Medical uses<unk>  (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<unk> ly include volume expanders, blood-based products, blood substitutes, medications and nutrition. Fluid solutions Fluids may be administered as part of "volume expansion", or fluid replacement, through the<unk>  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 colloids. Crystalloids are aqueous solutions of mineral salts or other water-soluble molecules. Colloids contain larger insoluble molecules, such as gelatin. Blood itself is considered a colloid. The most commonly used crystalloid fluid is normal saline, a solution of sodium chloride at 0.9% concentration, which is 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 burns. Colloids preserve a high colloid osmotic pressure in the blood, while, on the other hand, this parameter is decreased by crystalloids due to hemodilution. Crystalloids generally are much cheaper than colloids. Buffer solutions which are used to correct acidosis or alkalosis are also administered through<unk>  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<unk> ly as a buffering solution is sodium bicarbonate. Medication and treatment Saline and 5% dextrose solution (Left), levofloxacin 750mg (Right), and log sheet hanging from an IV pole.|alt=Photograph of two<unk>  solution bags (containing glucose and levofloxacin, respectively) and a paper log sheet hanging from a pole. Medications may be mixed into the fluids mentioned above, commonly normal saline, or dextrose solutions. Compared with other routes of administration, such as oral medications, the IV route is the fastest way to deliver fluids and medications throughout the body. 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. In atrial fibrillation, IV amiodarone may be administered to attempt to restore normal heart rhythm. IV medications can also be used for chronic health conditions such as cancer, for which chemotherapy drugs are commonly administered<unk> ly. 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. 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. For some medications, there is virtually zero oral bioavailability. For this reason certain types of medications can only be given<unk> ly, as there is insufficient uptake by other routes of administration. The unpredictability of oral bioavailability in different people is also a reason for a medication to be administered IV, as with furosemide. 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. 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. Blood products A blood product (or blood-based product) is any component of blood which is collected from a donor for use in a blood transfusion. Blood transfusions can be used in massive blood loss due to 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. Nutrition Parenteral nutrition is the act of providing required nutrients to a person through an<unk>  line. This is used in people who are unable to get nutrients normally, by eating and digesting food. A person receiving parenteral nutrition will be given an<unk>  solution which may contain salts, dextrose, amino acids, lipids and vitamins. 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<unk> ly, it is called total parenteral nutrition (TPN), whereas if a person is only receiving some of their nutrition<unk> ly it is called partial parenteral nutrition (or supplemental parenteral nutrition). Imaging 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. 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. Other uses Use in sports IV rehydration was formerly a common technique for athletes. The World Anti-Doping Agency prohibits<unk>  injection of more than 100mL per 12 hours, except under a medical exemption. The United States Anti-Doping Agency notes that, as well as the dangers inherent in IV therapy, "IVs can be used to change blood test results (such as hematocrit where EPO or blood doping is being used), mask urine test results (by dilution) or by administering prohibited substances in a way that will more quickly be cleared from the body in order to beat an anti-doping test". Players suspended after attending "boutique IV clinics" which offer this sort of treatment include footballer Samir Nasri in 2017 and swimmer Ryan Lochte in 2018. Use for hangover treatment In the 1960s, John Myers developed the "Myers' cocktail", a non-prescription IV solution of vitamins and minerals marketed as a hangover cure and general wellness remedy. The first "boutique IV" clinic, offering similar treatments, opened in Tokyo in 2008. These clinics, whose target market was described by Elle as "health nuts who moonlight as heavy drinkers", have been publicized in the 2010s by glamorous celebrity customers.<unk>  is also used in people with acute ethanol toxicity to correct electrolyte and vitamin deficiencies which arise from alcohol consumption. Others In some countries, non-prescription<unk>  glucose is used to improve a person's energy, but is not a part of routine medical care in countries such as the United States where glucose solutions are prescription drugs. Improperly administered<unk>  glucose (called "ringer"), such as that which is administered clandestinely in store-front clinics, poses increased risks due to improper technique and oversight.<unk>  access is also sometimes used outside of a medical setting for the self-administration of recreational drugs, such as heroin and fentanyl, cocaine, methamphetamine, DMT, and others.
Intravenous therapy
Intraoperative blood salvage
Expanded access
Continuous hyperthermic peritoneal perfusion
Moral treatment
Infusion therapy
Damage control surgery
Minimized extracorporeal circulation