Abstract:
A surgical handpiece having an integrated aspiration pump and vacuum and/or flow sensor. Suitable pumps included micromachined peristaltic pumps and ultrasonic pumps.

Description:
This invention relates to a surgical handpiece and more particularly an ophthalmic phacoemulsification handpiece. 
     BACKGROUND OF THE INVENTION 
     A typical ultrasonic surgical device suitable for ophthalmic procedures consists of an ultrasonically driven handpiece, an attached hollow cutting tip, an 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 at its nodal points. 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; and 4,922,902, the entire contents of which are incorporated herein by reference. 
     When used to perform phacoemulsification, 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 in the eye tissue in order to gain access to the anterior chamber of the eye. The cutting tip is ultrasonically vibrated along its longitudinal axis within the irrigating sleeve by the crystal-driven ultrasonic horn, thereby emulsifying upon contact 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 or a flow source in the console draws or aspirates the emulsified tissue from the eye through the open end of the cutting tip, the bore of the cutting tip, the horn bore, 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 outside surface of the cutting tip. 
     Existing phacoemulsification systems have the aspiration pumping mechanism and the vacuum sensing hardware contained within the console. The irrigation and aspiration tubings used to connect the handpiece to the control console typically can be up to two meters in length. These flexible tubings necessarily introduce some fluidic compliance and/or delay into the otherwise closed fluid systems, making it difficult to control exactly what is occurring at the surgical site. 
     One suggested method of increasing the fluidic response of the system is disclosed in U.S. Pat. No. 5,733,256, the entire contents of which being incorporated herein by reference. The system disclosed in this patent places the pressure, vacuum and flow sensors either in, or very near to, the handpiece. While such an arrangement can increase the sensitivity of the system, the aspiration pumping mechanism is located in the control console, allowing the fluidic compliance and delay difficulties associated with the prior art systems to remain. 
     Accordingly, a need continues to exist for an integrated ultrasonic handpiece that minimizes fluidic compliance and delay. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention improves upon prior art surgical handpieces by integrating the aspiration pump and vacuum and/or flow sensors within the handpiece. Suitable pumps include micromachined peristaltic pumps and ultrasonic pumps. 
     Accordingly, one objective of the present invention to provide a phacoemulsification system that minimizes fluidic compliance and delay. 
     A further objective of the present invention to provide an ultrasonic handpiece having an integrated vacuum and/or flow sensors. 
     Another objective of the present invention to provide an ultrasonic handpiece having an integrated aspiration pump. 
     Other objects, features and advantages of the present invention will become apparent with reference to the drawings, and the following description of the drawings and claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic cross-sectional view of the handpiece of the present invention. 
     FIG. 2 is a cross-sectional view of one embodiment of the handpiece of the present invention. 
     FIG. 3 is a schematic illustration of the operation of an ultrasonic pump that may be used with the present invention. 
     FIG. 4 is a cross-sectional view of a second embodiment of the handpiece of the present invention similar to FIG. 1 but without a medial sensing section. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     As best seen in FIG. 1, handpiece  10  of the present invention is generally divided into proximal pumping section  29 , medial sensing section  35  and distal transducer section  15 , which are contained within hollow outer shell  12 . Distal transducer section  15  includes ultrasonic horn  14 , ultrasonic cutting tip  16 , compression nut  13  and piezoelectric crystals  18 . Distal transducer section  15  is held within hollow shell  12  by seals  20  and  22 . Shell  12  and distal transducer section  15  are of any conventional construction well-known in the art. 
     Proximal pumping section  29  generally contains pump  28  which aspirates fluid from the surgical site through tip  16 , lumen  25  and out aspiration port  30 . Pump  28  may be any suitable micropump, such as the ultrasonic micropump described below, or a micromachined peristaltic pump such as the pump described in U.S. Pat. No. 5,705,018, the entire contents of which being incorporated herein by reference. 
     Medial sensing section  35  generally contains sensor  32 , which may be any suitable vacuum or flow sensor such as the MEMS sensor described in U.S. Pat. No. 5,733,256 or sensor Model No. EPI-050 available from Entran Devices. Sensor  32  provides feedback to the control console (not shown) for precise monitoring and control of vacuum and/or flow in handpiece  10 . Isolator  38  helps prevent mechanical energy transfer between pumping section  29  and transducer section  15 . Suitable isolators  38  include silicone rubber O-rings. 
     Pumping section  29 , sensing section  35  and transducer section  15  are held within hollow shell  12  by seals  20  and  22 . Seals  20  and  22  may be of any conventional construction well-known in the art. 
     Irrigation fluid is supplied to the surgical site through lumen  24  and tip cap sleeve  26  in a conventional manner. Electric power and feedback signals for pump  28 , sensor  32  and piezoelectric crystals  18  are provided to/from the control console (not shown) through electrical fitting  34 . 
     As best seen in FIG. 4, handpiece  210  may alternatively be constructed without medial sensor section  35 . 
     As best seen in FIG. 2, proximal pumping section  129  of handpiece  110  may contain ultrasonic micropump  128 , having external ultrasonic pump horn  127  and internal ultrasonic pump horn  133 , piezoelectric crystals  135  and compression nut  139 . Pumping chamber  136  is formed between internal horn  133  and external horn  127 . Internal horn  133  may be threaded at rear seal  122  to allow internal horn  133  to be replaced. This internal horn design places a nodal point at rear seal  122  and allows aspiration port  130  to be connected directly to this nodal point. The pumping action within micropump  128  is created by the pressure differential produced by pump horn  133  and the fluid within pumping chamber  136 . Micropump  128 , at resonant frequency, produces vibrational nodes at crystals  135  and rear seal  122  and vibrational antinodes at distal end  131  of pump horn  133  and distal end  141  of compression nut  139 . 
     FIG. 3 generally illustrates the operation of micropump  128 . As internal pump horn  133  vibrates, there is a net increase in pressure at point P 3  relative to point P 2  that is created by the nonlinearities in energy transfer between internal pump horn  133  and the fluid within pumping chamber  136 . Using the feedback signal from sensor  132 , the control console (not shown) can precisely control the vacuum and/or flow within lumen  125  by adjusting the power supplied to piezoelectric crystals  135 . Placing both the sensor and the pump immediate to the surgical site minimizes the control delay of conventional systems. 
     While certain embodiments of the present invention have been described above, these descriptions are given for purposes of illustration and explanation. Variations, changes, modifications and departures from the systems and methods disclosed above may be adopted without departure from the scope or spirit of the present invention.