A Brief Introduction to the Working Principle of Ventilators
A ventilator is an artificial mechanical ventilation device used to assist or control a patient's spontaneous breathing movements, thereby achieving the function of gas exchange in the lungs, reducing human consumption, and facilitating the recovery of respiratory function.
The clinical application of ventilators is divided into two major categories. One category focuses on respiratory diseases, including lung infections, atelectasis, asthma, pulmonary edema, etc., which affect the gas exchange function in the lungs. In this case, the treatment with the ventilator mainly improves the gas exchange in the lungs, increasing the oxygen concentration in the blood and removing carbon dioxide. The second category focuses on surgical operations, which helps patients recover from anesthesia, maintains normal respiratory function, reduces the movement of respiratory muscles, and lowers oxygen consumption.
Basic Working Principle of Ventilators
The working principle of any ventilator lies in the pressure difference of gases. Generally, the working principle of a ventilator is divided into two ways:
1. Positive Pressure Ventilators increase gas pressure, connecting through tubes to the patient's airway intubation. Gas flows through the airway and bronchi directly into the alveoli; this is the inspiration phase. During exhalation, the ventilator tube communicates with the atmosphere. Since the alveolar pressure is greater than atmospheric pressure, the gas inside the alveoli is expelled automatically until it equals atmospheric pressure.
2. Negative Pressure Ventilators place the patient's chest or entire body in a sealed container, with the airway connected to the atmosphere. When the pressure inside the container is lower than atmospheric pressure, the chest is pulled and expanded, causing the alveolar pressure to drop below atmospheric pressure, allowing air to enter the alveoli during the inspiration phase. When the container's pressure turns positive, the thorax is compressed, reducing its size. The alveolar pressure increases, exceeding atmospheric pressure, and the gas inside the alveoli is expelled outside the body during the exhalation phase. Due to their large size, high power requirements, and low ventilation efficiency, these types of ventilators have been phased out of use.
Source: Ventilator Service Network http://www.bjykfy.com/huxiji3.htm