Medical infusion and aspiration system

Details Medical infusion and aspiration system Medical infusion and aspiration system

2001-06-15

2003-05-20

Casler, Brian L. (Department: 3763)

Surgery

Means for introducing or removing material from body for...

Treating material introduced into or removed from body...

C604S131000, C604S030000, C604S031000, C604S035000, C604S189000, C128SDIG001

Reexamination Certificate

active

06565535

ABSTRACT:

FIELD OF INVENTION
This invention relates to medical systems, and more specifically, to a medical infusion and aspiration system which provides a highly accurate, easily operated, disposable and reliable way to deliver any type of liquid or reagent with few moving parts.
BACKGROUND
There exists numerous ways to pump and aspirate liquids, beginning with a doubly open pipette and progressing to highly sophisticated electromechanical software correcting systems with many moving parts and error checking systems. Improvements in pumping systems have centered on the use of electronic controls to compensate for the mechanical limitations of current pumping systems, which generally use non-rigid materials. Many of these more sophisticated pumping mechanisms have valves and chambers that disturb the reagents normally used in such devices. The basic problem has been that in medical and other applications, there have been only a few instances where pulsatile infusion is required, and in those instances, the conventional pumping systems merely rely upon starting and stopping the pump to achieve a pulsatile regimen. Furthermore, the approach to accuracy in pumping has been to slow the device so that a precise metering could take place, which is not desired in several new medical treatments. Current products only offer pump accuracy specifications of plus- or minus 2 to 5 percent, over the entire reservoir, nor for each pulse, thereby making individual deliveries much less accurate. Thus, since there has been no apparent need for a device which could both be accurate, and still pump at a relatively high rate of flow, the field had not included a pump which can be both accurate in a pulsatile delivery, and have high rates of flow. The use of higher volumes in delivering medicines are often not medically indicated and many of the current systems have resorted to averaging out individual error to get a reportable accuracy level which is tolerable but never optimal. In fact, reporting and delivering accuracy over the entire reservoir does not deliver what the newer treatments now desire, and leads the user to believe in individual accuracy of each aliquot which in not in fact delivered.
In addition, many of the problems associated with mistakes in the delivery of medicines into patients have resulted from errors in the concentrations of the active reagent. Furthermore, most medicines have a relationship to the weight of a patient, such that their drug labels give levels of optimal administration, which should not be exceeded in the ordinary practice of medicine. Other sources of inaccurate concentrations in the delivery of medicines are the forces of ionization and collection of medicines on the surfaces of the bag or container used as a reservoir to store and deliver the medicine. The medicine can also collect on the sides of the container, and only be delivered in a relatively short period of time.
In addition to the problems discussed above, most medicines have protein or other complex molecules which are relatively easily damaged with any type of gate, valve or force which causes shearing upon the opening and closing of mechanism to stop flow. These proteins have the ability to aggregate and become ineffective, thereby giving to the patient a medicine which has changed in its effective concentration. Shear and aggregation can also occur with having flows in areas which have a high pressure.
Furthermore, many current pumping devices use syringes and have no ability to overcome the natural slip-stick or chatter associated with the storage of energy in the elastic and pliable surfaces and structures, allowing for the syringe moving face (“Plunger”) to move forward in irregular motions. Hysteresis and the natural tendency of plungers not to move until a force overcomes the inertia and sticking forces cause delivery of most syringe pumps to be sporadically subject so differing levels of sticking (sticktion). When these devices overcome this inertia and hysteresis, they tend to overrun and deliver at different speeds. In addition, many pumping devices vary their delivery according to the viscosity of the fluid being distributed.
Another drawback with current infusion devices is that most medicines must be withdrawn from a container, and put into the system for administration. This process requires withdrawing the medicine with a needle and then infusing the medicine into a bag or other container. The use of needles presents a hazard to the user and also introduces losses of reagent during the priming of current infusion devices.
What is needed is a medical infusion and aspiration system that avoids the disadvantages of pre-existing medical infusion and aspiration devices, that is accurate in pulsatile delivery, that is capable of high rates of flow, that provides a means to automatically avoid errors in concentrations, reagent and medicine type, that avoids the problem of shear, and other medicine degrading pressure problems, that avoids the slip-stick, chatter, overruns, and the problem of hysteresis by breaking the seating forces in a lateral motion, that does not vary the delivery profile by the viscosity of the reagent, that avoids the tendency of reagents to separate when in a diluted environment, that is inexpensive and may be used by the manufacturer in glass lined or plastic, as both the pumping cartridge and the shipping and storage cartridge, that eliminates avoids loss of reagent in the priming of the infusion device and the need for withdrawing the medicine with a needle, and that achieves extraordinary accuracy without error correcting software or expensive volumetric measurement and control systems.
SUMMARY
Accordingly, the present invention is a medical infusion and aspiration system capable of accurate pulsatile delivery at high rates of flow. Another important characteristic of the invention is that the device provides a means to automatically avoid errors in concentration, reagent and medicine type, avoids the problems of shear and other medicine degrading pressure problems. The system also avoids the slip-stick, chatter, overruns, and the problem of hysteresis by breaking the seating forces in a lateral motion that does not vary the delivery profile by the viscosity of the reagent. The system also eliminates the tendency of reagents to separate when in a diluted environment. Other important characteristics of the invention include disposability, inexpensive cost and use by the manufacturer in glass lined or plastic, as both the pumping cartridge and the shipping and storage cartridge thus avoiding loss of reagent in the priming of an infusion device. The current invention also eliminates the need for withdrawing the medicine with a needle and achieves extraordinary accuracy without error correcting software or expensive volumetric measurement and control systems.
The current invention consists of a cassette cartridge pumping and aspirating system. The cassette cartridge contains a plunger, a reservoir area where the reagent is filled, a neck opening for the connection of the cartridge to a tube which travels to where the infusion takes place, and an in-line sensor area where probes for sampling are located. The in-line area probes are used to provide input to a pumping device. The current invention has only one moving part in relation to the delivery mechanism. Simplicity allows for more accuracy and lower costs. It also allows for a single handed adaption of the cassette to the pumping device, freeing the other hand and avoiding accidental sticking with “sharps” such as needles which are contaminated with blood or other materials.
In a preferred embodiment, the cartridge is cylindrical in shape and has a reservoir area, a neck opening, and encoded area. The cartridge may be made of glass, plastic steel or ceramics. It is preferable that the outer surface of the cartridge be threaded. The reservoir area is preferably used for containing a reagent and may be pre-filled, thereby enabling the seller to market pre-filled reagent cartridges. The preferred embodiment eliminates expe

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