Hypodermic needle

A hypodermic needle (from Greek ὑπο- (under-), and δέρμα (skin)), one of a category of medical tools which enter the skin, called sharps, is a very thin, hollow tube with a sharp tip that contains a small opening at the pointed end. It is commonly used with a syringe, a hand-operated device with a plunger, to inject substances into the body (e.g., saline solution, solutions containing various drugs or liquid medicines) or extract fluids from the body (e.g., blood). They are used to take liquid samples from the body, for example taking blood from a vein in venipuncture. Large-bore hypodermic intervention is especially useful in catastrophic blood loss or treating shock. A hypodermic needle is used for rapid delivery of liquids, or when the injected substance cannot be ingested, either because it would not be absorbed (as with insulin), or because it would harm the liver. There are many possible routes for an injection, with the arm being a common location. The hypodermic needle also serves an important role in research environments where sterile conditions are required. The hypodermic needle significantly reduces contamination during inoculation of a sterile substrate. The hypodermic needle reduces contamination for two reasons: First, its surface is extremely smooth, which prevents airborne pathogens from becoming trapped between irregularities on the needle's surface, which would subsequently be transferred into the media (e.g. agar) as contaminants; second, the needle's surface is extremely sharp, which significantly reduces the diameter of the hole remaining after puncturing the membrane and consequently prevents microbes larger than this hole from contaminating the substrate. The ancient Greeks and Romans knew injection as a method of medicinal delivery from observations of snakebites and poisoned weapons. There are also references to 'anointing' and 'inunction' in the Old Testament as well as the works of Homer, but injection as a legitimate medical tool was not truly explored until the 17th century. Christopher Wren performed the earliest confirmed experiments with crude hypodermic needles, performing intravenous injection into dogs in 1656. These experiments consisted of using animal bladders (as the syringe) and goose quills (as the needle) to administer drugs such as opium intravenously to dogs. Wren and others' main interest was to learn if medicines traditionally administered orally would be effective intravenously. In the 1660s, J. D. Major of Kiel and J. S. Elsholtz of Berlin were the first to experiment with injections in humans. These early experiments were generally ineffective and in some cases fatal. Injection fell out of favor for two centuries. The 19th century saw the development of medicines that were effective in small doses, such as opiates and strychnine. This spurred a renewed interest in direct, controlled application of medicine. 'Some controversy surrounds the question of priority in hypodermic medication.' Francis Rynd is generally credited with the first successful injection in 1844. Alexander Wood’s main contribution was the all-glass syringe in 1851, which allowed the user to estimate dosage based on the levels of liquid observed through the glass. Wood used hypodermic needles and syringes primarily for the application of localized, subcutaneous injection (localized anesthesia) and therefore was not as interested in precise dosages. Simultaneous to Wood's work in Edinburgh, Charles Pravaz of Lyon also experimented with sub-dermal injections in sheep using a syringe of his own design. Pravaz designed a syringe measuring 3 cm (1.18 in) long and 5 mm (0.2 in) in diameter; it was made entirely of silver. Charles Hunter, a London surgeon, is credited with the coining of the term 'hypodermic' to describe subcutaneous injection in 1858. The name originates from two Greek words: hypo, 'under', and derma, 'skin'. Furthermore, Hunter is credited with acknowledging the systemic effects of injection after noticing that a patient's pain was alleviated regardless of the injection’s proximity to the pained area. Hunter and Wood were involved in a lengthy dispute over not only the origin of the modern hypodermic needle, but also because of their disagreement to the medicine's effect once administered. Dr. Wood can be largely credited with the popularization and acceptance of injection as a medical technique, as well as the widespread use and acceptance of the hypodermic needle. The basic technology of the hypodermic needle has stayed largely unchanged since the 19th century, but as the years progressed and medical and chemical knowledge improved, small refinements have been made to increase safety and efficacy, with needles being designed and tailored for very particular uses. The trend of needle specification for use began in the 1920s, particularly for the administration of insulin to diabetics. The onset of World War II spurred the early development of partially disposable syringes for the administration of morphine and penicillin on the battlefield. Development of the fully disposable hypodermic needle was spurred on in the 1950s for several reasons. The Korean War created blood shortages and in response disposable, sterile syringes were developed for collecting blood. The widespread immunization against polio during the period required the development of a fully disposable syringe system. The 1950s also saw the rise and recognition of cross-contamination from used needles. This led to the development of the first fully disposable plastic syringe by New Zealand pharmacist Colin Murdoch in 1956. This period also marked a shift in interest from needle specifications to general sterility and safety. The 1980s saw the rise of the HIV epidemic and with it renewed concern over the safety of cross-contamination from used needles. New safety controls were designed on disposable needles to ensure the safety of medical workers in particular. These controls were implemented on the needles themselves, such as retractable needles, but also in the handling of used needles, particularly in the use of hard-surface disposal receptacles found in every medical office today..