Intravenous therapy
Overview
Intravenous therapy or IV therapy is the infusion of liquid substances directly into a vein
Vein
In the circulatory system, veins are blood vessels that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are the pulmonary and umbilical veins, both of which carry oxygenated blood to the heart...

. The word intravenous simply means "within a vein
Vein
In the circulatory system, veins are blood vessels that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are the pulmonary and umbilical veins, both of which carry oxygenated blood to the heart...

". Therapies administered intravenously are often called specialty pharmaceuticals. It is commonly referred to as a drip because many systems of administration employ a drip chamber
Drip chamber
A drip chamber is a device used to allow gas to rise out from a fluid so that it is not passed downstream. They are commonly employed in delivery systems of intravenous therapy and act to prevent air embolism....

, which prevents air from entering the blood stream (air embolism
Air embolism
An air embolism, or more generally gas embolism, is a pathological condition caused by gas bubbles in a vascular system. The most common context is a human body, in which case it refers to gas bubbles in the bloodstream...

), and allows an estimation of flow rate.

Intravenous therapy may be used to correct electrolyte
Electrolyte
In chemistry, an electrolyte is any substance containing free ions that make the substance electrically conductive. The most typical electrolyte is an ionic solution, but molten electrolytes and solid electrolytes are also possible....

 imbalances, to deliver medications, for blood transfusion
Blood transfusion
Blood transfusion is the process of receiving blood products into one's circulation intravenously. Transfusions are used in a variety of medical conditions to replace lost components of the blood...

 or as fluid replacement
Fluid replacement
Fluid replacement or fluid resuscitation is the medical practice of replenishing bodily fluid lost through sweating, bleeding, fluid shifts or other pathologic processes. Fluids can be replaced via oral administration , intravenous administration, rectally, or hypodermoclysis, the direct injection...

 to correct, for example, dehydration
Dehydration
In physiology and medicine, dehydration is defined as the excessive loss of body fluid. It is literally the removal of water from an object; however, in physiological terms, it entails a deficiency of fluid within an organism...

.

Compared with other routes of administration
Route of administration
A route of administration in pharmacology and toxicology is the path by which a drug, fluid, poison, or other substance is taken into the body.-Classification:Routes of administration are usually classified by application location...

, the intravenous route is the fastest way to deliver fluids and medications throughout the body.
Encyclopedia
Intravenous therapy or IV therapy is the infusion of liquid substances directly into a vein
Vein
In the circulatory system, veins are blood vessels that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are the pulmonary and umbilical veins, both of which carry oxygenated blood to the heart...

. The word intravenous simply means "within a vein
Vein
In the circulatory system, veins are blood vessels that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are the pulmonary and umbilical veins, both of which carry oxygenated blood to the heart...

". Therapies administered intravenously are often called specialty pharmaceuticals. It is commonly referred to as a drip because many systems of administration employ a drip chamber
Drip chamber
A drip chamber is a device used to allow gas to rise out from a fluid so that it is not passed downstream. They are commonly employed in delivery systems of intravenous therapy and act to prevent air embolism....

, which prevents air from entering the blood stream (air embolism
Air embolism
An air embolism, or more generally gas embolism, is a pathological condition caused by gas bubbles in a vascular system. The most common context is a human body, in which case it refers to gas bubbles in the bloodstream...

), and allows an estimation of flow rate.

Intravenous therapy may be used to correct electrolyte
Electrolyte
In chemistry, an electrolyte is any substance containing free ions that make the substance electrically conductive. The most typical electrolyte is an ionic solution, but molten electrolytes and solid electrolytes are also possible....

 imbalances, to deliver medications, for blood transfusion
Blood transfusion
Blood transfusion is the process of receiving blood products into one's circulation intravenously. Transfusions are used in a variety of medical conditions to replace lost components of the blood...

 or as fluid replacement
Fluid replacement
Fluid replacement or fluid resuscitation is the medical practice of replenishing bodily fluid lost through sweating, bleeding, fluid shifts or other pathologic processes. Fluids can be replaced via oral administration , intravenous administration, rectally, or hypodermoclysis, the direct injection...

 to correct, for example, dehydration
Dehydration
In physiology and medicine, dehydration is defined as the excessive loss of body fluid. It is literally the removal of water from an object; however, in physiological terms, it entails a deficiency of fluid within an organism...

.

Compared with other routes of administration
Route of administration
A route of administration in pharmacology and toxicology is the path by which a drug, fluid, poison, or other substance is taken into the body.-Classification:Routes of administration are usually classified by application location...

, the intravenous route is the fastest way to deliver fluids and medications throughout the body. Some medications, as well as blood transfusion
Blood transfusion
Blood transfusion is the process of receiving blood products into one's circulation intravenously. Transfusions are used in a variety of medical conditions to replace lost components of the blood...

s and lethal injection
Lethal injection
Lethal injection is the practice of injecting a person with a fatal dose of drugs for the express purpose of causing the immediate death of the subject. The main application for this procedure is capital punishment, but the term may also be applied in a broad sense to euthanasia and suicide...

s, can only be given intravenously.

Infused substances

Substances that may be infused intravenously include volume expanders, blood-based products, blood substitutes, medications, nutrition.

Volume expanders

There are two main types of volume expander; crystalloids and colloids. Crystalloids are aqueous solution
Solution
In chemistry, a solution is a homogeneous mixture composed of only one phase. In such a mixture, a solute is dissolved in another substance, known as a solvent. The solvent does the dissolving.- Types of solutions :...

s of mineral salts or other water-soluble molecules. Colloids contain larger insoluble molecules, such as gelatin
Gelatin
Gelatin is a translucent, colorless, brittle , flavorless solid substance, derived from the collagen inside animals' skin and bones. It is commonly used as a gelling agent in food, pharmaceuticals, photography, and cosmetic manufacturing. Substances containing gelatin or functioning in a similar...

. Blood
Blood
Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....

 is a colloid.
  • Colloids preserve a high colloid osmotic pressure in the blood, while, on the other hand, this parameter is decreased by crystalloids due to hemodilution. However, there is still controversy with regard to the actual difference in efficacy between colloids and crystalloids. Crystalloids generally are much cheaper than colloids.
  • The most commonly used crystalloid fluid is normal saline
    Saline (medicine)
    In medicine, saline is a general term referring to a sterile solution of sodium chloride in water but is only sterile when it is to be placed intravenously, otherwise, a saline solution is a salt water solution...

    , a solution of sodium chloride
    Sodium chloride
    Sodium chloride, also known as salt, common salt, table salt or halite, is an inorganic compound with the formula NaCl. Sodium chloride is the salt most responsible for the salinity of the ocean and of the extracellular fluid of many multicellular organisms...

     at 0.9% concentration, which is close to the concentration in the blood (isotonic
    Isotonic
    The term isotonic may refer to;*Isotonic for the term associated with muscle contraction*An isotone in nuclear physics*Sports drinks are sometimes designed in an isotonic way to assist athletes rehydrate while balancing electrolytes...

    ). Lactated Ringers, also known as, Ringer's lactate or Ringer's acetate, is another isotonic solution often used for large-volume fluid replacement.

Blood-based products

A blood product
Blood product
A blood product is any component of the blood which is collected from a donor for use in a blood transfusion. Whole blood is uncommonly used in transfusion medicine at present; most blood products consist of specific processed components such as red blood cells, blood plasma, or platelets.-Relation...

 (or blood-based product) is any component of blood
Blood
Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....

 which is collected from a donor for use in a blood transfusion
Blood transfusion
Blood transfusion is the process of receiving blood products into one's circulation intravenously. Transfusions are used in a variety of medical conditions to replace lost components of the blood...

. Blood transfusions can be life-saving in some situations, such as massive blood loss due to trauma
Physical trauma
Trauma refers to "a body wound or shock produced by sudden physical injury, as from violence or accident." It can also be described as "a physical wound or injury, such as a fracture or blow." Major trauma can result in secondary complications such as circulatory shock, respiratory failure and death...

, or can be used to replace blood lost during surgery
Surgery
Surgery is an ancient medical specialty that uses operative manual and instrumental techniques on a patient to investigate and/or treat a pathological condition such as disease or injury, or to help improve bodily function or appearance.An act of performing surgery may be called a surgical...

. Blood transfusions may also be used to treat a severe anaemia or thrombocytopenia
Thrombocytopenia
Thrombocytopenia is a relative decrease of platelets in blood.A normal human platelet count ranges from 150,000 to 450,000 platelets per microliter of blood. These limits are determined by the 2.5th lower and upper percentile, so values outside this range do not necessarily indicate disease...

 caused by a blood disease. People with hemophilia usually need a replacement of clotting factor, which is a small part of whole blood. People with sickle-cell disease
Sickle-cell disease
Sickle-cell disease , or sickle-cell anaemia or drepanocytosis, is an autosomal recessive genetic blood disorder with overdominance, characterized by red blood cells that assume an abnormal, rigid, sickle shape. Sickling decreases the cells' flexibility and results in a risk of various...

 may require frequent blood transfusions. Early blood transfusions consisted of whole blood
Whole blood
Whole blood is a term used in transfusion medicine for human blood from a standard blood donation. The blood is typically combined with an anticoagulant during the collection process, but is generally otherwise unprocessed...

, but modern medical practice commonly uses only components of the blood, such as fresh frozen plasma
Fresh frozen plasma
The term fresh frozen plasma refers to the liquid portion of human blood that has been frozen and preserved after a blood donation and will be used for blood transfusion...

 or cryoprecipitate
Cryoprecipitate
Cryoprecipitate, also called "Cryoprecipitated Antihemophilic Factor", "Cryoprecipitated AHF", and most commonly just "cryo", is a frozen blood product prepared from plasma.It is often transfused as a four to six unit pool instead of as a single product...

.

Blood substitutes

Blood substitutes (also called artificial blood or blood surrogates) are artificial substances aiming to provide an alternative to blood-based products acquired from donors.

The main blood substitutes used today are volume expanders such as crystalloids and colloids mentioned above. Also, oxygen-carrying substitutes are emerging.

Buffer solutions

Buffer solution
Buffer solution
A buffer solution is an aqueous solution consisting of a mixture of a weak acid and its conjugate base or a weak base and its conjugate acid. It has the property that the pH of the solution changes very little when a small amount of strong acid or base is added to it. Buffer solutions are used as a...

s are used to correct acidosis
Acidosis
Acidosis is an increased acidity in the blood and other body tissue . If not further qualified, it usually refers to acidity of the blood plasma....

 or alkalosis
Alkalosis
Alkalosis refers to a condition reducing hydrogen ion concentration of arterial blood plasma . Generally, alkalosis is said to occur when pH of the blood exceeds 7.45. The opposite condition is acidosis .-Causes:...

. Lactated Ringer's solution
Lactated Ringer's solution
Lactated Ringer's solution is a solution that is isotonic with blood and intended for intravenous administration. It may also be given subcutaneously....

 also has some buffering effect. A solution more specifically used for buffering purpose is intravenous sodium bicarbonate
Intravenous sodium bicarbonate
Intravenous sodium bicarbonate is a solution for intravenous administration that increases plasma bicarbonate, buffers excess hydrogen ion concentration, raises blood pH and reverses the clinical manifestations of acidosis....

.

Other medications

Medication
Medication
A pharmaceutical drug, also referred to as medicine, medication or medicament, can be loosely defined as any chemical substance intended for use in the medical diagnosis, cure, treatment, or prevention of disease.- Classification :...

s may be mixed into the fluids mentioned above. Certain types of medications can only be given intravenously, such as when there is insufficient uptake enteral
Enteral
In pharmacology, Enteral is a term used to describe routes of drug administration that involve absorption of the drug through the gastrointestinal tract. The term may also be used to describe something as residing in the gastrointestinal tract...

ly, transdermal
Transdermal
Transdermal is a route of administration wherein active ingredients are delivered across the skin for systemic distribution. Examples include transdermal patches used for medicine delivery, and transdermal implants used for medical or aesthetic purposes....

ly or transmucosally. Examples include intravenous immunoglobulin
Intravenous immunoglobulin
Intravenous immunoglobulin is a blood product administered intravenously. It contains the pooled IgG extracted from the plasma of over one thousand blood donors. IVIG's effects last between 2 weeks and 3 months...

 and propofol
Propofol
Propofol is a short-acting, intravenously administered hypnotic agent. Its uses include the induction and maintenance of general anesthesia, sedation for mechanically ventilated adults, and procedural sedation. Propofol is also commonly used in veterinary medicine...

.

Other

  • Parenteral nutrition is feeding a person intravenously, bypassing the usual process of eating
    Eating
    Eating is the ingestion of food to provide for all organisms their nutritional needs, particularly for energy and growth. Animals and other heterotrophs must eat in order to survive: carnivores eat other animals, herbivores eat plants, omnivores consume a mixture of both plant and animal matter,...

     and digestion
    Digestion
    Digestion is the mechanical and chemical breakdown of food into smaller components that are more easily absorbed into a blood stream, for instance. Digestion is a form of catabolism: a breakdown of large food molecules to smaller ones....

    . The person receives nutritional formulas containing salt
    Salt
    In chemistry, salts are ionic compounds that result from the neutralization reaction of an acid and a base. They are composed of cations and anions so that the product is electrically neutral...

    s, glucose
    Glucose
    Glucose is a simple sugar and an important carbohydrate in biology. Cells use it as the primary source of energy and a metabolic intermediate...

    , amino acid
    Amino acid
    Amino acids are molecules containing an amine group, a carboxylic acid group and a side-chain that varies between different amino acids. The key elements of an amino acid are carbon, hydrogen, oxygen, and nitrogen...

    s, lipid
    Lipid
    Lipids constitute a broad group of naturally occurring molecules that include fats, waxes, sterols, fat-soluble vitamins , monoglycerides, diglycerides, triglycerides, phospholipids, and others...

    s and added vitamin
    Vitamin
    A vitamin is an organic compound required as a nutrient in tiny amounts by an organism. In other words, an organic chemical compound is called a vitamin when it cannot be synthesized in sufficient quantities by an organism, and must be obtained from the diet. Thus, the term is conditional both on...

    s.
  • Drug injection
    Drug injection
    In substance dependence and recreational drug use, drug injection is a method of introducing a drug into the body with a hollow needle and a syringe which is pierced through the skin into the body...

     used for recreational substances usually enters by the intravenous route.

Intravenous access devices

These can all be used to obtain blood (e.g. for testing), also known as phlebotomy
Phlebotomy
Phlebotomy is the process of making an incision in a vein.It is associated with the following concepts:* Venipuncture, the practice of collecting venous blood samples* The main practice of a phlebotomist, an individual trained to draw blood...

 as well as for the administration of medication/fluids.

Hypodermic needle

The simplest form of intravenous access is by passing a hollow needle
Hypodermic needle
A hypodermic needle is a hollow needle commonly used with a syringe to inject substances into the body or extract fluids from it...

 through the skin directly into the vein. This needle can be connected directly to a syringe (used either to withdraw blood or deliver its contents into the bloodstream) or may be connected to a length of tubing and thence whichever collection or infusion system is desired.

The most convenient site is often the arm, especially the veins on the back of the hand, or the median cubital vein
Median cubital vein
In human anatomy, the median cubital vein is a superficial vein of the upper limb. It connects the basilic and cephalic vein and is often used for venipuncture . It lies in the cubital fossa superficial to the bicipital aponeurosis.There exists a fair amount of variation of the median cubital vein...

 at the elbow, but any identifiable vein can be used. Often it is necessary to use a tourniquet
Tourniquet
An emergency tourniquet is a tightly tied band applied around a body part sometimes used in an attempt to stop severe traumatic bleeding. Tourniquets are also used during venipuncture and other medical procedures. Severe bleeding means the loss of more than 1,000 ml of blood. This flow of blood...

 which restricts the venous drainage of the limb and makes the vein bulge. Once the needle is in place, it is common to draw back slightly on the syringe to aspirate blood, thus verifying that the needle is really in a vein. The tourniquet should be removed before injecting to prevent extravasation
Extravasation
Extravasation is the accidental administration of intravenously infused medicinal drugs into the surrounding tissue, either by leakage , or direct exposure...

 of the medication.

Peripheral cannula

This is the most common intravenous access method in both hospital
Hospital
A hospital is a health care institution providing patient treatment by specialized staff and equipment. Hospitals often, but not always, provide for inpatient care or longer-term patient stays....

s and pre-hospital services. A peripheral IV line (PVC or PIV)
Peripheral venous catheter
In medicine, a peripheral venous catheter is a catheter placed into a peripheral vein in order to administer medication or fluids...

consists of a short catheter
Catheter
In medicine, a catheter is a tube that can be inserted into a body cavity, duct, or vessel. Catheters thereby allow drainage, administration of fluids or gases, or access by surgical instruments. The process of inserting a catheter is catheterization...

 (a few centimeters long) inserted through the skin into a peripheral vein
Peripheral vein
Peripheral Veins are the veins not in the chest or abdomen . These veins lead deoxygenated blood from the capillaries in the extremities back to the heart....

 (any vein not inside the chest or abdomen). This is usually in the form of a cannula
Cannula
A cannula or canula is a tube that can be inserted into the body, often for the delivery or removal of fluid or for the gathering of data...

-over-needle device, in which a flexible plastic cannula
Cannula
A cannula or canula is a tube that can be inserted into the body, often for the delivery or removal of fluid or for the gathering of data...

 comes mounted on a metal trocar
Trocar
A trocar is a medical instrument with a sharply pointed end, often three-sided, that is used inside a hollow cylinder to introduce this into blood vessels or body cavities...

. Once the tip of the needle and cannula are located in the vein the trocar is withdrawn and discarded and the cannula advanced inside the vein to the appropriate position and secured. Blood may be drawn at the time of insertion.

Any accessible vein can be used although arm
Arm
In human anatomy, the arm is the part of the upper limb between the shoulder and the elbow joints. In other animals, the term arm can also be used for analogous structures, such as one of the paired forelimbs of a four-legged animal or the arms of cephalopods...

 and hand
Hand
A hand is a prehensile, multi-fingered extremity located at the end of an arm or forelimb of primates such as humans, chimpanzees, monkeys, and lemurs...

 veins are used most commonly, with leg
Human leg
The human leg is the entire lower extremity or limb of the human body, including the foot, thigh and even the hip or gluteal region; however, the precise definition in human anatomy refers only to the section of the lower limb extending from the knee to the ankle.Legs are used for standing,...

 and foot
Foot
The foot is an anatomical structure found in many vertebrates. It is the terminal portion of a limb which bears weight and allows locomotion. In many animals with feet, the foot is a separate organ at the terminal part of the leg made up of one or more segments or bones, generally including claws...

 veins used to a much lesser extent. In infants the scalp
Scalp
The scalp is the anatomical area bordered by the face anteriorly and the neck to the sides and posteriorly.-Layers:It is usually described as having five layers, which can conveniently be remembered as a mnemonic:...

 veins are sometimes used.

The caliber of cannula is commonly indicated in gauge
American wire gauge
American wire gauge , also known as the Brown & Sharpe wire gauge, is a standardized wire gauge system used since 1857 predominantly in the United States and Canada for the diameters of round, solid, nonferrous, electrically conducting wire...

, with 14 being a very large cannula (used in resuscitation settings) and 24-26 the smallest. The most common sizes are 16-gauge (midsize line used for blood donation and transfusion), 18- and 20-gauge (all-purpose line for infusions and blood draws), and 22-gauge (all-purpose pediatric line). 12- and 14-gauge peripheral lines actually deliver equivalent volumes of fluid faster than central lines, accounting for their popularity in emergency medicine
Emergency medicine
Emergency medicine is a medical specialty in which physicians care for patients with acute illnesses or injuries which require immediate medical attention. While not usually providing long-term or continuing care, emergency medicine physicians diagnose a variety of illnesses and undertake acute...

. These lines are frequently called "large bores" or "trauma lines".

To make the procedure more tolerable for children medical staff may apply a topical local anaesthetic (such as EMLA or Ametop) for about 45 minutes beforehand.

The part of the catheter that remains outside the skin is called the connecting hub; it can be connected to a syringe
Syringe
A syringe is a simple pump consisting of a plunger that fits tightly in a tube. The plunger can be pulled and pushed along inside a cylindrical tube , allowing the syringe to take in and expel a liquid or gas through an orifice at the open end of the tube...

 or an intravenous infusion line, or capped with a bung
Bung
A bung is truncated cylindrical or conical closure to seal a container, such as a bottle, tube or barrel. Unlike a lid which encloses a container from the outside without displacing the inner volume, a bung is partially inserted inside the container to act as a seal...

 between treatments. Ported cannula
Cannula
A cannula or canula is a tube that can be inserted into the body, often for the delivery or removal of fluid or for the gathering of data...

e have an injection port on the top that is often used to administer medicine.

In cases of shock, a venous cutdown
Venous cutdown
Venous cutdown is an emergency procedure in which the vein is exposed surgically and then a cannula is inserted into the vein under direct vision. It is used to get vascular access in trauma and hypovolemic shock patients when peripheral cannulation is difficult or impossible. The saphenous vein is...

 may be necessary.

Complications

If the cannula is not sited correctly, or the vein is particularly fragile and ruptures, blood may leak into the surrounding tissues, this situation is known as a "tissuing" or a "blown vein". Using this cannula to administer medications causes extravasation
Extravasation
Extravasation is the accidental administration of intravenously infused medicinal drugs into the surrounding tissue, either by leakage , or direct exposure...

 of the drug which can lead to edema
Edema
Edema or oedema ; both words from the Greek , oídēma "swelling"), formerly known as dropsy or hydropsy, is an abnormal accumulation of fluid beneath the skin or in one or more cavities of the body that produces swelling...

, causing pain and tissue damage, and even necrosis
Necrosis
Necrosis is the premature death of cells in living tissue. Necrosis is caused by factors external to the cell or tissue, such as infection, toxins, or trauma. This is in contrast to apoptosis, which is a naturally occurring cause of cellular death...

 depending on the medication. The person attempting to obtain the access must find a new access site proximal to the "blown" area to prevent extravasation of medications through the damaged vein. For this reason it is advisable to site the first cannula at the most distal appropriate vein.

If a patient needs frequent venous access, the veins may scar and narrow, making any future access extremely difficult or impossible.

A peripheral IV cannot be left in the vein indefinitely, because of the risk of insertion-site infection leading to phlebitis
Phlebitis
Phlebitis is an inflammation of a vein, usually in the legs.When phlebitis is associated with the formation of blood clots , usually in the deep veins of the legs, the condition is called thrombophlebitis...

, cellulitis
Cellulitis
Cellulitis is a diffuse inflammation of connective tissue with severe inflammation of dermal and subcutaneous layers of the skin. Cellulitis can be caused by normal skin flora or by exogenous bacteria, and often occurs where the skin has previously been broken: cracks in the skin, cuts, blisters,...

 and sepsis
Sepsis
Sepsis is a potentially deadly medical condition that is characterized by a whole-body inflammatory state and the presence of a known or suspected infection. The body may develop this inflammatory response by the immune system to microbes in the blood, urine, lungs, skin, or other tissues...

. The US Centers for Disease Control and Prevention
Centers for Disease Control and Prevention
The Centers for Disease Control and Prevention are a United States federal agency under the Department of Health and Human Services headquartered in Druid Hills, unincorporated DeKalb County, Georgia, in Greater Atlanta...

 updated their guidelines and now advise the cannula need to be replaced every 96 hours. This was based on studies organised to identify causes of Methicillin-resistant Staphylococcus aureus
Methicillin-resistant Staphylococcus aureus
Methicillin-resistant Staphylococcus aureus is a bacterium responsible for several difficult-to-treat infections in humans. It is also called multidrug-resistant Staphylococcus aureus and oxacillin-resistant Staphylococcus aureus...

 MRSA infection in hospitals. In the United Kingdom, the UK Department of health published their finding about risk factors associated with increased MRSA infection, now include intravenous cannula, central venous catheters and urinary catheters as the main factors increasing the risk of spreading antibiotic resistant strain bacteria
Antibiotic resistance
Antibiotic resistance is a type of drug resistance where a microorganism is able to survive exposure to an antibiotic. While a spontaneous or induced genetic mutation in bacteria may confer resistance to antimicrobial drugs, genes that confer resistance can be transferred between bacteria in a...

.

Central IV lines

Central IV lines
Central venous catheter
In medicine, a central venous catheter is a catheter placed into a large vein in the neck , chest or groin...

 flow through a catheter with its tip within a large vein, usually the superior vena cava
Superior vena cava
The superior vena cava is truly superior, a large diameter, yet short, vein that carries deoxygenated blood from the upper half of the body to the heart's right atrium...

 or inferior vena cava
Inferior vena cava
The inferior vena cava , also known as the posterior vena cava, is the large vein that carries de-oxygenated blood from the lower half of the body into the right atrium of the heart....

, or within the right atrium
Atrium (anatomy)
In anatomy, the atrium , sometimes called auricle , refers to a chamber or space. For example, the term is used for a portion of the lateral ventricle in the brain and the blood collection chamber of the heart...

 of the heart. This has several advantages over a peripheral IV:
  • It can deliver fluids and medications that would be overly irritating to peripheral veins because of their concentration or chemical composition. These include some chemotherapy
    Chemotherapy
    Chemotherapy is the treatment of cancer with an antineoplastic drug or with a combination of such drugs into a standardized treatment regimen....

     drugs and total parenteral nutrition
    Total parenteral nutrition
    Parenteral nutrition is feeding a person intravenously, bypassing the usual process of eating and digestion. The person receives nutritional formulae that contain nutrients such as glucose, amino acids, lipids and added vitamins and dietary minerals...

    .
  • Medications reach the heart immediately, and are quickly distributed to the rest of the body.
  • There is room for multiple parallel compartments (lumen) within the catheter, so that multiple medications can be delivered at once even if they would not be chemically compatible within a single tube.
  • Caregivers can measure central venous pressure
    Central venous pressure
    Central venous pressure describes the pressure of blood in the thoracic vena cava, near the right atrium of the heart...

     and other physiological variables through the line.


Central IV lines carry risks of bleeding, infection, gangrene
Gangrene
Gangrene is a serious and potentially life-threatening condition that arises when a considerable mass of body tissue dies . This may occur after an injury or infection, or in people suffering from any chronic health problem affecting blood circulation. The primary cause of gangrene is reduced blood...

, thromboembolism and gas embolism (see Risks below). They are often more difficult to insert correctly as the veins are not usually palpable and rely on an experienced clinician knowing the appropriate landmarks and/or using an ultrasound probe
Medical ultrasonography
Diagnostic sonography is an ultrasound-based diagnostic imaging technique used for visualizing subcutaneous body structures including tendons, muscles, joints, vessels and internal organs for possible pathology or lesions...

 to safely locate and enter the vein. Surrounding structures, such as the pleura and carotid artery
Carotid artery
Carotid artery can refer to:* Common carotid artery* External carotid artery* Internal carotid artery...

 are also at risk of damage with the potential for pneumothorax
Pneumothorax
Pneumothorax is a collection of air or gas in the pleural cavity of the chest between the lung and the chest wall. It may occur spontaneously in people without chronic lung conditions as well as in those with lung disease , and many pneumothoraces occur after physical trauma to the chest, blast...

 or even cannulation of the artery.

There are several types of central IVs, depending on the route that the catheter takes from the outside of the body to the vein.

Peripherally inserted central catheter

PICC lines are used when intravenous access is required over a prolonged period of time or when the material to be infused would cause quick damage and early failure of a peripheral IV and when a conventional central line may be too dangerous to attempt. Typical uses for a PICC include: long chemotherapy
Chemotherapy
Chemotherapy is the treatment of cancer with an antineoplastic drug or with a combination of such drugs into a standardized treatment regimen....

 regimens, extended antibiotic
Antibiotic
An antibacterial is a compound or substance that kills or slows down the growth of bacteria.The term is often used synonymously with the term antibiotic; today, however, with increased knowledge of the causative agents of various infectious diseases, antibiotic has come to denote a broader range of...

 therapy, or total parenteral nutrition
Total parenteral nutrition
Parenteral nutrition is feeding a person intravenously, bypassing the usual process of eating and digestion. The person receives nutritional formulae that contain nutrients such as glucose, amino acids, lipids and added vitamins and dietary minerals...

.

The PICC line is inserted through a sheath into a peripheral vein sometimes using the Seldinger technique
Seldinger technique
The Seldinger technique is a medical procedure to obtain safe access to blood vessels and other hollow organs. It is named after Dr. Sven-Ivar Seldinger , a Swedish radiologist from Mora, Dalarna County, who introduced the procedure in 1953....

 or modified Seldinger technique, under ultrasound guidance, usually in the arm, and then carefully advanced upward until the catheter is in the superior vena cava or the right atrium. This is usually done by measuring the distance to an external landmark, such as the suprasternal notch, to estimate the optimal length. An X-ray must be used to verify that the tip is in the right place when fluoroscopy was not used during the insertion.

A PICC may have a single (single-lumen) tube and connector, two(double-lumen) or three (triple-lumen) compartments, each with its own external connector. Power-injectable PICCs are now available as well. From the outside, a single-lumen PICC resembles a peripheral IV, except that the tubing is slightly wider.

The insertion site requires better protection than that of a peripheral IV, due to the higher risk of serious infection if bacteria travel up the catheter. However, a PICC poses less of a systemic infection risk than other central IVs, because the insertion site is usually cooler and dryer than the sites typically used for other central lines. This helps to slow the growth of bacteria which could reach the bloodstream by traveling under the skin along the outside of the catheter.

The chief advantage of a PICC over other types of central lines is that it is safer to insert with a relatively low risk of uncontrollable bleeding and essentially no risks of damage to the lungs or major blood vessels. Although special training is required, a PICC does not require the skill level of a physician or surgeon. It is also externally unobtrusive, and with proper hygiene, care, and some good luck, can be left in place for months to years if needed for patients who require extended treatment.

The chief disadvantage is that it must be inserted and then travel through a relatively small peripheral vein which can take a less predictable course on the way to the superior vena cava and is therefore somewhat more time consuming and more technically difficult to place in some patients. Also, as a PICC travels through the axilla, it can become kinked causing poor function.

Central venous lines

There are several types of catheters that take a more direct route into central veins. These are collectively called central venous lines
Central venous catheter
In medicine, a central venous catheter is a catheter placed into a large vein in the neck , chest or groin...

.

In the simplest type of central venous access, a catheter is inserted into a subclavian
Subclavian vein
The subclavian veins are two large veins, one on either side of the body. Their diameter is approximately that of the smallest finger.-Path:Each subclavian vein is a continuation of the axillary vein and runs from the outer border of the first rib to the medial border of anterior scalene muscle...

, internal jugular
Internal jugular vein
The two internal jugular veins collect the blood from the brain, the superficial parts of the face, and the neck.-Path:On both sides and at the base of the brain, the inferior petrosal sinus and the sigmoid sinus join to form the internal jugular vein...

, or (less commonly) a femoral vein
Femoral vein
In the human body, the femoral vein is a blood vessel that accompanies the femoral artery in the femoral sheath. It begins at the adductor canal and is a continuation of the popliteal vein...

 and advanced toward the heart until it reaches the superior vena cava or right atrium.

Because all of these veins are larger than peripheral veins there is greater blood flow past the tip of the catheter meaning irritant drugs are more rapidly diluted with less chance of extravasation
Extravasation
Extravasation is the accidental administration of intravenously infused medicinal drugs into the surrounding tissue, either by leakage , or direct exposure...

. It is commonly believed that fluid can be pushed faster through a central venous catheter but as they are often divided into multiple lumens then the internal diameter is less than that of a large-bore peripheral cannula. They are also longer, which as reflected in Poiseuille's law, requires higher pressure to achieve the same flow, all other variables being equal.

Tunnelled Lines

Another type of central line, called a Hickman line
Hickman line
A Hickman line is an intravenous catheter most often used for the administration of chemotherapy or other medications, as well as for the withdrawal of blood for analysis. Some types of Hickman lines are used mainly for the purpose of apheresis or dialysis...

 or Broviac catheter, is inserted into the target vein and then "tunneled" under the skin to emerge a short distance away. This reduces the risk of infection, since bacteria from the skin surface are not able to travel directly into the vein; these catheters are also made of materials that resist infection and clotting.

Implantable ports

A port
Port (medical)
In medicine, a port is a small medical appliance that is installed beneath the skin. A catheter connects the port to a vein...

 (often referred to by brand names such as Port-a-Cath or MediPort) is a central venous line that does not have an external connector; instead, it has a small reservoir that is covered with silicone rubber and is implanted under the skin. Medication is administered intermittently by placing a small needle through the skin, piercing the silicone, into the reservoir. When the needle is withdrawn the reservoir cover reseals itself. The cover can accept hundreds of needle sticks during its lifetime. It is possible to leave the ports in the patient's body for years; if this is done however, the port must be accessed monthly and flushed with an anti-coagulant, or the patient risks it getting plugged up. If it is plugged it becomes a hazard as a thrombus
Thrombus
A thrombus , or blood clot, is the final product of the blood coagulation step in hemostasis. It is achieved via the aggregation of platelets that form a platelet plug, and the activation of the humoral coagulation system...

 will eventually form with an accompanying risk of embolisation. Removal of a port is usually a simple outpatient procedure; however, installation is more complex and a good implant is fairly dependent on the skill of the radiologist. Ports cause less inconvenience and have a lower risk of infection than PICCs, and are therefore commonly used for patients on long-term intermittent treatment.

Other equipment

A standard IV infusion set consists of a pre-filled, sterile container (glass bottle, plastic bottle or plastic bag) of fluids with an attachment that allows the fluid to flow one drop at a time, making it easy to see the flow rate (and also reducing air bubbles); a long sterile tube with a clamp to regulate or stop the flow; a connector to attach to the access device; and connectors to allow "piggybacking" of another infusion set onto the same line, e.g., adding a dose of antibiotics to a continuous fluid drip.

An infusion pump
Infusion pump
An infusion pump infuses fluids, medication or nutrients into a patient's circulatory system. It is generally used intravenously, although subcutaneous, arterial and epidural infusions are occasionally used....

allows precise control over the flow rate and total amount delivered, but in cases where a change in the flow rate would not have serious consequences, or if pumps are not available, the drip is often left to flow simply by placing the bag above the level of the patient and using the clamp to regulate the rate; this is a gravity drip.

A rapid infuser can be used if the patient requires a high flow rate and the IV access device is of a large enough diameter to accommodate it. This is either an inflatable cuff placed around the fluid bag to force the fluid into the patient or a similar electrical device that may also heat the fluid being infused.

Intermittent infusion

Intermittent infusion is used when a patient requires medications only at certain times, and does not require additional fluid. It can use the same techniques as an intravenous drip (pump or gravity drip), but after the complete dose of medication has been given, the tubing is disconnected from the IV access device. Some medications are also given by IV push or bolus, meaning that a syringe is connected to the IV access device and the medication is injected directly (slowly, if it might irritate the vein or cause a too-rapid effect). Once a medicine has been injected into the fluid stream of the IV tubing there must be some means of ensuring that it gets from the tubing to the patient. Usually this is accomplished by allowing the fluid stream to flow normally and thereby carry the medicine into the bloodstream; however, a second fluid injection is sometimes used, a "flush", following the injection to push the medicine into the bloodstream more quickly.

Infection

Any break in the skin carries a risk of infection. Although IV insertion is an aseptic procedure, skin-dwelling organisms such as Coagulase-negative staphylococcus or Candida albicans
Candida albicans
Candida albicans is a diploid fungus that grows both as yeast and filamentous cells and a causal agent of opportunistic oral and genital infections in humans. Systemic fungal infections including those by C...

may enter through the insertion site around the catheter, or bacteria may be accidentally introduced inside the catheter from contaminated equipment. Moisture introduced to unprotected IV sites through washing or bathing substantially increases the infection risks.

Infection of IV sites is usually local, causing easily visible swelling, redness, and fever. If bacteria do not remain in one area but spread through the bloodstream, the infection is called septicemia and can be rapid and life-threatening. An infected central IV poses a higher risk of septicemia, as it can deliver bacteria directly into the central circulation.

Phlebitis

Phlebitis
Phlebitis
Phlebitis is an inflammation of a vein, usually in the legs.When phlebitis is associated with the formation of blood clots , usually in the deep veins of the legs, the condition is called thrombophlebitis...

 is inflammation of a vein that may be caused by infection, the mere presence of a foreign body (the IV catheter) or the fluids or medication being given. Symptoms are warmth, swelling, pain, and redness around the vein. The IV device must be removed and if necessary re-inserted into another extremity.

Due to frequent injections and recurring phlebitis, scar tissue can build up along the vein. The peripheral veins of intravenous drug addicts, and of cancer patients undergoing chemotherapy, become sclerotic and difficult to access over time, sometimes forming a hard “venous cord”.

Infiltration / Extravasation

Infiltration occurs when an IV fluid or medication accidentally enters the surrounding tissue rather than the vein. This occurs more frequently with chemotherapeutic agents and people who have tuberculosis
Tuberculosis
Tuberculosis, MTB, or TB is a common, and in many cases lethal, infectious disease caused by various strains of mycobacteria, usually Mycobacterium tuberculosis. Tuberculosis usually attacks the lungs but can also affect other parts of the body...

. It is also known as extravasation (which refers to something escaping the vein). It may occur when the vein itself ruptures (the elderly are particularly prone to fragile veins due to a paucity of supporting tissues), where the vein is damaged during insertion of the intravascular access device or the device is not sited correctly or where the entry point of the device into the vein becomes the path of least resistance (e.g. if a cannula is in a vein for some time, the vein may scar and close and the only way for fluid to leave is along the outside of the cannula where it enters the vein).
It is characterized by coolness and pallor to the skin as well as localized swelling or edema. It is usually not painful. It is treated by removing the intravenous access device and elevating the affected limb so that the collected fluids can drain away. Sometimes injections of hyaluronidase
Hyaluronidase
The hyaluronidases are a family of enzymes that degrade hyaluronic acid.In humans, there are six associated genes, including HYAL1, HYAL2, HYAL3, and PH-20/SPAM1.-Use as a drug:...

 can be used to speed the dispersal of the fluid/drug. Infiltration is one of the most common adverse effects of IV therapy and is usually not serious unless the infiltrated fluid is a medication damaging to the surrounding tissue, in which case extensive necrosis
Necrosis
Necrosis is the premature death of cells in living tissue. Necrosis is caused by factors external to the cell or tissue, such as infection, toxins, or trauma. This is in contrast to apoptosis, which is a naturally occurring cause of cellular death...

 can occur.

Fluid overload

This occurs when fluids are given at a higher rate or in a larger volume than the system can absorb or excrete. Possible consequences include hypertension
Hypertension
Hypertension or high blood pressure is a cardiac chronic medical condition in which the systemic arterial blood pressure is elevated. What that means is that the heart is having to work harder than it should to pump the blood around the body. Blood pressure involves two measurements, systolic and...

, heart failure, and pulmonary edema
Pulmonary edema
Pulmonary edema , or oedema , is fluid accumulation in the air spaces and parenchyma of the lungs. It leads to impaired gas exchange and may cause respiratory failure...

.

Hypothermia

The human body is at risk of accidentally induced hypothermia when large amounts of cold fluids are infused. Rapid temperature changes in the heart may precipitate ventricular fibrillation.

Electrolyte imbalance

Administering a too-dilute or too-concentrated solution can disrupt the patient's balance of sodium
Sodium
Sodium is a chemical element with the symbol Na and atomic number 11. It is a soft, silvery-white, highly reactive metal and is a member of the alkali metals; its only stable isotope is 23Na. It is an abundant element that exists in numerous minerals, most commonly as sodium chloride...

, potassium
Potassium
Potassium is the chemical element with the symbol K and atomic number 19. Elemental potassium is a soft silvery-white alkali metal that oxidizes rapidly in air and is very reactive with water, generating sufficient heat to ignite the hydrogen emitted in the reaction.Potassium and sodium are...

, magnesium
Magnesium
Magnesium is a chemical element with the symbol Mg, atomic number 12, and common oxidation number +2. It is an alkaline earth metal and the eighth most abundant element in the Earth's crust and ninth in the known universe as a whole...

, and other electrolyte
Electrolyte
In chemistry, an electrolyte is any substance containing free ions that make the substance electrically conductive. The most typical electrolyte is an ionic solution, but molten electrolytes and solid electrolytes are also possible....

s. Hospital patients usually receive blood tests to monitor these levels.

Embolism

A blood clot or other solid mass, as well as an air bubble, can be delivered into the circulation through an IV and end up blocking a vessel; this is called embolism
Air embolism
An air embolism, or more generally gas embolism, is a pathological condition caused by gas bubbles in a vascular system. The most common context is a human body, in which case it refers to gas bubbles in the bloodstream...

. Peripheral IVs have a low risk of embolism, since large solid masses cannot travel through a narrow catheter, and it is nearly impossible to inject air through a peripheral IV at a dangerous rate. The risk is greater with a central IV.

Air bubbles of less than 30 microliters are thought to dissolve into the circulation harmlessly. Small volumes do not result in readily detectable symptoms, but ongoing studies hypothesize that these "micro-bubbles" may have some adverse effects. A larger amount of air, if delivered all at once, can cause life-threatening damage to pulmonary
Lung
The lung is the essential respiration organ in many air-breathing animals, including most tetrapods, a few fish and a few snails. In mammals and the more complex life forms, the two lungs are located near the backbone on either side of the heart...

 circulation, or, if extremely large (3-8 milliliters per kilogram of body weight), can stop the heart.

One reason veins are preferred over arteries for intravascular administration is because the flow will pass through the lungs before passing through the body. Air bubbles can leave the blood through the lungs. A patient with a heart defect causing a right-to-left shunt is vulnerable to embolism from smaller amounts of air. Fatality by air embolism is vanishingly rare, although this is in part because it is so difficult to diagnose.

History

Intravenous drip technology developed out the work of Hirschfeld, Hyman and Wanger
Justine Johnstone
Justine Johnstone was an American stage and silent screen actress who retired to become a pathologist and expert on syphilis. She also was part of the team that developed the modern intravenous drip technique....

 on injection rate ca 1930.

See also

  • Blood substitutes
    Blood substitutes
    A blood substitute is a substance used to mimic and fulfill some functions of biological blood, usually in the oxygen-carrying sense...

  • Blood transfusion
    Blood transfusion
    Blood transfusion is the process of receiving blood products into one's circulation intravenously. Transfusions are used in a variety of medical conditions to replace lost components of the blood...

  • Bolus (medicine)
    Bolus (medicine)
    In medicine, a bolus is the administration of a medication, drug or other compound that is given to raise its concentration in blood to an effective level...

  • Dialysis
    Dialysis
    In medicine, dialysis is a process for removing waste and excess water from the blood, and is primarily used to provide an artificial replacement for lost kidney function in people with renal failure...

  • Hypodermic needle
    Hypodermic needle
    A hypodermic needle is a hollow needle commonly used with a syringe to inject substances into the body or extract fluids from it...

  • Life support
    Life support
    Life support, in medicine is a broad term that applies to any therapy used to sustain a patient's life while they are critically ill or injured. There are many therapies and techniques that may be used by clinicians to achieve the goal of sustaining life...

  • Oral rehydration therapy
    Oral rehydration therapy
    Oral rehydration therapy is a simple treatment for dehydration associated with diarrhoea, particularly gastroenteritis or gastroenteropathy, such as that caused by cholera or rotavirus. ORT consists of a solution of salts and sugars which is taken by mouth...

  • Saline flush
    Saline Flush
    A saline flush is the method of clearing out feeding tubes and intravenous lines of any food, medicine, or other perishable liquids so that they can keep the area of entering clean and sterile. Typically in flushing a intravenous cannula, a 5ml syringe of saline is emptied into the medication port...


External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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