therapeutic ventilators are often used for patients with complicated and serious illness, which require complete functions and can perform various breathing modes to meet the needs of illness changes. Anesthetic ventilators are mainly used in patients undergoing anesthesia surgery, and most patients have no major cardiopulmonary abnormalities. The required ventilators can be basically used as long as they can change the volume, breathing frequency and inspiratory-respiratory ratio and can do IPPV.
Basic principle of ventilator: Most of the commonly used breathing machines are operated by the inner and outer double-ring air passages of the air bag (or folding bellows), and the inner ring air passage and air flow are communicated with the patient's airway, while the outer ring air passage and air flow are mainly used to squeeze the breathing bag or bellows and press the fresh air in the air bag (or bellows) into the patient's alveoli for gas exchange, which is called driving air. Because it is not connected with the patient's airway, compressed oxygen or compressed air can be used.
The most original and accurate method is to use a U-shaped tube with one end communicating with the airway, and the fluctuation of airway pressure causes the fluctuation of the water column. You can also use a metal air drum to communicate with the airway, and the fluctuation of airway pressure causes the tympanic membrane to fluctuate, and the tympanic membrane can be transmitted to the pointer to see the pressure figure it refers to. At present, the voltage sensor is used to monitor the changes of airway pressure (including inspiratory pressure, peak pressure, plateau pressure and end-expiratory pressure) during the breathing cycle. Continuous monitoring of airway pressure is the easiest way to understand the lung and airway conditions and whether there is any abnormality in the pipeline. The change of airway pressure makes the sensor generate corresponding electrical signals, which are displayed digitally after being processed by electronic system.
because the machine needs a lot of oxygen when working, it is usually obtained from the central gas supply system or oxygen cylinders in the hospital. Every gas input from the steel cylinder into the loop must pass through a filter, a one-way vent valve and a regulator, and the regulator can reduce the pressure to the appropriate working pressure of the anesthesia machine. The central gas supply system does not need a regulator, because the gas has dropped to about 4 kg. The suitable working pressure of anesthesia machine is 3-6 kg. Most anesthesia machines have an oxygen source fault alarm system. If the oxygen pressure is below 2.8 kg, the machine will reduce or cut off the flow of other gases and start the alarm.
the flow rate of each gas in the continuous flow device is controlled by the flowmeter and displayed by the flowmeter. The flowmeter can be mechanical or electronic sensor with LCD. After passing through the control valve and flowmeter, the gas enters the low-pressure loop, and if necessary, passes through the evaporation tank, and then is supplied to the patient. In a good anesthesia machine, the flow control mechanism of nitrous oxide and oxygen should be linked, so that the ratio of oxygen to nitrous oxide will never drop to the minimum (.25L/ min).