiment of a control system that can be used with the present invention showing a flow sensor in the instrument and measuring air flow of the pressurized infusion source to calculate infusion fluid flow. 
     FIG. 6 is a block diagram of a sixth embodiment of a control system that can be used with the present invention showing the pressurized infusion source as a compressed compliant bag and the infusion fluid flow calculated from the rate of infusion source compression. 
     FIG. 7 is a flow chart illustrating the operation of an infusion flow control mode that can be used with the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     As seen in FIG. 1, in a first embodiment of the present invention, control system  10  for use in operating handpiece  12  includes control console  14 . Control console  14  generally includes control module or CPU  16 , aspiration pump  18 , handpiece power supply  20 , irrigation flow sensor  22  and valve  24 . Console  14  may be any commercially available surgical control console such as the ACCURUS® surgical system available from Alcon Laboratories, Inc., Fort Worth, Tex. CPU  16  may be any suitable microprocessor, micro controller, computer or digital logic controller. Pump  18  may be any suitable pump, such as a peristaltic, diaphragm or venturi pump. Power supply  20  may be any suitable ultrasound driver, such as incorporated in the ACCURUS® surgical system available from Alcon Laboratories, Inc., Fort Worth, Tex. Sensor  22  may be any commercially available flow sensor, such as Models Nos. T101D or T201D available from Transonic Systems, Inc., Ithaca, N.Y. Valve  24  may be any suitable valve such as a solenoid-activated pinch valve. Infusion source  26  may be any commercially available irrigation solution provided in bottles or bags. 
     In use, sensor  22  is connected to handpiece  12  and infusion fluid source  26  through irrigation lines  30 ,  32  and  34 . Sensor  22  measures the flow of irrigation fluid from source  26  to handpiece  12  and supplies this information to CPU  16  through cable  36 . The irrigation fluid flow data may be used by CPU  16  to control the operating parameters of console  14  using software commands that are well known in the art. For example, CPU  16  may, through cable  40 , vary the output of power supply  20  being sent to handpiece  12  though power cable  42 . CPU  16  may also use data supplied by sensor  22  to vary the operation of pump  18  through cable  44 , which aspirates fluid from handpiece  12  through line  46  and into collection container  28  through line  48 . CPU  16  may also use data supplied by sensor  22  and the applied output of power supply  20  to provide audible tones to the user. 
     As seen in FIG. 2, in a second embodiment of the present invention, control system  110  for use in operating handpiece  112  includes control console  114 . Control console  114  generally includes control module or CPU  116 , aspiration pump  118 , handpiece power supply  120  and valve  124 . Flow sensor  122  is contained within handpiece  112 . 
     In use, tip  150  is connected to fluid source  126  through sensor  122  through irrigation lines  130 ,  132  and  134 . Sensor  122  measures the flow of irrigation fluid from source  126  to tip  150  and supplies this information to CPU  116  through cable  136 . CPU  116 , through cable  138 , may open and close valve  124  so as to vary the amount of irrigation fluid reaching tip  150  from source  126 . CPU  116  may also, through cable  140 , vary the output of power supply  120  being sent to handpiece  112  through power cable  142 . CPU  116  may also use data supplied by sensor  122  to vary the operation of pump  118  through cable  144 , which aspirates fluid from handpiece  112  through line  146  and into collection container  128  through line  148 . CPU  116  may also use data supplied by sensor  122  and the applied output of power supply  120  to provide audible tones to the user. 
     As seen in FIG. 3, in a third embodiment of the present invention, control system  210  for use in operating handpiece  212  includes control console  214 . Control console  214  generally includes control module or CPU  216 , aspiration pump  218 , handpiece power supply  220 , valve  224 , pressurizing source  229 , and pressure sensor  227 . Flow sensor  222  is connected to handpiece  212  and infusion fluid source  226  through irrigation lines  230 ,  232  and  234 . Infusion source  226  may be any commercially available irrigation solution provided in bottles. Pressurizing source  229  pressurizes infusion source  226  through line  252  and is controlled by CPU  216  through cable  250 . Pressurizing source  229  may be any commercially available pressure controller, such as incorporated in the ACCURUS® surgical system available from Alcon Laboratories, Inc., Fort Worth, Tex. Pressure sensor  227  measures the pressure of infusion source  226  through lines  254  and is monitored by CPU  216  through cable  256 . Pressure sensor  227  may be any suitable commercially available pressure sensor, such as Model MPX5100 available from Motorola, Inc., Phoenix, Ariz. 
     In use, sensor  222  measures the flow of irrigation fluid from source  226  to handpiece  212  and supplies this information to CPU  216  through cable  236 . The irrigation fluid flow data may be used by CPU  216  to control the operating parameters of console  214  using software commands that are well known in the art. For example, CPU  216 , through cable  250 , may control pressurizing source  229  while reading pressure sensor  227  data through cable  256  so as to vary the pressure and amount of irrigation fluid reaching handpiece  212  from source  226 . CPU  216  may also, through cable  240 , vary the output of power supply  220  being sent to handpiece  212  through power cable  242 . CPU  216  may also use data supplied by sensor  222  to vary the operation of pump  218  through line  244 , which aspirates fluid from handpiece  212  through line  246  and into collection container  228  through line  248 . CPU  216  may also use data supplied by sensor  222  and the applied output of power supply  220  to provide audible tones to the user. 
     As seen in FIG. 4, in a fourth embodiment of the present invention, control system  310  for use in operating handpiece  312  includes control console  314 . Control console  314  generally includes control module or CPU  316 , aspiration pump  318 , handpiece power supply  320 , valve  324 , pressurizing source  329 , and pressure sensor  327 . Flow sensor  322  is contained within handpiece  312 . Infusion source  326  may be any commercially available irrigation solution provided in bottles. Pressurizing source  329  may be any commercially available pressure controller. Pressure sensor  327  may be any suitable commercially available pressure sensor. 
     In use, sensor  322  measures the flow of irrigation fluid from source  326  to handpiece  312  and supplies this information to CPU  316  through cable  336 . The irrigation fluid flow data may be used by CPU  316  to control the operating parameters of console  314  using software commands that are well known in the art. For example, CPU  316 , through cable  350 , may control pressurizing source  329  while reading pressure sensor  327  data through cable  356  so as to vary the pressure and amount of irrigation fluid reaching handpiece  312  from source  326 . CPU  316  may also, through cable  340 , vary the output of power supply  320  being sent to handpiece  312  through power cable  342 . CPU  316  may also use data supplied by sensor  322  to vary the operation of pump  318  through cable  344 , which aspirates fluid from handpiece  312  through line  346  and into collection container  328  through line  348 . CPU  316  may also use data supplied by sensor  322  and the applied output of power supply  320  to provide audible tones to the user. 
     As seen in FIG. 5, in a fifth embodiment of the present invention, control system  410  for use in operating handpiece  412  includes control console  414 . Control console  414  generally includes control module or CPU  416 , aspiration pump  418 , handpiece power supply  420 , valve  424 , pressurizing source  429 , and pressure sensor  427 . Airflow sensor  423  is connected to pressurizing source  429  and infusion source  426  through lines  432  and  452 . Sensor  423  may be any commercially available flow sensor, such as Model AWM3100V available from Honeywell Micro Switch, Freeport, Ill. Infusion source  426  may be any commercially available irrigation solution provided in bottles. 
     In use, sensor  423  measures the flow of air into the infusion source  426  and supplies this information to CPU  416  through cable  436 . The airflow data may be used by CPU  416  along with information from pressure sensor  427  for the calculation of infusion flow to the handpiece through line  434 . This infusion flow calculation may be used to control the operating parameters of console  414  using software commands that are well known in the art. For example, CPU  416 , through cable  450 , may control pressurizing source  429  while reading pressure sensor  427  data through cable  456  so as to vary the pressure and amount of irrigation fluid reaching handpiece  412  from source  426 . CPU  416  may also, through cable  440 , vary the output of power supply  420  being sent to handpiece  412  through power cable  442 . CPU  416  may also use this infusion flow calculation to vary the operation of pump  418  through cable  444 , which aspirates fluid from handpiece  412  through line  446  and into collection container  428  through line  448 . CPU  416  may also use this infusion flow calculation and the applied output of power supply  420  to provide audible tones to the user. 
     As seen in FIG. 6, in a sixth embodiment of the present invention, control system  510  for use in operating handpiece  512  includes control console  514 . Control console  514  generally includes control module or CPU  516 , aspiration pump  518 , handpiece power supply  520 , valve  524 , pressurizing source  530 , and pressure sensor  527 . Infusion source  525  may be any commercially available irrigation solution provided in bags or a custom compliant container. Pressurizing source  530  is a compressing device that squeezes infusion source  525  through mechanical link  553  in order to pressurize the fluid. The rate of compression of the infusion source is controlled by CPU  516  through cable  550 . 
     In use, CPU  516  calculates the infusion flow to the handpiece through line  534  based on the compression rate of pressurizing source  530  and the pressure data from pressure sensor  527 . This infusion flow calculation may be used to control the operating parameters of console  514  using software commands that are well known in the art. For example, CPU  516 , through cable  550 , may control pressurizing source  530  while reading pressure sensor  527  data through cable  556  so as to vary the pressure and amount of irrigation fluid reaching handpiece  512  from source  525 . CPU  516  may also, through cable  540 , vary the output of power supply  520  being sent to handpiece  512  though power cable  542 . CPU  516  may also use this infusion flow calculation to vary the operation of pump  518  through cable  544 , which aspirates fluid from handpiece  512  through line  546  and into collection container  528  through line  548 . CPU  516  may also use this infusion flow calculation and the applied output of power supply  520  to provide audible tones to the user. 
     As seen in FIG. 7, when the system of the present invention is monitoring infusion flow, the system monitors the current infusion flow and compares the actual flow against a predetermined flow rate. If infusion flow is above the predetermined rate, no action is taken by the system. If the infusion flow is below the predetermined rate, the system may take a variety of actions, such as changing the power delivered to the ultrasound handpiece, providing a variable tone to the surgeon or changing the aspiration pressure. 
     This description is given for purposes of illustration and explanation. It will be apparent to those skilled in the relevant art that changes and modifications may be made to the invention described above without departing from its scope or spirit.