ISPG, Inc.

Loss of Resistance (LOR Technique)


Loss of Resistance Syringe Inventor
Dr. Francis Rynd

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 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
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.

How is a LOR technique performed?

Loss of resistance technique
Loss of resistance technique

While inserting an epidural needle, once it passes in between 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". The epidural space is usually found between 40 and 60mm from the skin.

All-glass syringe manufacturing process

Parts of all-glass syringe with metal luer lock
Parts of all-glass syringe with metal luer lock

The raw glass tubes used to make the barrels and plungers of our 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. Our syringes are then inspected and packaged in a controlled environment.

Our syringes have three major uses:

1. Syringes for injections
2. Syringes for aspiration
3. Syringes suitable for the LOR technique

What kinds of glass syringes are available?

Our syringe materials consist of:

Tip options

Important notes

What standards ISPG syringes meet

Contact us for a quote.


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