APPARATUS FOR CONTROLLING FLUID FLOW THROUGH A SURGICAL INSTRUMENT AND THE TEMPERATURE OF AN ULTRASONIC INSTRUMENT

Abstract: An apparatus including an aspiration conduit (1), a pump (2) and a pressure transducer (3) and logic console (4) which determines vacuum level fluctuations in the aspiration conduit. The aspiration conduit is connected to a surgical cavity. The pump (2) creates a vacuum in the aspiration conduit (1) downstream and transports the fluid and/or tissue material from the surgical cavity, through the aspiration conduit and into a collection container (11). The logic console (4) responds to a predetermined rate of decrease in vacuum in the aspiration conduit (2) and causes an electric signal to be sent to the pump (2), which upon receipt of the signal reverses its action and/or to an electromechanical valve located along the aspiration conduit (2) that in response to receipt of the signal occludes the aspiration conduit and terminates the removal of tissue or fluid from the surgical cavity. The reversal of rotation prevents the occurrence of a fluid surge that would result in the collapse of a surgical cavity. In addition, a surgical tool (24) is disconnected from its source of power when the temperature of the surgical tool is above a predetermined value.

Description: APPARATUS FOR CONTROLLING FLUID FLOW THROUGH A SURGICAL INSTRUMENT AND THE TEMPERATURE OF AN ULTRASONIC INSTRUMENT FIELD AND BACKGROUND OF THE INVENTION This invention relates to an apparatus and method which controls the rate of fluid flow through a closed or partially closed hydraulic system. The apparatus controls the rate of fluid flow at a surgical site, thus preventing the occurrence of a fluid surge, the sudden increase of vacuum within a surgical cavity, and the collapse of the cavity. The collapse of the cavity leads to severe damage of the delicate structures within the surgical cavity, such as an iris, cornea or lens capsule which surround the human lens in the case of eye surgery involving cataract removal, or the walls of the human gallbladder or ureter in the case of stone removal, or the walls of the human arteries in the case of arterial plaque removal, or the lining of joints in the case of tissue removal. Conventionally, material removal from a cavity is effected with fluid flow and aspiration conduits in a surgical handpiece. Ultrasonic or laser and/or mechanical cutting are employed to reduce the unwanted material to a size which may flow uninhibited through the aspiration conduit. However, such material may not always be invariably reduced to an appropriate size, thus resulting in an obstruction in the aspiration conduit. A fluid surge at the surgical cavity generally occurs when an obstruction is suddenly released or when trapped air creates uncontrolled aspiration forces within the aspiration conduit. As the obstruction impedes fluid flow within the aspiration conduit, the pump employed by the system continues to operate, thereby increasing the vacuum in the pre- pump conduit. Upon release of the obstruction from its location within the conduit, a fluid surge develops and travels from the surgical cavity into the aspiration conduit. The fluid surge is caused by the decrease in vacuum and a rebound of the aspiration conduit, which had partially collapsed in response to the vacuum within it. Other reasons for the occurrence of the fluid surge include the expansion and contraction of air which may at times gain access to the aspiration conduit. A fluid surge may be caused by the sudden contraction of air within the aspiration conduit upon release of an obstruction, when such air had previously expanded during obstruction of the aspiration conduit. Conventionally, the elasticity of the aspiration conduit as well as the air spaces within the container used for collection and/or air introduced into the system during operation may act to create forces which may collapse or expand the conduit and thereby create undesirable, uncontrolled aspiration forces within the system. This can result in periods of undesirable and dangerously increased flow through the aspiration system, with subsequent loss of pressure within the surgical cavity causing collapse of the cavity. SUMMARY OF THE INVENTION The invention's object is to prevent a fluid surge from occurring during aspiration from a surgical cavity which would result in the collapse of the cavity. This is accomplished by occluding the aspiration conduit and/or reversing the flow at some portion of the aspiration system. The invention embodies an aspiration conduit, which may extend from a surgical handpiece into a collection container, and a pump, which reverses rotation upon receiving an electric signal from a logic console which receives information from a pressure transducer of a sudden decrease in vacuum (increase in pressure) in the pre- pump aspiration conduit. The function of the logic console is to monitor pressure changes within the aspiration conduit as a function of time. Thus, by standard means, the rate of vacuum change within the system can be constantly monitored. Should the rate of vacuum loss exceed a predetermined rate, the logic console would send an electronic signal to the pump which in turn would reverse rotation at a rate and duration which are predetermined and may be programmable, i.e. the rate and/or duration of pump reversal could be proportional to the rate of vacuum loss. Another mechanism which may be employed to prevent a fluid surge, and which mechanism may be used with or without simultaneous pump reversal, is the following. Upon determining that a sudden decrease of vacuum within the pre-pump aspiration conduit has developed, the logic console sends an electronic signal to an electromechanically operated valve situated at the aspiration conduit at a location which is within or in close proximity to the surgical handpiece. The valve acts to compress or otherwise occlude the aspiration conduit, thus immediately terminating the removal of tissue or fluid from the surgical site. Upon the receipt of electronic information from the pressure transducer that vacuum levels within the aspiration conduit have been reduced to a predetermined level and/or that elimination of the rapid decrease in vacuum within the aspiration conduit by either the aforementioned pump reversal, aspiration conduit obstruction, or by standard venting means have been accomplished, the logic console would deliver an electric signal to the electromechanical system responsible for occlusion of the aspiration conduit, and such obstruction would be relieved by opening of the valve mechanism. BRIEF DESCRIPTION OF THE DRAWINGS The nature and advantages of the invention will be better understood when the detailed description of the invention is considered in conjunction with the drawings provided herein: FIG.1 illustrates schematically a fluid control system comprised of an aspiration conduit 1 , which is connected to a collection container, a pump, a pressure transducer, a logic console and an electromechanical valve. FIG.2 illustrates schematically a system for removing fluid and/or tissue from a surgical site, the system being comprised of an ultrasonic surgical handpiece, an ultrasonic generator, a thermostat, and a thermocouple. DETAILED DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENTS The flow control apparatus of the invention is adaptable to any surgical instrument which is used to aspirate tissues and/or fluids from the body. As shown in Fig. 1, fluid and/or material is drawn from the surgical cavity via a surgical handpiece 10 through the aspiration fluid conduit 1 by the pump 2 and is discharged into a collection container 11. A peristaltic pump 2 is preferred, but not required in this invention, because of its lack of contamination, good controllability, and high suction capability. The pump 2 simulates a ferris wheel, rotating and containing sequential protuberances which squeeze the aspiration fluid conduit 1 , thereby creating vacuum and flow. Other pumps capable of causing a reversal of fluid flow to occur, such as a scroll pump, may also be used. A pressure transducer 3 constantly monitors pressure within the aspiration conduit 1, and thereby senses any fluctuations of vacuum, which always occur in the development of a fluid surge within said conduit. The transducer relays such information to the logic console 4 which monitors the rate of pressure change as a function of time. The logic console can be any conventional logic console now available on the market and well known to those skilled in the art. At the moment the rate of vacuum loss reaches or exceeds a pre-determined value, the logic console 4 generates an electric signal which is relayed to the pump 2. The electric signal may be proportional to the rate of change in the vacuum level. Upon receiving such signal, the pump 2 reverses its rotation, thereby increasing the pressure in the pre-pump aspiration conduit and thus preventing the occurrence of a fluid surge. Also, as a separate function or in conjunction with the above described mechanism, a signal that the rate of vacuum loss has exceeded a predetermined level may be sent from the logic console to an electromechanical control valve 5 situated at or near the surgical handpiece. This valve would then be activated, compressing or otherwise occluding the aspiration conduit. Upon the receipt of electronic information from the pressure transducer that vacuum levels within the aspiration conduit have been reduced to a predetermined level and/or that elimination of the rapid decrease in vacuum within the aspiration conduit by either the aforementioned pump reversal, aspiration conduit obstruction, or by standard venting means have been accomplished, the logic console would deliver an electric signal to the pump 2 which may thereby reverse to its normal rotation and/or to the electromechanical system responsible for occlusion of the aspiration conduit, whereby such obstruction would be relieved by opening of the valve mechanism. As illustrated in Figure 2, the apparatus may be used in conjunction with an ultrasonic surgical handpiece 24, which reduces the material removed from the surgical cavity to a suitable size for aspiration purposes, and an ultrasonic generator 25 for powering the surgical handpiece 24. In employing an ultrasonic surgical handpiece 24, a thermocouple 29 and a thermostat 28 may be used. The thermocouple 29 will sense the temperature at a selected point of the handpiece, and will relay a signal to the thermostat 28 of such reading. The thermostat 28 will determine when the thermocouple relayed information indicates that the temperature has reached a maximum, predetermined limit. The thermostat will then send a signal to the ultrasonic generator 25 to terminate its power to the surgical handpiece 24, thus preventing the development of a dangerously high temperature at the site, which might otherwise damage the surrounding tissues. The system of Fig.2 can be used with the system of Fig.1.

Claims: WHAT IS CLAIMED IS: 1. An apparatus for controlling fluid flow through a surgical instrument in response to sudden release of an obstruction, comprising an aspiration conduit adapted for connection with a surgical instrument; a pump connected to said aspiration conduit; a sensor that senses pressure level within said aspiration conduit; and a logic console that directs actuation of said pump to pump fluid to flow in one direction through said aspiration conduit to create suction at a pressure level within said aspiration conduit and thereby remove fluid material from the surgical instrument handpiece, said logic console making a determination based on the pressure sensed by said sensor as to whether a rate of decrease in vacuum level within said aspiration conduit as results from release of an obstruction in said aspiration conduit exceeds an acceptable rate of decrease in vacuum level and, if so, directing said pump to effect reversal in flow direction of the fluid through said aspiration conduit and thereby causing said pressure to increase within said aspiration conduit and prevent the fluid from surging into the aspiration conduit from the surgical instrument and thereafter, in response to making a further determination based on the pressure sensed by said sensor of an occurrence of at least any one of attainment of acceptable vacuum level within said aspiration conduit and an elimination of the rate of decrease in vacuum level within said aspiration conduit in excess of the acceptable rate of decrease, directing said pump to resume fluid flow in said one direction through said aspiration conduit. 2. An apparatus as in claim 1, characterised in that said sensor is a pressure transducer, further comprising a logic console that monitors changes is said pressure within said aspiration conduit as a function of time and which provides a signal to said pump to effect said flow reversal in response to monitoring said sudden rise in said pressure. 3. An apparatus as in claim 2, characterised in that said logic console provides said flow reversal at any one of a rate and a duration which is proportional to a rate of vacuum loss within said aspiration conduit. 4. An apparatus as in claim 1 , further characterised by a valve occluding said aspiration conduit in response to a rate of vacuum loss within said aspiration conduit exceeding a level. 5. An apparatus as in claim 1, characterised by a surgical handpiece connected to said aspiration conduit. 6. An apparatus for controlling fluid to a surgical instrument in response to sudden release of an obstruction, comprising an aspiration conduit adapted for connection with a surgical instrument; a valve connected to said aspiration conduit and arranged to occlude the same; a sensor that senses pressure within said aspiration conduit; and a logic console making a determination as to whether a rate of vacuum decrease within said aspiration conduit as results from release of an obstruction in said aspiration conduit exceeds an acceptable rate of decrease based on pressure levels sensed by said sensor and, if so, directing said valve to actuate to occlude said aspiration conduit and thereafter, in response to making a further determination with the logic console based on the pressure levels sensed by said sensor of an occurrence of at least one of an attainment of an acceptable vacuum level within said aspiration conduit and an elimination of the rate of vacuum loss within said aspiration conduit in excess of the acceptable rate of decrease, directing said valve to actuate to open said aspiration conduit. 7. An apparatus as in claim 6 in combination with a surgical instrument handpiece that has a source of power for powering the handpiece; a temperature sensor that senses temperature at an exterior surface of said handpiece; and a thermostat for shutting off said source of power to said handpiece in response to the temperature sensor sensing the temperature as exceeding a level. 8. An apparatus as in claim 7, characterised in that said temperature sensor is a thermocouple. 9. An apparatus as in claim 6, characterised by a surgical handpiece connected to said aspiration conduit. 10. An apparatus as in claim 10, further comprising: a collection container downstream of said valve and said aspiration conduit and into which is received the removed fluid and material. 11. An apparatus for stopping operation of a surgical instrument handpiece that is powered by a source of power, comprising a temperature sensor arranged to sense temperature on an exterior surface of the handpiece; and a thermostat responsive to said temperature sensor sensing temperature above a level for shutting off the source of power to said handpiece. 12. An apparatus as in claim 10, characterised in that said temperature sensor is a thermocouple. 13. A method of controlling fluid flow through a surgical instrument in response to sudden release of an obstruction, comprising the steps of: sensing pressure within an aspiration conduit that is adapted for connection with a surgical instrument handpiece; pumping fluid to flow in one direction through said aspiration conduit to suction at a pressure level within said aspiration conduit and thereby remove fluid material from the surgical instrument; effecting reversal in flow direction of the fluid in response to making a determination with a logic console based on the step of sensing that a rate of decrease in vacuum within the aspiration conduit as results from release of an obstruction in the aspiration conduit exceeds an acceptable rate of decrease, said reversal causing said pressure within said aspiration conduit to increase; thereafter making a further determination with the logic console based on the step of sensing of an occurrence of at least one of an attainment of an acceptable vacuum level within the aspiration conduit and an elimination of the rate of decrease in vacuum level within the aspiration conduit in excess of said acceptable rate of decrease; and resuming fluid flow in said one direction in response to making the further determination of the occurrence having taken place. 14. A method as in claim 13, characterised in that said flow reversal is carried out at any one of a rate and a duration which is proportional to a rate of vacuum loss within said aspiration conduit. 15. A method as in claim 13, further characterised by a valve occluding said aspiration conduit in response to a rate of vacuum loss within said aspiration conduit exceeding a level. 16. A method for controlling fluid flow to a surgical instrument in response to sudden release of an obstruction, comprising the steps of: removing fluid and material from the surgical instrument; sensing a pressure level within said aspiration conduit; and occluding the aspiration conduit by closing a valve in response to making a determination with a logic console that a rate of vacuum decrease within said aspiration conduit exceeds an acceptable rate of decrease based on pressure levels sensed by said sensor as results from a release of an obstruction in said aspiration conduit and, thereafter, opening the aspiration conduit by opening the valve in response to making a further determination with the logic console based on the pressure levels sensed by said sensor of an occurrence of at least one of an attainment of an acceptable vacuum level within said aspiration conduit and an elimination of the rate of vacuum loss within said aspiration conduit in excess of the acceptable rate of decrease. 17. A method as in claim 16, further characterised by steps of sensing temperature at an exterior surface of said handpiece while the exterior surface is at a surgical site in tissue; and shutting off said source of power to said handpiece in response to sensing the temperature as exceeding a level. 18. A method of stopping operation of a surgical instrument handpiece, comprising the steps of: sensing temperature at an exterior surface of a surgical instrument handpiece while the exterior surface of the handpiece is at a surgical site in tissue; and shutting off a source of power to said handpiece in response to the temperature sensor sensing the temperature as exceeding a level.

Inventors: MACKOOL RICHARD, MACKOOL, RICHARD
Applicants: MACKOOL RICHARD, MACKOOL, RICHARD
Application year: 1996
Main classification: A61M1
IPC codes: A61B17, A61B19, A61F9, A61M1