An iron lung, also known as a tank ventilator or Drinker tank, is a type of negative pressure ventilator (NPV); a mechanical respirator which encloses most of a person's body, and varies the air pressure in the enclosed space, to stimulate breathing.It assists breathing when muscle control is lost, or the work of breathing exceeds the person's ability. Need for this treatment may result from diseases including polio and botulism and certain poisons (for example, barbiturates, tubocurarine).
The use of iron lungs is largely obsolete in modern medicine, as more modern breathing therapies have been developed,and due to the eradication of polio in most of the world. However, in 2020, the COVID-19 pandemic revived some interest in the device as a cheap, readily-producible substitute for positive-pressure ventilators, which were feared to be outnumbered by patients potentially needing temporary artificially assisted respiration.
The iron lung is typically a large horizontal cylinder, in which a person is laid, with their head protruding from a hole in the end of the cylinder, so that their full head (down to their voice box) is outside the cylinder, exposed to ambient air, and the rest of their body sealed inside the cylinder, where air pressure is continuously cycled up and down, to stimulate breathing.
To cause the patient to inhale, air is pumped out of the cylinder, causing a slight vacuum, which causes the patient's chest and abdomen to expand (drawing air from outside the cylinder, through the patient's exposed nose or mouth, into their lungs). Then, for the patient to exhale, the air inside the cylinder is compressed slightly (or allowed to equalize to ambient room pressure), causing the patient's chest and abdomen to partially collapse, forcing air out of the lungs, as the patient exhales the breath through their exposed mouth and nose, outside the cylinder.
Examples of the device include the Drinker respirator, the Emerson respirator, and the Both respirator. Iron lungs can be either manually or mechanically powered but normally are powered by an electric motor linked to a flexible pumping diaphragm (commonly opposite the end of the cylinder from the patient's head).Larger "room-sized" iron lungs were also developed, allowing for simultaneous ventilation of several patients (each with their heads protruding from sealed openings in the outer wall), with sufficient space inside for a nurse or a respiratory therapist to be inside the sealed room, attending the patients.
Smaller, single-patient versions of the iron lung include the so-called cuirass ventilator (named for the cuirass, a torso-covering body armor). The cuirass ventilator encloses only the patient's torso, or chest and abdomen, but otherwise operates essentially the same as the original, full-sized iron lung. A lightweight variation on the cuirass ventilator is the jacket ventilator or poncho or raincoat ventilator, which uses a flexible, impermeable material (such as plastic or rubber) stretched over a metal or plastic frame over the patient's torso.
Humans, like most mammals, breathe by negative pressure breathing:the rib cage expands and the diaphragm contracts, expanding the chest cavity. This causes the pressure in the chest cavity to decrease, and the lungs expand to fill the space. This, in turn, causes the pressure of the air inside the lungs to decrease (it becomes negative, relative to the atmosphere), and air flows into the lungs from the atmosphere: inhalation. When the diaphragm relaxes, the reverse happens and the person exhales. If a person loses part or all of the ability to control the muscles involved, breathing becomes difficult or impossible.
In 1670, English scientist John Mayow came up with the idea of external negative pressure ventilation. Mayow built a model consisting of bellows and a bladder to pull in and expel air.The first negative pressure ventilator was described by British physician John Dalziel in 1832. Successful use of similar devices was described a few years later. Early prototypes included a hand-operated bellows-driven "Spirophore" designed by Dr Woillez of Paris (1876), and an airtight wooden box designed specifically for the treatment of polio by Dr Stueart of South Africa (1918). Stueart's box was sealed at the waist and shoulders with clay and powered by motor-driven bellows.
The first of these devices to be widely used however was developed in 1928 by Drinker and Shaw of the United States.The iron lung, often referred to in the early days as the "Drinker respirator", was invented by Philip Drinker (1894–1972) and Louis Agassiz Shaw Jr., professors of industrial hygiene at the Harvard School of Public Health. The machine was powered by an electric motor with air pumps from two vacuum cleaners. The air pumps changed the pressure inside a rectangular, airtight metal box, pulling air in and out of the lungs.
The first clinical use of the Drinker respirator on a human was on October 12, 1928, at the Boston Children's Hospital in the US.The subject was an eight-year-old girl who was nearly dead as a result of respiratory failure due to polio. Her dramatic recovery, within less than a minute of being placed in the chamber, helped popularize the new device.
Boston manufacturer Warren E. Collins began production of the iron lung that year.Although it was initially developed for the treatment of victims of coal gas poisoning, it was most famously used in the mid-20th century for the treatment of respiratory failure caused by poliomyelitis.
Danish physiologist August Krogh, upon returning to Copenhagen in 1931 from a visit to New York where he saw the Drinker machine in use, constructed the first Danish respirator designed for clinical purposes. Krogh's device differed from Drinker's in that its motor was powered by water from the city pipelines. Krogh also made an infant respirator version.
In 1931, John Haven Emerson (1906–1997) introduced an improved and less expensive iron lung.The Emerson iron lung had a bed that could slide in and out of the cylinder as needed, and the tank had portal windows which allowed attendants to reach in and adjust limbs, sheets, or hot packs. Drinker and Harvard University sued Emerson, claiming he had infringed on patent rights. Emerson defended himself by making the case that such lifesaving devices should be freely available to all. Emerson also demonstrated that every aspect of Drinker's patents had been published or used by others at earlier times. Since an invention must be novel to be patentable, prior publication/use of the invention meant it was not novel and therefore unpatentable. Emerson won the case, and Drinker's patents were declared invalid.
The United Kingdom's first iron lung was designed in 1934 by Robert Henderson, an Aberdeen doctor. Henderson had seen a demonstration of the Drinker respirator in the early 1930s and built a device of his own upon his return to Scotland. Four weeks after its construction, the Henderson respirator was used to save the life of a 10-year-old boy from New Deer, Aberdeenshire, who was suffering from poliomyelitis. Despite this success, Henderson was reprimanded for secretly using hospital facilities to build the machine.
The Both respirator, a negative pressure ventilator, was invented in 1937 when Australia's epidemic of poliomyelitis created an immediate need for more ventilating machines to compensate for respiratory paralysis. Although the Drinker model was effective and saved lives, its widespread use was hindered by the fact that the machines were very large, heavy (about 750 lbs or 340 kg), bulky, and expensive. In the US, an adult machine cost about $2000 in 1930, and £2000 delivered to Melbourne in 1936. The cost in Europe in the mid-1950s was around £1500. Consequently, there were few of the Drinker devices in Australia and Europe.
The South Australia Health Department asked Adelaide brothers Edward and Don Both to create an inexpensive "iron lung".Biomedical engineer Edward Both designed and developed a cabinet respirator made of plywood that worked similarly to the Drinker device, with the addition of a bi-valved design which allowed temporary access to the patient's body. Far cheaper to make (only £100) than the Drinker machine, the Both Respirator also weighed less and could be constructed and transported more quickly. Such was the demand for the machines that they were often used by patients within an hour of production.
Visiting London in 1938 during another polio epidemic, Both produced additional respirators there which attracted the attention of William Morris (Lord Nuffield), a British motor manufacturer and philanthropist. Nuffield, intrigued by the design, financed the production of approximately 1700 machines at his car factory in Cowley, and donated them to hospitals throughout all parts of Britain and the British Empire.Soon, the Both-Nuffield respirators were able to be produced by the thousand at about one-thirteenth the cost of the American design. By the early 1950s, there were over 700 Both-Nuffield iron lungs in the United Kingdom, but only 50 Drinker devices.
Rows of iron lungs filled hospital wards at the height of the polio outbreaks of the 1940s and 1950s, helping children, and some adults, with bulbar polio and bulbospinal polio. A polio patient with a paralyzed diaphragm would typically spend two weeks inside an iron lung while recovering.
Polio vaccination programs have virtually eradicated new cases of poliomyelitis in the developed world. Because of this, and the development of modern ventilators, and widespread use of tracheal intubation and tracheotomy, the iron lung has mostly disappeared from modern medicine. In 1959, there were 1,200 people using tank respirators in the United States, but by 2004 there were only 39.By 2014, there were only 10 people left with an iron lung.
Positive pressure ventilation systems are now more common than negative pressure systems. Positive pressure ventilators work by blowing air into the patient's lungs via intubation through the airway; they were used for the first time in Blegdams Hospital, Copenhagen, Denmark, during a polio outbreak in 1952.It proved a success and soon superseded the iron lung throughout Europe.
The iron lung now has a marginal place in modern respiratory therapy. Most patients with paralysis of the breathing muscles use modern mechanical ventilators that push air into the airway with positive pressure. These are generally efficacious and have the advantage of not restricting patients' movements or caregivers' ability to examine the patients as significantly as an iron lung does.
Despite the advantages of positive ventilation systems, negative pressure ventilation is a truer approximation of normal physiological breathing and results in a more normal distribution of air in the lungs. It may also be preferable in certain rare conditions,such as central hypoventilation syndrome, in which failure of the medullary respiratory centers at the base of the brain results in patients having no autonomic control of breathing. At least one reported polio patient, Dianne Odell, had a spinal deformity that caused the use of mechanical ventilators to be contraindicated.
There are patients who today still use the older machines, often in their homes, despite the occasional difficulty of finding the various replacement parts.Joan Headley of Post-Polio Health International said that as of May 28, 2008, there were about 30 patients in the U.S. still using an iron lung. That figure may be inaccurately low; Houston alone had 19 iron lung patients living at home in 2008. Martha Mason of Lattimore, North Carolina, died on May 4, 2009, after spending 60 of her 72 years in an iron lung.
On October 30, 2009, June Middleton of Melbourne, Australia, who had been entered in the Guinness Book of Records as the person who spent the longest time in an iron lung, died aged 83, having spent more than 60 years in her iron lung.
In 2013, the Post-Polio Health International (PHI) organizations estimated that there were only six to eight iron lung users in the United States; as of 2017 its executive director knew of none. Press reports then emerged, however, of at least three (perhaps the last three)users of such devices, sparking interest amongst those in the makerspace community such as Naomi Wu in the manufacture of the obsolete components, particularly the gaskets. Another is retired lawyer Paul Alexander, 74, of Dallas.
In early 2020, reacting to the COVID-19 pandemic, to address the urgent global shortage of modern ventilators (needed for patients with advanced, severe COVID-19 disease), some enterprises developed prototypes of new, readily-producible versions of the iron lung. These developments included:
A ventilator is a machine that provides mechanical ventilation by moving breathable air into and out of the lungs, to deliver breaths to a patient who is physically unable to breathe, or breathing insufficiently. Ventilators are computerized microprocessor-controlled machines, but patients can also be ventilated with a simple, hand-operated bag valve mask. Ventilators are chiefly used in intensive-care medicine, home care, and emergency medicine and in anesthesiology.
Mechanical ventilation, assisted ventilation or intermittent mandatory ventilation (IMV), is the medical term for artificial ventilation where mechanical means are used to assist or replace spontaneous breathing. This may involve a machine called a ventilator, or the breathing may be assisted manually by a suitably qualified professional, such as an anesthesiologist, Registered Nurse, paramedic or other first responder, by compressing a bag valve mask device.
Intensive care medicine, also called critical care medicine, is a medical specialty that deals with seriously or critically ill patients who have, are at risk of, or are recovering from conditions that may be life-threatening. It includes providing life support, invasive monitoring techniques, resuscitation, and end-of-life care. Doctors in this specialty are often called intensive care physicians, critical care physicians or intensivists.
Respiratory arrest is caused by apnea or respiratory dysfunction severe enough it will not sustain the body. Prolonged apnea refers to a patient who has stopped breathing for a long period of time. If the heart muscle contraction is intact, the condition is known as respiratory arrest. An abrupt stop of pulmonary gas exchange lasting for more than five minutes may damage vital organs especially the brain, possibly permanently. Lack of oxygen to the brain causes loss of consciousness. Brain injury is likely if respiratory arrest goes untreated for more than three minutes, and death is almost certain if more than five minutes.
Artificial ventilation is a means of assisting or stimulating respiration, a metabolic process referring to the overall exchange of gases in the body by pulmonary ventilation, external respiration, and internal respiration. It may take the form of manually providing air for a person who is not breathing or is not making sufficient respiratory effort, or it may be mechanical ventilation involving the use of a mechanical ventilator to move air in and out of the lungs when an individual is unable to breathe on their own, for example during surgery with general anesthesia or when an individual is in a coma or trauma.
A resuscitator is a device using positive pressure to inflate the lungs of an unconscious person who is not breathing, in order to keep them oxygenated and alive. There are three basic types: a manual version consisting of a mask and a large hand-squeezed plastic bulb using ambient air, or with supplemental oxygen from a high-pressure tank. The second type is the Expired Air or breath powered resuscitator. The first appearance of the second type was the Brooke Airway introduced in 1957. The third type is an oxygen powered resuscitator. These are driven by pressurized gas delivered by a regulator, and can either be automatic or manually controlled. The most popular type of gas powered resuscitator are Time Cycled, Volume Constant Ventilators. In the early days of pre-hospital emergency services, pressure cycled devices like the Pulmotor were popular but yielded less than satisfactory results. One of the first modern resuscitation ventilators was the HARV, later called the PneuPac 2R or Yellow Box. Most modern resuscitators are designed to allow the patient to breathe on his own should he recover the ability to do so. All resuscitation devices should be able to deliver >85% oxygen when a gas source is available.
A bag valve mask (BVM), sometimes known by the proprietary name Ambu bag or generically as a manual resuscitator or "self-inflating bag", is a hand-held device commonly used to provide positive pressure ventilation to patients who are not breathing or not breathing adequately. The device is a required part of resuscitation kits for trained professionals in out-of-hospital settings (such as ambulance crews) and is also frequently used in hospitals as part of standard equipment found on a crash cart, in emergency rooms or other critical care settings. Underscoring the frequency and prominence of BVM use in the United States, the American Heart Association (AHA) Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiac Care recommend that "all healthcare providers should be familiar with the use of the bag-mask device." Manual resuscitators are also used within the hospital for temporary ventilation of patients dependent on mechanical ventilators when the mechanical ventilator needs to be examined for possible malfunction or when ventilator-dependent patients are transported within the hospital. Two principal types of manual resuscitators exist; one version is self-filling with air, although additional oxygen (O2) can be added but is not necessary for the device to function. The other principal type of manual resuscitator (flow-inflation) is heavily used in non-emergency applications in the operating room to ventilate patients during anesthesia induction and recovery.
High-frequency ventilation is a type of mechanical ventilation which utilizes a respiratory rate greater than four times the normal value. and very small tidal volumes. High frequency ventilation is thought to reduce ventilator-associated lung injury (VALI), especially in the context of ARDS and acute lung injury. This is commonly referred to as lung protective ventilation. There are different types of high-frequency ventilation. Each type has its own unique advantages and disadvantages. The types of HFV are characterized by the delivery system and the type of exhalation phase.
John Haven "Jack" Emerson was an American inventor of biomedical devices, specializing in respiratory equipment. He is perhaps best remembered for his work in improving the iron lung.
Continuous positive airway pressure (CPAP) is a form of positive airway pressure (PAP) ventilation in which a constant level of pressure greater than atmospheric pressure is continuously applied to the upper respiratory tract of a person. The application of positive pressure may be intended to prevent upper airway collapse, as occurs in obstructive sleep apnea, or to reduce the work of breathing in conditions such as acute decompensated heart failure. CPAP therapy is highly effective for managing obstructive sleep apnea. Compliance and acceptance of use of CPAP therapy can be a limiting factor, with 8% of people stopping use after the first night and 50% within the first year.
The history of polio (poliomyelitis) infections began during prehistory. Although major polio epidemics were unknown before the 20th century, the disease has caused paralysis and death for much of human history. Over millennia, polio survived quietly as an endemic pathogen until the 1900s when major epidemics began to occur in Europe. Soon after, widespread epidemics appeared in the United States. By 1910, frequent epidemics became regular events throughout the developed world primarily in cities during the summer months. At its peak in the 1940s and 1950s, polio would paralyze or kill over half a million people worldwide every year.
The Both respirator, also known as the Both Portable Cabinet Respirator, was a negative pressure ventilator invented by Edward Both in 1937. Made from plywood, the respirator was an affordable alternative to the more expensive designs that had been used prior to its development, and accordingly came into common usage in Australia. More widespread use emerged during the 1940s and 1950s, when the Both respirator was offered free of charge to Commonwealth hospitals by William Morris.
An orinasal mask, oro-nasal mask or oral-nasal mask is a breathing mask that covers the mouth and the nose only. It may be a complete independent item, as an oxygen mask, or on some anaesthetic apparatuses, or it may be fitted as a component inside a fullface mask on underwater breathing apparatus, a gas mask or an industrial respirator to reduce the amount of dead space. It may be designed for its lower edge to seal on the front of the lower jaw or to go under the chin.
Bjørn Aage Ibsen (August 30, 1915 – August 7, 2007) was a Danish anesthetist and founder of intensive-care medicine. He graduated in 1940 from medical school at the University of Copenhagen and trained in anesthesiology from 1949 to 1950 at the Massachusetts General Hospital, Boston. He became involved in the 1952 poliomyelitis outbreak in Denmark, where 2722 patients developed the illness in a 6-month period with 316 suffering respiratory or airway paralysis. Treatment had involved the use of the few negative pressure ventilators available, but these devices, while helpful, were limited and did not protect against aspiration of secretions. After detecting high levels of CO2 in blood samples and inside a little boy's lung, Ibsen changed management directly. He instituted protracted positive pressure ventilation by means of intubation into the trachea, and enlisting 200 medical students to manually pump oxygen and air into the patients lungs. In this fashion, mortality declined from 90% to around 25%. Patients were managed in 3 special 35 bed areas, which aided charting and other management.
Modes of mechanical ventilation are one of the most important aspects of the usage of mechanical ventilation. The mode refers to the method of inspiratory support. In general, mode selection is based on clinician familiarity and institutional preferences, since there is a paucity of evidence indicating that the mode affects clinical outcome. The most frequently used forms of volume-limited mechanical ventilation are intermittent mandatory ventilation (IMV) and continuous mandatory ventilation (CMV). There have been substantial changes in the nomenclature of mechanical ventilation over the years, but more recently it has become standardized by many respirology and pulmonology groups. Writing a mode is most proper in all capital letters with a dash between the control variable and the strategy.
Intermittent Mandatory Ventilation (IMV) refers to any mode of mechanical ventilation where a regular series of breaths are scheduled but the ventilator senses patient effort and reschedules mandatory breaths based on the calculated need of the patient. Similar to continuous mandatory ventilation in parameters set for the patients pressures and volumes but distinct in its ability to support a patient by either supporting their own effort or providing support when patient effort is not sensed. IMV is frequently paired with additional strategies to improve weaning from ventilator support or to improve cardiovascular stability in patients who may need full life support.
A negative pressure ventilator (NPV) is a type of mechanical ventilator that stimulates an ill person's breathing by periodically applying negative air pressure to their body to expand and contract the chest cavity.
The Bragg-Paul Pulsator, also known as the Bragg-Paul respirator, was a non-invasive medical ventilator invented by William Henry Bragg and designed by Robert W. Paul in 1933 for patients unable to breathe for themselves due to illness.
An open-source ventilator is a disaster-situation ventilator made using a freely licensed (open-source) design, and ideally, freely available components and parts. Designs, components, and parts may be anywhere from completely reverse-engineered or completely new creations, components may be adaptations of various inexpensive existing products, and special hard-to-find and/or expensive parts may be 3D-printed instead of purchased. As of early 2020, the levels of documentation and testing of open-source ventilators was well below scientific and medical-grade standards.
Carl Gunnar David Engström was a Swedish physician and innovator. He is the inventor of the first intermittent positive pressure mechanical ventilator that could deliver breaths of controllable volume and frequency and also deliver inhalation anesthetics.
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