Anesthesia machine is an important tool for general anesthesia in modern hospitals. Its main function is to inhale anesthesia, replace breathing, and supply oxygen for patients. The anesthesia machine is therefore designed from gas supply devices including: oxygen (O2), air (Ai r), nitrous oxide (nitrogen/N2O), safety devices, alarm systems, monitoring systems; anesthesia ventilators instead of respiratory management and other operations Parts, residual gas removal system. The mixed gas reaches the evaporator through the air inlet (1). One way through the bypass passage (3) to reach the gas outlet (2), the other through the internal air passage to the zero point lock point (6), if the evaporation canister is open (zero button has been pressed), the gas will pass the zero lock point (6) Reaching the pressure compensating device (11), this device can automatically change the evaporant gas of the anesthetic when the main airway pressure changes, without causing fluctuations in the anesthetic concentration at the output port (2), and the pressure compensating device (11) After the gas will reach the vapor chamber, the gas in the vapor chamber will be mainly mixed with the vapor absorbed and evaporated by the fine core bundle, and passed through the air passage to the evaporation tank control hole (4). This hole (4) will be controlled by the knob (13). Control, which will determine the amount of anesthetic vapor output from this orifice, as the temperature compensation device (9) drives its up and down movement and pressure compensation (11) to eliminate pressure fluctuations and gas confluence, gas passing through the bypass port (3) There is a certain ratio of the amount of gas passing through the evaporation tank hole (4), which determines the concentration of the anesthetic at the outlet (2), and changing the T ratio by (13) also changes the anesthetic concentration. 3 <br> <br> breathing circuit breathing circuit air passage means is combined with an anesthesia machine connected to a patient, the patient is anesthetized conveying the mixed gas, the gas exhaled by the patient reinfusion, thereby achieving the normal exchange of oxygen and carbon dioxide gas. Mainly by breathing pipeline, CO2 absorption tank, suction flap, storage airbag, mask, machine control - manual control valve, exhaust valve, pressure limiting valve, development / semi-open valve. An directional cycle of gas formation from the valve and the conduit utilizes sodium and lime in the CO2 absorption tank to absorb CO2 and moisture to supply fresh gas to the patient. Machine Control - Manual control valve allows users to manually control or choose the machine control through an anesthesia ventilator; semi-open valve, pressure limiting valve, etc. can make the breathing circuit flexible control, pressure limit, is conducive to spontaneous breathing. Yancheng Rongtai Labware Co.,Ltd , https://www.shtestlab.com
The basic classification of anesthesia machine is as follows: According to function: All-purpose, popular and portable; according to the flow size: high-flow anesthesia machine, low-flow anesthesia machine; according to patient age: adult, pediatric and adult children.
At present, the development of anesthesia machines at home and abroad is rapidly developing, and gradually developed into an intelligent, multi-functional type, until the new trend in the field of anesthesia - anesthesia workstations.
According to the structural principle of modern anesthesia machine, it can be divided into: gas supply and delivery system, anesthetic gas volatilization tank, breathing circuit, anesthesia breathing machine, safety monitoring system and residual gas removal system.
1 gas supply conveyor system
Gas supply system includes: compressed gas cylinder (or central gas source), check valve, relief valve, filter, pressure gauge, gas pressure regulator, flow meter and N2O - O2 proportional interlock control device, laugh - oxygen cutoff Valves, etc.
。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。. The high-pressure gas needs to be filtered through the filter, the one-way valve restricts the flow direction, and the pressure-reducing valve decompresses, and the high-pressure and variable gas, which may have particles, is turned into a low-pressure and stable pure gas source for use in the anesthesia machine. The operation of the system should be prohibited from any grease, flammable substances and possible avoidance of contact, and more attention should be paid to avoid various gas connection errors. Therefore, different gases in the design must be distinguished by pipes of different colors; the joints of different gases are designed to be non-interchangeable. The new anesthesia machine provides air (Ai r) air supply based on the original O2 and N2O, which reduces complications during general anesthesia and improves safety and reliability.
The anesthesia machine must be equipped with flow meters of various gas sources. The flowmeters are in L/min and mL / min (or below 2L / min flow tubes). Two reading flow tubes are available for low-flow anesthesia. At the same time, it must be equipped with N2O-O2 proportional interlock control device to ensure that the output of the anesthetic gas oxygen concentration level is not less than 25%; when the oxygen supply is insufficient or interrupted, the laughing gas supply is automatically cut off. Common N2O-O2 proportional interlock control device, laugh-oxygen cut-off valve is a mechanical device, beware of malfunction, in the daily use, you must pay attention to the ratio of O2, N2O, check whether the flowmeter leaks, rely on anesthesia machine or other The monitoring system monitors the O2 and N2O concentrations in the breathing circuit and more accurately measures the current anesthesia machine operation. Many modern anesthesia machines have a 55L / min oxygen bypass, which can be quickly and directly entered into the breathing circuit through the emergency interface, which greatly facilitates the oxygen supply operation of the clinical anesthesiologist.
2 anesthetic gas volatilization tank
The volatile tank is an important part of the anesthesia machine. Its quality not only marks the manufacturing level of the anesthesia machine, but also the effect and success or failure of inhalation anesthesia, which directly relates to the safety of the patient.
The basic principle of the volatile tank is to use the temperature of the surrounding environment and the change of the heat source to turn the anesthetic into an evaporating gas, and through a certain amount of carrier gas, a part of the gas carries the saturated anesthetic gas and becomes a gas stream with a certain concentration of anesthetic vapor. , directly into the anesthesia circuit.
Volatile tanks are classified according to anesthetic drugs: ether, halothane, enflurane, isoflurane. The new anesthetic has sevoflurane, fluorocyclopropane, etc.; according to the evaporation principle: bubbling type, heating type, dripping type, natural evaporation type.
The important factors affecting the output concentration of the volatile tank are: temperature, pressure, flow, contact area of ​​the carrier gas and the anesthetic, the volume of the anesthetic volume and the placement of the volatile tank in the anesthesia circuit.
Most of the anesthesia machines are equipped with a natural evaporation type of volatile tank, and at the same time, a volatile tank outside the loop of the ventilator (outer loop volatile tank), a volatile tank connected by a separate oxygen stream, and then mixed with the main air stream for inhalation. . Therefore, the output concentration of the volatile tank is relatively constant, mainly affected by the ambient temperature and the size of the fresh air. In order to avoid the influence of the external temperature difference on the output concentration of the volatile tank, the modern volatile tank uses the principle of temperature, pressure and flow compensation device to ensure the accuracy of the output concentration. The main principle is shown in Figure 1. 
High-grade anesthesia machines can be equipped with multiple anesthesia volatilization tank interfaces, which can be connected to several volatile tanks.
The modern breathing circuit is integrated, and the layout of each component is reasonable, compact, miniaturized, small in capacity, small in leakage, and low in compliance. The circuit is designed with various monitoring probe interfaces, pressure limiting valves, fresh gas isolation valves, etc. for clinical anesthesiologists. The integrated breathing circuit and components can be easily disassembled, and the cleaning and disinfection of the components show a new design style.
4 anesthesia ventilator
Anesthesia ventilators have become an integral part of anesthesia machines. Due to mechanical ventilation in inhalation anesthesia, it has developed rapidly in recent years, and is fully functional and miniaturized.
The anesthesia ventilator is driven by pneumatic, pneumatic electronic control and electric. Pneumatic respirators are more old-fashioned products. They use compressed oxygen as the power source and consume a large amount of oxygen. They are eliminated respirators. Most of the anesthesia machines equipped with anesthesia machines are oxygen-driven, electronically controlled; The anesthesia ventilator is a built-in electric electronically controlled ventilator that does not require a driver. It can be ventilated by the atmosphere to ensure the safety of the patient in case of gas failure. The typical anesthesia ventilator is a pneumatic electronically controlled ventilator, which is in a transparent sealed enclosure. The inside and outside of the folding capsule are two sets of pneumatic circuits, which drive the gas to compress the folding capsule, drive the anesthetic gas into the patient, and form a two-loop system of driving gas source and anesthetic airflow.
The operation of the anesthesia ventilator is divided into four phases: inflation into the lungs, inspiration to exhalation; ventilation of the lungs, exhalation to inspiration. The commonly used anesthesia machine is pneumatically controlled, and the gas supply device adopts a folded capsule, which is driven by compressed gas or flows through a flow regulating valve or a suction valve into the circulation loop. The electronic control or microcomputer processor calculates according to the breathing mode and the set parameters, thereby controlling the corresponding electromagnetic valve to open and close, and sending out the required amount of gas.
Modern anesthesia ventilators have evolved into versatile ventilators that provide patients with nearly complete multiple breathing patterns, including spontaneous breathing (SPON T), manual ventilation (MANUAL), constant volume ventilation (VC), and constant pressure ventilation ( PCV) Synchronous Intermittent Command Ventilation (S IMV), Pressure Support Ventilation (PSV) and even models with Pressure Regulated Capacity Control Ventilation (PRVC). The setting range of respiratory parameters is also very wide, such as tidal volume 20 ~ 1500ml, respiratory rate 6 ~ 99bpm, respiratory ratio 1: 3 ~ 4: 1, pressure support 2 ~ 60cmH2O. . . . .
5 Safety Monitoring System
Modern anesthesia machines have safety monitoring systems. The system includes: an oxygen supply alarm, an oxygen supply/interruption gas shutoff device, a capacity and concentration monitoring section, and a fault alarm. The main monitoring components are: inhaled oxygen concentration, exhaled tidal volume, airway pressure, minute ventilation, end-tidal CO2 concentration, and anesthetic gas concentration. Microcomputer processing and display of various data, with alarm device system, especially breathing, circulation, nerve, muscle monitoring functions can be achieved, greatly improving the quality of clinical use of anesthesia and patient safety, improve the success rate of surgery .
6 residual gas removal system
The residual gas removal system collects the excess residual gas in the anesthesia machine and the exhaled gas exhaled by the patient, and discharges it through the pipeline to the operating room to avoid air pollution in the operating room. It mainly consists of exhaust gas collection and discharge devices consisting of: regulating valve, discharge valve, vacuum generator, piping and connecting parts.
7 Conclusion
Modern anesthesia machines are developing towards intelligent and integrated systems. The components are coordinated, flexible and reliable, compact and reasonable, and the interface is clear and friendly, and the operation is convenient and fast. Electronically controlled gas delivery system, built-in electronically controlled anesthesia ventilator, integrated breathing circuit, integrated gas monitoring system, high and low micro-flow anesthesia is the best combination of modern anesthesia machine.