Intravenous therapy
Intravenous therapy (abbreviated as IV therapy) is a medical technique that administers fluids, medications and nutrients directly into a person's vein. The intravenous route of administration is commonly used for rehydration or to provide nutrients for those who cannot, or will not—due to reduced mental states or otherwise—consume food or water by mouth. It may also be used to administer medications or other medical therapy such as blood products or electrolytes to correct electrolyte imbalances. Attempts at providing intravenous therapy have been recorded as early as the 1400s, but the practice did not become widespread until the 1900s after the development of techniques for safe, effective use.
"The Drip" redirects here. For the Schitt's Creek episode, see The Drip (Schitt's Creek). For other uses, see Drip.Intravenous therapy
IV therapy, iv therapy
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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.
Types[edit]
Bolus[edit]
Some medications can be administered as a bolus dose, which is called an "IV push". A syringe containing the medication is connected to an access port in the primary tubing and the medication is administered through the port.[27] A bolus may be administered rapidly (with a fast depression of the syringe plunger) or may be administered slowly, over the course of a few minutes.[27] The exact administration technique depends on the medication and other factors.[27] In some cases, a bolus of plain IV solution (i.e. without medication added) is administered immediately after the bolus to further force the medicine into the bloodstream. This procedure is termed an "IV flush". Certain medications, such as potassium, are not able to be administered by IV push due to the extremely rapid onset of action and high level of effects.[27]
Infusion[edit]
An infusion of medication may be used when it is desirable to have a constant blood concentration of a medication over time, such as with some antibiotics including beta-lactams.[28] Continuous infusions, where the next infusion is begun immediately following the completion of the prior, may also be used to limit variation in drug concentration in the blood (i.e. between the peak drug levels and the trough drug levels).[28] They may also be used instead of intermittent bolus injections for the same reason, such as with furosemide.[29] Infusions can also be intermittent, in which case the medication is administered over a period of time, then stopped, and this is later repeated. Intermittent infusion may be used when there are concerns about the stability of medicine in solution for long periods of time (as is common with continuous infusions), or to enable the administration of medicines which would be incompatible if administered at the same time in the same IV line, for example vancomycin.[30]
Failure to properly calculate and administer an infusion can result in adverse effects, termed infusion reactions. For this reason, many medications have a maximum recommended infusion rate, such as vancomycin[30] and many monoclonal antibodies.[31] These infusion reactions can be severe, such as in the case of vancomycin, where the reaction is termed "red man syndrome".[30]
Secondary[edit]
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]
Adverse effects[edit]
Pain[edit]
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]
Certain medications also have specific sensations of pain associated with their administration IV. This includes potassium, which when administered IV can cause a burning or painful sensation.[44] The incidence of side effects specific to a medication can be affected by the type of access (peripheral versus central), the rate of administration, or the quantity of drug administered. When medications are administered too rapidly through an IV line, a set of vague symptoms such as redness or rash, fever, and others may occur; this is termed an "infusion reaction" and is prevented by decreasing the rate of administration of the medication. When vancomycin is involved, this is commonly termed "Red Man syndrome" after the rapid flushing which occurs after rapid administration.[45]
Infection and inflammation[edit]
As placement of an intravenous line requires breaking the skin, there is a risk of infection. Skin-dwelling organisms such as coagulase-negative staphylococcus or Candida albicans may enter through the insertion site around the catheter, or bacteria may be accidentally introduced inside the catheter from contaminated equipment. Infection of an IV access site is usually local, causing easily visible swelling, redness, and fever. However, pathogens may also enter the bloodstream, causing sepsis, which can be sudden and life-threatening. A central IV line poses a higher risk of sepsis, as it can deliver bacteria directly into the central circulation. A line which has been in place for a longer period of time also increases the risk of infection.[32]: 358, 373
Inflammation of the vein may also occur, called thrombophlebitis or simply phlebitis. This may be caused by infection, the catheter itself, or the specific fluids or medication being given. Repeated instances of phlebitis can cause scar tissue to build up along a vein. A peripheral IV line cannot be left in the vein indefinitely out of concern for the risk of infection and phlebitis, among other potential complications. However, recent studies have found that there is no increased risk of complications in those whose IVs were replaced only when clinically indicated versus those whose IVs were replaced routinely.[46] If placed with proper aseptic technique, it is not recommended to change a peripheral IV line more frequently than every 72–96 hours.[47]
Phlebitis is particularly common in intravenous drug users,[48] and those undergoing chemotherapy,[49] whose veins can become sclerotic and difficult to access over time, sometimes forming a hard, painful "venous cord". The presence of a cord is a cause of discomfort and pain associated with IV therapy, and makes it more difficult for an IV line to be placed as a line cannot be placed in an area with a cord.[50]
History[edit]
Discovery and development[edit]
The first recorded attempt at administering a therapeutic substance via IV injection was in 1492, when Pope Innocent VIII fell ill and was administered blood from healthy individuals.[56] If this occurred, the treatment did not work and resulted in the death of the donors while not healing the pope.[56] This story is disputed by some, who claim that the idea of blood transfusions could not have been considered by the medical professionals at the time, or that a complete description of blood circulation was not published until over 100 years later. The story is attributed to potential errors in translation of documents from the time, as well as potentially an intentional fabrication, whereas others still consider it to be accurate.[57] One of the leading medical history textbooks for medical and nursing students has claimed that the entire story was an anti-semitic fabrication.[58]
In 1656 Sir Christopher Wren and Robert Boyle worked on the subject. As stated by Wren, "I Have Injected Wine and Ale in a liveing Dog into the Mass of Blood by a Veine, in good Quantities, till I have made him extremely drunk, but soon after he Pisseth it out." The dog survived, grew fat, and was later stolen from his owner. Boyle attributed authorship to Wren.[59]
Richard Lower showed it was possible for blood to be transfused from animal to animal and from animal to man intravenously, a xenotransfusion. He worked with Edmund King to transfuse sheep's blood into a man who was mentally ill. Lower was interested in advancing science but also believed the man could be helped, either by the infusion of fresh blood or by the removal of old blood. It was difficult to find people who would agree to be transfused, but an eccentric scholar, Arthur Coga, consented and the procedure was carried out by Lower and King before the Royal Society on 23 November 1667.[60] Transfusion gathered some popularity in France and Italy, but medical and theological debates arose, resulting in transfusion being prohibited in France.
There was virtually no recorded success with any attempts at injection therapy until the 1800s, when in 1831 Thomas Latta studied the use of IV fluid replacements for cholera treatment.[56][61] The first solutions which saw widespread use for IV injections were simple "saline-like solutions", which were followed by experiments with various other liquids, including milk, sugar, honey, and egg yolk.[56] In the 1830s, James Blundell, an English obstetrician, used intravenous administration of blood to treat women bleeding profusely during or after delivery.[56] This predated the understanding of blood type, leading to unpredictable results.
Modern usage[edit]
Intravenous therapy was expanded by Italian physician Guido Baccelli in the late 1890s[62] and further developed in the 1930s by Samuel Hirschfeld, Harold T. Hyman and Justine Johnstone Wanger[63][64] but was not widely available until the 1950s.[65] There was a time, roughly the 1910s–1920s, when fluid replacement that today would be done intravenously was likelier to be done with a Murphy drip, a rectal infusion; and IV therapy took years to increasingly displace that route. In the 1960s, the concept of providing a person's complete nutritional needs through an IV solution began to be seriously considered. The first parenteral nutrition supplementation consisted of hydrolyzed proteins and dextrose.[56] This was followed in 1975 with the introduction of intravenous fat emulsions and vitamins which were added to form "total parenteral nutrition", or that which includes protein, fat, and carbohydrates.[56]
