Principle and structure of anesthesia machine
Modern anesthesia machines can be divided into: gas supply and delivery system, volatilizer (evaporator), breathing circuit system, anesthesia ventilator, safety detection system, residual gas removal system, etc. according to structural principles.
1. Gas supply and delivery system
The air supply source of the anesthesia machine is oxygen, laughing gas, air, etc., and it needs to use a low and stable pressure gas. The modern anesthesia machine gas supply and delivery system can accurately control the supply of fresh mixed gas and the proportion of various gases in the mixed gas, so as to ensure that the patient can inhale enough fresh gas, and also ensure that the oxygen concentration in the supply gas is not less than 25%.
2. Volatile tank
The volatilizer is also called a vaporizer. It is an important part of the anesthesia machine. It uses changes in temperature and heat source to evaporate the anesthetic into a gas. Pass a certain amount of carrier gas, and part of the gas will take away the saturated anesthetic gas. The air flow with a certain concentration of anesthetic drug vapor directly enters the anesthesia circuit. With the improvement of the design, the use of the electronic evaporation tank enables the automatic control of the concentration of anesthetics, reduces the possibility of human error, and improves the safety of inhalation anesthesia. High-end anesthesia machines can be equipped with multiple anesthesia volatilization tank interfaces, which can be connected to several volatilization tanks.
3. Breathing circuit system
The breathing circuit system is a combined airway device connected to the patient, which delivers anesthesia mixture to the patient and returns the patient's exhaled air to achieve normal breathing gas exchange and anesthetic gas exchange. The breathing circuit of modern anesthesia machines tends to be compact and integrated, which greatly reduces the dead space and detachable parts of the pipeline, thereby reducing circuit resistance, improving breathing compliance, and reducing the possibility of gas leakage. The integrated breathing circuit is also easy to disassemble, clean and disinfect. Some companies have adopted automatic bypass CO2 absorbers, so that the absorber can be replaced quickly and easily during the operation without affecting the gas balance in the breathing circuit.
4. Anesthesia ventilator
Anesthesia ventilator is a tool to implement mechanical ventilation, used to assist and control the patient's breathing, improve the patient's oxygenation and ventilation, support circulatory function, etc., as a treatment for respiratory failure. The four basic functions that a ventilator must have are inflating the lungs, converting inhalation to exhalation, expelling alveolar air, and exhaling and exhaling to inhaling, which cycle back and forth in turn. Modern anesthesia machines have used electric electronically controlled ventilator. For example, electronically controlled piston ventilator. Its biggest feature is that no driving gas is required. In the absence of any gas, it can control the patient's breathing precisely like a therapeutic ventilator.
5. Safety inspection system
The safety detection system includes: low oxygen pressure automatic cut-off device and various pressure, volume and concentration monitoring parts and fault alarms. The system uses a microcomputer to process and display various data, and is attached with a corresponding alarm device to realize all physiological and biochemical functions, especially breathing, circulation, nerve, muscle monitoring and other functions through the system.
The modern anesthesia machine integrates various monitoring systems required in the operation into the anesthesia machine, forming a powerful anesthesia workstation with the anesthesia machine. These monitoring systems not only include functions such as respiratory gas monitoring, anesthetic gas analysis, and depth of anesthesia monitoring. The monitoring system not only automatically prompts the anesthesiologist with the obtained values, but also automatically adjusts the fresh air flow of the anesthesia machine, the concentration of the medicine in the vaporizer, and controls the working conditions of the respirator, helping the anesthesiologist to safely perform inhalation anesthesia. At the same time, the anesthesia machine automatically records the values obtained by the various electronic sensors in the machine, and the analysis software automatically generates a patient anesthesia work report to the anesthesiologist after the entire anesthesia is over.
6. Residual air removal system
The residual air removal system collects the excess residual air in the anesthesia machine and the exhaust gas exhaled by the patient, and discharges it out of the operating room through a pipe to avoid air pollution in the operation. This system includes: residual gas collection device, conveying pipeline, connecting device, residual gas treatment pipe.
With the rapid development of industrial technology of anesthesia machines, anesthesia machines are becoming more and more electronic, integrated and intelligent. The various components are closely integrated to assist in the work. Especially the application of anesthesia workstation, its friendly user interface, comprehensive patient physiological parameter monitoring, integrated breathing circuit, high-performance respirator, electronically controlled gas delivery system in scenic spots, and powerful patient anesthesia management system all represent The development direction of modern anesthesia machine technology.
