Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Reexamination Certificate
1999-12-21
2002-08-27
Dawson, Glenn K. (Department: 3763)
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
C604S070000, C604S131000
Reexamination Certificate
active
06440105
ABSTRACT:
This application claims priority of German Patent Application Number 198 59 133.0-41, filed Dec. 21, 1998, the entire disclosure of which is considered to be part of the present disclosure and is specifically incorporated by reference herein.
The present invention relates to an ejection device for the high-pressure ejection of a liquid or a liquid containing solid particles, comprising a head unit and a pressure chamber which opens into a distal ejection opening and is delimited by a working piston which, upon application of an elastic impact on its end facing away from the pressure chamber, is capable of transmitting a compression wave by which the pressure chamber-facing end of the working piston is displaceable into the pressure chamber so that the volume thereof is reduced. The reduction in volume of the pressure chamber is significantly smaller than the volume of the pressure chamber resulting in high-pressure ejection of a small quantity of the liquid through the ejection opening. Further, the ejection device comprises a drive unit having a drive member which is accelerated along an acceleration portion within the drive unit to generate the elastic impact to be transmitted to the working piston.
Ejection devices of the above described type are known, for example, from EP 771 219, which describes said devices as being specially designed for the ejection of precisely dosed, minute amounts of liquid, which may be in the range of cubic millimeters, so that these devices are particularly well-suited as medical instruments for the injection of minute doses of liquid drugs which are to be administered with high precision.
The ejection of such small amounts of liquid is achieved by the drive member transmitting only an elastic impact to the working piston so that the latter is not moved any further into the pressure chamber by the drive member. That is, after having transmitted the impact, the drive member no longer exerts any external driving force upon the working piston so that the amount of liquid contained in the pressure chamber and defined by the working piston is not ejected in the way it would in a common syringe, but exclusively by means of the compression wave excited by the impact transmitted through the working piston. The compression wave propagates into the pressure chamber and causes the liquid to be ejected from the ejection opening at high pressure. The ejection pressure, and thus the volume or amount of liquid ejected from the opening, may be precisely controlled by suitably adjusting the velocity of the drive member since this velocity determines the magnitude of the impact which is transmitted.
According to the ejection devices described in EP 0 771 219, the volume of the pressure chamber considerably exceeds the stroke volume of the working piston so that a small, precisely dosed amount of liquid may be ejected regardless of the actual size of the pressure chamber.
To prevent the drive member from exerting any external force on the working piston after the impact has been transmitted, it is possible, for example, to stop the application of a driving force acting on the drive member towards the working piston as soon as the transmission of the impact starts, or to provide a stopper which prevents the drive member from transmitting any force to the working piston after the impact has been transmitted.
The working piston is preferably made of a solid material which transmits elastic shock waves with as little loss as possible, such as a metallic material. The drive member may be any component which can be accelerated across an acceleration portion, such as a drive piston which may be accelerated within a drive pipe and is preferably coaxially aligned with the working piston. However, the drive member may also be designed other than as a piston, for example as a plate or a rocker arm which acts upon the working piston so that a driving impact is exerted thereupon.
The drive member may be driven pneumatically, hydraulically, mechanically, or electromagnetically. The means driving the drive member may be designed such that they enable only a single working stroke of the drive member. However, the drive member may preferably be driven such that it successively transmits periodically repeated impact pulses so that the total amount of liquid being ejected may be controlled by suitably adjusting the number of repetitions.
In the endoscopic version known from EP 0 771 219, the working piston is formed as a probe extending within the endoscopic catheter and having a proximal probe head arranged in an acceleration pipe. The acceleration pipe accommodates a working piston which acts upon the probe head so that a compression wave is excited within the probe that causes the end of the probe located in the catheter to be displaced into the pressure chamber formed by the lumen of the catheter, so that liquid is ejected.
However, the ejection devices known from EP 0 771 219 are difficult to clean and sterilize because of the integral structure of their head units containing the liquid to be ejected.
The present invention provides an ejection device of the initially mentioned type whose head unit may be easily cleaned and sterilized, and which at the same time enables an adequate protection of the liquid to be ejected from contamination, and in particular from any contamination caused by the drive unit of the device.
According to the present invention, the pressure chamber of the ejection device is at least partially formed by a pressure cavity provided in the head unit of the device. Furthermore, the head unit and the drive unit of the device are formed as separate, independent units which are mounted to each other by means of a separable mounting coupling. Further, an intermediary member is provided between the working piston and the acceleration portion, which is formed as a separate component and transmits the elastic impact from the drive member to the working piston. Said intermediary member is arranged in the drive unit of the device and provides a tight seal between the acceleration portion of the drive unit and the working piston.
Since the head unit and the drive unit of the ejection device according to the present invention are designed as separate units which are separably connected to each other, the head unit containing the liquid to be ejected may be easily and separately cleaned and sterilized. The drive unit requires either no sterilization at all, or only local sterilization at its end facing the head unit. Since said two units of the ejection device are separately sealed, and since especially the acceleration portion of the drive unit is sealed against the head unit, any contamination of the liquid accommodated in the head unit by dirt particles or pathogens present in the drive unit is safely prevented. Further, it is possible to easily and, thus, quickly replace the head unit by another one containing a different liquid drug, for example.
In the ejection device according to the present invention, the impact is transmitted via the intermediary member which is acted upon by the drive member. When the drive member abuts against the intermediary member, a shock wave is excited within the intermediary member which propagates therethrough and is transmitted by the intermediary member to the working piston which in turn transmits the shock wave into the liquid contained in the pressure chamber. The intermediary member is particularly advantageous since it transmits the impact to the working member while remaining itself in a stationary position, provided that it has been designed with a suitable mass and abuts against the working piston preferably without play. In this way, the sealing of the acceleration portion achieved by means of the intermediary member is ensured also during impact transmission.
This sealing principle for impact drives is also described in DE 196 18 971 A1, although in connection with a kidney stone crusher.
The intermediary member is preferably made of a solid material which transmits elastic shock waves possibly without loss, such as a me
Dawson Glenn K.
Ferton Holding SA
Griffin & Szipl, P.C.
Maynard Jennifer
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