Inhalation anesthesia has been perfected since 1846, when Browning first applied ether anesthesia. The development of modern pharmacology, the progress of science and technology, especially the application of computer technology, have greatly improved the level of modern inhalation anesthesia.
Inhalation anesthesia is easy to control, safe and effective. The general anesthesia trolley is the first choice for surgery in the current hospital. The so-called anesthesia refers to the method of temporarily losing all or part of the organism in order to perform surgical treatment.
There are various methods of anesthesia, such as acupuncture anesthesia, injection anesthesia and inhalation anesthesia. At present, the method of general anesthesia used in hospitals is still mainly inhalation anesthesia. An anesthesia machine is an instrument that uses inhalation anesthesia for general anesthesia.
Inhalation anesthesia is the delivery of anesthetics (agents) into the patient's alveoli through a mechanical circuit to form anesthesia gas partial pressure. After dispersing into the blood, it directly inhibits the central nervous system, resulting in general anesthesia.
1. Air anesthesia machine
The air anesthesia machine is a semi-open anesthesia device, which is mainly composed of a liquid medicine tank, an ether adjustment switch, a foldable bellows, a one-way valve for inhalation and exhalation, and a bellows.
The device is light and suitable, and can directly use air and oxygen as carrier gas for assisted breathing and controlled breathing. The air anesthesia machine can meet various surgical requirements.
Its working principle is that after the patient completes anesthesia induction, the air anesthesia machine is connected to a closed mask or tracheal tube, and when inhaling, the anesthesia mixed gas enters the patient's body through the opened inspiratory valve.
When exhaling, the expiratory valve is opened, and the inspiratory valve is closed at the same time, exhaling the exhaled gas. When using assisted or controlled breathing, a foldable bellows can be used.
Press down when inhaling and pull up when exhaling to ensure that the patient has sufficient ventilation. At the same time, according to actual needs, adjust the ether switch of the anesthesia machine to maintain a stable level of anesthesia.
The disadvantage of this device is that the concentration of ether is low, which can only be used as the maintenance of anesthesia, and the consumption of ether is large, which is easy to cause environmental pollution.
2. DC anesthesia machine
The DC anesthesia machine is composed of high pressure oxygen, pressure reducer, flow meter and anesthetic liquid vaporizer.
3. Circulating closed anesthesia machine
The closed-circulation anesthesia machine supplies the patient with a low flow of anesthesia mixed gas through the outgas valve (door) in a one-way flow, and the exhaled gas enters the CO2 absorber through the exhalation valve for repeated use.
Its structure is mainly composed of oxygen supply and nitrous oxide device, gas flow meter, evaporator, CO2 absorber, one-way valve, breathing pipeline, outgas valve, storage bag, etc.
Modern general anesthesia machines are also equipped with ventilator airway pressure, expiratory flow, end-tidal CO2 concentration, inhalation anesthetic concentration, oxygen concentration monitor, hypoxia alarm and hypoxia-nitrous oxide automatic protection device.