Editing Subcutaneous administration (section)

==Technique==
[[File:Needle-insertion-angles-1.png|thumb|right|Comparison of angle of subcutaneous injection of a needle with other injection types.]]
Subcutaneous injections are performed by cleaning the area to be injected followed by an injection, usually at a 45-degree angle to the skin when using a syringe and needle, or at a 90-degree angle (perpendicular) if using an injector pen. The appropriate injection angle is based on the length of needle used, and the depth of the subcutaneous fat in the skin of the specific person. A 90-degree angle is always used for medications such as [[heparin]]. If administered at an angle, the skin and underlying tissue may be pinched upwards prior to injection. The injection is administered slowly, lasting about 10 seconds per milliliter of fluid injected, and the needle may be left in place for 10 seconds following injection to ensure the medicine is fully injected.<ref name=Taylor/>{{rp|724}}

===Equipment===
The [[Birmingham gauge#Sizes of hypodermic needles|gauge]] of the needle used can range from 25 gauge to 27 gauge, while the length can vary between {{frac|1|2}}-inch to {{frac|5|8}}-inch for injections using a syringe and needle.<ref name=Taylor/>{{rp|722}} For subcutaneous injections delivered using devices such as [[injector pen]]s, the needle used may be as thin as 34 gauge (commonly 30–32 gauge), and as short as 3.5&nbsp;mm (commonly 3.5&nbsp;mm to 5&nbsp;mm).<ref name="MD2019">{{cite journal | vauthors = Leonardi L, Viganò M, Nicolucci A | title = Penetration force and cannula sliding profiles of different pen needles: the PICASSO study | journal = Medical Devices: Evidence and Research | volume = 12 | pages = 311–317 | date = 28 August 2019 | pmid = 31695523 | pmc = 6717876 | doi = 10.2147/MDER.S218983 | doi-access = free }}</ref> Subcutaneous injections can also be delivered via a pump system which uses a cannula inserted under the skin. The specific needle size/length, as well as appropriateness of a device such as a pen or pump, is based on the characteristics of a person's skin layers.<ref name=Taylor />{{rp|722–724}}

===Locations===
[[File:Subcutaneous-injection-sites-274x300.png|thumb|Subcutaneous injection sites]]
Commonly used injection sites include:<ref name=Taylor />{{rp|723}}
* The outer area of the [[upper arm]].
* The abdomen, avoiding a 2-inch circle around the navel.
* The front of the [[thigh]], between 4&nbsp;inches from the top of the thigh and 4&nbsp;inches above the knee.
* The upper back.
* The upper area of the [[buttock]], just behind the [[human pelvis|hip bone]].

The choice of specific injection site is based on the medication being administered, with [[heparin]] almost always being administered in the abdomen, as well as preference. Injections administered frequently or repeatedly should be administered in a different location each time, either within the same general site or a different site, but at least one inch away from recent injections.<ref name=Taylor />{{rp|724}}

===Self-administration===
As opposed to intramuscular or intravenous injections, subcutaneous injections can be easily performed by people with minor skill and training required. The injection sites for self-injection of medication are the same as for injection by a healthcare professional, and the skill can be taught to patients using pictures, videos, or models of the subcutaneous tissue for practice. People who are to self-inject medicine subcutaneously should be trained how to evaluate and rotate the injection site if complications or contraindications arise. Self-administration by subcutaneous injection generally does not require disinfection of the skin outside of a hospital setting as the risk of infection is extremely low, but instead it is recommended to ensure that the site and person's hands are simply clean prior to administration.<ref name="Mayo2016">{{cite journal | vauthors = Frid AH, Kreugel G, Grassi G, Halimi S, Hicks D, Hirsch LJ, Smith MJ, Wellhoener R, Bode BW, Hirsch IB, Kalra S, Ji L, Strauss KW | display-authors = 6 | title = New Insulin Delivery Recommendations | journal = Mayo Clinic Proceedings | volume = 91 | issue = 9 | pages = 1231–1255 | date = September 2016 | pmid = 27594187 | doi = 10.1016/j.mayocp.2016.06.010 | name-list-style = vanc | doi-access = free }}</ref>

===Infusion===
'''Subcutaneous infusion''', also known as '''interstitial infusion''' or '''hypodermoclysis''', is a form of subcutaneous (under the skin) administration of fluids to the body, often [[saline (medicine)|saline]] or glucose solutions.<ref>[http://www.merriam-webster.com/medical/hypodermoclyses "hypodermoclysis"], ''Merriam-Webster's medical dictionary online''. Retrieved July 19, 2009.</ref> It is the infusion counterpart of [[subcutaneous injection]] with a syringe.

Subcutaneous infusion can be used where a slow rate of fluid uptake is required compared to [[intravenous infusion]].  Typically, it is limited to 1 mL per minute, although it is possible to increase this by using two sites simultaneously.  The chief advantages of subcutaneous infusion over intravenous infusion is that it is cheap and can be administered by non-medical personnel with minimal supervision.  It is therefore particularly suitable for home care.  The enzyme [[hyaluronidase]] can be added to the fluid to improve absorption during the infusion.<ref>Menahem Sasson, Pesach Shvartzman, [http://www.aafp.org/afp/20011101/1575.html "Hypodermoclysis: an alternative infusion technique"], ''American Family Physician'', vol. 64, no. 9, pp. 1575-1579 (November 1, 2001).</ref>

Subcutaneous infusion can be speeded up by applying it to multiple sites simultaneously.  The technique was pioneered by [[Evan O'Neill Kane]] in 1900.  Kane was looking for a technique that was as fast as intravenous infusion but not so risky to use on trauma patients in unhygienic conditions in the field.<ref>Edwin M. Hasbrouck, [https://jamanetwork.com/journals/jama/article-abstract/477272 "An improved device for rapid hypodermoclysis"], ''Journal of the American Medical Association'', '''34''', p.&nbsp;1273, 1900.</ref>