They have a bevel-pointed introducer to facilitate insertion of the needle. Figure 1. Figure 2. Figure 3. Both are fitted with detachable rubber diaphragms to make repeated intravenous injection easier. Figure 5: This is a s portable lumbar puncture set used to measure the pressure of and test the cerebrospinal fluid which flows when the spinal meninges have been punctured.
Figure 6: Haemorrhoid needles are characterised by a shoulder on the haft a few millimetres short of the needle tip to prevent deep penetration when injecting the haemorrhoids.
A secure needle-lock ensured that the increased pressure required to inject the viscous oil did not detach the needle. Figure 5. Figure 6. The needles pictured below represent the range of needles and packaging which were commonplace between and They often became blunt with multiple use, were impossible to clean and sterilise adequately and caused infections leading to cellulitis and abscesses. Sharpening needles was sometimes solved by including a suitably shaped carborundum stone in the injection set.
Needle sharpening devices were needed for rapid and consistent sharpening of many needles by large institutions Figures 7. Figure 7. Figure 8.
The Mussel Shell Figure 9. It was not until later that pharmaceutical manufacturers prepared sterile injections in sealed glass ampoules.
Probably the oldest syringe in the collection c has a small metal barrel with a plain glass tube to contain a medication. It is crude and has a waxed linen piston with thumb-hold on the plunger. The needle has a screw fitting like another of the older syringes in the collection with its ferrous metal ends and non-sterilisable, ivory thumb piece on a plunger with a rubber piston.
Figure Figure 9. There were a variety in syringes made from all glass to all metal, but the Rekordspritze introduced by the Berlin instrument makers Dewitt and Hertz in gained prominence through its dependability, lack of leakage and jamming, and ease of dismantling to enable sterilisation. This pattern persisted until plastic superseded it. Enlarged head 21 should preferably be beveled so that its tip is larger than its rear.
This will allow enlarged head 21 to be inserted into groove 20 but will resist extraction of enlarged head 21 from groove Thus, groove 20 will engage arms 16 via enlarged head This engagement will resist any effort to pull sheath 13 away from diaphragm 17 in the direction of sharp end 11 of needle In the preferred embodiment, when plunger 7 is depressed, it will encounter diaphragm Continued depression of plunger 7 will push diaphragm 17 forward along needle Diaphragm 17 will already be in engagement with arms 16 or it will encounter arms 16 as it is advanced.
In either case, diaphragm 17 will push arms 16 , and thus sheath 13 forward as diaphragm 17 is advanced by plunger 7. Diaphragm 17 , needle 10 , sheath 13 , arms 16 , plunger 7 , and barrel 2 should be appropriately sized relative to one another so that sheath 13 is in covered position 15 by the time plunger 7 is fully depressed.
Plunger side 19 of diaphragm 17 should preferably be sized to match washer end 8 of plunger 7. By making washer end 8 and diaphragm 17 match, the user of syringe 1 will be able to more fully evacuate barrel 2 by depressing plunger 7 , thereby reducing the risk that some of the medication contained in syringe 1 might not be administered.
Making the surface of plunger side 19 of diaphragm 17 conical and concave will make plunger side 19 of diaphragm 17 act like a funnel for directing air to needle 10 when syringe 1 is pointed upward or for directing medication to needle 10 when syringe 1 is pointed downward. This will help prevent any air from being trapped in syringe 1 prior to the administration of an injection and help prevent any medication from being trapped in syringe 1 during an injection.
Syringe 1 is preferably provided with a locking mechanism for securing sheath 13 in covered position One locking mechanism includes a bar 22 that extends at least partly across the interior of barrel 2. Bar 22 should preferably be substantially perpendicular to the longitudinal axis of barrel 2.
Arms 16 should be provided with a first tooth 23 and preferably with a second tooth 24 as well. Arms 16 and bar 22 should be positioned so that teeth 23 and 24 will encounter bar 22 as arms 16 ,and sheath 13 are advanced. Teeth 23 and 24 should be positioned on arms 16 so that they face bar 22 , preferably on the inside surface 29 of arms First tooth 23 and second tooth 24 should be positioned relative to each other so that second tooth 24 is closer to enlarged head 21 , when it is present, than first tooth The space between first tooth 23 and second tooth 24 should be at least as wide as bar First tooth 23 should have a leading edge 25 and a trailing edge Trailing edge 26 should face enlarged head 21 and leading edge 25 should be generally opposite trailing edge Second tooth 24 should have a leading edge 27 and a trailing edge 28 similarly positioned.
Leading edge 25 on first tooth 23 should preferably be beveled so that first tooth 23 will deflect and pass over bar 22 when first tooth 23 encounters bar Trailing edge 26 of first tooth 23 should preferably have a flat face or otherwise be configured to prevent first tooth 23 from passing back over bar Leading edge 27 of second tooth 24 should also preferably be configured to prevent second tooth from passing over bar 22 , preferably by providing leading edge 27 of second tooth 24 with a flat face as well.
From the foregoing, it should be apparent that after first tooth 23 has passed bar 22 , bar 22 will be locked between first tooth 23 and second tooth This will prevent arms 16 , and thus sheath 13 , from being advanced or retracted from this position. By positioning and sizing arms 16 , bar 22 , teeth 23 and 24 , needle 10 and sheath 13 appropriately relative to one another, syringe 1 can be configured so that sheath 13 is in covered position 15 by the time bar 22 is locked in place between first tooth 23 and second tooth Positioning the locking mechanism within barrel 2 will shield the locking mechanism from external tampering, making the locking mechanism more difficult to defeat and thus less liable to be reused.
In one embodiment, first tooth 23 may be provided with a rounded hemispherical external shape. This will allow tooth 23 to pass over bar 22 more easily. Although such a configuration may be easier to defeat that the beveled arrangement described above, such potential deficiencies may be overcome by configuring plunger 7 to lockingly engage barrel 2 when plunger 7 is fully depressed, as described in more detail below. It should be noted that syringe I may be used without second tooth First tooth 23 will operate in the manner described above; however, second tooth 24 will not be present to prevent sheath 13 from being extracted over sharp end 11 of needle This function may be performed by the interaction between enlarged head 21 and groove 20 in diaphragm 17 , if present.
In another embodiment, first tooth 23 should be positioned so that it is adjacent to bar 22 prior to the advancement of arms When first tooth 23 is in this position, almost any advancement of sheath 13 will cause first tooth 23 to pass over bar This will minimize or eliminate any play in sheath 13 so that once it is advanced even a very slight degree, sheath 13 will be prevented from retreating toward plunger end 4 of barrel 2. In this mechanism, plunger 7 is provided with at least one locking tooth The use of multiple locking teeth 30 will create a more secure lock but may make depression of plunger 7 more difficult.
While the inventor contemplates the use of two locking teeth 30 in the preferred embodiment, the number desired may vary with the application and with the size and resilience of the tooth Plunger locking tooth 30 should have a leading edge 31 facing washer end 8 of plunger 7 and trailing edge 32 facing control end 9. Sides 5 of barrel 2 contain a locking ring 33 , which is preferably an annular feature, but which may simply be one or more inward indentations on sides 5 which serve to reduce the diameter of barrel 2.
Plunger locking tooth 30 should be positioned on plunger 7 so that plunger locking tooth 30 will encounter locking ring 33 as plunger 7 is advanced. Leading edge 31 of plunger locking tooth 30 should be beveled so that plunger locking tooth 30 will pass over locking ring Trailing edge 32 of plunger locking tooth 30 should be flat or otherwise configured to prevent plunger locking tooth 30 from passing back over locking ring Plunger locking tooth 30 and locking ring 33 are preferably positioned relative to one another so that by the time plunger locking tooth 30 passes over locking ring 33 , sheath 13 will be in covered position Thus, the engagement between plunger locking tooth 30 and locking ring 33 will prevent plunger 7 from being withdrawn.
Locked in place, plunger 7 will prevent syringe 1 from being reused and it will prevent sheath 13 from being forced back into exposed position Thus, locking tooth 30 and locking ring 33 perform the same function as first tooth 23 and bar As stated above, they may be used together or in place of each other.
The same is true of bar 22 and second tooth 24 and enlarged head 21 and groove 20 ; they may be used together or is place of one another. Plunger 7 is preferably sized so that entire plunger 7 is contained within barrel 2 when plunger 7 is fully depressed.
Control end 9 of plunger 7 is preferably sized and positioned so that it is either flush with plunger end 4 of barrel 2 or between plunger end 4 and needle end 3. Locking plunger 7 in this position will make plunger 7 difficult to access which will make it more difficult to overcome the locking mechanism securing plunger 7 in its fully depressed position in barrel 2. When syringe 1 is assembled, sheath 13 will necessarily be in exposed position To protect sharp end 11 of needle 10 during shipping and preusage handling, syringe 1 is preferably provided with a removable cover 34 which encloses sharp end 11 of needle When syringe 1 is ready for filling or use, cover 34 may be removed and discarded or retained and replaced over needle 10 and sheath 13 after sheath 13 has been moved into covered position 15 in order to provide additional protection.
In no event should cover 34 be used instead of advancing sheath 13 into covered position 15 as this would create an opportunity for dirty needle sticks. Sheath 13 has a tip end In the preferred embodiment, at least tip end 35 of sheath 13 is hypodermically insertable with needle By making sheath 13 or at least tip end 35 hypodermically insertable with needle 10 , sheath 13 may be moved into covered position 15 prior to the time needle 10 is extracted from the patient by fully depressing plunger 7 before removing needle If this procedure is followed, sharp end 11 of needle 10 will never be exposed after it is dirty.
In operation, the preferred embodiment of safety syringe 1 may come pre-filled or empty. In either case, the operator, typically a doctor, nurse or other health care professional, will remove cover 34 and fill syringe 1 by inserting needle 10 into a medication vial and retracting plunger 7 if syringe 1 is empty. An excess amount of medication should preferably be drawn into syringe 1.
The excess may then be expelled prior to administering the injection by turning syringe 1 so that sharp end 11 of needle 10 is facing upward and depressing plunger 7 slightly. This will expel any air that may be trapped in syringe 1 and reduce the medication volume to the desired amount.
At this point, sharp end 11 of needle 10 will be hypodermically inserted into the patient. We have non-RN staff providing care for patients, and many do not have the IV experience or device knowledge as in years past when IV teams cared for all patients with a vascular access device.
This further increases the risk of needlestick injury. Training on the use of these devices is at times incomplete due to a variety of factors most likely due to the staffing crisis. In August , California became the first state to pass a safety initiative to protect health care workers from accidental needlestick injury by contaminated needles used to start IVs, draw labs, and give injections.
Twenty more states have similar legislation pending. Shortly thereafter in July, California health care facilities have either put the safety devices into use or have a plan of action to implement their use within the next several months. Congress reconvenes to vote on the Needlestick Prevention Act of Health care workers are beginning to use these devices, many with successful transitions. But the transition is far from complete. There are still health care workers who do not like safety devices, some of whom stash conventional product to fall back on if they do not have successful outcomes with the new safety products.
Change is hard, particularly when it involves a product we are used to and have had success with. This is especially true when it involves an invasive and oftentimes painful procedure to our patients.
However, remember that many of these safety devices were developed using input by health care workers themselves and, as a result, are user-friendly. This change in practice must happen not only because of the protection offered to health care workers, but also the protection from accidental needlesticks offered to patients.
Studies have shown that needlestick injuries significantly decrease when safety devices are put into use. The upfront cost of health care is not the only concern. It is unlikely that coverage would extend to a worker whose facility has safety devices to use and the worker opts not to use them.
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