Considerable effort has been directed to reducing the transmission of disease, e.g., infections or viruses, which may result from the use of medical equipment, particularly surgical needles used with syringes and related equipment. Medical personnel routinely must administer surgical needles to patients, such as to give injections, and must dispose of the contaminated needle in a safe and effective manner. Containers for receiving the needle and syringe are well known and in use, but these do not address potential exposure of health care workers or other patients or personnel to contaminated needles or the consequent possibility of disease transmission during the period after removal of the needle from the patient but prior to depositing the needle and/or syringe into the disposal container. Because millions of injections and similar procedures are performed each year, any protective device intended to address this problem must not only be safe and effective, but also cost efficient. Devices have been proposed for protecting medical personnel and others after the needle has been removed from the patient and prior to depositing the needle in a disposal container. For example, Landis U.S. Pat. No. 4,664,259 discloses a housing hingedly attached to the needle hub. The Landis housing has a longitudinal slot to allow passage of the needle into the housing and a needle engaging hook member integral with the housing for engaging the needle and preventing the housing from being rotated to expose the used needle after the needle has entered the housing and engaged the hook member. Advantageously, the Landis housing may be rotated to the closed position in a one-handed motion. That is, the user holds the syringe and places the housing against a surface. By exerting pressure on the syringe the housing is biased into the closed position in alignment with and enclosing the needle without involving the user's other hand. Molding considerations indicate that the Landis hook member for engaging the needle may best be molded with the housing in the open position so that the needle retaining hook member may be accessed during molding both through the longitudinal slot as well as through an aperture in the rear wall of the housing opposite the slot. This is important since ease of molding contributes to the cost efficiency of the device. The Landis housing structure has been incorporated into NEEDLE PRO needle protection devices available from Concord/Portex, Keene New Hampshire, a Smiths Industries Company.
In the Landis and Concord/Portex structures the longitudinal slot for reception of the contaminated needle remains open as the needle passes through the slot and engages the hook member. As the needle passes the tip of the hook member the needle and/or hook member flex and thereafter resiliently snap into place after the needle passes the hook tip so that the needle is positioned behind the hook tip. Because the longitudinal slot is open at all relevant times during this closing motion, including when the needle snaps past the hook, it is possible that bodily fluids or tissue particles may become airborne and travel back out of the open slot toward the user. Indeed, the preferred one-handed technique for moving the housing from the open position to the closed position involves biasing the housing against a surface with the open longitudinal slot facing the user, so any fluid droplets or particulate matter exiting the slot after the needle snaps back against the hook after passing the hook tip necessarily are directed toward the user.
Thus, despite the significant advantages of the Landis housing structure there remains a need for a safety sheath device which not only securely covers a used needle in a one-handed motion but which also prevents exposure to contaminated bodily fluids or tissue particles released from the needle during closure of the housing about the needle.