Hallways

Hallways are multiply halogenated hydrocarbons with an oxygen bridge (ether bridge) as a functional group. All five known Flurane belong to the inhalation narcotics and are characterized by a very good hypnotic, i.e. drowsy effect. Their analgesic effect, however, is weak, so that Flurane is usually used in anesthesia together with other preparations with a higher analgesic effect.

What are hallways?

The term Flurane encompasses five different, multiply halogenated hydrocarbons. As a characteristic feature, they all have a so-called ether bridge, an oxygen bridge with two organic residues (organyl groups). All of them are colorless, non-flammable liquids with a boiling point of 45 to 60 degrees Celsius. In the case of desflurane, which is used almost as standard as an inhalation anesthetic, the boiling temperature is only 23.5 degrees at normal pressure.

All five hallways are characterized by their inertia and the fact that they are light-stable and do not react with metals or plastics. With the exception of sevoflurane, which has a pleasant smell, a pungent odor with irritation of the upper respiratory tract is characteristic of the other four hallways.

The three fluranes iso-, sevo- and desflurane, together with laughing gas (nitrous oxide), are among the most important inhalable anesthetics. Halothane, which was frequently used until the 1970s, hardly plays a role anymore due to possible side effects and has been largely substituted by Flurane. In order to avoid possible mix-ups, the containers in the individual corridors are marked with certain colors as standard.

Pharmacological effect on the body and organs

The different flurans that are used as volatile anesthetics have different effects and are therefore listed separately. What all hallways have in common is their good hypnotic and, in some cases, muscle-relaxing properties with at the same time weak analgesic effects. Therefore, Flurane are mostly used in combination with suitable pain-reducing agents.

Isoflurane is a commonly used anesthetic from the Flurane group. It causes blood vessels to dilate, which in turn lowers arterial blood pressure. The particular advantage of the anesthetic is the low metabolism of only about 0.2 percent. This means that by far the greater part of the active ingredient is exhaled, so that isoflurane can also be used in patients with damaged liver.

Another frequently used anesthetic from the Flurane group is sevoflurane, which, unlike the other Flurane, does not irritate the mucous membrane and has a pleasant smell. The properties have led to the fact that the agent has also found widespread use in pediatric anesthesia.

Desflurane, also an anesthetic from the Flurane group, has developed into a kind of standard anesthetic. A special feature is its rapid flow of anesthesia, which makes it easy to control. However, because of its irritant effect on the respiratory mucous membranes, the agent is not suitable for induction of anesthesia by inhalation.

While all corridors consist of non-flammable liquids, methoxyflurane is the only representative that is easily flammable and combustible in the liquid state in the temperature range from minus 35 degrees to 104.5 degrees. Methoxyflurane was only used as an anesthetic until the 1970s. Enflurane, which also belongs to the group of five furans, is rarely used as an anesthetic anymore.

Medical application & use for treatment & prevention

From the group of the five known flurans, only isoflurane, desflurane and sevoflurane played an essential role in modern anesthesia. The three corridors are used as so-called volatile anesthetics, which are used as inhalation anesthetics via special evaporators.

Because of their low molecular weight, high vapor pressure and low boiling point, flurans are well suited for evaporation technology. As the sole anesthetic, however, they are less suitable because of their weak pain-relieving properties. They are usually combined with pain relievers to form what is known as balanced anesthesia.

A major reason for using Fluranen as inhalation anesthetics is their high effectiveness and their good controllability of the depth of anesthesia by adding them to the inspiratory air. The speed with which the anesthetic reacts to changes in the concentration in the inhaled gas mixture depends mainly on the solubility of the anesthetic in the blood. Poor solubility results in quick effectiveness, ie a quick "fall asleep" but also a short drainage time.

The blood-gas partition coefficient is a measure of the solubility of the volatile agent. Coefficients below one indicate that the partial pressures between the gas in the alveoli and the blood can quickly equalize and thus quickly take effect. This applies to both directions, for the "flooding" of the anesthesia and for the discharge when the inspiratory gas mixture no longer contains any narcotic.

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Risks & side effects

The three main fluranes, iso-, des- and sevoflurane, also differ in terms of possible side effects. Desflurane is characterized by the fewest side effects. This is mainly due to its low metabolism of less than 0.1 percent. This means that the likelihood of liver damage from degradation products of the agent is extremely low. In very rare cases, desflurane - like other inhalation anesthetics - can trigger malignant hyperthermia if there is an appropriate genetic predisposition to this. Malignant hyperthermia is a life-threatening condition that can lead to an increase in temperature, muscle rigidity and metabolic imbalance if no immediate countermeasures are initiated. Incorrect maintenance of the carbon dioxide absorber in the anesthesia machines can lead to the development of dangerous carbon monoxide.

Sevoflurane, which is often used in pediatric anesthesia, has a slightly higher metabolism rate of 3 to 5 percent, which releases certain organic fluorine products and inorganic fluorine, which, according to previous observations, did not cause any kidney toxicity. Sevoflurane is also approved in Germany for low-dose long-term anesthesia (artificial coma) without a time limit.