Apparatus for controlling fluid flow through a surgical instrument and the temperature of an ultrasonic instrument

An apparatus essentially consisting of an aspiration conduit, a pump, and a pressure transducer and logic console which senses vacuum level fluctuations in the aspiration conduit. The aspiration conduit is connected to a surgical cavity. The pump creates a vacuum in the pre-pump aspiration conduit and transports the fluid and/or tissue material from the surgical cavity, through the aspiration conduit and into a collection container. The logic console responds to a predetermined rate of decrease in vacuum in the pre-pump aspiration conduit and causes an electric signal to be sent to 1) the pump, which upon receiving such signal, reverses its action and/or: 2) an electromechanical valve located along the aspiration conduit, which upon receiving such signal acts to occlude the aspiration conduit and terminate the removal of tissue or fluid from the surgical site. The reversal of rotation prevents the occurrence of a fluid surge which would result in the collapse of the surgical cavity. In addition a surgical tool is disconnected from its source of power when the temperature of the surgical tool is above a predetermined value.

FIELD AND BACKGROUND OF THE INVENTION 
This invention relates to an apparatus which controls the rate of fluid 
flow through a closed or partially closed hydraulic system. In particular, 
this invention concerns an apparatus which 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 
thereof. 
The delicate structures within the surgical cavity, such as an iris, cornea 
or lens capsule which surround the human lens in the case of the eye, or 
the walls of the human gallbladder or ureter in cases of stone removal, or 
the walls of the human arteries in cases of removal of arterial plaque, or 
the lining of joints in cases of tissue removal therefrom, can experience 
severe damage from such a collapse. 
This invention relates particularly to the field of eye surgery in which 
material such as a cataract is removed from the eye, and other types of 
surgery involving the removal of material from within a surgical cavity by 
the use of fluid flow and aspiration methods. Devices for this purpose 
exist in the field of eye surgery, as well as surgery involving stone 
removal from the gallbladder, kidneys, or ureters. Such methods have also 
been utilized to remove obstructions from arteries. 
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 pursuant to two 
events. One such event is when an obstruction, as aforementioned above, is 
released. The other such event is when trapped air creates uncontrolled 
aspiration forces within the aspiration conduit. 
The sudden release of an obstruction, which may occur at any location in 
the pre-pump aspiration conduit, results in the occurrence of a fluid 
surge. 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, a fluid surge develops and travels from the surgical cavity 
into the aspiration conduit. The fluid surge is caused by the 
aforementioned 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. 
Generally, fluid aspiration devices require the use of a flexible conduit 
as well as containers to collect the aspirated fluid and/or material. Such 
devices may also employ mechanisms whereby the flexible conduit may be 
vented to the atmosphere in order to release accumulated vacuum within the 
tubing. 
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 being treated and the collapse 
thereof. 
Various prior art devices have been disclosed for controlling fluid flow 
and the direction thereof during the removal of material from within the 
surgical cavity. However, devices employing the automated reversal of a 
pump, in combination with a pressure transducer and logic system, have not 
been disclosed. 
Mechanisms currently in existence to prevent a fluid surge include 
intermittent venting of fluid into the aspiration conduit from another 
source. Such systems require a second source of fluid and shunting valves 
which may be costly to manufacture and/or more prone to failure than the 
aspiration system described herein. The apparatus disclosed in this 
specification is safer, less costly to manufacture, and more efficient 
than the other fluid control system. 
U.S. Pat. No. 4,705,500 to Reimels discloses an aspiration-irrigation 
system, utilizing a peristaltic pump and a foot operable control unit 
which controls the speed and rotational direction of the pump. The control 
unit essentially consists of a foot pedal and a control box. 
The rotational direction of the pump is a function of the depression of the 
pedal. Rotation of the pump counter-clockwise creates a negative pressure 
within the aspiration. port, causing aspiration of fluid/tissue particles, 
while rotation of the pump clockwise creates a positive pressure for 
ejection of blockage particles. 
Although Reimels recites a pump which reverses rotation, it does not 
disclose or suggest a pressure transducer or a logic system, which senses 
pressure changes and transmits such information to the pump, which may 
then automatically reverse its rotation as described in this application. 
Rather, the operator must manually reverse the rotation of the pump by 
varying the amount of pressure on the pedal. 
U.S. Pat. No. 4,832,685 to Haines discloses an irrigation-aspiration 
apparatus consisting of an aspiration conduit, a peristaltic pump, and a 
pressure transducer connected to the aspiration conduit. The pressure 
transducer generates an electrical signal proportional to the vacuum in 
the aspiration conduit. 
An obstruction in the aspiration is indicated by the vacuum exceeding a 
pre-set level, whereby the pressure transducer shuts off the pump. The 
obstruction is ejected from the aspiration conduit by equalizing the 
pressures in an irrigation conduit and the aspiration conduit, which is 
accomplished by filing the conduit system with liquid. As soon as the 
pressure is equalized, the pressure transducer detects the lower level of 
suction and restarts the pump. 
Although Haines recites a peristaltic pump and a pressure transducer, it 
does not disclose or suggest that the pump reverses rotation upon the 
vacuum exceeding a predetermined value. 
U.S. Pat. No. 4,180,074 to Murry discloses an irrigation-aspiration device 
comprised of an aspiration tube, a peristaltic pump, a pressure 
transducer, and a diaphragm. Although Murry recites a peristaltic pump and 
a pressure transducer, it does not disclose reversal of the peristaltic 
pump when a blockage of the aspiration tube occurs. 
Additionally, U.S. Pat. No. 4,493,698 to Wang discloses a method for 
controlling the vacuum level in a debris receptacle and aspiration conduit 
during surgery. Such method primarily consists of an aspiration conduit, a 
peristaltic pump, a pressure transducer, potentiometers, and a controller. 
The system's vacuum is pre-set by the potentiometer, which sends signals of 
the desired vacuum level to the controller. The controller receives the 
signal of the actual vacuum in the aspiration conduit from the pressure 
transducer and adjusts the opening of valves in order to maintain the 
desired pressure in the aspiration conduit. 
Like the aforementioned patens of Murry and Haines, Wang does not disclose 
or suggest the reversing of the pump'rotation when an occlusion occurs. 
U.S. Pat. No. 4,798,580 to DeMeo discloses an irrigation and aspiration 
system. However, it does not disclose a pressure transducer nor the 
reversal of the pump when an occlusion in the aspiration conduit occurs. 
SUMMARY OF THE INVENTION 
The invention's object is to overcome the disadvantages in the prior art 
devices by providing an improved fluid control apparatus for use during 
surgery. More specifically, 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.

DETAILED DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENTS 
The invention will now be described with reference to the preferred 
embodiments thereof illustrated in FIGS. 1 and 2. 
The flow conduit apparatus 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. 
As illustrated in FIG. 1, it stimulates 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 FIG. 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. 
It is accordingly intended that all matter contained in the above 
description or shown in the accompanying drawings be interpreted as 
illustrative rather than in a limiting sense. 
It is also to be understood that the following claims are intended to cover 
all of the generic and specific features of the invention as described 
herein, and all statements of the scope of the invention which, as a 
matter of language, might be said to fall there between.