LV10585B - Hypodermic needle - Google Patents

Abstract

The hypodermic injection needle has two interconnected sections with different internal diameters or the needle has one section, the diameter of which declines to one direction. Examples of application of the needles are supplied.

Description

HYPODERMIC NEEDLES

This invention reduced to hypodermic needles. '

The invention is particularly applicable to hypodermic use with syringes for delivering intravenous fluids such as X-ray contrast fluids, drugs, blooc products, and other fluids in situations where high flow rates are reguired or where the viscosity of the fluid is injected. high. In a general context, the invention of the hypodermic needle is applicable to the administration of fluids via veins, arteries, intra-muscular injections, intrathecal injections, and in other situations, the use of high-flow or fine-needle vould be an advantage. The hypodermic needle of the invention is thus applicable · in medical, dental, pharmaceutical and veterinary practices.

The hypodermic needle of invention may also have applications in other fields, 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 = (P ₂ - P _x ) Πγ ⁴ 8μ1 vhere: P ₂ - Pi is the pressure difference betveen the ends of the tube r is the internals 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 a problem for many years, since the length and diameter of the needle are fixed by practical considerations. For example, in order to minimize discomfort to the patient and to be able to gain access to small veins, it is desirable to use needles as small as possible with 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 only parameter vhich can conveniently be varied, in order to increase flow of fluid, is pressure. To this end, mechanical injectors and levers have been used in order to increase pressure, but pressure style has to be limited by safety considerations when injecting into patients.

The present invention therefore seeks to provide an improved form of the hypodermic needle which obviates the disadvantages of the hypodermic needle by substantially reducing the force reguired to inject the fluid. The invention seeks to mimimimse the length of the narrow tubing of the pointed maximization of the interna radius using thin walled tubing. Pouseille's eguation that an radius of tube only 10% in flow by a factor of

110

100 end of the needle and of this narrow tubing by It will be noted from increase in the interns will result in increase *, viz. 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 a tubing of two different diameters that 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 having an outer diameter less than the internal diameter of the first section, the first and second sections being fixedly secured together to prevent relative movement of said tube sections.

An outboard end of first section will be largely be pointed out.

The tubes of the first and second sections will be made up of stainless steel.

In order that the invention may be more readily understood, the embodiments of the paragraph will now be described, by way of example, with reference to being made to the accompanying drawings, as follows: Figure 1 is a longitudinal sectional elevation of a hypodermic needle of invention;

Fig. 2 is a longitudinal sectional elevation of a hypodermic needle in accordance with a second embodiment of the invention;

Fig. 3 is a longitudinal sectional elevation of a hypodermic needle in accordance with a third embodiment of the invention;

Figure 4 is a longitudinal sectional elevation showing an alternative form of a hypodermic needle in accordance with the invention; and

Figure 5 is a longitudinal sectional elevation showing an alternative form of hypodermic needle in accordance with the invention.

Referring to the drawings, and firstly to Fig. 1, a hypodermic needle in accordance with the invention, indicated generally by reference numeral 2, comprising an aluer 4 carrying a first section 6 of a hollow tubing which from a second section 8 of hollow tubing.

Section 6 is a length of thin walled stainless steel tubing, 16 gangs and section 8 is a length of thin walled tubing, 21 gauge, the sections being silver soldered together, as indicated by reference numeral 10, within section 6 in order to prevent relative movement of said sections.

It will be appreciated that section 6 and 8 of tubing may be composed of material other than stainless steel, for example alloys, material of plastics, glass, and other substances, and that other methods of securing the sections together may be utilized. In addition, gauges other than those specified may be used.

As will be seen, the inside diameter of section 8 is less than that of section 6. Specifically, the inside diameter of the 21 gauge and the 18 gauge stainless steel tubing used are · nominally 0.025 inches and 0.036 inches respectively, and outside diameters are nominally 0.032 inches and 0.049 inches. Thus, section 8 will locate comfortably within section 6.

The hypodermic needle thus has two internally diameters, the net result of which is the force reguired to deliver fluid at a given pulse - not shown, but which needle is attached through the intermediate 4 of the luer reduced.

The outboard end of section 8 is ground to point, as indicated by reference numeral 12, so that it can easily and readily pierce the skin,

Referring now to Figure 2, the hypodermic needle 14 comprises a first section 16 of a constant section 18 and a second section 18A of a constant section diameter and a second portion

18Β vhose interns diameter decreases from first portion 18A to pointed end 20 of needle.

Figure 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 inside diameter of the second section 26 decreases from the shoulder 28 - vhose the inside diameter is tapered - to the pointed end 30 of the needle.

The hypodermic needle 32 of Figure 4 consists of a single section 34 vhich is connected directly to the luer 36 and vhich has a tapered internal diameter which decreases iror the luer to the pointed end of the needle.

The completed shovn in ^: In the picture 5 shovs the hypodermic needle. The completed shovn in In the picture 5 shovs the hypodermic needle 40 of unitary construction and having a

first section 42 and second section 44 similar to that shown in Figure 3, but having curved walls 46 and a curved tapering internal diameter, the taper again decreasing from the luer of the needle to the pointed end 48 of the needle.

The needles described above are woolly composted of stainless steel, but they may be composed of alloys, plastics material, glass, of other substances.

In a style further alternative to the present invention, the hypodermic needle may be formed from a single length of hollov tubing having two of the more fixed internal diameters. The thickness of the valley of the tubing may be constant or it may vary along the length of the needle.

Sample needles in accordance with Fig. 1 have been assembled and tested as follovs:

TEACH 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.

TEACHING PROCEDURE

The syringe is filled with 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 of 1.7kg or 2.5kg is put on the plunger. The solution flows through the hypodermic needle and the time the plunger takes from the 4Omi mark to the 30ml mark is measured.

Flow is given as ml / min at 20 ° C.

RESULTS

The results from the flow testing with saline are given in Table 1. The vzeight used with 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 = _5v FLOVZ (ML / MIN) 21g X 14 Gillette * 0.13 * Nevz hypodermic 46.5 13th needle G 18 (44.0 - 49.9) Nevz hypodermic 64.8 9th needle unmarked (61.0 - 70.0) * measurement fast as result lml in 8 minutes As expested, the needle in under vzith

invention shovzed in every case an incised flovz for the same applied force and thus confers a distinct advantage over a standard hypodermic needle.

With a hypodermic needle in accordance with the invention, the force reguired to deliver the fluid at a given rat is significantly reduced. Al themati vely, with a given force, the flow is greatly increased. This is particularly useful where the flow of fluid is reguired or where the fluidity of the fluid is high, such as in the case of 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, the invention has been described in relation to intravenous injections, it has to be fully understood that the needle in accordance with the invention is simply applicable and useful in other situations.

Claims (16)

A hypodermic needle in association with an X-ray contrast fluid and means for passing a fluid therethrough, characterized in that said needle is a multidiameter. 2. The hypodermic needle according to claim 1, wherein the needle comprises a first section of a thin diameter tubing and a second section of a small diameter tubing vvhose extensional diameter is less than the internal diameter of said first section. 3. The hypodermic needle according to claim 2, wherein the first section is larger than the second section. 4. The hypodermic needle according to claim 3, vvherein the internal diameters of said first and second sections are constant. 5. The hypodermic needle according to any claims 2 to 4, vvherein said first and second sections are fixedly secured together to prevent relative movement of said sections. 6. The hypodermic needle according to any of claims 2 to 5 is pointed out. 7. The hypodermic needle according to any of claims 2 to 6 is made of stainless steel. 8. The hypodermic needle according to claim 2, wherein said second section of thin vvalled tubing comprises a first portion of a constant internal diameter and a second portion having an internal diameter decreases from said first portion. 9. A hypodermic needle according to claim 1, wherein said needle is of unitary construction and comprises a first portion of a thin tubing of constant internal diameter and a second portion of a thin tubular tubing having an internal diameter of said first portion, said first and second portions being connected together by an integral shoulder. 10. The hypodermic needle according to claim 1, comprising a single straight vvalled portion of a thin vvalled tubing having an internal diameter vvhich decreasing to the end of said needle. 11. A hypodermic needle according to claim 1, wherein said needle comprises a single section of thin vvalled tubing having a curved inner and outer diameter and an inner diameter vvhich decreasing to the outer end of said needle. 12. The hypodermic needle according to any of claims 2 to 11 was tubing of a circular cross-section. 13. The 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 one of claims 1 to 11, wherein said X-ray contrast fluid is an X-ray contrast agent having an iodine content of 320 mg / ml or greater. 15. A method of generating an X-ray image of a human or animal subject or part of a vvherein an X-ray contrast fluid is introduced into a subject subject hypodermically via a hypodermic needle to provide an enhanced image contrast and an image of the subject subject or part is then generated, characterized in that said needle is multidiameter. 16. A method as claimed in claim 15 in an X-ray contrast fluid having an iodine content of 320 mg I / ml or greater.