Oxygenator

An oxygenator is a medical device that is capable of exchanging oxygen and carbon dioxide in the blood of human patient during surgical procedures that may necessitate the interruption or cessation of blood flow in the body, a critical organ or great blood vessel. These organs can be the heart, lungs or liver, while the great vessels can be the aorta, pulmonary artery, pulmonary veins or vena cava. An oxygenator is typically utilized by a perfusionist in cardiac surgery in conjunction with the heart-lung machine. However, oxygenators can also be utilized in extracorporeal membrane oxygenation in neonatal intensive care units by nurses.

For most cardiac operations such as coronary artery bypass grafting, the cardiopulmonary bypass is performed using a heart-lung machine (or cardiopulmonary bypass machine). The heart-lung machine serves to replace the work of the heart during the open bypass surgery. The machine replaces both the heart's pumping action and the lungs' gas exchange function. Since the heart is stopped during the operation, this permits the surgeon to operate on a bloodless, stationary heart.

One component of the heart-lung machine is the oxygenator. The oxygenator component serves as the lung, and is designed to expose the blood to oxygen and remove carbon dioxide. It is disposable and contains about 2–4 m² of a membrane permeable to gas but impermeable to blood, in the form of hollow fibers. Blood flows on the outside of the hollow fibers, while oxygen flows in the opposite direction on the inside of the fibers. As the blood passes through the oxygenator, the blood comes into intimate contact with the fine surfaces of the device itself. Gas containing oxygen and medical air is delivered to the interface between the blood and the device, permitting the blood cells to absorb oxygen molecules directly.

Heparin-coated blood oxygenator

Rationale

Operations which involve uncoated CPB circuits require a high dose of systemic heparin. Although the effects of heparin are reversible by administering protamine, there are a number of side effects associated with this. Side effects can include allergic reaction to heparin resulting in thrombocytopenia, various reactions to the administration of protamine and post-operative hemorrhage due to inadequate reversal of the anticoagulation. Systemic heparin does not completely prevent clotting or the activation of complement, neutrophils, and monocytes, which are the principal mediators of the inflammatory response. This response produces a wide range of cytotoxins, and cell-signaling proteins that circulate throughout the patient's body during surgery and disrupt homeostasis. The inflammatory responses can produce microembolic particles. A greater source of such microemboli are caused by the suction of surgical debris and lipids into the CPB circuit.[1]

Microparticles obstruct arterioles that supply small nests of cells throughout the body and, together with cytotoxins, damage organs and tissues and temporarily disturb organ function. All aspects of cardiopulmonary bypass, including manipulation of the aorta by the surgeon, may be associated with neurological symptoms following perfusion. Physicians refer to such temporary neurological deficits as “pumphead syndrome.” Heparin-coated blood oxygenators are one option available to a surgeon and a perfusionist to decrease morbidity associated with CPB to a limited degree.

Heparin-coated oxygenators are thought to:

  • Improve overall biocompatibility and host homeostasis
  • Mimic the natural endothelial lining of the vasculature
  • Reduce the need for systemic anticoagulation
  • Better maintain platelet count
  • Reduce adhesion of plasma proteins
  • Prevent denaturation and activation of adhered proteins and blood cells
  • Avoid complications resulting from an abnormal pressure gradient across the oxygenator

Surgical outcomes

Heparin coating is reported to result in similar characteristics to the native endothelium. It has been shown to inhibit intrinsic coagulation, inhibit host responses to extracorporeal circulation, and lessen postperfusion, or “pumphead,” syndrome. Several studies have examined the clinical efficacy of these oxygenators.

Mirow et al. 2001 examined the effects of heparin-coated cardiopulmonary bypass systems combined with full and low dose systemic heparinization in coronary artery bypass patients. The researchers concluded that

  • Heparin-coated extracorporeal circuits with reduced systemic heparinization lead to significantly increased thrombin generation.
  • Postoperative bleeding was reduced with low systemic heparinization, but the reduction was not significant.

Ovrum et al. 2001 compared the clinical outcomes of 1336 patients with the Carmeda Bioactive Surface and Duraflo II coatings. The researchers concluded that:

  • Duraflo II patients required less heparin to keep the target activated clotting time
  • Effects on renal function and platelets were similar
  • Incidences of perioperative MI, stroke, and hospital mortality were similar
  • Reduced incidence of postoperative atrial fibrillation compared to identical uncoated controls
  • Overall clinical results were favorable in both groups

Statistics and conclusions from more studies are available here. Clearly, heparin-coated blood oxygenators exhibit some advantages over non-coated oxygenators. Some hospitals use heparin-coated oxygenators for the large majority of their cases requiring cardiopulmonary bypass. It is unclear whether most surgeons actually reduce the amount of systemic heparin used when their patients are being perfused with heparin-coated oxygenators. Ultimately, each surgeon makes this decision based upon the needs of individual patient.

Although they offer advantages, these oxygenators are not widely regarded by surgeons as revolutionary breakthroughs in cardiopulmonary bypass. This is attributable to the fact that most of the morbidity associated with CPB is not caused by the contact between the blood with the oxygenator. The leading cause of hemolysis and microemboli is the return of blood suctioned from the surgical field to the CPB circuit. This blood has come into contact with air, lipids and debris that can significantly increase system inflammatory response. Surgeons are instead looking to off-pump cardiac procedures, wherein surgery is performed on beating hearts, as the next “big thing” in open heart surgery.

Coated circuits have not been proven to alter surgical outcomes in any statistically significant manner. Furthermore, coated circuits are significantly more expensive than conventional circuits.

See also

Footnotes

  1. ^ "Cardiotomy Suction: A Major Source of Brain Lipid Emboli During Cardiopulmonary Bypass". Ann Thorac Surg 1998;65:1651-1655.
Artificial gills (human)

Artificial gills are unproven conceptualised devices to allow a human to be able to take in oxygen from surrounding water. This is speculative technology that has not been demonstrated in a documented fashion. Natural gills work because nearly all animals with gills are thermoconformers (cold-blooded), so they need much less oxygen than a thermoregulator (warm-blood) of the same size. As a practical matter, therefore, it is unclear that a usable artificial gill could be created because of the large amount of oxygen a human would need extracted from the water.

Bubble oxygenator

A bubble oxygenator is an early implementation of the oxygenator used for cardiopulmonary bypass. It has since been supplanted by the membrane oxygenator

as a result of advances in material science. Some continue to promote it as a low-cost alternative allowing greater self-sufficiency.

Cardiac surgery

Cardiac surgery, or cardiovascular surgery, is surgery on the heart or great vessels performed by cardiac surgeons. It is often used to treat complications of ischemic heart disease (for example, with coronary artery bypass grafting); to correct congenital heart disease; or to treat valvular heart disease from various causes, including endocarditis, rheumatic heart disease, and atherosclerosis. It also includes heart transplantation.

Cardiopulmonary bypass

Cardiopulmonary bypass (CPB) is a technique that temporarily takes over the function of the heart and lungs during surgery, maintaining the circulation of blood and the oxygen content of the patient's body. The CPB pump itself is often referred to as a heart–lung machine or "the pump". Cardiopulmonary bypass pumps are operated by perfusionists. CPB is a form of extracorporeal circulation. Extracorporeal membrane oxygenation is generally used for longer-term treatment.

Cardiothoracic surgery

Cardiothoracic surgery (also known as thoracic surgery) is the field of medicine involved in surgical treatment of organs inside the thorax (the chest)—generally treatment of conditions of the heart (heart disease) and lungs (lung disease). In most countries, cardiac surgery (involving the heart and the great vessels) and general thoracic surgery (involving the lungs, esophagus, thymus, etc.) are separate surgical specialties; the exceptions are the United States, Australia, New Zealand, and some EU countries, such as the United Kingdom and Portugal.

Charles Drew (surgeon)

Charles Edwin Drew (15 December 1916 – 31 May 1987) was a cardiothoracic surgeon best known for assisting Sir Clement Price Thomas in King George VI's pneumonectomy in 1951.

He went on to conduct pioneering research on profound hypothermia in cardiac surgery and what came to be known as the 'Drew technique'.

Drew died from throat cancer at the age of 70 in 1987, leaving his wife Maureen and two children.

Clarence Dennis

Clarence Dennis, M. D., Ph.D., (June 16, 1909 – July 11, 2005) was an American cardiothoracic surgeon best known for his work in pioneering cardiopulmonary bypass (CPB). He had invented one of the first heart-lung bypass machines, and in 1951 he became the first to use such a device during an open-heart operation.

E. Converse Peirce 2nd

Edmund Converse Peirce 2nd (October 9, 1917 – August 8, 2003) was an American physician who was professor and director of hyperbaric medicine at the Mount Sinai School of Medicine in Manhattan, New York City from 1966 to 1991. During his career, Peirce published over 150 research articles and is notable for his well-regarded contributions to the refinement of artificial circulatory technologies including the membrane oxygenator.

Hottonia palustris

Hottonia palustris, the water violet or featherfoil, is an aquatic plant in the family Primulaceae, from Europe and northern Asia.

Jagera (plant)

Jagera is a genus of 4 species of forest trees known to science, constituting part of the plant family Sapindaceae.

They grow naturally in the rainforests and associated forests of eastern Australia, New Guinea and the Moluccas.In Australia, Jagera pseudorhus is the most well known, and commonly named foambark, due to the saponins in the bark foaming after heavy rain. Indigenous Australians use this foam as the de-oxygenator of waterway pools for temporarily suffocating their fish enabling easy catching.

The genus is named after Herbert de Jager, a Dutch orientalist and associate of the botanist Georg Eberhard Rumphius.

In the last few decades various new names have been formally published, numbers of them subsequently corrected to synonyms of earlier names and a few remaining recognised as genuine new species or varieties.One recognised species in Malesia apparently remains still to be formally described.

Joanna Rajkowska

Joanna Rajkowska (born 1968) is a Polish contemporary artist who came onto the Polish art scene in the 1990s. Her most famous work is called "Greetings from Jerusalem Avenue", a 15-meter-tall (50-foot) artificial palm tree installed on Warsaw's Jerusalem Avenue.

The installation was organized by the Warsaw Centre for Contemporary Art (13 December 2002 – 13 December 2003). Since then, the palm tree has become a permanent fixture of Warsaw, as it was not removed at the end of the official exhibition but instead came under the protection of the President of Warsaw.

It went neglected and leafless two years later, until the artist and friends mounted its restoration. It still stands in the center of the city. In the summer of 2007, the palm underwent a complete makeover, becoming more weatherproof and easier to maintain (unlike natural palms, its fronds require periodic manual replacement).

Liquid ventilator

A liquid ventilator is similar to a medical ventilator except that it should be able to ensure reliable total liquid ventilation with a breatheable liquid (a perfluorocarbon) · . Liquid ventilators are prototypes that may have been used for animal experimentations but experts recommend continued development of a liquid ventilator toward clinical applications.

List of Estonian Americans

This is a list of notable Estonian-Americans, including both original immigrants who obtained American citizenship and their American descendants.

To be included in this list, the person must have a Wikipedia article showing they are Estonian American or must have references showing they are Estonian American and are notable.

Membrane oxygenator

A membrane oxygenator is a device used to add oxygen to, and remove carbon dioxide from the blood. It can be used in two principal modes: to imitate the function of the lungs in cardiopulmonary bypass (CPB), and to oxygenate blood in longer term life support, termed extracorporeal membrane oxygenation, ECMO. A membrane oxygenator consists of a thin gas permeable membrane separating the blood and gas flows in the CPB circuit; oxygen diffuses from the gas side into the blood, and carbon dioxide diffuses from the blood into the gas for disposal.

Minimized extracorporeal circulation

Minimized extracorporeal circulation (MECC) is a kind of cardiopulmonary bypass (heart-lung machine), a part of heart surgery. The introduction of extracorporeal circulation has facilitated open heart surgery. The development of modern techniques in extracorporeal circulation is the result of the combined efforts of physiologists, physicians, and engineers. During the first half of the 20th century scientists refined their methods in the development of extracorporeal circulation so that it could be used in humans.

In 1937 Gibbon reports the first successful use of extracorporeal circulation in animals (in this case, cats). On May 6, 1953 Gibbon performed his first successful operation using an extracorporeal circuit in an 18-year-old woman who had a large atrial septum defect with a large left-to-right shunt. It was Lillehei who one year later introduced the bubble oxygenator, simple and inexpensive, opening the doors of open heart surgery to all surgeons around the world.

The first commercial minimized extracorporeal circulation was the CorX System from Cardiovention, a start-up company from the USA. This system included an integrated centrifugal pump – polypropylene oxygenator, a complete heparin-coated surface and a low priming volume. One of the most effective Mini-Systems (MECC Maquet) was introduced almost at the same time (1999). The increasing application in clinical practice explains this machine's success. The benefits of this type of extracorporeal circulation are that a lower consumption of blood and blood products is observed in the peri-operative and post-operative phase and that a lower inflammatory response is being measured in peri-operative blood samples in comparison to conventional cardiopulmonary bypass.

Operating theater

An operating theater (also known as a good room, operating suite, theatre (British English), operation suite or OR) is a facility within a hospital where surgical operations are carried out in an aseptic environment.

Historically, the term "operating theatre" referred to a non-sterile, tiered theater or amphitheater in which students and other spectators could watch surgeons perform surgery. Contemporary operating rooms are devoid of a theatre setting, making the term "operating theater" a misnomer. There are only two old-style operating theaters left, both of which are preserved as part of museums.

Perfusionist

A perfusionist, also known as a Clinical Perfusionist, Cardiovascular Perfusionist, Clinical Perfusion Scientist, or Medical Perfusionist, is a healthcare professional who uses the cardiopulmonary bypass machine (heart–lung machine) during cardiac surgery and other surgeries that require cardiopulmonary bypass to manage the patient's physiological status.

Perfusionists form part of the wider cardiothoracic surgical team which includes cardiac surgeons, anesthesiologists and physician assistants. The perfusionist shares responsibility with the cardiac surgeon and anesthesiologist for the management of the physiological and metabolic needs of the cardiac surgical patient, so that the surgeon may operate on a still,or unbeating heart during certain procedures. The cardiac surgeon is in overall command of the operation. This is accomplished through the utilization of the heart–lung machine, as well as its associated components of an oxygenator, filters, reservoirs and tubing. The perfusionist is responsible for the management of circulatory and respiratory functions of the patient which has a great effect on the patient systemic condition and allows the cardiac surgeon to focus on the actual surgical procedure and less on the immediate needs of the patient. Other responsibilities include autologous blood collection and processing, implementation and management of the intra-aortic balloon pump, and management of extracorporeal membrane oxygenation, as well as monitoring of anticoagulation, electrolyte, acid-base balance and blood-gas composition. In many tertiary hospitals, perfusionists are also key personnel in placing and managing patients on ventricular assist devices as a bridge to recovery or heart transplantation and supporting patients receiving lung or liver transplants. In some hospitals, perfusionists can be involved in procurement of cardiothoracic donor organs for transplantation.

Subantarctic Mode Water

Subantarctic mode water (SAMW) is an important water mass in the Earth's oceans. It is formed near the Subantarctic Front on the northern flank of the Antarctic Circumpolar Current. The surface density of Subantarctic Mode Water ranges between about 1026.0 and 1027.0 kg/m3 and the core of this water mass is often identified as a region of particularly low stratification.

Another important facet of SAMW is that silicate (an important nutrient for diatoms) is depleted relative to nitrate. This depletion can be tracked over much of the globe, suggesting that SAMW helps set the blend of nutrients delivered to low-latitude ocean ecosystems, and thus determines the balance of species within these ecosystems.

SAMW is a very homogenous layer that forms north of the Subantarctic Front and is also referred to as a pycnostad. Its uniformity can be attributed to convective overturning that also serves to ventilate it resulting in the high dissolved oxygen value of >6ml/l.

It has slightly less dissolved oxygen than the surface water layer above it, but greater dissolved oxygen than the water masses below it. It has some variability in temperature, salinity and density in the Pacific Ocean. From west to east, the density increases from 1026.9 kg/m³ to 1027.1 kg/m³, the temperature decreases from 8.5 °C to 5.5 °C, and the salinity decreases from 34.62 ppt to 34.25 ppt (psu) In the region where the Peru-Chile Undercurrent flows above the SAMW, the SAMW can be distinguished as having locally-characteristic low phosphorus, silicate and other nutrient concentrations in comparison.

It moves by the transference of heat energy via the Subtropical anticyclonic gyre and retains its individuality as differentiated with the less-salty Antarctic Intermediate Water below it and the more highly oxygenated surface water above it. The oxygen maximum portion of SAMW sinks at 28˚S to 700m and lifts back to 500m around 15˚S after oxygen levels decreased.SAMW acts as an oxygenator for mid oceanic depths in the Southern oceans. Near the surface it picks up atmospheric oxygen and carbon dioxide and then sinks, or subducts near the Indian Ocean, contributing to the Indian subtropical gyre and cooling and contributing to the Antarctic Circumpolar Current (ACC).

Wayne Quinton

Wayne Everett Quinton (January 4, 1921 – January 22, 2015) was a developer of over 30 biomedical devices, including the Quinton catheter. He also invented a lightweight treadmill, for cardiac stress testing - the prototype of those used in fitness centers.

Quinton was raised in Rigby, Idaho. He received a degree in mechanical engineering from the University of Washington in 1959. He previously attended Ricks College (now BYU-Idaho) and Montana State University. A week after Pearl Harbor, he arrived in Seattle and began working for Boeing to work on the B-29 bomber.

He was hired by the University of Washington for an Arctic Acclimatization study and subsequently as the sole member of the instrument shop.

Among Quinton's inventions was a shunt with Belding Scribner and David Dillard that allowed for repeated kidney dialysis procedures on an individual, making the process one that truly extended the patient's life expectancy. He was also involved with the following inventions: structure to allow polio patients to get into a sitting position; movable camera boom and cart to reduce time taking autopsy photos; uniform bubble oxygenator for use during open-heart surgery; hydraulic gastrointestinal biopsy instrument; Mitral valve finger knife for use during open-heart surgery; small aortic valve dilator for use during open-heart surgery; high-speed machine to test fatigue in artificial heart valves; Teflon tracheotomy plug to aid patients with paralytic polio.

Although Quinton was raised in a rural Mormon community, it wasn't until age 35 that he was baptized a member of The Church of Jesus Christ of Latter-day Saints.

Wayne Quinton died of congestive heart failure, age 94, at his home in the Highlands area of Seattle, Washington.

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