GB2125487A

GB2125487A - Infusion-aspiration apparatus

Info

Publication number: GB2125487A
Application number: GB08223763A
Authority: GB
Inventors: Dermot John Pierse; Christopher William Balch
Original assignee: HPW Ltd
Current assignee: HPW Ltd
Priority date: 1982-08-18
Filing date: 1982-08-18
Publication date: 1984-03-07

Abstract

An infusion-aspiration apparatus (10) in which both the infusion and aspiration functions can be controlled by one person. The plungers of the infusion and aspiration syringes (22,30) are each driven by a motor (34) and an associated rack and pinion (14,16 and 18,20) and the two racks and pinions are drivingly coupled together by way of a differential drive gear (44). The gear (44) includes a spider (50) which can be driven by a second motor (58). When the second motor (58) is stationary the aspiration and infusion rates are equal. The second motor (58) can be energised to rotate its shaft in either direction and at variable speeds to vary the aspiration rate in relation to the infusion rate. <IMAGE>

Description

SPECIFICATION Infusion-aspiration apparatus This invention relates to infusion-aspiration apparatus.

In various surgical matters, for example anterior chamber cleansing for extra capsular procedures, it is necessary to infuse a sterile liquid into the chamber being cleansed whilst simultaneously aspirating the liquid which also carries matter being removed. To maintain a constant pressure in the chamber and to prevent, in particular, any collapse of the tissue walls it is important to maintain control over the relative rates of aspiration and infusion.

Traditionally, this has been done by using two hand-held syringes, one for infusing and the other for aspirating; this required the services of a surgeon and of a highly skilled assistant.

According to the present invention, infusion-aspiration apparatus comprises first drive means for driving an infusion means at a first predetermined rate, second drive means for driving an aspiration means at a second predetermined rate and differential-drive means coupled between the said first and second drive means for controlling the relative drive rates of the infusion means and the aspiration means.

Preferably, the first drive means includes a motor coupled to drive the infusion means at said first predetermined rate.

The motor may be provided with control means for varying its speed of rotation and hence the first predetermined rate.

The differential drive means may be pm- vided with control means for varying the relative drive rates of said aspiration means and infusion means.

The differential drive means may comprise an epicyclic gear train having a first sun wheel fixedly secured to the first drive means, a second sun wheel fixedly secured to the second drive means and planet gears coupling together said first and second sun wheels.

Control means for said gear train may be a spider member arranged to engage said sun wheels and coupled to be rotated by a second motor such that, in operation, when the second motor is stationary, the relative drive rates of the infusion means and aspiration means have a predetermined ratio, and when said second motor is energised, the said ratio can be varied about said predetermined ratio depending upon the speed and direction of rotation of the second motor.

Thus apparatus according to the invention facilitates the infusion-aspiration process and enables a surgeon to carry out the procedure without the need for a highly skilled assistant and to maintain fine control of the pressure of the liquid in the chamber being cleansed.

One form of infusion-aspiration apparatus embodying the invention will now be described, by way of example, with reference to the accompanying diagrammatic drawings, in which; Figure 1 is a front view of the apparatus; Figure 2 is a side view of the apparatus of Fig. 1; Figure 3 is a front view of part of the apparatus of Fig. 1; and Figure 4 is a sectional view taken on the line IV-IV of Fig. 3.

Referring to the drawings, there is shown an infusion-aspiration apparatus 10. In use the apparatus 10 is mounted vertically, as shown in Figs. 1 and 2, by means of a mounting member 12 for securing it to a suitable stand or support member (not shown).

The apparatus includes two racks 14,1 8 driven by pinions 16,20 respectively.

An infusion syringe 22 can be fixedly secured on a support member 24 by means of a syringe retaining spring 26 and its plunger 22a can be secured to a drive carriage 28 by a clamp 28a. The carriage 28 is mounted on the rack 14 to cause the plunger 22ato move in the syringe body with movement of the rack 14.

Similarly an aspiration syringe 30 can be fixedly secured to the support member 24 by a spring 26 and its plunger 30a secured to a drive carriage 32 by a clamp 32a. The carriage 32 is mounted for movement with the rack 18 to cause the plunger 30a to move in the syringe body with movement of the rack 18.

In operation the infusion syringe 22 is filled with a liquid and the aspiration syringe 20 is empty with its plunger 30a fully inserted.

Drive means (to be described) is provided to drive the pinions 16,20 in opposite directions so that the rack 14 causes the plunger 22a to move into the syringe 22 and force the fluid from the syringe by way of flexible tubing (not shown) into the chamber (not shown) to be cleansed.

At the same time the plunger 30a is moved in the opposite direction in the syringe 30 thereby to suck, or aspirate, from the chamber the fluid and any matter carried from the chamber by the fluid. In operation, the velocities of the plungers 22a,30a would usually be equal so that the rate of aspiration is equal to the rate of infusion.

The drive apparatus for the syringe plungers 22a,30a will now be described in more detail.

An electric motor 34 mounted on the frame of the main body 36 of the apparatus 10 is arranged to drive a worm 37 and wheel 38, the wheel 38 being fixedly secured to a main shaft 40 which is, in turn, fixedly secured to the infusion drive pinion 16. Thus when the motor 34 is energised it drives the infusion rack 14 in a direction determined by the direction of rotation of the motor shaft 34a to cause the plunger 22a to move in a direction to discharge or to charge the syringe 22 with fluid.

The infusion drive pinion 16 is also fixedly connected to a primary sun wheel bevel gear 42 of a differential gear arrangement 44 which is arranged to drive a secondary sun wheel bevel gear 46 by way of planet gears 48. The sun wheel 46 is fixedly connected to the aspiration drive pinion 20. The planet gears 48 are mounted on a spider 50 and, provided that the spider remains stationary, operation of the motor 34 will cause the pinions 16,20 to drive their associated carriages 28,32 on racks 14,18 at the same rate but in opposite directions so that the aspiration rate will equal the infusion rate.

The spider 50 is fixedly secured to a spider shaft 52 which is, in turn fixedly secured to a wheel 54 arranged to be driven by a worm 56 and a second motor 58. The shaft 52 passes through gear wheels 46 and 20 in such a manner that they are free running on the shaft. Thus the spider shaft can be driven by the motor 58 by way of the worm 56 and wheel 54, the ratios of which are so chosen as to prevent back driving by the wheel when the motor 58 is stationary and without external brakes being applied to the motor shaft 56a or spider shaft 52. The gears thus operate as an epicyclic gear train in a similar fashion to a differential gear.

Thus when the motor 58 is stationary the infusion and aspiration drive 14,16 and 18,20 respectively run at the same speed but in opposite directions as aforementioned.

Operation of the motor 58 will rotate the spider 50 and, depending upon the selected direction, will increase or decrease the velocity of the aspiration drive 18,20 in relation to the infusion drive 14,16.

Thus the ratio of the speed of aspiration to the speed of infusion can be varied and controlled, by control of the speed and direction of the motor shaft 56a. This can extend from a speed several times the fundamental speed to a reduction to zero, or even in the reverse direction so that the aspiration carriage 32 moves in the same direction as the infusion carriage 28.

Speed and direction controls for the motors 34 and 58 are shown generally by control knobs 60 on the front panel of the apparatus 10. A cable 62 is provided for connection to a source of electrical supply for the apparatus 10.

A control level 64 is pivotally mounted on the apparatus 10 and is arranged to lift the drive pinions 16,20 from the mesh or their associated drive racks 14,18. This facilitates precise positioning of the carriages 28,32 on the racks 14,18 respectively which will depend on the contents and design of the syringes being used.

The speed and direction of rotation of the shaft 58a of the motor 58 can be varied by the surgeon by means of a foot control (not shown) connected to the apparatus 10 via a cable 66.

It will be appreciated that the infusionaspiration apparatus, which is capable of operation by one person, can use standard, packed-sterile components, such as syringes and flexible tubing which are both relatively cheap and readily available in a medical environment. A wide range of sizes and styles of syringe can be easily attached to the apparatus 10 by simple clamping techniques.

Claims

1. Infusion-aspiration apparatus comprising first drive means for driving an infusion means at a first predetermined rate, second drive means for driving an aspiration means at a second predetermined rate and differentialdrive means coupled between the said first and second drive means for controlling the relative drive rates of the infusion means and the aspiration means.

2. Apparatus according to Claim 1, in which the first drive means includes a motor coupled to drive the infusion means at said first predetermined rate.

3. Apparatus according to claim 2, in which the motor is provided with control means for varying the speed of rotation and hence the first predetermined rate.

4. Apparatus according to any one of the preceding claims, in which the differential drive means is provided with control means for varying the relative drive rates of said aspiration means and infusion means.

5. Apparatus according to Claim 4, in which the differential drive means comprises an epicyclic gear train having a first sun wheel fixedly secured to the first drive means, a second sun wheel fixedly secured to the second drive means and planet gears coupling together said first and second sun wheels.

6. Apparatus according to Claim 5, including control means for said gear train, said control means comprising a spider member arranged to engage said sun wheels and coupled to be rotated by a second motor such that, in operation, when the second motor is stationary, the relative drive rates of the infusion means and aspiration means have a predetermined ratio, and when said second motor is energised the said ratio can be varied about said predetermined ratio depending upon the speed and direction of rotation of the second motor.

7. Apparatus according to any one of the preceding claims in which each of said infusion drive means and aspiration drive means comprises a rack driven by a pinion and carriage means mounted for movement on said rack for operating the infusion means and aspiration means respectively.

8. Apparatus according to Claim 7, comprising means for disengaging each pinion from its associated rack to facilitate mounting of its associated infusion or aspiration means.

9. Infusion-aspiration apparatus, constructed, arranged and adapted to operate substantially as hereinbefore described with reference to and as illustrated in the accompanying diagrammatic drawings.