In 1832, Scottish doctors designed the first negative pressure ventilator. But what made the negative pressure ventilator popular was the "iron lung" invented by two experts at Harvard University in 1928. It was used to treat children with polio.
The patient lies in a heavy iron box, with only the head exposed, and a "pump" at the tail of the machine, responsible for creating positive and negative pressure to expand the lungs. Since negative pressure ventilators cannot solve the problems of airway patency and effective oxygenation of the lungs, a positive pressure ventilator came into being.
In general, clinical patients may use a ventilator as long as they have the risk of respiratory failure or secondary respiratory failure, such as sleep apnea syndrome, chronic obstructive pulmonary disease, cardio-cerebrovascular disease, asthma, multiple organ failure, severe infection, Recovery after general anesthesia, etc.
Why do you need a lot of ventilators in the epidemic?
Because the new coronavirus destroys the alveolar cavity, oxygen cannot enter the capillaries and be transported to all parts of the body, and people will develop hypoxemia and even respiratory failure.
The ventilator is like an intelligent bicycle pump, which opens the alveoli through positive pressure, presses the liquid in the alveolar cavity into the alveolar space, reduces alveolar edema, and allows oxygen to enter the alveolar cavity;
And by increasing the pressure in the alveolar cavity, oxygen molecules are promoted to enter the capillaries in the alveolar space. During respiratory failure, the ventilator can help relieve respiratory muscle fatigue through assisted breathing.
At present, the commonly used medical ventilators are mainly non-invasive and invasive.
1. The nasal high-flow humidified oxygen therapy instrument commonly used in epidemic situations is also a ventilator in principle and is mainly suitable for patients with mild to moderate hypoxemia who have spontaneous breathing.
2. The non-invasive ventilator is aimed at patients with moderate respiratory failure who have spontaneous breathing. Wear a mouth-nose mask or full-face mask when using it.
3. The invasive ventilator is mainly used to treat patients with severe respiratory failure or no spontaneous breathing, which requires oral or nasal tracheal intubation or tracheotomy.
The above three types of ventilators can only solve some of the oxygenation problems. When the condition deteriorates and the heart and lungs lose their function, ECMO (external membrane lung oxygenation) should be used to assist support.
The above information is provided by the ventilator manufacturer.