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Development history of modern ventilator

Date:2020-06-13

The year 1915 was marked as the beginning of the development of modern ventilator. Dr. Mol-gaard and Lund in Copenhagen and surgeon Giertz in Stockholm began to work on ventilators, but their achievements are poorly documented.

In October 1928, Drinker and Shaw successfully treated an 8-year-old girl in a coma due to polio respiratory failure with a box-type negative-pressure ventilator they developed, known worldwide as the "iron lung," thus creating a milestone in the history of mechanical ventilation. Extracorporeal negative pressure ventilators such as iron lung, double iron lung, chest armor type and belt type have been used in large numbers in clinical practice, but their inherent defects have been exposed despite some results:

1.Their efficacy is extremely low, their total mortality rate in treating respiratory failure is as high as 80%, and the treatment of acute respiratory distress syndrome (ARDS) caused by war injuries has not been successful;
2. Airway management is difficult, and airway secretions are difficult to discharge;
3. They cannot be applied in surgical anesthesia. 

In 1934, Frenkner developed the first pneumatic pressure limiting respirator --- "Spiropulsator", its air source from the steel cylinder, the gas through two pressure reducing valves, to produce a pressure of 50cm water column. Exhalation through the balancer to obtain sufficient airflow, inhalation time is controlled by a switch, air flow through the inhalation tube into the lungs, when the internal pressure rises to the expected requirements, the valve closes. 

In 1940, Frenkner and Crafoord collaborated on the "Spiropulsator", which was the first anesthesia ventilator that could be used simultaneously with cyclopropane. 

In 1942, Bennett, an American engineer, invented an oxygen supply device with an on-demand valve for use in high altitude flights. In 1948, the intermittent positive pressure ventilator TV-2P was developed to treat acute and chronic respiratory failure. 

In 1946, Bennett developed the first intermittent positive pressure ventilator with the basic structure of modern ventilator and applied it in the clinic. Since then, the air-controlled-pneumatic pressure-limited ventilator has become the mainstream form of positive pressure ventilator. The main representative models of this period are Bennet PR-1A and Bird mark VII, which belong to the first generation of modern ventilators. However, in clinical practice, it was found that these types of positive pressure ventilators often failed to ensure effective tidal volume. To make up for this deficiency, designers developed a capacity monitoring device and began to explore the development of capacity-limited ventilators.

In 1950, Engstrom of Sweden developed the world's first volume-converting ventilator, marking the birth of the second generation of modern ventilators. Since then, positive pressure ventilation technology has reached a new level.

In 1951, Engstrom Medical in Sweden produced the first constant-volume ventilator, the Engstrom 100, which saved a large number of patients from respiratory failure caused by epidemic poliomyelitis. Many European engineers, physicians and others invested in the research of ventilators, and the output of ventilator types reached more than ten types.

In the 1960s, the respirator was more widely used. In 1964, Emerson's postoperative ventilator, an electrically controlled ventilator with breathing time that could be adjusted at will, was an electronic circuit ventilator equipped with a compressed air pump, and various functions were regulated electronically, changing the situation that the ventilator was completely controlled by mechanical movements in the past, and the ventilator began to cross into the era of sophisticated electronics.

In 1970, a jet-controlled pneumatic ventilator using the jet principle was developed. This ventilator is controlled by airflow and all sensors, logic elements, amplifiers and regulation functions are based on the jet principle.

Since the 1980s, the rapid development of computer technology has led to a deeper understanding of respiratory physiology, while new design ideas (such as fluid control principles) and new technologies (such as electronic computer technology) have been adopted. The multifunctional computer-based third-generation ventilator has functions that were not possible in the past, such as monitoring, alarming, and recording.

From the 1990s to the present, ventilator ventilation technology has become more and more sophisticated and has begun to enter the era of intelligent ventilation.

Prunus Padus 8 ventilator

Conclusion
 
In terms of ventilation pressure, the development of ventilators has been a path of development from extracorporeal negative pressure ventilation to positive pressure ventilation. Early on, extensive research was conducted in the field of extracorporeal negative pressure technology. However, the development and application of this box-type negative pressure ventilator was greatly limited because it required manual power and had fatal flaws. People began to seek other ways of ventilation, and gradually began to study positive pressure ventilation. In fact, positive pressure ventilation has been of interest to some scholars, mainly in the fields of surgery and anesthesia, since it was possible to establish an artificial airway. Due to the improvement of artificial airway technology and the establishment of direct laryngoscopic tracheal intubation, positive pressure ventilation was developed more rapidly in the field of surgery and anesthesia, and later was gradually applied to the resuscitation of patients undergoing thoracic surgery and ARDS in combat injuries.
 
From the perspective of ventilation technology, the development of ventilator is accompanied by the development of electronics, computer information technology and other disciplines. Early ventilators used pneumatic control and pneumatic-mechanical technologies such as pistons and bellows, which were not highly sensitive and had imperfect monitoring functions. With the development of electronics, electronic technology was introduced into the design of ventilators, and volume pressure monitoring systems and alarm systems controlled by potentiometers were developed, which greatly facilitated clinical practice. after the 1990s, with the development of computer information technology, ventilation technology continued to develop in the direction of intelligence, and the ventilator ventilation function was also improved.

References：

1.《Ventilator status and development trend》https://wenku.baidu.com/view/bb641d6fbdd126fff705cc1755270722182e5969.html?fr=search 

2.《History and development of ventilators》https://wenku.baidu.com/view/5af274fea0116c175f0e4899.html

In 1950, Engstrom of Sweden developed the world's first volume-converting ventilator, marking the birth of the second generation of modern ventilators. Since then, positive pressure ventilation technology has reached a new level.