In this Chapter:
5.1. Drugs for inhalation anesthesia
5.1.1. Volatile liquids
5.1.2. Gases
5.2. Drugs for noninhalation (intravenous) anesthesia
5.3. Combined use of general anesthetics
5.4. Combined use of general anesthetics with drugs of different pharmacological groups
The drugs from this group are used for surgical anesthesia. This state is characterized by the reversible inhibition of the CNS functions, including loss of consciousness, inhibition of sensitivity (first of all pain sensitivity) and reflex reactions and the reduction of skeletal muscle tone. This definition, used in anaesthesiology, comprises only external manifestations of general anesthesia.
The main effects of general anesthetics are caused by the inhibition of the interneuronal (synaptic) transmission in the CNS. The transmission of afferent impulses, corticosubcortical interrelations, functions of the diencephalon, midbrain, spinal cord, etc. are impaired. The functional disintegration of the CNS, associated with the impairment of the synaptic transmission, determines the development of general anesthesia.
Due to the absence of selective action of general anesthetics and a great variability in their chemical structure, they were initially thought to have the same inhibitory effect on different neurons. It was suggested that their nonspecific physicochemical binding with the neuronal membranes (except for axonal membranes which seem not to be affected by these drugs in anesthetic concentrations) occurs due to the interaction with lipids and (or) proteins, and also probably with the water molecules, covering membranes. This results in the dysfunction of the membrane and probably in reversible changes of its ultrastructure. One of the possible manifestations of the interaction between general anesthetics and the postsynaptic