1. Field of the Invention
The invention relates to a needle assembly capable of withdrawing medicine from a vial, injecting into a port in a patient, and preventing accidental punctures or xe2x80x9csticksxe2x80x9d from a contaminated needle. In particular, the invention relates to a needle assembly including a sharp hollow needle for penetrating a septum of a vial. The needle assembly also includes a blunt cannula for injecting into an injection port. The blunt cannula concentrically surrounds the sharp hollow needle, forms a liquid-tight seal with the cannula, and retractably extends relative to the sharp hollow needle.
2. Description of the Related Art
The spread of contagious blood-born diseases such as HIV and Hepatitis has provided incentive for many to invent syringes with safety devices to prevent people from accidentally sticking themselves or others with contaminated needles. These safety syringes have not become accepted because they are too difficult to use or too expensive.
As stated, many needle safety shield devices have been devised to reduce the risk of inadvertent needle punctures. Many of these devices are designed to slide over a used needle to a position where the needle is completely encased permanently so that an inadvertent needle puncture would be eliminated.
There are also needles called xe2x80x9cNeedleless needlesxe2x80x9d or xe2x80x9cblunt plastic cannulasxe2x80x9d that are needle substitutes. These blunt plastic cannulas are similar to needles in shape but are plastic and have a blunt end. They are only able to gain access into the body by way of a pre-slit injection port connected to a catheter. The injection port is designed specifically for receiving blunt plastic cannulas. These blunt plastic cannulas have a tremendous advantage over the conventional steel needles. Once the blunt plastic cannula is locked in place on the syringe, the fear of a possible contaminated needle stick is eliminated; the blunt plastic cannula cannot pierce the skin and only can gain access into the body through the pre-slit injection recepticle.
However, blunt plastic cannulas cannot pierce the rubber septums used to seal medicine vials. Therefore, a syringe having only a plastic blunt cannula cannot withdraw medicine from a vial through a rubber septum.
Another problem with some of the Needle safety shield devices (where the needle is permanently encased by an outer connecting structure) is that although the user can shield a used contaminate needle, a moment still exists where the sharp used needle is exposed. In this moment, a contaminated needle puncture can occur. Furthermore, the moment when the syringe is first removed is the most dangerous moment for accidental needle sticks caused by an uncooperative or convulsing patient.
Syringes with exchangeable blunt cannulas and sharp needles exist. A clean sharp needle is initially attached to a syringe. The sharp needle can pierce the rubber septum of a medicine vial for withdrawal of the medicine. Once filled, the still uncontaminated sharp needle is removed and a blunt plastic cannula is screwed onto the syringe. The patient is injected with the syringe and blunt cannula by using a pre-slit injection port. The now contaminated blunt plastic cannula is unable to pierce the caregiver""s skin.
Although, the syringe with exchangeable tips appears to provide a solution, in practice, most health care workers have chosen not to use these syringes because they are too time consuming to use. When a nurse withdraws an intravenous solution from a vial, which must be accessed by a steel needle, rarely will the nurse, who is pushed for time, stop and change the steel needle and find a blunt plastic cannula with which to replace it. Again, this makes a contaminated needle strike possible.
Buttgen et al. (U.S. Pat. No. 6,015,396) disclose an Automatic Cannula Withdrawing Device for Injection Syringes. The syringe withdraws into a housing as the injection is completed. The housing shields the used needle and prevents unintended sticks. The housing does not form a cannula that can inject into a septum. Furthermore, if the volume held in the syringe is not fully injected, the needle is not retracted and unintentional sticks can occur.
Alexander (U.S. Pat. No. 5,993,418) discloses a Safety Syringe. In Alexander, the syringe includes a needle surrounded by fluid-tight barrel. The needle extends beyond the barrel and allows the needle to penetrate a vial and the skin of a patient. When the plunger is fully compressed, a lever causes the needle to retract within the barrel. The barrel of the safety syringe is not a cannula that can allow injections through pre-slit injection port. If the plunger is not fully compressed, the needle does not withdraw into the barrel. So, a used needle still can stick an injector.
Caizza (U.S. Pat. No. 5,755,696) discloses a Syringe Filling and Delivery Device. The syringe includes a needle and a coaxial cannula surrounding the needle. Springs urge the needle within the cannula. Pressing harder than the springs to extend the needle through the septum fills the syringe. During injection the cannula penetrates a rubber septum without extending the needle. No lock is included in Caizza. So, under enough force, such as an accident, a used needle can extend beyond the cannula and stick the injector.
Kraus et al. (U.S. Pat. No. 5,704,919) disclose an Intravenous Cannula Assembly. The assembly is for inserting a catheter intravenously. Once inserted, fluids can be injected or withdrawn through the assembly. The assembly includes a coaxial needle and cannula. Initially, the needle extends longer than the cannula. The extended needle pierces a patient""s skin and vein. The needle is then withdrawn into a telescoping sleeve for disposal leaving a connected cannula. Separate tubing is then connected to the cannula. The Assembly is not a syringe. Because the needle is removed from the back of the assembly (where the volume of liquid to be injected would be in a syringe), the device cannot be adapted to a syringe.
Haber et al. (U.S. Pat. No. 4,950,250) disclose a Collapsible Needle Cover. The cover folds to expose a needle. The needle is exposed during injection and withdrawal of fluid from a vial. The unfolded cover prevents unintended sticks when extended. The cover is not able to act as a cannula through which injections take place.
It is accordingly an object of the invention to provide a needle assembly capable of withdrawing medicine from a vial having a rubber septum and injecting the medicine into a port in a patient while not endangering the care giver with an accidental stick with a contaminated used needle.
With the foregoing and other objects in view there is provided, in accordance with the invention, a needle assembly. The needle assembly includes a sharp hollow needle for penetrating a septum of a vial. The needle assembly also includes a blunt cannula for injecting into an injection port. The blunt cannula concentrically surrounds the sharp hollow needle and forms a liquid-tight seal with the needle. The blunt cannula retractably extends relative to the sharp hollow needle. By extending beyond the needle, the blunt cannula can be used to inject medicine into a port in a patient. However, this blunt cannula acts as a shield over the sharp needle, so, once the blunt cannula has been deployed, the sharp needle cannot penetrate a caregiver""s skin.
In accordance with a further feature of the invention, the needle assembly includes a syringe connected longitudinally to the blunt cannula.
In accordance with a further feature of the invention, the needle assembly includes a wing having an upper wing element and a lower wing element joined by a hinge. The wing is fixed proximally to the sharp hollow needle and unfolds at the hinge to extend the blunt cannula beyond said sharp hollow needle.
In accordance with a further feature of the invention, the wing includes a lock preventing the wing from unfolding once the wing has been unfolded.
In accordance with a further feature of the invention, the wing angles backwardly from the blunt cannula.
In accordance with a further feature of the invention, the needle assembly includes a further wing.
In accordance with a further feature of the invention, the needle assembly includes a cylinder concentrically and proximally fixed to the sharp needle and extending distally therefrom. The cylinder slidably holds the blunt cannula. The blunt cannula travels within the cylinder and thereby extends beyond the sharp needle.
In accordance with a further feature of the invention, the cylinder defines a slot. This slot can be longitudinal. In addition, the blunt cannula has a pawl traveling in the slot. The slot can include a barb. The barb locks the pawl when the blunt cannula is extended. By locking the pawl, the barb locks the blunt cannula in a deployed position that guards the needle.
In accordance with a further feature of the invention, the needle assembly includes a syringe connecting longitudinally to the sharp hollow needle cylinder. The syringe includes a cylinder and a plunger traveling longitudinally in the cylinder.
In accordance with a further feature of the invention, the needle assembly includes a further longitudinal cylinder fixed to the blunt cannula. A conventional syringe having a sharp hollow needle and a first cylinder inserts in the needle assembly. The first cylinder travels in the further longitudinal cylinder. The sharp hollow needle extends beyond the blunt cannula when the cylinder is retracted within the further cylinder and withdraws within the blunt cannula when the cylinder is deployed.
In accordance with a further feature of the invention, the further cylinder defines a longitudinal slot and the cylinder includes a pawl traveling in the longitudinal slot.
In accordance with a further feature of the invention, the sharp hollow needle is threaded to connect to a syringe having a complimentary threaded connector.
In accordance with a further feature of the invention, the blunt cannula is threaded to connect to a syringe having a complimentary threaded connector.
In accordance with a further feature of the invention, the sharp hollow needle and the blunt cannula remain water tight under a pressure generated during injection.
Other features that are considered as characteristic for the invention are set forth in the appended claims.
The object of the invention is to provide a needle assembly that prevents accidental sticks with a contaminated needle while allowing access to any drug or multiple dose vials. The needle assembly combines the benefit of using the conventional steel needle, needle shield, and the blunt plastic cannula or needleless needle. The needle assembly has a proximal end and a distal end. The proximal end is near a syringe. The distal end is near the tip of the needle and cannula.
A further object of the invention to provide a female twist lock fitting that joins the proximal end of the device to the male twist lock fitting at the distal end of a syringe. The needle assembly then can encase and permanently bind a conventional steel needle.
Another object of the invention is to provide a needle assembly having wings extending laterally from the female twist lock. The cannula surrounds the needle and is connected to the wings. These wings include a proximal wing element and a distal wing element located bilaterally of the sharp hollow needle. The wings can be unfolded (deployed) so that the cannula extends beyond the tip of the needle. The wings can include locks to prevent them from refolding and exposing the contaminated needle.
In accordance with another feature of the invention, the dimensions of the needle assembly and guard can allow them to be used for intramuscular injections. Intramuscular needles are especially dangerous because they are longer and, therefore, more cumbersome than subdural needles.
Although the invention is illustrated and described herein as embodied in a needle assembly, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims. An intramuscular needle needs to penetrate the skin and the underlying muscle. Accordingly, intramuscular needles are typically one-and-one-half inches (1 xc2xdxe2x80x3) long.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.