Editing Intravenous therapy (section)

===Medical uses===
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Intravenous (IV) access is used to administer medications and fluid replacement which must be distributed throughout the body, especially when rapid distribution is desired. Another use of IV administration is the avoidance of [[first-pass metabolism]] in the [[liver]]. Substances that may be infused intravenously include [[volume expander]]s, [[Blood product|blood-based products]], [[blood substitutes]], medications and nutrition.

====Fluid solutions====
{{Main|Volume expander|Buffer solution}}
Fluids may be administered as part of "volume expansion", or fluid replacement, through the intravenous route. Volume expansion consists of the administration of fluid-based solutions or suspensions designed to target specific areas of the body which need more water. There are two main types of volume expander: [[crystalloids]] and [[colloid]]s. Crystalloids are [[aqueous solution]]s of mineral salts or other water-soluble molecules. Colloids contain larger insoluble molecules, such as [[gelatin]]. [[Blood]] itself is considered a colloid.<ref name="CCRP2020">{{cite journal |last1=Noonpradej |first1=Seechad |last2=Akaraborworn |first2=Osaree |title=Intravenous Fluid of Choice in Major Abdominal Surgery: A Systematic Review |journal=Critical Care Research and Practice |date=3 August 2020 |volume=2020 |pages=1–19 |doi=10.1155/2020/2170828|pmid=32832150 |pmc=7421038 |doi-access=free }}</ref>

The most commonly used crystalloid fluid is [[saline (medicine)|normal saline]], a solution of [[sodium chloride]] at 0.9% concentration, which is [[Isotonicity|isotonic]] with blood. Lactated Ringer's (also known as ''[[Ringer's lactate]]'') and the closely related ''Ringer's acetate'', are mildly [[hypotonic]] solutions often used in those who have significant [[burn]]s. Colloids preserve a high [[colloid osmotic pressure]] in the blood, while, on the other hand, this parameter is decreased by crystalloids due to hemodilution.<ref name="gregory">{{cite web |last1=Martin |first1=Gregory S. |title=An Update on Intravenous Fluids |url=http://www.medscape.com/viewarticle/503138 |website=Medscape |publisher=WebMD |access-date=25 August 2020}}</ref> Crystalloids generally are much cheaper than colloids.<ref name=gregory/>

[[Buffer solution]]s which are used to correct [[acidosis]] or [[alkalosis]] are also administered through intravenous access. [[Lactated Ringer's solution]] used as a fluid expander or base solution to which medications are added also has some buffering effect. Another solution administered intravenously as a buffering solution is [[intravenous sodium bicarbonate|sodium bicarbonate]].<ref>{{cite journal |last1=Fujii |first1=Tomoko |last2=Udy |first2=Andrew |last3=Licari |first3=Elisa |last4=Romero |first4=Lorena |last5=Bellomo |first5=Rinaldo |title=Sodium bicarbonate therapy for critically ill patients with metabolic acidosis: A scoping and a systematic review |journal=Journal of Critical Care |date=June 2019 |volume=51 |pages=184–191 |doi=10.1016/j.jcrc.2019.02.027|pmid=30852347 |s2cid=73725286 }}</ref>

====Medication and treatment====
[[File:Glass IV.jpg|right|thumb|[[Saline (medicine)|Saline]] and 5% [[dextrose]] solution (left), [[levofloxacin]] 750mg (right), and log sheet hanging from an IV pole|alt=Photograph of two intravenous solution bags (containing glucose and levofloxacin, respectively) and a paper log sheet hanging from a pole]]
[[Medication]]s may be mixed into the fluids mentioned above, commonly normal saline, or [[dextrose]] solutions.<ref name="Flynn2007" /> Compared with other [[route of administration|routes of administration]], such as [[Oral administration|oral medications]], the IV route is the fastest way to deliver fluids and medications throughout the body.<ref>{{cite web |title=What is an IV Vitamin Therapy? A Complete Guide by Nepenthe |url=https://www.nepenthewellness.com/complete-guide-to-iv-vitamin-therapy/ |access-date=2022-09-02 |language=en-US}}</ref> For this reason, the IV route is commonly preferred in emergency situations or when a fast onset of action is desirable. In extremely high blood pressure (termed a hypertensive emergency), IV antihypertensives may be given to quickly decrease the blood pressure in a controlled manner to prevent organ damage.<ref name=JEM2012>{{cite journal |last1=Peacock |first1=W. Frank |last2=Hilleman |first2=Daniel E. |last3=Levy |first3=Phillip D. |last4=Rhoney |first4=Denise H. |last5=Varon |first5=Joseph |title=A systematic review of nicardipine vs labetalol for the management of hypertensive crises |journal=The American Journal of Emergency Medicine |date=July 2012 |volume=30 |issue=6 |pages=981–993 |doi=10.1016/j.ajem.2011.06.040|pmid=21908132 }}</ref> In atrial fibrillation, IV [[amiodarone]] may be administered to attempt to restore normal heart rhythm.<ref>{{cite journal |last1=Vardas |first1=Panos E. |last2=Kochiadakis |first2=George E. |title=Amiodarone for the Restoration of Sinus Rhythm in Patients with Atrial Fibrillation |journal=Cardiac Electrophysiology Review |date=September 2003 |volume=7 |issue=3 |pages=297–299 |doi=10.1023/B:CEPR.0000012400.34597.00|pmid=14739732 }}</ref> IV medications can also be used for chronic health conditions such as cancer, for which chemotherapy drugs are commonly administered intravenously. In some cases, such as with [[vancomycin]], a loading or bolus dose of medicine is given before beginning a dosing regimen to more quickly increase the concentration of medication in the blood.<ref>{{cite journal |last1=Álvarez |first1=Rocío |last2=López Cortés |first2=Luis E. |last3=Molina |first3=José |last4=Cisneros |first4=José M. |last5=Pachón |first5=Jerónimo |title=Optimizing the Clinical Use of Vancomycin |journal=Antimicrobial Agents and Chemotherapy |date=May 2016 |volume=60 |issue=5 |pages=2601–2609 |doi=10.1128/AAC.03147-14|pmid=26856841 |pmc=4862470 |s2cid=9560849 }}</ref>

The [[bioavailability]] of an IV medication is by definition 100%, unlike oral administration where medication may not be fully absorbed, or may be metabolized prior to entering the bloodstream.<ref name="Flynn2007">{{cite book | last=Flynn | first=Edward | title=xPharm: The Comprehensive Pharmacology Reference | chapter=Pharmacokinetic Parameters | publisher=Elsevier | year=2007 | isbn=978-0-08-055232-3 | doi=10.1016/b978-008055232-3.60034-0 | pages=1–3}}</ref> For some medications, there is virtually zero oral bioavailability. For this reason certain types of medications can only be given intravenously, as there is insufficient uptake by other [[routes of administration]],<ref name="BCcampus">{{cite book |last1=Doyle |first1=GR |last2=McCutcheon |first2=JA |title=Clinical Procedures for Safer Patient Care |date=13 November 2015 |publisher=BCcampus |location=Victoria, BC |url=https://opentextbc.ca/clinicalskills/chapter/6-9-iv-main-and-mini-bag-medications/ |chapter=7.5}}</ref> such is the case of severe dehydration where the patient is required to be treated via IV therapy for a quick recovery.<ref>{{cite web |url=https://my.clevelandclinic.org/health/treatments/21635-iv-fluids |access-date=2023-09-30 |website=Cleveland Clinic |title=IV Fluids|language=en}}</ref> The unpredictability of oral bioavailability in different people is also a reason for a medication to be administered IV, as with [[furosemide]].<ref>{{cite journal |last1=Boles Ponto |first1=Laura L. |last2=Schoenwald |first2=Ronald D. |title=Furosemide (Frusemide) A Pharmacokinetic/Pharmacodynamic Review (Part I) |journal=Clinical Pharmacokinetics |date=1 May 1990 |volume=18 |issue=5 |pages=381–408 |doi=10.2165/00003088-199018050-00004|pmid=2185908 |s2cid=32352501 }}</ref> Oral medications also may be less desirable if a person is nauseous or vomiting, or has severe diarrhea, as these may prevent the medicine from being fully absorbed from the gastrointestinal tract. In these cases, a medication may be given IV only until the patient can tolerate an oral form of the medication. The switch from IV to oral administration is usually performed as soon as viable, as there is generally cost and time savings over IV administration. Whether a medication can be potentially switched to an oral form is sometimes considered when choosing appropriate antibiotic therapy for use in a hospital setting, as a person is unlikely to be discharged if they still require IV therapy.<ref>{{cite journal |last1=Wetzstein |first1=GA |title=Intravenous to oral (iv:po) anti-infective conversion therapy. |journal=Cancer Control |date=March 2000 |volume=7 |issue=2 |pages=170–6 |doi=10.1177/107327480000700211 |pmid=10783821|doi-access=free }}</ref>

Some medications, such as [[aprepitant]], are chemically modified to be better suited for IV administration, forming a [[prodrug]] such as [[fosaprepitant]]. This can be for pharmacokinetic reasons or to delay the effect of the drug until it can be metabolized into the active form.<ref>{{cite journal |last1=Patel |first1=P |last2=Leeder |first2=JS |last3=Piquette-Miller |first3=M |last4=Dupuis |first4=LL |title=Aprepitant and fosaprepitant drug interactions: a systematic review. |journal=British Journal of Clinical Pharmacology |date=October 2017 |volume=83 |issue=10 |pages=2148–2162 |doi=10.1111/bcp.13322 |pmid=28470980|pmc=5595939 }}</ref>

====Blood products====
{{Main|Blood product|Blood transfusion|Blood substitute}}
A [[blood product]] (or ''blood-based product'') is any component of [[blood]] which is collected from a donor for use in a [[blood transfusion]].<ref>{{cite web|url=https://www.nhlbi.nih.gov/health-topics/blood-transfusion|title=Blood Transfusion {{!}} National Heart, Lung, and Blood Institute (NHLBI)|website=www.nhlbi.nih.gov|access-date=2019-06-16}}</ref> Blood transfusions can be used in massive blood loss due to [[Physical trauma|trauma]], or can be used to replace blood lost during [[surgery]]. Blood transfusions may also be used to treat a severe [[anaemia]] or [[thrombocytopenia]] caused by a [[blood disease]]. Early blood transfusions consisted of [[whole blood]], but modern medical practice commonly uses only components of the blood, such as [[packed red blood cells]], [[fresh frozen plasma]] or [[cryoprecipitate]].<ref>{{cite journal |last1=Avery |first1=Pascale |last2=Morton |first2=Sarah |last3=Tucker |first3=Harriet |last4=Green |first4=Laura |last5=Weaver |first5=Anne |last6=Davenport |first6=Ross |title=Whole blood transfusion versus component therapy in adult trauma patients with acute major haemorrhage |journal=Emergency Medicine Journal |date=June 2020 |volume=37 |issue=6 |pages=370–378 |doi=10.1136/emermed-2019-209040|pmid=32376677 |s2cid=218532376 |url=https://qmro.qmul.ac.uk/xmlui/handle/123456789/64119 |doi-access=free }}</ref>

====Nutrition====
{{main|Parenteral nutrition}}
[[File:Patient lying in hospital bed in intensive care unit in Germany in 2015.jpg|thumb|This patient of an [[intensive care unit]] of a German hospital could not eat due to a prior surgical operation of the [[Abdomen|abdominal region]] which was complicated by a severe [[sepsis]]. He received [[antibiotics]], parenteral nutrition and pain killers via automated injection employing [[syringe driver]]s (background, right).]] 
[[Parenteral nutrition]] is the act of providing required nutrients to a person through an intravenous line. This is used in people who are unable to get nutrients normally, by [[eating]] and [[digestion|digesting]] food. A person receiving parenteral nutrition will be given an intravenous solution which may contain [[salt (chemistry)|salt]]s, [[dextrose]], [[amino acid]]s, [[lipid]]s and [[vitamin]]s. The exact formulation of a parenteral nutrition used will depend on the specific nutritional needs of the person it is being given to. If a person is only receiving nutrition intravenously, it is called total parenteral nutrition (TPN), whereas if a person is only receiving some of their nutrition intravenously it is called partial parenteral nutrition (or supplemental parenteral nutrition).<ref>{{cite book |last1=Halter |first1=Jeffrey B. |last2=Ouslander |first2=Joseph G. |last3=Studenski |first3=Stephanie |last4=High |first4=Kevin P. |last5=Asthana |first5=Sanjay |last6=Supiano |first6=Mark A. |last7=Ritchie |first7=Christine |editor1-last=Edmonson |editor1-first=Karen G. |editor2-last=Davis |editor2-first=Kim J. |title=Hazzard's geriatric medicine and gerontology |publisher=McGraw Hill |location=New York |isbn=978-0-07-183345-5 |edition=Seventh |chapter=Chapter 35|date=23 December 2016 }}</ref>

====Imaging====
{{main|Contrast agent}}
Medical imaging relies on being able to clearly distinguish internal parts of the body from each other. One way this is accomplished is through the administration of a [[contrast agent]] into a vein.<ref>{{cite journal |last1=Runge |first1=VM |last2=Ai |first2=T |last3=Hao |first3=D |last4=Hu |first4=X |title=The developmental history of the gadolinium chelates as intravenous contrast media for magnetic resonance. |journal=Investigative Radiology |date=December 2011 |volume=46 |issue=12 |pages=807–16 |doi=10.1097/RLI.0b013e318237913b |pmid=22094366|s2cid=8425664 }}</ref> The specific imaging technique being employed will determine the characteristics of an appropriate contrast agent to increase visibility of blood vessels or other features. Common contrast agents are administered into a peripheral vein from which they are distributed throughout the circulation to the imaging site.<ref>{{cite journal |last1=Rawson |first1=JV |last2=Pelletier |first2=AL |title=When to Order a Contrast-Enhanced CT. |journal=American Family Physician |date=1 September 2013 |volume=88 |issue=5 |pages=312–6 |pmid=24010394}}</ref>