Intravenous

Intravenous means "within a vein." Most often it refers to giving medicines or fluids through a needle or tube inserted into a vein. This allows the medicine or fluid to enter your bloodstream right away. For example, your health care provider may prescribe medicines to be given through a vein, or an intravenous (IV) line.

Intravenous

The intravenous route is the fastest way to deliver medications and fluid replacement throughout the body as they are introduced directly into the circulatory system and thus quickly distributed. For this reason, the intravenous route of administration is also used for the consumption of some recreational drugs. Many therapies are administered as a "bolus" or one-time dose, but they may also be administered as an extended infusion or drip. The act of administering a therapy intravenously, or placing an intravenous line ("IV line") for later use, is a procedure which should only be performed by a skilled professional. The most basic intravenous access consists of a needle piercing the skin and entering a vein which is connected to a syringe or to external tubing. This is used to administer the desired therapy. In cases where a patient is likely to receive many such interventions in a short period (with consequent risk of trauma to the vein), normal practice is to insert a cannula which leaves one end in the vein, and subsequent therapies can be administered easily through tubing at the other end. In some cases, multiple medications or therapies are administered through the same IV line.

IV lines are classified as "central lines" if they end in a large vein close to the heart, or as "peripheral lines" if their output is to a small vein in the periphery, such as the arm. An IV line can be threaded through a peripheral vein to end near the heart, which is termed a "peripherally inserted central catheter" or PICC line. If a person is likely to need long-term intravenous therapy, a medical port may be implanted to enable easier repeated access to the vein without having to pierce the vein repeatedly. A catheter can also be inserted into a central vein through the chest, which is known as a tunneled line. The specific type of catheter used and site of insertion are affected by the desired substance to be administered and the health of the veins in the desired site of insertion.

Placement of an IV line may cause pain, as it necessarily involves piercing the skin. Infections and inflammation (termed phlebitis) are also both common side effects of an IV line. Phlebitis may be more likely if the same vein is used repeatedly for intravenous access, and can eventually develop into a hard cord which is unsuitable for IV access. The unintentional administration of a therapy outside a vein, termed extravasation or infiltration, may cause other side effects.

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 expanders, blood-based products, blood substitutes, medications and nutrition.

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 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.[1]

Buffer solutions 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 sodium bicarbonate.[3]

Medications may be mixed into the fluids mentioned above, commonly normal saline, or dextrose solutions.[4] 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.[5] 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.[6] In atrial fibrillation, IV amiodarone may be administered to attempt to restore normal heart rhythm.[7] 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.[8]

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.[4] 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,[9] such is the case of severe dehydration where the patient is required to be treated via IV therapy for a quick recovery.[10] The unpredictability of oral bioavailability in different people is also a reason for a medication to be administered IV, as with furosemide.[11] 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.[12]

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 digesting food. A person receiving parenteral nutrition will be given an intravenous 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 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).[16]

IV rehydration was formerly a common technique for athletes.[19] The World Anti-Doping Agency prohibits intravenous injection of more than 100mL per 12 hours, except under a medical exemption.[19] 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".[19] Players suspended after attending "boutique IV clinics" which offer this sort of treatment include footballer Samir Nasri in 2017[20] and swimmer Ryan Lochte in 2018.[21]

In some countries, non-prescription intravenous 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.[24] Improperly administered intravenous glucose (called "ringer"), such as that which is administered clandestinely in store-front clinics, poses increased risks due to improper technique and oversight.[24] Intravenous 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.[25]

Any additional medication to be administered intravenously at the same time as an infusion may be connected to the primary tubing; this is termed a secondary IV, or IV piggyback.[27] This prevents the need for multiple IV access lines on the same person. When administering a secondary IV medication, the primary bag is held lower than the secondary bag so that the secondary medication can flow into the primary tubing, rather than fluid from the primary bag flowing into the secondary tubing. The fluid from the primary bag is needed to help flush any remaining medication from the secondary IV from the tubing.[27] If a bolus or secondary infusion is intended for administration in the same line as a primary infusion, the molecular compatibility of the solutions must be considered.[27] Secondary compatibility is generally referred to as "y-site compatibility", named after the shape of the tubing which has a port for bolus administration.[27] Incompatibility of two fluids or medications can arise due to issues of molecular stability, changes in solubility, or degradation of one of the medications.[27]

Placement of an intravenous line inherently causes pain when the skin is broken and is considered medically invasive. For this reason, when other forms of administration may suffice, intravenous therapy is usually not preferred. This includes the treatment of mild or moderate dehydration with oral rehydration therapy which is an option, as opposed to parenteral rehydration through an IV line.[41][42] Children in emergency departments being treated for dehydration have better outcomes with oral treatment than intravenous therapy due to the pain and complications of an intravenous line.[41] Cold spray may decrease the pain of putting in an IV.[43] 041b061a72