Anesthetics — the group of substance causing a surgical anesthesia. The condition of an anesthesia is characterized by reversible oppression of central nervous system with consciousness switching off, suppression of sensitivity (first of all painful) and reflex reactions, decrease in a tone of skeletal muscles. Anesthetics oppress interneural (synoptic) transfer of excitement to central nervous system. At the same time transfer of afferent impulses is broken, corticosubcortical relationship, function of an intermediate, average, spinal cord and with disturbance of synoptic transfer change, and causes development of an anesthesia.
The sensitivity of various departments of central nervous system to the general anesthetics of a neyoodinakov, as defines the sequence of approach of stages of a naryokoz: analgesias, excitement, a surgical anesthesia, awakening (at overdose — a stage of paralysis or agonal). However the expressiveness of separate grades of anesthesia can be unequal at use of razyony narcotic means. So, the excitement stage when using not inhalation general anesthetics, as a rule, is absent, the analgesia stage, etc. can differ on duration and expressiveness. All stages can be tracked at use of etherization.
Approach of the I grade of anesthesia — an analgesia — is characterized gradual utrayoty pain at preservation of other types of sensitivity and a muscle tone. Owing to the small duration of a stayodiya of an analgesia it is possible to perform only simple short-term operations: vskryyotiye of abscesses, etc. Emergence of a stage of an analgesia is connected with oppression of interneural transfer of excitement on esodic nerves and snizheyoniy functional activity of a cerebral cortex at partial maintaining consciousness.
Motive and speech excitement, increase in a tone of skeletal muscles are characteristic of the following stage — excitement —; a stage of an opasyon in view of possibility of serious complications of reflex character: vomitings, disturbances of breath, warm activity, up to an apnoea and cardiac arrest that is connected with oppression of brake protsesyos in a cerebral cortex and elimination of brake influence of bark on underlying departments of a brain ("a subcortex revolt") — consciousness is lost. In soyovremenny anesthesiology try to avoid this stage, applying the komyobinirovanny, potentiated anesthesia with preliminary introduction of neyyoroleptik, tranquilizers, hypnotic drugs, analgetics and also the anesthetics causing fast approach of a grade of anesthesia without excitement stage.
The stage of a surgical anesthesia is caused by manifestation of the oppressing action of narcotic means on a head and spinal cord that is connected with oppression of interneural transfer of excitement in these departments of central nervous system. Signs of a stage of a surgical anesthesia are loss painful and other viyod of sensitivity, consciousness switching off, oppression of a reflex akyotivnost, a relaxation of skeletal muscles. Breath becomes gluboyoky and equal, the rhythm of warm reductions and the ABP are normalized. In a stage of a surgical anesthesia distinguish 3 anesthetic planes (depending on its depth): poyoverkhnostny, expressed and deep. The deep anesthesia borders on a peredoyozirovka, and here it is necessary special attention of the anesthesiologist, a poyoskolka synapses of different departments of central nervous system are unequally sensitive to anesthetics therefore they inadequately react to their same doses. The greatest sensitivity synapses of an aktiviyoruyushchy reticular formation of a trunk of a brain, the smallest — synapses of the centers of a medulla possess therefore the last react only to high concentrations of narcotic means in blood. At a peredozirovyoka there can come oppression of the vital centers of a medulla — respiratory and vasomotor, and the patient can die from paralysis of a respiratory center (a paralysis stage, or agonal). In order to avoid it it is necessary to stop urgently introduction of a narcotic sredyostvo and to take measures for restoration of the broken functions of dykhatelyyony and cardiovascular systems.
Usually the last is the awakening stage which begins right after the termination of administration of anesthetics: the central nervous system functions, reflexes vosyostanavlivatsya gradually (in the sequence, the return to their disappearance), consciousness is restored. After awakening the patients poyogruzhatsya in a dream which can proceed several hours.
In the course of a preparation for surgery the premedication including appointment to the patient of the calming, analgetic, cholinolytic, cardiovascular and other drugs is carried out. These means apply with the purpose to weaken negative influence on an organism of the emotional stress preceding operation and to warn the possible by-effects connected with an anesthesia and surgery (reflex reactions, disturbances of a hemodynamics, strengthening of secretion of glands of airways, etc.). Premedication facilitates carrying out an anesthesia: reduction of concentration or a dose of the means applied to an anesthesia is possible, the excitement phase, etc. is less expressed.
During an anesthesia and at an exit from it also use analgetics, muscle relaxants (or dekurariziruyushchy means), cardiovascular drugs, etc., promoting preservation of functions of an organism at the physiological level.
In recent years for the general anesthesia widely use intravenous administration of various combinations of neurotropic means, aiming to receive the so-called balanced anesthesia without use of traditional inhalation anesthetics. One of methods of the general anesthesia of a such type based on use of neuroleptics (Droperidolum) in combination with analgetics (fentanyl, trimeperidine, etc.), is the neuroleptanalgesia (NLA). Other multicomponent method — the ataralgeziya, or a trankvilanalgeziya, also provides use of analgetics (fentanyl, trimeperidine, etc.) in combination with tranquilizers (diazepam, Phenazepamum or other), sodium Oxubatum, cholinolytics (atropine, a metatsiniya iodide) and other drugs.
One of methods of the general anesthesia is administration of narcotic analgetics (morphine or other) to the spinal canal.
Depending on ways of introduction to an organism the narcotic means podyorazdelyatsya on two groups: inhalation, arriving through lungs, and not inhalation which enter in other ways (intravenously, vnutrimyyoshechno, etc.).