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What Is a Filter Needle?

Any medical procedure which involves blood must be undergone with extreme caution, especially when it involves injecting fluid directly into the bloodstream. Gloves are worn, medications are covered and needles are sterilized and disposed of. The filter needle is another protection used to prevent contaminants from entering into a syringe, where they could then be injected into the body.

  1. Operation

    • A filter needle places a removable glass filtering device at the base of a syringe needle. The filter creates a one-way flow when withdrawing fluid into the syringe, which runs through one filter within the needle, and redirects the fluid through a second filter during injection. Effectively any medication is filtered both on the way in and out of the syringe.

    Previous Devices

    • Previous to the use of needle filters there remained a possibility of contaminants entering the syringe from the medication, most likely picked up from residue within the container. Without the use of a filter, anything brought into the syringe would be injection into the patient. Early filters minimized the possibility of injecting contaminants, but did not restrict flow to one direction, making it necessary to use a different device for withdrawal and injection.

    Invention

    • Originally filed for patent in 1976, the filter needle was created as an improvement on previous syringe designs. These syringes allowed medical personnel to use the same device for withdrawal of medication into the syringe tube, and injection from the tube back through the needle. The filter needle also added a second filtration system which removes any possible contaminants contained that may have escaped through the first filter or are picked up from within the tube. Filter needles were designed to be compatible with the sizes and specifications of existing syringe types.

    Placement

    • The filter system is placed at the back end of the needle, within the mounting. The needle is attached to the filter which then attaches to the syringe chamber. As all needles are disposed of after one use, the filter is disposed as well.

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