Recent articles in medical journals demonstrate the hidden costs of using needles to administer medication to patients, and the like. One article reports that fully one third of all work-related hospital accidents relate to needlesticks. Needle stick injuries have a potential devastating long term impact on hospital workers with the increasing risks of blood-borne disease transmission, particularly diseases such as human immunodeficiency virus (HIV) and hepatitis B. That same article reports needle stick injury rates in excess of one per ten employees. A second article determined the average cost (not including costs associated with employee loss due to debilitating injury) to be $405 per injury. These costs are in addition to the known costs associated with the purchase and disposal of the needled devices.
A third article reports the hospital handling of needles leading to needle stick injuries as being
1) intramuscular or subcutaneous injections, PA1 2) intravenous catheters, PA1 3) disassembly of the needled devices, PA1 4) recapping attempts, PA1 5) multistep procedures (e.g., multi-component medication mixing), PA1 6) disposal of needles.
This same article reported that only 18% of the needle stick injuries involved in this study could be addressed by an improved disposal technique and concluded that only a portion of those 18% could be eliminated by such improved handling techniques. This article suggests the answer lies in eliminating the unnecessary use of needled devices, that is, usage of needleless and protected needle devices is encouraged.
The risks associated with using needles and the advantages of needleless transfer systems for medication are further detailed in U.S. Pat. No. 5,092,840, which is hereby incorporated by reference. The significant reduction of the risk of transmitting blood-borne diseases make the use of such a needleless system very attractive. Still, it is important that the valve used with various medications be workable without exacting a substantial penalty in the area of cost. To this end, the present invention presents a particular workable, cost-effective valve mechanism.
The present valve mechanism includes a slidable member that is engaged and operated by the blunt end of a needleless syringe which engages a slit in a relatively thick elastomeric membrane to force open a passageway that permits medication to be withdrawn. This valve can be provided with an optional vent passage that may be equipped with a one-way valve to avoid medication leakage. The vent passageway may be required in some applications requiring larger valves.
It will be appreciated that although the advantages of a needleless transfer system will be readily apparent to a majority of the members of the medical profession, there will be some practitioners that may, for certain applications, wish to continue to utilize needles. It is therefore important that the valve which may be utilized to successfully introduce a needleless transfer system be capable of being operated by a needle, as well.
This valve will be used in a number of applications requiring multiple repeated uses. It will, therefore, be important that the valve membrane be capable of resealing and that it be durable to standup to this repeated usage. The pre-slit, thick membrane employed with the present valve mechanism has several advantages over a relatively thin membrane. First, the thick membrane does reseal preventing the flow of both air and fluid into and out of the valve. Second, the thick design is more durable, able to withstand the wear and tear of repeated uses. Lastly, it will be appreciated the thick membrane will be less likely to be cut and disintegrated by the point of a needle. Such damage to the membrane would be undesirable, not only from the standpoint of the integrity and operability of the valve, but from the perspective of contaminating the medicine with particles which break off from the valve.
The slidable member has a tapering leading end to facilitate insertion with a rounded tip portion to reduce the wear and tear on the membrane. Further, the present valve can easily be employed with a needle during transitional usage, that is, use during the transition period necessary for needleless systems to gain widespread acceptance. The internal surface of the slide which has a tapered portion designed to engage and grip the lead end, or nozzle, of a needleless syringe, will serve to guide the needle to the pre-formed slit, avoiding unnecessary penetration of the membrane which could result in deterioration.
In defining the term "relatively thick", Applicant has determined a range of thicknesses, as they relate to the diameter of the membrane, of between 25 and 75%, and more preferably, between 40 and 50% of the membrane diameter, provides acceptable performance.
Various other features, advantages and characteristics of the present invention will become apparent after a reading of the following specification.