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. [1]
It was the first 'Intermittent Abdominal Pressure Ventilator' (IAPV). [2]
The Pulsator applied pressure externally upon the body to force exhalation, and the natural elasticity of the chest and the weight of the internal organs upon the diaphragm produced inhalation when that external pressure was removed. This method is now described as 'intermittent abdominal pressure ventilation', in contrast to negative pressure ventilators, commonly called 'iron lungs', that force inhalation and rely on chest elasticity to produce exhalation. [2]
Bragg came up with the idea for the machine to help a friend suffering from muscular dystrophy. His first version comprised a football bladder strapped to the patient's chest connected to a second football bladder sandwiched between two boards hinged together. Squeezing of the second bladder inflated the first, which compressed the chest and forced exhalation from the lungs. [3] [4] The first version built by scientific instrument maker R W Paul was water-powered - it was used for 17 hours per day for 3 years, except when the water supply froze one hard winter. It consumed about 700 gallons (3 cubic metres) of water per day. [5] [6]
The commercial Pulsator designed by Paul consisted of a belt worn around the patient's abdomen and lower thorax that was rhythmically filled with air from bellows being driven electrically. A gauge indicated the pressure being applied to the chest, and the rate of compression could be modified to suit the patient's breathing. An escape-valve on the bellows controlled the pressure being applied. [7] The 1934 model could be driven by hand, water or electric power, one case having used water power for a year. [8] Following an analysis of the ventilation induced by the 1934 model, physiologist Phyllis Tookey Kerridge recommended some modifications that greatly improved the efficiency and usability of the belt. [9] A quieter and more portable model was produced in 1937. [10]
The advantages of the design were its ease of transportation and use, it did not impede orthopaedic and nursing care, and could prevent lung collapse in some cases. Disadvantages were that inhalation depended upon elastic recoil of the chest and upon gravity pulling the diaphragm back down, and so breathing could be shallow and the patient could not lie down; attention was required in its use, and the action gave the patient more discomfort compared with cabinet (iron lung) respirators. [11]
It was built in Britain by Siebe Gorman & Company Ltd. [8]
The Pulsator was used predominantly for the treatment of diphtheria and anterior poliomyelitis-related respiratory paralysis. Other conditions treated with some degree of success were drug overdoses, and muscular dystrophy. [12]
The Pulsator and the 'iron lung' where the only respirators available during the severe outbreak of poliomyelitis in the United Kingdom in 1938. [3] By March 1939 there were 43 Pulsators known to be in use in the British Isles, more common than the 'iron lungs', but already vastly outnumbered by the new Both respirators, [13] which had been selected by a Medical Research Council committee investigating the shortage of equipment needed to cope with the polio epidemic. [3] The Both was chosen over the equally effective Bragg-Paul when Lord Nuffield offered to give the both to hospitals for free. This choice probably curtailed the further development of the Pulsator. [14]
In 1950 the Pulsator was still in use in Great Britain, Ireland and Portugal, still being the preferred ventilator for polio cases in Ireland. [11]
An early documented use of the Pulsator was at the Cork Street Fever Hospital, Dublin. From 1935 to 1938 all cases of post-diphtheria respiratory paralysis were treated with the Pulsator, only one of which died due to respiratory failure (when the machine broke down). [7]
Use of the Pulsator spread in the late 1950s due to its convenience and portability for chronically ill patients. [15]
The Pulsator provided life-saving treatment for many people in the early days of artificial ventilation. When the only alternative was the 'iron lung', the much less intrusive treatment of the Pulsator allowed for a more normal life for its patients.
As the first 'Intermittent Abdominal Pressure Ventilator', the Pulsator was the forerunner of various newer apparatuses, in particular the 'Pneumobelt' which subsequently became a generic name for the genre. [2] [16] [17] A 1991 study concluded that IAPV was effective for the long-term daytime treatment of respiratory insufficiency and could avoid the need for tracheostomy. While the less-severely ill patients preferred IPPV (intermittent positive pressure ventilation), IAPV was found to be best for severe cases, and was the preferred type of mechanical assistance in the seated position. However it should not be used for 24 hours a day, and its effectiveness for some patients could decline after years of use. [2]
Although considered obsolete by 2014, superseded by newer types of ventilators, Pneumobelts were still manufactured at least until 2008. [18] [19]
A ventilator is a type of breathing apparatus, a class 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 may be 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 using a machine called a ventilator to fully or partially provide artificial ventilation. Mechanical ventilation helps move air into and out of the lungs, with the main goal of helping the delivery of oxygen and removal of carbon dioxide. Mechanical ventilation is used for many reasons, including to protect the airway due to mechanical or neurologic cause, to ensure adequate oxygenation, or to remove excess carbon dioxide from the lungs. Various healthcare providers are involved with the use of mechanical ventilation and people who require ventilators are typically monitored in an intensive care unit.
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.
An iron lung 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.
Positive airway pressure (PAP) is a mode of respiratory ventilation used in the treatment of sleep apnea. PAP ventilation is also commonly used for those who are critically ill in hospital with respiratory failure, in newborn infants (neonates), and for the prevention and treatment of atelectasis in patients with difficulty taking deep breaths. In these patients, PAP ventilation can prevent the need for tracheal intubation, or allow earlier extubation. Sometimes patients with neuromuscular diseases use this variety of ventilation as well. CPAP is an acronym for "continuous positive airway pressure", which was developed by Dr. George Gregory and colleagues in the neonatal intensive care unit at the University of California, San Francisco. A variation of the PAP system was developed by Professor Colin Sullivan at Royal Prince Alfred Hospital in Sydney, Australia, in 1981.
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.
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.
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 rest of the world. 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.
Pulmonary hygiene, formerly referred to as pulmonary toilet, is a set of methods used to clear mucus and secretions from the airways. The word pulmonary refers to the lungs. The word toilet, related to the French toilette, refers to body care and hygiene; this root is used in words such as toiletry that also relate to cleansing.
Airway pressure release ventilation (APRV) is a pressure control mode of mechanical ventilation that utilizes an inverse ratio ventilation strategy. APRV is an applied continuous positive airway pressure (CPAP) that at a set timed interval releases the applied pressure. Depending on the ventilator manufacturer, it may be referred to as BiVent. This is just as appropriate to use, since the only difference is that the term APRV is copyrighted.
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.
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.
Continuous mandatory ventilation (CMV) is a mode of mechanical ventilation in which breaths are delivered based on set variables. Still used in the operating room, in previous nomenclature, CMV referred to "controlled mechanical ventilation", a mode of ventilation characterized by a ventilator that makes no effort to sense patient breathing effort. In continuous mandatory ventilation, the ventilator can be triggered either by the patient or mechanically by the ventilator. The ventilator is set to deliver a breath according to parameters selected by the operator. "Controlled mechanical ventilation" is an outdated expansion for "CMV"; "continuous mandatory ventilation" is now accepted standard nomenclature for mechanical ventilation. CMV today can assist or control itself dynamically, depending on the transient presence or absence of spontaneous breathing effort. Thus, today's CMV would have been called ACV in older nomenclature, and the original form of CMV is a thing of the past. But despite continual technological improvement over the past half century, CMV may still be uncomfortable for the patient.
Many terms are used in mechanical ventilation, some are specific to brand, model, trademark and mode of mechanical ventilation. There is a standardized nomenclature of mechanical ventilation that is specific about nomenclature related to modes, but not settings and variables.
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.
Phyllis Margaret Tookey Kerridge was a chemist and physiologist. She is notable for creating the miniature pH electrode, her work on artificial respiration, and her pioneering work shaping the discipline of audiometry.
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.
A breathing apparatus or breathing set is equipment which allows a person to breathe in a hostile environment where breathing would otherwise be impossible, difficult, harmful, or hazardous, or assists a person to breathe. A respirator, medical ventilator, or resuscitator may also be considered to be breathing apparatus. Equipment that supplies or recycles breathing gas other than ambient air in a space used by several people is usually referred to as being part of a life-support system, and a life-support system for one person may include breathing apparatus, when the breathing gas is specifically supplied to the user rather than to the enclosure in which the user is the occupant.
§3.12 The Use of the Cuirass Ventilator, Belt Type
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