King says, while a ventilator might save your life, it is certainly not a pleasant experience. And while a young and healthy person with COVID-19 might not need a ventilator, there are others who will.
A ventilator is a piece of medical technology 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 (as standalone units) and in anesthesiology (as a component of an anesthesia machine).
In its simplest form, a modern positive pressure ventilator, consists of a compressible air reservoir or turbine, air and oxygen supplies, a set of valves and tubes, and a disposable or reusable "patient circuit". The air reservoir is pneumatically compressed several times a minute to deliver room-air, or in most cases, an air/oxygen mixture to the patient. If a turbine is used, the turbine pushes air through the ventilator, with a flow valve adjusting pressure to meet patient-specific parameters. When over pressure is released, the patient will exhale passively due to the lungs' elasticity, the exhaled air being released usually through a one-way valve within the patient circuit called the patient manifold.
Ventilators may also be equipped with monitoring and alarm systems for patient-related parameters (e.g., pressure, volume, and flow) and ventilator function (e.g., air leakage, power failure, mechanical failure), backup batteries, oxygen tanks, and remote control. The pneumatic system is nowadays often replaced by a computer-controlled turbopump.
Modern ventilators are electronically controlled by a small embedded system to allow exact adaptation of pressure and flow characteristics to an individual patient's needs. Fine-tuned ventilator settings also serve to make ventilation more tolerable and comfortable for the patient. In Canada and the United States, respiratory therapists are responsible for tuning these settings, while biomedical technologists are responsible for the maintenance. In the United Kingdom and Europe the management of the patient's interaction with the ventilator is done by critical care nurses.
Noninvasive methods, such as continuous positive airway pressure (CPAP) and non-invasive ventilation, which are adequate for patients who require a ventilator only while sleeping and resting, mainly employ a nasal mask. Invasive methods require intubation, which for long-term ventilator dependence will normally be a tracheotomy cannula, as this is much more comfortable and practical for long-term care than is larynx or nasal intubation.
As failure may result in death, mechanical ventilation systems are classified as life-critical systems, and precautions must be taken to ensure that they are highly reliable, including their power supply. Ventilatory failure is the inability to sustain a sufficient rate of CO2 elimination to maintain a stable pH without mechanical assistance, muscle fatigue, or intolerable dyspnea. Mechanical ventilators are therefore carefully designed so that no single point of failure can endanger the patient. They may have manual backup mechanisms to enable hand-driven respiration in the absence of power (such as the mechanical ventilator integrated into an anaesthetic machine). They may also have safety valves, which open to atmosphere in the absence of power to act as an anti-suffocation valve for spontaneous breathing of the patient. Some systems are also equipped with compressed-gas tanks, air compressors or backup batteries to provide ventilation in case of power failure or defective gas supplies, and methods to operate or call for help if their mechanisms or software fail. Power failures, such as during a natural disaster, can create a life-threatening emergency for people using ventilators in a home care setting. Battery power may be sufficient for a brief loss of electricity, but longer power outages may require going to a hospital.
The history of mechanical ventilation begins with various versions of what was eventually called the iron lung, a form of noninvasive negative-pressure ventilator widely used during the polio epidemics of the twentieth century after the introduction of the "Drinker respirator" in 1928, improvements introduced by John Haven Emerson in 1931, and the Both respirator in 1937. Other forms of noninvasive ventilators, also used widely for polio patients, include Biphasic Cuirass Ventilation, the rocking bed, and rather primitive positive pressure machines.
In 1949, John Haven Emerson developed a mechanical assister for anaesthesia with the cooperation of the anaesthesia department at Harvard University. Mechanical ventilators began to be used increasingly in anaesthesia and intensive care during the 1950s. Their development was stimulated both by the need to treat polio patients and the increasing use of muscle relaxants during anaesthesia. Relaxant drugs paralyse the patient and improve operating conditions for the surgeon but also paralyse the respiratory muscles. In 1953 Bjørn Aage Ibsen set up what became the world's first Medical/Surgical ICU utilizing muscle relaxants and controlled ventilation.
In the United Kingdom, the East Radcliffe and Beaver models were early examples. The former used a Sturmey-Archer bicycle hub gear to provide a range of speeds, and the latter an automotive windscreen wiper motor to drive the bellows used to inflate the lungs. Electric motors were, however, a problem in the operating theatres of that time, as their use caused an explosion hazard in the presence of flammable anaesthetics such as ether and cyclopropane. In 1952, Roger Manley of the Westminster Hospital, London, developed a ventilator which was entirely gas-driven and became the most popular model used in Europe. It was an elegant design, and became a great favourite with European anaesthetists for four decades, prior to the introduction of models controlled by electronics. It was independent of electrical power and caused no explosion hazard. The original Mark I unit was developed to become the Manley Mark II in collaboration with the Blease company, which manufactured many thousands of these units. Its principle of operation was very simple, an incoming gas flow was used to lift a weighted bellows unit, which fell intermittently under gravity, forcing breathing gases into the patient's lungs. The inflation pressure could be varied by sliding the movable weight on top of the bellows. The volume of gas delivered was adjustable using a curved slider, which restricted bellows excursion. Residual pressure after the completion of expiration was also configurable, using a small weighted arm visible to the lower right of the front panel. This was a robust unit and its availability encouraged the introduction of positive pressure ventilation techniques into mainstream European anesthetic practice.
Intensive care environments around the world revolutionized in 1971 by the introduction of the first SERVO 900 ventilator (Elema-Schönander), constructed by Björn Jonson. It was a small, silent and effective electronic ventilator, with the famous SERVO feedback system controlling what had been set and regulating delivery. For the first time, the machine could deliver the set volume in volume control ventilation.
Microprocessor control led to the third generation of intensive care unit (ICU) ventilators, starting with the Dräger EV-A in 1982 in Germany which allowed monitoring the patient's breathing curve on an LCD monitor. One year later followed Puritan Bennett 7200 and Bear 1000, SERVO 300 and Hamilton Veolar over the next decade. Microprocessors enable customized gas delivery and monitoring, and mechanisms for gas delivery that are much more responsive to patient needs than previous generations of mechanical ventilators.
An open-source ventilator is a disaster-situation ventilator made using a freely-licensed design, and ideally, freely-available components and parts. Designs, components, and parts may be anywhere from completely reverse-engineered to 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 sourced.
Among ventilators that might be brought into the COVID-19 fight, there have been many concerns. These include current availability, the challenge of making more and lower cost ventilators, effectiveness, functional design, safety, portability, suitability for infants, assignment to treat other illnesses, and operator training. Deploying the best possible mix of ventilators can save the most lives.
Although not formally open-sourced, the Ventec V+ Pro ventilator was developed in April 2020 as a shared effort between Ventec Life Systems and General Motors, to provide a rapid supply of 30,000 ventilators capable of treating COVID-19 patients.
A major worldwide design effort began during the 2019-2020 coronavirus pandemic after a Hackaday project was started,[non-primary source needed] in order to respond to expected ventilator shortages causing higher mortality rate among severe patients.
The University of Minnesota Bakken Medical Device Center initiated a collaboration with various companies to bring a ventilator alternative to the market that works as a one-armed robot and replaces the need for manual ventilation in emergency situations. The Coventor device was developed in a very short time and approved on April 15, 2020, by the FDA, only 30 days after conception. The mechanical ventilator is designed for use by trained medical professionals in intensive care units and easy to operate. It has a compact design and is relatively inexpensive to manufacture and distribute. The cost is only about 4% of a normal ventilator. In addition, this device does not require pressurized oxygen or air supply, as is normally the case. A first series is manufactured by Boston Scientific. The plans are to be freely available online to the general public without royalties. 041b061a72