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medicine Medicine is the science and practice of caring for a patient, managing the diagnosis, prognosis, prevention, treatment, palliation of their injury or disease, and promoting their health. Medicine encompasses a variety of health care p ...
, a catheter (/ˈkæθətər/) is a thin tube made from medical grade materials serving a broad range of functions. Catheters are medical devices that can be inserted in the body to treat diseases or perform a surgical procedure. Catheters are manufactured for specific applications, such as cardiovascular, urological, gastrointestinal, neurovascular and ophthalmic procedures. The process of inserting a catheter is ''catheterization''. In most uses, a catheter is a thin, flexible tube (''soft'' catheter) though catheters are available in varying levels of stiffness depending on the application. A catheter left inside the body, either temporarily or permanently, may be referred to as an "indwelling catheter" (for example, a peripherally inserted central catheter). A permanently inserted catheter may be referred to as a "permcath" (originally a trademark). Catheters can be inserted into a body cavity, duct, or vessel, brain, skin or adipose tissue. Functionally, they allow drainage, administration of fluids or gases, access by surgical instruments, and also perform a wide variety of other tasks depending on the type of catheter. Special types of catheters, also called probes, are used in preclinical or clinical research for sampling of lipophilic and hydrophilic compounds, protein-bound and unbound drugs, neurotransmitters, peptides and proteins, antibodies, nanoparticles and nanocarriers, enzymes and vesicles.


Etymology

"Catheter" (from Greek καθετήρ ''kathetḗr'') comes from the Greek verb καθίεμαι ''kathíemai'', meaning "to thrust into" or "to send down" because the catheter allowed fluid to be "sent down" from the body.


Uses

Placement of a catheter into a particular part of the body may allow: * Draining
urine Urine is a liquid by-product of metabolism in humans and in many other animals. Urine flows from the kidneys through the ureters to the urinary bladder. Urination results in urine being excreted from the body through the urethra. Cellul ...
from the
urinary bladder The urinary bladder, or simply bladder, is a hollow organ in humans and other vertebrates that stores urine from the kidneys before disposal by urination. In humans the bladder is a distensible organ that sits on the pelvic floor. Urine ent ...
as in urinary catheterization, using intermittent catheters or Foley catheter inserted through
urethra The urethra (from Greek οὐρήθρα – ''ourḗthrā'') is a tube that connects the urinary bladder to the urinary meatus for the removal of urine from the body of both females and males. In human females and other primates, the urethra ...
. When the urethra is damaged, suprapubic catheterisation is used instead. The suprapubic catheter is inserted through the lower part of the abdomen directly into the urinary bladder. * drainage of urine from the kidney by percutaneous (through the skin) nephrostomy * drainage of fluid collections, e.g. an abdominal abscess * pigtail catheter: used to drain air from around the lung ( pneumothorax) * administration of intravenous fluids,
medication A medication (also called medicament, medicine, pharmaceutical drug, medicinal drug or simply drug) is a drug used to diagnose, cure, treat, or prevent disease. Drug therapy (pharmacotherapy) is an important part of the medical field an ...
or
parenteral nutrition Parenteral nutrition (PN) is the feeding of nutritional products to a person intravenously, bypassing the usual process of eating and digestion. The products are made by pharmaceutical compounding companies. The person receives a nutritional mi ...
with a peripheral venous catheter or central venous catheter *
angioplasty Angioplasty, is also known as balloon angioplasty and percutaneous transluminal angioplasty (PTA), is a minimally invasive endovascular procedure used to widen narrowed or obstructed arteries or veins, typically to treat arterial atheroscler ...
,
angiography Angiography or arteriography is a medical imaging technique used to visualize the inside, or lumen, of blood vessels and organs of the body, with particular interest in the arteries, veins, and the heart chambers. Modern angiography is perform ...
, balloon septostomy, balloon sinuplasty, cardiac electrophysiology testing, catheter ablation. Often the Seldinger technique is used. * direct measurement of
blood pressure Blood pressure (BP) is the pressure of circulating blood against the walls of blood vessels. Most of this pressure results from the heart pumping blood through the circulatory system. When used without qualification, the term "blood pressure" ...
in an artery or
vein Veins are blood vessels in humans and most other animals 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 ...
* direct measurement of
intracranial pressure Intracranial pressure (ICP) is the pressure exerted by fluids such as cerebrospinal fluid (CSF) inside the skull and on the brain tissue. ICP is measured in millimeters of mercury ( mmHg) and at rest, is normally 7–15 mmHg for a supine adult ...
* administration of anaesthetic medication into the
epidural Epidural administration (from Ancient Greek ἐπί, , upon" + ''dura mater'') is a method of medication administration in which a medicine is injected into the epidural space around the spinal cord. The epidural route is used by physicians an ...
space, the
subarachnoid space In anatomy, the meninges (, ''singular:'' meninx ( or ), ) are the three membranes that envelop the brain and spinal cord. In mammals, the meninges are the dura mater, the arachnoid mater, and the pia mater. Cerebrospinal fluid is located ...
, or around a major nerve bundle such as the
brachial plexus The brachial plexus is a network () of nerves formed by the anterior rami of the lower four cervical nerves and first thoracic nerve ( C5, C6, C7, C8, and T1). This plexus extends from the spinal cord, through the cervicoaxillary canal in ...
* transfer of fertilized embryos, from in vitro fertilization, or sperm, during artificial insemination, into the uterus * administration of
oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as ...
, volatile anesthetic agents, and other breathing gases into the lungs using a
tracheal tube A tracheal tube is a catheter that is inserted into the trachea for the primary purpose of establishing and maintaining a patent airway and to ensure the adequate exchange of oxygen and carbon dioxide. Many different types of tracheal tubes a ...
* subcutaneous administration of insulin or other medications, with the use of an
infusion set An infusion set is used with devices such as an insulin pump. The purpose of an infusion set is to deliver insulin under the skin, fulfilling a similar function like an intravenous line. It is a complete tubing system to connect an insulin ...
and
insulin pump An insulin pump is a medical device used for the administration of insulin in the treatment of diabetes mellitus, also known as continuous subcutaneous insulin therapy. The device configuration may vary depending on design. A traditional pum ...


History


Ancient inventors

Ancient Chinese used onion stalks, the Romans, Hindus, and Greeks used tubes of wood or precious metals. The ancient
Syria Syria ( ar, سُورِيَا or سُورِيَة, translit=Sūriyā), officially the Syrian Arab Republic ( ar, الجمهورية العربية السورية, al-Jumhūrīyah al-ʻArabīyah as-Sūrīyah), is a Western Asian country loc ...
ns created catheters from reeds.


Modern

The earliest invention of the flexible catheter was during the 18th century. Extending his inventiveness to his family's medical problems,
Benjamin Franklin Benjamin Franklin ( April 17, 1790) was an American polymath who was active as a writer, scientist, inventor, statesman, diplomat, printer, publisher, and political philosopher. Encyclopædia Britannica, Wood, 2021 Among the leading inte ...
invented the flexible catheter in 1752 when his brother John suffered from bladder stones. Franklin's catheter was made of metal with segments hinged together with a wire enclosed to provide rigidity during insertion. According to a footnote in his letter in Volume 4 of the Papers of Benjamin Franklin (1959), Franklin credits Francesco Roncelli-Pardino from 1720 as the inventor of a flexible catheter. In fact, Franklin claims the flexible catheter may have been designed even earlier. An early modern application of the catheter was employed by Claude Bernard for the purpose of cardiac catheterization in 1844. The procedure involved entering a horse's ventricles via the jugular vein and carotid artery. This appears to be an earlier and modern application of the catheter because this catheter approach technique is still performed by neurosurgeons, cardiologists, and cardiothoracic surgeons. David S. Sheridan invented the modern disposable catheter in the 1940s. Prior to this, some reusable catheters consisted of braided cotton tubes, which were varnished, heat-treated and polished. As these were primarily produced in France, the advent of
World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposing ...
threatened the supply chain. In 1959, Teschan first described central venous catheter as means of blood vessel access for
haemodialysis Hemodialysis, also spelled haemodialysis, or simply dialysis, is a process of purifying the blood of a person whose kidneys are not working normally. This type of dialysis achieves the extracorporeal removal of waste products such as creatini ...
. Other reusable catheters consisted of red rubber tubes. Although sterilized prior to reuse, they still posed a high risk of infection and often led to the spread of disease. In 1982, Quinton together with Dr Sakharam Mahurkar, a nephrologist at County Cook Hospital in Chicago, developed dual-lumen catheter which became the standard for haemodialysis and apheresis. Sheridan was dubbed the "Catheter King" by ''
Forbes ''Forbes'' () is an American business magazine owned by Integrated Whale Media Investments and the Forbes family. Published eight times a year, it features articles on finance, industry, investing, and marketing topics. ''Forbes'' also r ...
'' magazine in 1988. He also invented the modern "disposable" plastic endotracheal tube now used routinely in surgery.


Materials


Urinary catheters

A range of
polymer A polymer (; Greek '' poly-'', "many" + '' -mer'', "part") is a substance or material consisting of very large molecules called macromolecules, composed of many repeating subunits. Due to their broad spectrum of properties, both synthetic a ...
s are used for the construction of catheters, including
silicone rubber Silicone rubber is an elastomer (rubber-like material) composed of silicone—itself a polymer—containing silicon together with carbon, hydrogen, and oxygen. Silicone rubbers are widely used in industry, and there are multiple formul ...
,
nylon Nylon is a generic designation for a family of synthetic polymers composed of polyamides ( repeating units linked by amide links).The polyamides may be aliphatic or semi-aromatic. Nylon is a silk-like thermoplastic, generally made from petr ...
, polyurethane, polyethylene terephthalate (PET), latex, and thermoplastic elastomers. Silicone is one of the most common implantable choice because it is inert and unreactive to body fluids and a range of medical fluids with which it might come into contact. On the other hand, the polymer is weak mechanically, and a number of serious fractures have occurred in catheters. For example, silicone is used in Foley catheters where fractures have been reported, often requiring surgery to remove the tip left in the bladder. There are many different types of catheters for bladder problems. A typical modern intermittent catheter is made from polyurethane and comes in different lengths and sizes for men, women and children. Some catheters are packed in a sterile saline solution.


Catheters used in interventional procedures

Polyimide Polyimide (sometimes abbreviated PI) is a polymer containing imide groups belonging to the class of high-performance plastics. With their high heat-resistance, polyimides enjoy diverse applications in roles demanding rugged organic materials, e. ...
s are used to manufacture vascular catheters for insertion into small vessels in the neck, head and brain. Guiding catheters (catheters that guides angioplasty balloons and stents) is made up of polytetrafluoroethylene (PTFE) innermost layer which is lubricant, followed by
stainless steel Stainless steel is an alloy of iron that is resistant to rusting and corrosion. It contains at least 11% chromium and may contain elements such as carbon, other nonmetals and metals to obtain other desired properties. Stainless steel's r ...
braid wire outer layer which helps to provide support for the catheter and prevent kinking while travelling through blood vessels, and
Nylon Nylon is a generic designation for a family of synthetic polymers composed of polyamides ( repeating units linked by amide links).The polyamides may be aliphatic or semi-aromatic. Nylon is a silk-like thermoplastic, generally made from petr ...
elastomer outermost layer which provides extra support for the catheter and preserve the curvature of the catheter while passing through tortuous vessels. Some catheters have a thin
hydrophilic A hydrophile is a molecule or other molecular entity that is attracted to water molecules and tends to be dissolved by water.Liddell, H.G. & Scott, R. (1940). ''A Greek-English Lexicon'' Oxford: Clarendon Press. In contrast, hydrophobes ar ...
surface coating. When immersed in water this coating swells to a smooth, slippery film making the catheter safer and more comfortable to insert. Since this wire is too slippery to handle, torque devices are used to control the direction and spin the wire. It is useful in subintimal angioplasty. However, care should be taken as it can easily cause dissection of vascular wall.


Interventional procedures


Diagnostic catheters

There are various catheters used in
angiography Angiography or arteriography is a medical imaging technique used to visualize the inside, or lumen, of blood vessels and organs of the body, with particular interest in the arteries, veins, and the heart chambers. Modern angiography is perform ...
procedures. Diagnostic catheters direct wires through blood vessels.
Radiocontrast agent Radiocontrast agents are substances used to enhance the visibility of internal structures in X-ray-based imaging techniques such as computed tomography (contrast CT), projectional radiography, and fluoroscopy. Radiocontrast agents are typically ...
is then injected through the catheter to visualise the vessels via various imaging methods such as computed tomography (CT), projectional radiography, and
fluoroscopy Fluoroscopy () is an imaging technique that uses X-rays to obtain real-time moving images of the interior of an object. In its primary application of medical imaging, a fluoroscope () allows a physician to see the internal structure and function ...
. Pigtail catheter is a non-selective catheter with multiple side holes that can deliver large volumes of contrast into a blood vessel for imaging purposes. Cobra catheter is a selective catheter used to catheterise downgoing vessels in the abdomen. Cobra catheters move forward by pushing and are removed by pulling. Sidewinder catheter is a selective catheter is used to navigate the aorta. Headhunter, Newton, Simmons, Bentson, and Berenstein catheters are used to navigate the into one of the three branches of the arch of aorta. Yashiro Catheter is a selective, hydrophilic catheter designed for optimal entry into celiac trunk. Whereas endothelial cell sampling through endovascular sampling with coils, stents, stent retrievers, or guidewires suffer from poor selectivity and a low or highly variable cell yield, a micro-3D-printed device adapted for endovascular techniques can harvest endothelial cells for transcriptomic analysis.


Balloon catheters

There are also balloon catheters used in
angioplasty Angioplasty, is also known as balloon angioplasty and percutaneous transluminal angioplasty (PTA), is a minimally invasive endovascular procedure used to widen narrowed or obstructed arteries or veins, typically to treat arterial atheroscler ...
procedures such as plain balloon catheters that is useful in passing tight vessel stenosis, drug coated balloons that contains paclitaxel on the surface to prevent smooth muscle cells proliferation of the vessel walls, thus reducing the likehood of vessel blockage in the future, high pressure balloons that can open stubborn vessel stenoses in veins and arteriovenous fistula, and cutting balloon angioplasty that contains 3 to 4 small blades on its surface (endotomes) that helps to control the distribution of balloon dilatation more uniformly and cut through resistant stenosis due to fibrous scar tissue.


Dialysis catheters

There is no difference in achieving adequacy of blood flow, period of catheter usage, infection, and thromboembolism risk whether the dialysis catheter has step-tip, split-tip, or symmetrical tip. Palidrome catheter is superior to Permcath catheter in terms of maximum blood flow, dialysis adequecy, and annual patency rate. Similar to Permcath, Palidrome catheter has high infection and thromboembolism rate.


Adverse effects

"Any foreign object in the body carries an infection risk, and a catheter can serve as a superhighway for bacteria to enter the bloodstream or body", according to Milisa Manojlovich, a professor at the University of Michigan School of Nursing. Catheters can be difficult to clean, and therefore harbor antibiotic resistant or otherwise pathogenic bacteria.


See also

* Cannula * Foley catheter * French catheter scale * Gastrostomy * G-Tube *
Jejunostomy Jejunostomy is the surgical creation of an opening (stoma) through the skin at the front of the abdomen and the wall of the jejunum (part of the small intestine). It can be performed either endoscopically, or with open surgery. A jejunostomy may ...
* Stent


References

*


External links

{{Urologic surgical and other procedures *