Loss of Resistance Syringe



The word "syringe" comes from the Greek syrinx, which means tube. Initially, a cut was made in the body and the tube was inserted where they wanted to place medication.


Dr. Francis RyndFrancis Rynd, a physician from Ireland, is credited with the invention and first use of a hollow needle used in hypodermic syringes in 1844. He, however, did not publish his findings until 1861.

Dr. Alexander Wood Meanwhile, Dr. Alexander Wood, from Edinburgh, Scotland, was the first to inject a patient with morphine in 1853 using a true hypodermic needle with syringe and hollow needle. He published his paper, "A New Method for Treating Neuralgia by the Direct Application of Opiates to Painful Points" in the Edinburgh Medical and Surgical Journal in 1855.


Lucas and William Chance, partners and owners of Chance Brothers and Company, in Smethwick, Birmingham, England, were the first to manufacture an all-glass syringe featuring an interchangeable barrel and movable plunger in 1946 which set the stage for sterilization of components without having to match them.



What is a LOR syringe?


InjectionWhile inserting an epidural needle, once it passes inbetween the lower half of the anterior surface of the lamina above and the posterior surface of the lamina below, and through the ligament flava, there is a sudden loss of resistance; sometimes described as a negative pressure, on the syringe plunger when dura matter is pushed away from the vertebral canal. This is known as entering the epidural space, where medication may be injected, thus the name "Loss of Resistance" or LOR syringe. The epidural space is usually found between 40 and 60mm from the skin.




Manufacturing Process


The raw glass tubes used to make the barrels and plungers of LOR syringes are made using an extrusion process. The main ingredients in Borosilicate glass are silica sand and boric oxide, along with sodium oxide, aluminum oxide and ground lime, which are heated in a furnace to over 2,000° F. The molten glass is forced through a die that controls the O.D. (Outside Diameter) and a hollow cylinder inside the die that controls I.D. (Inside Diameter) and wall thickness. Air is then blown through the hollow cylinder to keep the glass from collapsing until it cools, at which point the continuous tube is cooled down more and then cut into lengths.

The plunger and barrel are shaped using roll forming equipment. This equipment has many stations with torches that progress the shape until the final plunger and barrel geometries are completed.
Graduations or other custom marks are added and all parts are subject to multiple washes and cleanings prior to final assembly of the barrel, tip and plunger. LOR syringes are then inspected and packaged in a controlled environment.


Loss of Resistance Syringe


How to Use


LOR syringes have three major uses:
1. Syringe for injections
2. Syringe for aspiration
3. Syringe to identify LOR space


The plunger should be inserted fully into the barrel and the needle's female luer is securely attached to the male luer on the syringe barrel. Fluid is then drawn up through the needle into the barrel when the plunger handle is pulled back. If the needle tip remains completely in the fluid when pulling back on the plunger handle, no air will enter the barrel. The quantity of fluid can be identified using graduation marks on the barrel, or if no marks are present, the total volume of the barrel matches the size of the LOR syringe originally identified. To evacuate the liquid, simply push back on the plunger handle.


What kinds of LOR syringes are available?

• Glass-on-glass
• Clear or frosted barrels
• Plunger rod with silicone (for the saline method of locating epidural space)
• Plunger rod without silicone (for the air method of locating epidural space)
• 1cc, 2cc, 3cc, 5cc, 10cc, 20cc, 50cc, 100cc
• With or without graduations
• With or without tip caps
• Customize the barrel, flange, length and tip with company name, logos and other marks

LOR Syringe Materials consist of:
• Nontoxic, Borosilicate glass Type I for barrels and plungers (used for its high strength, heat resistance and optical clarity)
• Nickel or chrome-plated brass luers
• USP Class VI polycarbonate luers
• Cerium glass available
• Available with Neoprene sleeves


Tip Options

• Luer tapers are named after Hermann Wülfing Luer, a 19th Century medical instrument maker. They are a standardized system of small fittings which make a leak-free connection between syringe and needle.
• There are two types of Luer taper connections: Luer Lock and Luer Slip. The Luer Lock holds the female luer needle to the syringe's male luer using threads to lock the needle to the syringe. The Luer Slip is held together by friction between the female hub taper and the male luer taper on the syringe barrel only.
• For LOR Syringes, ISPG offers:
MLL - Metal Luer Lock Tip
MLS - Metal Luer Slip Tip
GLS - Glass Luer Slip Tip


Important Notes

• All LOR Syringes are tested to insure a smooth action and tight fit
• Reliable under repetitive usage
• May be used for anesthetic or other applications
• Bulk-clean, ready to be sterilized
• Certification and inspection reports available upon request
• With ISPG LOR syringes, resistance is up to or less than 0.2N


What standards ISPG LOR syringes meet

• Latex-free
• 510(k) registered and FDA compliant
• ANSI performance requirements for luers, including testing for leakage and separation resistance
• ISO 594/1, 594/2, 595/1, 595/2
• ISO 7886-1
• ISO 13485:2003
• ISO 9001:2008

• US FDA registered
• REACH and RoHS complaint


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