Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M1/00—Suction or pumping devices for medical purposes; Devices for carrying-off, for treatment of, or for carrying-over, body-liquids; Drainage systems
  • A61M1/71—Suction drainage systems
  • A61M1/74—Suction control
  • A61M1/743—Suction control by changing the cross-section of the line, e.g. flow regulating valves
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M1/00—Suction or pumping devices for medical purposes; Devices for carrying-off, for treatment of, or for carrying-over, body-liquids; Drainage systems
  • A61M1/71—Suction drainage systems
  • A61M1/74—Suction control
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F9/00—Methods or devices for treatment of the eyes; Devices for putting in contact-lenses; Devices to correct squinting; Apparatus to guide the blind; Protective devices for the eyes, carried on the body or in the hand
  • A61F9/007—Methods or devices for eye surgery
  • A61F9/00736—Instruments for removal of intra-ocular material or intra-ocular injection, e.g. cataract instruments
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M1/00—Suction or pumping devices for medical purposes; Devices for carrying-off, for treatment of, or for carrying-over, body-liquids; Drainage systems
  • A61M1/71—Suction drainage systems
  • A61M1/77—Suction-irrigation systems
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M39/00—Tubes, tube connectors, tube couplings, valves, access sites or the like, specially adapted for medical use
  • A61M39/22—Valves or arrangement of valves
  • A61M39/227—Valves actuated by a secondary fluid, e.g. hydraulically or pneumatically actuated valves
  • A61M39/228—Valves actuated by a secondary fluid, e.g. hydraulically or pneumatically actuated valves with a tubular diaphragm constrictable by radial fluid force

Definitions

• This invention relates to methods and means for accomplishing surgical removal of material from the eye with increased safety .
• a variety of procedures are currently being employed to accomplish removal of cataracts and other material from within the eye.
• One of those procedures is often referred to as an irrigation-aspiration method. It involves breaking, tearing or otherwise dividing the material to be removed into small fragments and aspirating those fragments from the eye into a fluid flow line by which they are carried away. Fluid pressure levels in the apparatus by which that procedure is practiced are dictated by the need to preserve pressure balance within the eye. More particularly, in the case of cataract removal, it is important to prevent or minimize collapse of the cornea into the cavity formed by removal of lens material. Difficulty in preventing such collapse has tended to discourage some surgeons form the use of the irrigation-aspiration method notwithstanding that it's successful use can result in substantially less discomfort to patients in the post-operative period.
• an incision is made on or about the corneal margin to gain access to the lens .
• a tool in the form of a probe which houses the outlet end of a fluid supply line and the inlet end of an aspiration line is inserted into the opening under the cornea.
• Some means is provided for dividing the lens material into small fragments.
• the means for dividing eye material may comprise no more than a cutting edge at or near the flow tube openings . More commonly an ultrasonically driven tool is included to aid in division of the material to be removed. The task is to separate that material and divide it into small pieces, aspirate that material from the eye and to replace the material so removed with water, actually a balanced, salt in water solution.
• the opening in which the probe is inserted is small, 6 millimeters or less and the opening tends to close so that a substantially closed cavity is formed as lens material is removed.
• the water is disposed under the cornea and serves to prevent corneal collapse into the cavity. It is the water in that cavity that is used to aspirate and carry away lens material. Accordingly the flow of water to the lens cavity must equal the flow of water being removed by aspiration augmented by enough water to account for increases in lens cavity size. The flow ratio must be maintained while maintaining enough water in the lens cavity to prevent the cornea's collapse.
• the inner surface of the cornea is covered by a layer of irreplaceable endothelium cells . Collapse of the cornea would bring those cells into destructive contact the the removal tool.
• Negative pressure in the aspiration circuit is developed by a pump in most practical systems. Peristaltic pumps are usually used but whatever the pump form, small cyclic variation in negative pressure occur and tend to make the cornea oscillate over the cavity being formed by lens . A greater and more troublesome pressure variation occurs when an occlusion or partial occlusion of the aspiration opening is overcome. Occlusion occurs when a piece of eye material too large to pass through the aspiration inlet is drawn to it. Pressure in the aspiration line is forced more negative by the aspiration pump until the blocking material is divided or drawn into the inlet and the occlusion is cleared.
• the negative aspiration pressure now greater in absolute value than the supply pressure, evacuates the lens cavity and collapses the cornea.
• the supply water includes entrained air and there may be bubbles in the supply.
• Still another object is to provide such improvements in a way that is inexpensive, is applicable to all current brands of irrigation-aspiration systems apparatus and requires less, not more, skill in performing such procedures as cataract removal.
• the objects and advantages of the invention stem, in part, from the provision of an article of manufacture for inclusion in the aspiration line of an irrigation-aspiration apparatus for conducting eye surgery by the irrigation-aspiration method the article comprising a flow tube the walls of which have sufficient renitence to maintain the flow path open at negative internal pressure values corresponding to the positive internal pressure values of the irrigation line of said apparatus, said walls being responsive to more negative internal pressures to deform to reduce the cross-sectional area of said flow path.
• a tool in the preferred form which comprises dividing means for dividing material found in the interior of an eye and two flow paths each having openings proximate to one another and to said dividing means .
• the tool further comprises a variable flow resisting element responsive to increasing negative pressure to increase it's resistance to flow connected in series with one of said flow paths .
• Figure 1 is a schematic diagram of a presently preferred irrigation-aspiration apparatus for use in conducting cataract removal by the irrigation-aspiration method
• Figure 2 is a schematic diagram of a fragment of the tool of the apparatus of Figure 1 shown as it might appear while in use during cataract removal;
• Figure 3 is a simplified, cross-sectional view of the preferred vacuum controlled flow resistor.
• Figure 4 is a graph depicting pressure variations in the eye and in the supply and aspirating flow paths in a representative situation in the absence of the invention.
• Figure 5 is a graph depicting pressure variations in the eye and tool in a representative situation during use of the apparatus of Figure 1 with the improvement of the invention in place;
• Figure 6 is a perspective view of a preferred form of double flowpath vacuum controlled flow resistor
• Figure 7 is a cross-sectional view of another, form of vacuum controlled resistor; and Figure 8 is a cross-sectional view taken on line 8-8 of Figure 7.
• the apparatus of Figure 1 includes a source of irrigation fluid, a balanced salt in water solution, referred to here as water. It includes a tool for removing material from the inner eye, a supply line arranged to conduct water under positive pressure from the source to the tool, a means for developing a negative pressure and an aspiration line arranged to utilize the negative pressure to conduct water and removed material from the tool.
• the elements thus far described form an irrigation- aspiration system of conventional form.
• the source is the water container 10.
• the supply line is numbered 12.
• the tool is numbered 14 and the aspiration line is numbered 16.
• the tool is mounted on a handle which is not shown here both because the handle per se does not form part of the invention and for the sake of clarity.
• the tool performs several f nctions . It must divide and sever the lens or other material to be removed. To that end it is formed with cutting edges at it's forward extremity at 22.
• Some tools incorporate ultrasonically activated elements to facilitate material division.
• the lens or other material is to be removed by aspiration into and along the aspiration line.
• the vehicle for aspiration is water which is supplied from the source 10 by line 12.
• the water is supplied at positive pressure by elevating the water container 10. In this case it is mounted on. a pole 30. In a typical case it is mounted about 30 inches above the working level of the tool.
• the operating surgeon may control the supply pressure by having the bottle elevated or lowered in some degree.
• Negative pressure for aspiration is developed by any convenient means and in the case of most systems is developed by connecting the aspiration line to a pump.
• Peristaltic pumps are commonly used and it is such a pump that is depicted at 32 in Figure 1.
• each of the supply aspiration line ends is necessarily small because those ends must be placed in close proximity to the cutting edges and they and the cutting edges are inserted through an edge opening the cornea into the lens to be viewed with a microscope during the removal phase of the procedure. That is depicted schematically in Figure 2 wherein the end of the tool is numbered 24. It extends under the cornea 26 into the lense 28.
• the conventional irrigation-aspiration apparatus includes a normally open, solenoid actuated clamp valve which may be mounted on the pump unit .
• the supply line is placed in the clamp structure such that it is pinched closed when the solenoid is closed by operation of a foot switch.
• Another valve responsive to operation of the foot switch and located in an air inlet line, opens the aspiration line to atmosphere.
• They are also the only protection in the conventional system against the consequences of a step function increase in negative pressure in the cavity from which material is being removed. The primary occasion for such an increase is the sudden relief, of blockage of the aspiration tube inlet. If a corneal collapse is observed, the surgeon can pinch of the water supply, open the aspiration line to relieve the negative pressure, and stop the pump.
• the lower dashed line of the graphs represents the negative pressure at the aspirating line inlet downstream from the occlusion and, in the case of Figure 5, upstream from the vacuum controlled resistor.
• the dottle line in Figure 5 represents pressure in the aspiration line downstream from the vacuum controlled resistor. If adjusted properly, the negative pressure at the aspiration line inlet balances the positive supply pressure so that the cavity pressure, the solid line, corresponds to ambient atmospheric pressure in the absence of an occlusion. When occlusion occurs, flow resistance at the aspiration inlet approached infinity.
• the pump pulls down the pressure in the aspiration line to a value substantially below normal operating value.
• the cavity pressure increases somewhat but the increase is limited because water leaks from the cavity via the incision.
• a vacuum responsive, variable flow resistance element in the aspiration line.
• a vacuum responsive, variable flow resistance element is included in Figure 1 where it is identified by the numeral 40. It forms part of the tool 14 in the preferred form. The effectiveness of the element is greatest when it is close to the aspiration line inlet .
• Element 40 may have a variety of forms. Flow resistance in a flow line varied with cross-section area, flow path shape, obstruction configuration, length of restrictions and some other factors. It is currently preferred to employ a flow section in the aspiration line which will deform in response to increase in negative pressure to reduce the cross-sectional area of the flow path and which tends to reform to increase flow area when aspirating line pressure becomes less negative.
• the currently preferred element having that quality is depicted in Figure 3 and is the element 40 of Figure 1. It is shown in cross-section taken on a plane which contains its longitudinal axis . It is an elongated cylindrical tube having reduced outer wall diameter and it has reduced wall thickness, except at its ends. In relaxed condition the renitence of the tube forces it to substantially cylindrical shape.
• the cross sectional area is approximately equal to the cross-section flow area, of the remainder of the aspiration line other than at the tool.
• the section of reduced wall thickness is at least one quarter of an inch long and more preferably is about one inch long.
• the wall thickness in the reduced area is from 0.020 inches to 0.001 inches. It has a cross sectional flow area in relaxed condition between 0.0005 to 0.05 square inches and is formed of an inert elastomeric material, preferably a silicon rubber. It should collapse nearly completely at some negative
• suction at the aspiration line inlet will not increase further. If the occlusion has not been cleared, suction is no longer available to clear it .
• the line must remain open in some degree to achieve clearance. As long as the line remains open in some degree, suction force is available by
• the pump controller can be arranged to cease pumping if negative pressure becomes excessive. Complete closure of the resistance element is then useful only in the vent of failure of the pump controller to limit suction.
• Figure 5 illustrates that effect of the negative pressure responsive, variable resistance of the invention is to convert the system that is normally underdamped at the eye cavity to an overdamped system immediately on release of an occlusion.
• the pressure of the irrigation fluid, the supply water is substantially constant before, during and after overcoming an occlusion with aspiration pressure.
• pressure in the cavity increases but the increase is slight because the water escapes at the incision from the space under the cornea.
• the pump "draws down" the aspiration line
• the degree in which the pressure downstream from the cavity is permitted to go negative is determined by the negative pressure at which the variable resistance device, element 40, shuts off communication in the line.
• variable resistance device 40 has limited the negative pressure of the aspiration line upstream from the device to a lesser value in Figure 5.
• the pressure of water in the eye cavity and the renitence of the variable resistance element tend to force the flow path of the variable resistance device to increased area and lower resistance.
• negative pressure downstream toward the pump tends to draw the device's walls to smaller area. Consequently, the device presents a considerably higher flow resistance at the beginning of the transition period which slowly decreases to a smaller value as the fluid flows through it. The net result is reduced rate of pressure change in the eye cavity and a much smaller and non-oscillatory negative pressure excursion and that translates into minimal corneal collapse.
• the scale lines and the dashed cavity pressure lines in Figure 4 and 5 correspond substantially to oscilloscope scale lines and traces recorded during actual test of a system with the vacuum controlled resistor in the case of Figure 5 and without it in the case of Figure 4.
• the bottle was mounted 70 centimeters above the tool.
• the supply and aspiration liens had an inside diameter of 2 millimeters .
• the vacuum controlled resistor had a relaxed inside diameter of 0.06 inches. It had a wall thickness reduced to 0.005 inches over a length of one inch and was made of medium hardness, silicon rubber flow tube. It was located in series in the aspiration line eight inches fro to aspiration line inlet .
• the interval between adjacent vertical scale lines represents one volt or 40 millimeters of mercury.
• the interval between horizontal scale lines is 0.2 seconds. In both Figures the occlusion was cleared at 0.4 seconds. In Figure 4, the eye cavity pressure dropped to about negative 90 millimeters of mercury. In Figure 5, inclusion of the vacuum controlled resistor limited the drop in the eye cavity to less than 20 millimeters of Mercury. In
• the negative pressure in the aspiration line upstream from the vacuum controlled resistor reached about 250 millimeters of mercury.
• Increasing the wall thickness of the resistor to 0.006 inches resulted in an reduction of the peak pressure to negative 300 millimeters and an increase to a wall thickness of 0.007 inches resulted in a peak pressure reduction to about 350 millimeters of mercury.
• the ratio of change in peak negative pressure to wall thickness change can be reduced substantially, the wall thickness dimension made less critical, by connecting two or more vacuum control resistors in parallel as shown in Figure 6. In some cases the parallel arrangement may be preferred.
• FIG. 7 Another variation is shown in Figures 7 and 8.
• the exterior of the vacuum controlled resistor 300 is subjected to the pressure in a chamber 302 which is included in series in the water supply line 304.
• the effect of the vacuum controlled resistor is made more uniform despite variation in the height of the supply water container.
• the degree in which flow resistance is increased is a joint function of the negative pressure in the aspiration line and the positive pressure in the supply line.
• vacuum controlled resistor is intended to be a generic description rather than a designator of only the particular form shown and described.

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• Health & Medical Sciences (AREA)
• Heart & Thoracic Surgery (AREA)
• Vascular Medicine (AREA)
• Engineering & Computer Science (AREA)
• Anesthesiology (AREA)
• Biomedical Technology (AREA)
• Hematology (AREA)
• Life Sciences & Earth Sciences (AREA)
• Animal Behavior & Ethology (AREA)
• General Health & Medical Sciences (AREA)
• Public Health (AREA)
• Veterinary Medicine (AREA)
• External Artificial Organs (AREA)

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Citations (8)

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• 1989
  • 1989-11-28 US US07/442,306 patent/US5106367A/en not_active Expired - Fee Related
• 1992
  • 1992-02-13 JP JP5514014A patent/JPH07505541A/ja active Pending
  • 1992-02-13 EP EP92913567A patent/EP0625916A4/en not_active Withdrawn
  • 1992-02-13 AU AU21984/92A patent/AU2198492A/en not_active Abandoned
  • 1992-02-13 WO PCT/US1992/001226 patent/WO1993015776A1/en not_active Application Discontinuation
  • 1992-03-28 TW TW081102398A patent/TW243411B/zh active

Patent Citations (8)

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