General anesthetics

A class of drugs that temporarily deprive animals of their sensation but maintain their lives. When such drugs act on the central nervous system, they must have a slight effect on the cerebral ventricle; there is a large distance between the amount of anesthesia and the amount of poisoning; and the original physiological function can be quickly restored after stopping the drug. [Mechanism] There is no unified view. There have been several explanations in recent years. 1 synaptic theory. It is believed that general anesthetics mainly inhibit the central nervous system by blocking the transmission of nerve impulses at the synaptic site. 2 brain stem reticulum activation system inhibition theory. It is believed that general anesthetics have selective inhibition on the brainstem reticulum activation system, and peripheral afferent impulses are inhibited, resulting in anesthesia. 3 molecular theory. It is believed that the effect of anesthetics on the central nervous system is mainly determined by the central phase of the central nervous system. Some inhaled anesthetics can promote the formation of hydrated microcrystals composed of molecules in the brain fluid. The crystallites have a cage structure, which can enclose the active side chain of the protein and other groups and ions in the cage, hindering its activity. Thereby interfering with the function of the brain produces anesthesia. As the blood concentration increases, the cerebral cortex is first anesthetized, followed by the subcortical center, the spinal cord again, and finally the brain. [Inhalation anesthetic] 1 halothane. Colorless flowing liquid, heavy weight, non-igniting, chloroform-like odor and burning sweetness. The anesthetic effect is stronger than ether, no irritating to the mucous membrane, short induction time, no excessive secretion, cough and throat. Used as an anesthetic and an anesthetic. 2 anesthetize ether. Colorless and clear volatile liquid, flammable, with specific odor, soluble in water, soluble in alcohol, oil and so on. When the ether vapor is mixed with air, it can explode in case of fire. After the animal inhaled ether, it first inhibited the cerebral cortex and the induction period was longer. Suitable for general anesthetics for small and medium animals. [Non-inhalation anesthetic] 1 chloral hydrate. It is bitter, irritating and smelly. It gradually volatilizes in the air; it is easily soluble in water, alcohol, chloroform and ether; it slowly decomposes under long-term sunlight, and it is easy to decompose when heated. It is rapidly converted to trichloroethanol after absorption, which has a strong inhibitory effect on the central nervous system. It can inhibit the brain stem network upward activation system, small dose sedation, medium dose hypnosis, high dose anesthesia and anticonvulsant. A general anesthetic for equine animals. 2 barbiturates. Barbituric acid itself has no sedative, hypnotic and anesthetic effects, but on the 5th carbon, the 1 or 3 nitrogen is replaced by a different group, and the oxygen on the 2 carbon is replaced by sulfur. Barbital for hypnosis or anesthesia. Due to the difference in structure and physicochemical properties of various derivatives, they also behave differently in terms of speed and duration. According to these characteristics, the barbiturates are classified into long-term (phenobarbital, barbital), medium-time (pentbarbital) and short-term or ultra-short (thiopental) drugs. Veterinarians often use intermediate or short-acting drugs as basic anesthesia or general anesthetics. 3 sodium pentobarbital. White crystal powder or granules; odorless, bitter, soluble in water. It inhibits the brain stem network upward activation system and produces hypnosis or anesthesia. It also inhibits the cerebral cortex, limbic system and hypothalamus. Sodium pentobarbital is an isomer of sodium pentobarbital. Its action, duration and application are similar to those of sodium pentobarbital. It can be used as a small animal anesthetic or as a sedative and basic anesthetic for various animals. . 4 ketamine, also known as ketamine. White crystal powder, soluble in water, slightly soluble in ethanol. It can block the brain contact path and the thalamus to project into the neocortex, resulting in an analgesic effect. Because it can temporarily and slightly inhibit the upward activation system, the limbic system, and even the entire central nervous system of the network structure, the consciousness is blurred or even lost. It can be used as a basic anesthetic, anesthetic and chemical preservative for horses, cattle, sheep and a variety of wild animals. Other inhaled and non-inhaled general anesthetics commonly used in clinical practice include methoxyflurane, enflurane, anesthetic chloroform, and thiosalum sodium.