How Does Anesthesia Work?
Oliver Wendell Holmes coined the term "anesthesia" in 1846 to describe drug-induced insensibility to sensation (particularly pain), shortly after the first publicized demonstration of inhaled ether rendered a patient unresponsive during a surgical procedure. Two broad classes of pharmacological agents, local and general, can result in anesthesia. Local anesthetics, such as Novocain, block nerve transmission to pain centers in the central nervous system by binding to and inhibiting the function of an ion channel in the cell membrane of nerve cells known as the sodium channel. This action obstructs the movement of nerve impulses near the site of injection, but there are no changes in awareness and sense perception in other areas.
In contrast, general anesthetics induce a different sort of anesthetic state, one of general insensibility to pain. The patient loses awareness yet his vital physiologic functions, such as breathing and maintenance of blood pressure, continue to function. Less is known about the mechanism of action of general anesthetics compared to the locals, despite their use for more than 150 years. The most commonly used general anesthetic agents are administered by breathing and are thus termed inhalational or volatile anesthetics. They are structurally related to ether, the original anesthetic. Their primary site of action is in the central nervous system, where they inhibit nerve transmission by a mechanism distinct from that of local anesthetics. The general anesthetics cause a reduction in nerve transmission at synapses, the sites at which neurotransmitters are released and exert their initial action in the body. But precisely how inhalational anesthetics inhibit synaptic neurotransmission is not yet fully understood. It is clear, however, that volatile anesthetics, which are more soluble in lipids than in water, primarily affect the function of ion channel and neurotransmitter receptor proteins in the membranes of nerve cells, which are lipid environments.
After the anesthesia induction, the air anesthesia machine and the closed mask or tracheal tube connected.When inhale, anesthesia mixed gas through the open breathing valve into the patient's body; breath, expiratory flap open, while smoking When the auxiliary or controlled breathing is used, it is possible to use a folding bellows, which is depressed and exhaled to ensure that the patient has sufficient ventilation, and adjusts it according to actual needs. Ether switch to maintain a stable level of anesthesia.
The disadvantage of this device is the low concentration of ether, can only be maintained as anesthesia, and the consumption of ether is large, easy to cause environmental pollution.