Inhalant chemicals nitrous oxide

Organic solvents inhaled by abusers include gasoline, glue, aerosols, amyl nitrite, butyl nitrite, typewriter correction fluid, lighter fluid, cleaning fluids, paint products, nail polish remover, waxes, and varnishes. Chemicals in these products include nitrous oxide, toluene, benzene, methanol, methylene chloride, acetone, methyl ethyl ketone, methyl butyl ketone, trichloroethylene, and trichloroethane. 

Nitrous oxide is the only inhalation anesthetic that is a gas. It is chemically inert. Nitrous oxide has little effect on overall cardiovascular function. Disadvantages are that it has no muscle relaxing effect and that it cannot be used on its own because of high Minimal Alveolar Concentration values needed for adequate anesthesia. During recovery there is a risk for hypoxia and anesthesia should be slowly tapered off to prevent this event. 

The chemical structures of the currently available inhaled anesthetics are shown in Figure 25-2. The most commonly used inhaled anesthetics are isoflurane, desflurane, and sevoflurane. These compounds are volatile liquids that are aerosolized in specialized vaporizer delivery systems. Nitrous oxide, a gas at ambient temperature and pressure, continues to be an important adjuvant to the volatile agents. However, concerns about environmental pollution and its ability to increase the incidence of postoperative nausea and vomiting (PONV) have resulted in a significant decrease in its use. 

Inhaled anesthetics currently in use include halo-genated volatile liquids such as desflurane, enflurane, halothane, isoflurane, methoxyflurane, and sevoflurane (Table 11-1). These volatile liquids are all chemically similar, but newer agents such as desflurane and sevoflurane are often used preferentially because they permit a more rapid onset, a faster recovery, and better control during anesthesia compared to older agents such as halothane.915 These volatile liquids likewise represent the primary form of inhaled anesthetics. The only gaseous anesthetic currently in widespread use is nitrous oxide, which is usually reserved for relatively short-term procedures (e.g., tooth extractions). Earlier inhaled anesthetics, such as ether, chloroform, and cyclopropane, are not currently used because they are explosive in nature or produce toxic effects that do not occur with the more modern anesthetic agents. 

Nitrous oxide is difficult to categorize. Technically, it is an inhalant, yet there are several characteristics that set the drug apart from the typical volatile substances that inhalant abusers favor. First, N20 is not as readily accessible as hair spray, glue, household cleaners, and other off-the-shelf huffing chemicals of choice. Secondly, since nitrous oxide is an actual prescription anesthetic, it may have more perceived prestige among users who would look down at most volatile substance abuse as kid s stuff. ... 

Modern inhalation anesthetics are nonexplosive agents that include the gas nitrous oxide as well as a number of volatile halogenated hydrocarbons. As a group, these agents decrease cerebrovascular resistance, resulting in increased perfusion of the brain. They cause bronchodilation and decrease minute ventilation. Their clinical potency cannot be predicted by their chemical structure, but potency does correlate with their solubility in lipid. The movement of these agents from the lungs to the different body compartments depends upon their solubility in blood and various tissues. Recovery from their effects is due to redistribution from the brain. 

Today we have sophisticated lab equipment to help us analyze the products of reactions. In the past, when such equipment was not available, chemists sometimes jeopardized their safety and health to determine the products of the reactions they studied. Sir Humphry Davy (1778-1829), a contributor to many areas of chemistry, thought nothing of inhaling the gaseous products of the chemical reactions that he carried out. He tried to breathe pure C02, then known as fixed air. He nearly suffocated himself by breathing hydrogen. In 1800, Davy inhaled dinitrogen monoxide, N20, otherwise known as nitrous oxide, and discovered its anaesthetic properties. What is nitrous oxide used for today ... 

Some inhalants show toxicity to blood and bone marrow. Benzene is a solvent that is very toxic to bone marrow. It can cause leukemia and severe anemia. Nitrous oxide does damage to bone marrow in chronic users. Another chemical in inhalants, methylene chloride, is converted to carbon monoxide in the body. Carbon monoxide can prevent the transport of oxygen in the blood and result in brain damage. 

The inhalation anesthetics in use arc halothanc. enfluranc. isofluranc. methoxyriurane. sevullurane. desfluranc. and nitrous oxide. Older agents such as ethylene and cyclopropane are obsolete because of a fundamental chemical prop-eny—they are explo.sive and flammable when mixed with oxygen. This adds an unacceptable level uf danger tu the production of anesthesia. 

Chemical synthesis did not seem, at first, a likely source of useful remedies. However, after Wohler s synthesis of urea, in 1828, a whole range of synthetic organic chemicals was introduced into medical practice. After several false starts, some relatively simple substances were adopted as inhalation anaesthetics, namely nitrous oxide, ether, and chloroform (1844-7) which, by giving the surgeon adequate time for his task, initiated a tremendous refinement and extension of the possibilities of surgery. 

Common names are arbitrary names that are not based on the chemical composition of compounds. Before chemistry was systematized, a substance was given a name that generally associated it with one of its outstanding physical or chemical properties. For example, quicksilver is a common name for mercury, and nitrous oxide (N2O), used as an anesthetic in dentistry, has been called laughing gas because it induces laughter when inhaled. Water and ammonia are also common names because neither provides any information about the chemical composition of the compounds. If every substance were assigned a common name, the amount of memorization required to learn over 12 million names would be astronomical. 

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