LV10585B - Hypodermic needle - Google Patents
Hypodermic needle Download PDFInfo
- Publication number
- LV10585B LV10585B LV930056A LV930056A LV10585B LV 10585 B LV10585 B LV 10585B LV 930056 A LV930056 A LV 930056A LV 930056 A LV930056 A LV 930056A LV 10585 B LV10585 B LV 10585B
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- LV
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- hypodermic needle
- section
- tubing
- needle according
- needle
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- Infusion, Injection, And Reservoir Apparatuses (AREA)
Description
HYPODERMIC NEEDLES
This invention relates to hypodermic needles.'
The invention is particularly applicable to hypodermic for use with syringes for delivering intravenous fluids such as X-ray contrast fluids, drugs, blooc products, and other fluids in situations where high flov rātes are reguired or where the viscosity of the fluid to be injected is high. In a general context, the hypodermic needle of the invention is applicable for ādministering fluids via veins, arteries, intra-muscular injections, intrathecal injections, and in other situations vhere the use of high flov or a fine needle vould be an advantage. The hypodermic needle of the invention is thus applicable.· in medical, dental, pharmaceutical and in veterinary practises.
The hypodermic needle of invention may also have applications in other areas, for example in the Chemical, petrochemical and engineering Industries.
I
The streamline flow of fluid in a tube is defined by Pouseille's formula as:
Flov = (P2 - Px) Πγ4 8μ1 vhere: P2 - Pi is the pressure difference betveen the ends of the tube r is the internai radius of the tube p is the viscosity of the fluid 1 is the length of the tube
In order therefore to increase the flow in the tube, the possibilities are: t.
(I) to increase the pressure difference;
(ii) to increase the radius of the tube;
(iii) to decrease the length of the tube;
(iv) to decrease the viscosity of the fluid;
The injection of viscous fluids in the medical field has posed problem for many years, since the length and the diameter of the needle are fixed by practical considerations. For example, in order to minimise discomfort to the patient and to be able to gain access to small veins, it is desirable to use needles vith as small an external diameter as possible. There is a practical limit to the minimum length that a needle needs to be in order to gain access to deep veins. The viscosity of the fluid to be injected often cannot be changed. Thus the only parameter vhich can conveniently be varied, in order to increase the flow of the fluid, is the pressure. To this end, mechanical the injectors and levers have been used in order to increase pressure, but the pressure stili has to ' be limited by safety considerations when injecting into patients.
The present invention therefore seeks to provide an improved form of hypodermic needle which vill obviate the disadvantages of knovn hypodermic needles by substantially reducing the force reguired to inject the fluid. The invention seeks to mimimimse the length of narrow tubing of the pointed maximise the internai radius using thin walled tubing. Pouseille's eguation that an radius of the tube of only 10% in the flow by a factor of
110
100 end of the needle and to of this narrow tubing by It will be noted from increase in the internai will result in an increase *, i.e. an increase of almost 50 per cent. This is therefore a much more effective way to increase the flow than increasing the delivery pressure.
According to the present invention there is provided a multi-diameter hypodermic needle.
Preferably, the hypodermic needle will comprise tubing of two different diameters which are connected together in series. The tubing will preferably be of circular crosssection.
The hypodermic .needle will preferably include a first section of thin walled small diameter tubing and a second section of thin walled tubing whose external diameter is less than the internai diameter of said first section, the first and second sections being fixedly secured together to prevent relative movement of said tube sections.
An outboard end of said first section will preferably be pointed.
The tubes of said first and second sections will preferably be composed of stainless Steel.
In order that the invention may be more readily understood, embodiments thereof will now be described, by way of example, reference being made to the accompanying drawings, wherein: Figurē 1 is a longitudinal sectional elevation of a hypodermic needle in accordance with a first embodiment of invention;
Figurē 2 is a longitudinal sectional elevation of a hypodermic needle in accordance with a second embodiment of the invention;
Figurē 3 is a longitudinal sectional elevation of a hypodermic needle in accordance with a third embodiment of invention;
Figurē 4 is a longitudinal sectional elevation showing an alternative form of a hypodermic needle in accordance with the invention; and
Figurē 5 is a longitudinal sectional elevation showing an further alternative form of a hypodermic needle in accordance vith the invention.
Referring to the drawings, and firstly to Figurē 1, a hypodermic needle in accordance with the invention, indicated generally by reference numeral 2, comprises aluer 4 carrying a first section 6 of hollow tubing which in turn carries and from which projects a second section 8 of hollow tubing.
The section 6 is a length of thin valled stainless steel tubing, 16 gange and the section 8 is a length of thin walled tubing, 21 gauge, the sections being silver soldered together, as indicated by reference numeral 10, within the section 6 in order to prevent relative movement of said sections.
It will be appreciated that the section 6 and 8 of tubing may be composed of materiāls other than stainless steel, for example alloys, plastics materiāls, glass, and other substances, and that other methods of securing the sections together may be utilised. In addition, gauges other than those specified may be used.
As will be seen, the internai diameter of the section 8 is less than that of section 6. Specifically, the internai diameters for the 21 gauge and the 18 gauge stainless steel tubing used are· nominally 0,025 ļnches and 0,036 inches respectively, and the outside diameters are nominally 0,032 inches and 0,049 inches. Thus the section 8 will locate comfortably within section 6.
The hypodermic needle thus has two internai diameters, the nett result of which is that the force reguired to deliver fluid at a given rāte from a syringe - not shown, but to which the needle is attached through the intermediary of the luer 4 - is considerably reduced.
The outboard end of the section 8 is ground to a point, as indicated by reference numeral 12, so that it can easily and readily pierce the skin,
Referring now to Figurē 2, the hypodermic needle 14 comprises a first section 16 of constant internai diameter and a second section 18 having a first portion 18A of constant internai diameter and a second portion
18Β vhose internai diameter decreases from the first portion 18A to the pointed end 20 of the needle.
Figurē 3 shows a hypodermic needle 22 of unitary construction. The needle consists of a first section 24 and a second section 26 connected together by an integral shoulder 28. The internai diameter of the second section 26 decreases from the shoulder 28 - vhose internai diameter is tapered - to the pointed end 30 of the needle.
The hypodermic needle 32 of Figurē 4 consists of a single section 34 vhich is connegted directly to luer 36 and vhich has a tapered internai diameter which decreases iror the luer to the pointed end of the needle.
The | embodiment | shovn | in : | Figurē | 5 | shovs | the |
hypodermic | needle. | ||||||
The | embodiment | shovn | in | Figurē | 5 | shovs | the |
hypodermic | needle 40 | of unitary construction | and having a |
first section 42 and a second section 44 similar to that shown in Figurē 3, but having curved walls 46 and a curved tapering internai diameter, the taper again decreasing from the luer of the needle to the pointed end 48 of the needle.
The needles described above vill preferably be comprosed of stainless steel, but al temati vely they may be composed of alloys, plastics materiāls, glass, of other substances.
In a stili further alternative embodiment of the present invention, the hypodermic needle may be formed from a single length of hollov tubing having two of more fixed internai diameters. The thickness of the vali of the tubing may be constant or it may vary along the length of the needle.
Sample needles in accordance vith Figurē 1 have been assembled and tested as follovs:
TĒST MATERIAL
- 60 ml syringe with luer lock connection, type Terumo
- hypodermic needle 21 G x l*t, type Gilette
- new hypodermic needle, marked G 18
- new hypodermic needle, unmarked
- veight 1,7kg
- veight 2,5kg
- stopvatch
-saline solution 0,9%, batch 060991
- Iodiacanol injection 320 mg 1/ml, batch number FF 011223.
TĒST PROCEDURE
The syringe is filled vith solution, saline or iodixanol injection. The hypodermic needle is connected to the syringe and the air is pressed out. The syringe is fixed in a holder and a veight, l,7kg or 2,5kg, is put on the plunger. The solution flovs through the hypodermic needle, and the time the plunger takes from the 4Omi mark to the 30ml mark is measured.
Flov is given as ml/min at 20°C.
RESULTS
The results from the flow testing with saline is given in Table 1. The vzeight used vzhen testing saline is l,7kg
TABLE 1
HYPODERMIC NEEDLE | TIME (SECS) | FLOW (ML/MIN) |
N = 5 | ||
21g X 14 | 18.1 | 33 |
Gillette | (17.7 - 18.4) | |
Nevz hypodermic | 8.9 | 67 |
needle G 18 | (8.7 - 9.0) | |
Nevz hypodermic | 10.2 | 59 |
needle unmarked | (9.9 - 10.5) | |
The results from | the flovz testing vzith iodixanol | |
injection 320 mg 1/ml | is given in | Table 2. The vzeight |
used vzhen testing iodixanol injection | is 2.5kg. |
TABLE 2.
HYPODERMIC NEEDLE | TIME (SECS) N = 5 v | FLOVZ (ML/MIN) |
21g X 14 Gillette | * | 0.13* |
Nevz hypodermic | 46.5 | 13 |
needle G 18 | (44.0 - 49.9) | |
Nevz hypodermic | 64.8 | 9 |
needle unmarked | (61.0 - 70.0) | |
* measurement | gavē as result lml in 8 minūtes | |
As expested, | the needle in | accordance vzith |
invention shovzed in every case an incteased flovz for the same applied force and thus confers a distinct advantage over a Standard hypodermic needle.
With a hypodermic needle in accordance vith the invention, the force reguired to deliver a fluid at a given rāte is considerably reduce. Al temati vely, with a given force the flow rāte is considerably increased. This is particularly useful where a flow rāte of the fluid is reguired or where the vicosity of the fluid is high, such as for example in the intravenous injection of an X - ray contrast fluid or in situations which are similar to such injections. It vill be understood that the needle may have more than tvo sections and more· than tvo sections and more than tvo internai diameters.
Finally, vhilst the invention has been described in relation to intravenous injections, it vill be fully understood that a needle in accordance vith the invention is egually applicable and useful in other situations.
Claims (16)
1. A hypodermic needle in association vvith an X-ray contrast fluid and means for passing said fluid therethrough, characterised in that said needle is multidiameter.
2. A hypodermic needle according to claim 1, vvherein said needle comprises a first section of thin vvalled small diameter tubing and a second section of thin vvalled small diameter tubing vvhose extemal diameter is less than the internai diameter of said first section.
3. A hypodermic needle according to claim 2, vvherein the internai diameter of the first section is greater than the internai diameter of the second section.
4. A hypodermic needle according to claim 3, vvherein the internai diameters of said first and second sections are constant.
5. A hypodermic needle according to any of claims 2 to 4, vvherein said first and second sections are fixedly secured together to prevent relative movement of said sections.
6. A hypodermic needle according to any of claims 2 to 5, vvherein an outboard end of said second section is pointed.
7. A hypodermic needle according to any of claims 2 to 6, vvherein said sections are composed of stainless Steel.
8. A hypodermic needle according to claim 2, vvherein said second section of thin vvalled tubing includes a first portion of constant internai diameter and a second portion having an internai diameter vvhich decreases from said first portion.
9. A hypodermic needle according to claim 1, vvherein said needle is of unitary construction and comprises a first portion of thin vvalled tubing of constant internai diameter and a second portion of thin vvalled tubing having an internai diameter vvhich decreases from said first portion, said first and second portions being connected together by an integral shoulder.
10. A hypodermic needle according to claim 1, vvherein said needle, comprises a single straight vvalled portion of thin vvalled tubing having an internai diameter vvhich decreases tovvards an outboard end of said needle.
11. A hypodermic needle according to claim 1, vvherein said needle comprises a single section of thin vvalled tubing having curved inner and outer vvalls and an internai diameter vvhich decreases tovvards an outboard end of said needle.
12. A hypodermic needle according to any of claims 2 to 11, wherein said tubing is of circular cross-section.
13. A hypodermic needle according to any of claims 1 to 11, in which said X-ray contrast fluid is viscous.
14. A hypodermic needle according to any of claims 1 to 11, in which said X-ray contrast fluid is an X-ray contrast aģent having an iodine content of 320 mg ί/ml or greater.
15. A method of generating an X-ray image of a human or animal subject or part thereof vvherein an X-ray contrast fluid is introduced into said subject hypodermically via a hypodermic needle to provide enhanced image contrast and an image of said subject or part is then generated, characterised in that said needle is multidiameter.
16. A method as claimed in claim 15 in vvhich said X-ray contrast fluid has an iodine content of 320 mg I/ml or greater.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
LV930056A LV10585B (en) | 1993-01-18 | 1993-01-18 | Hypodermic needle |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
LV930056A LV10585B (en) | 1993-01-18 | 1993-01-18 | Hypodermic needle |
Publications (2)
Publication Number | Publication Date |
---|---|
LV10585A LV10585A (lv) | 1995-04-20 |
LV10585B true LV10585B (en) | 1995-10-20 |
Family
ID=19735481
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
LV930056A LV10585B (en) | 1993-01-18 | 1993-01-18 | Hypodermic needle |
Country Status (1)
Country | Link |
---|---|
LV (1) | LV10585B (lv) |
-
1993
- 1993-01-18 LV LV930056A patent/LV10585B/lv unknown
Also Published As
Publication number | Publication date |
---|---|
LV10585A (lv) | 1995-04-20 |
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