Needle retraction mechanisms

Details Needle retraction mechanisms Needle retraction mechanisms

1997-01-29

1998-07-21

Stright, Jr., Ronald

Surgery

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

Treating material introduced into or removed from body...

604195, 604243, 128919, A61M 500

Patent

active

057828040

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

1. Field of Invention
The invention is concerned with improvements in or relating to retraction mechanisms for use in fluid handling devices, said mechanisms being arranged to bring about the retraction of a hollow needle into a housing after use. Such devices are used in many facets of the medical field, for the administration of drugs or a drip feed into a blood vessel, or for drawing off liquid samples, for example, blood from patients.
2. Description of the Related Art
It will be understood that there is a wide range of fluid handling devices incorporating needles in use in the field of medicine for the administration of drugs and the like for blood sampling, including use in procuring more than one sample from a patient over a period of time.
It is important that the needles of such devices, which are frequently intended for disposal after a single use, are rendered inoperative to prevent accidental injury or re-use with the substantial risk of cross-contamination.
Syringes provided with guards of one kind or another which are automatically deployed to shield the needle after use are known, as are syringes where the needle is automatically retracted after use into the body of the device.
The invention provides a fluid handling device having a needle retraction assembly adapted to bring about the retraction of a hollow needle after use comprising a hollow body portion provided at one end thereof with an end wall having a mounting portion including a needle passage, and a hollow needle having a mounting means and adapted to be movable between a first position in which a leading end portion of the needle protrudes from a front end portion of said mounting portion and a second position in which the needle is withdrawn within the hollow body portion, said mounting means including resilient means that act to bias the needle into the second, withdrawn, position, said needle being provided with an enlarged portion at a location spaced from the leading end portion thereof, there being provided retaining means to maintain the needle in its first position until use is completed, said retaining means comprising in combination an O-ring positioned in a circumferential groove in said enlarged portion and abutting the end of a sleeve which can be forced forwardly to dislodge the O-ring so as to permit the needle to move from its first position into its second position under the influence of said resilient means.
The sleeve may be restrained from rearward movement when the needle is in its first position by a shoulder which abuts a flange at the forward end of the body portion.
The resilient means may be a compression spring located between a forward reaction surface provided by the mounting portion and a rearward reaction surface provided by the forward end of the enlarged portion.
When the needle is in its first position the O-ring may be compressed between the enlarged portion and the mounting portion, which provides a relieved part at its forward end to receive the O-ring when it is dislodged.
The fluid handling device may be a syringe, there being a piston which may be depressed to travel through the body portion to discharge liquid therefrom through the needle, the piston being in the form of a tube having closed ends, the forward of which is provided with a closure member which is separable from the end by engagement with the sleeve as the piston is fully depressed to provide an aperture in the end through which the needle may pass to enter the interior of the piston as it assumes its second position.
The mounting portion may be off-centre and towards a peripheral edge of the body portion.
The cross-sections of the body portion and piston may be such as to prohibit incorrect assembly having regard to the position of the closure member.
The cross-sections of the body portion and piston may be such that whilst permitting assembly in more than one rotational position relative to one another, proper operation is assured, there being more than one closure member in the end of the piston

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