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NONINHALATION ANESTHETICSBARBITURATES — they are derivatives of barbituric acid. shutdown of consciousness). Application of barbiturates for basal narcosis during short-term operations envisages a compulsory readiness to ALV. Side effects — a dose-dependent depression of breathing up to apnea and KETAMINE (ketalar, ketanest, kalipsol).
Barbituric acid Barbiturates of short and ultra-short action — thiopental sodium (pentothal), hexenal (hexobarbital), thiamilal, metohexithal are used for anesthesia. They are soluble in water in the form of sodium salts, but their solutions are sharply alkaline, unstable (2.5% thiopental solution has pH > 10 and it is stored no more than 2 weeks) and prepared ex tempore. In the concentrations, higher than recommended for administration, they are painful upon introduction and may cause thrombosis of veins. In therapeutic doses they exert influence on synapses of the reticular formation — activating the system of cerebral cortex, that is why a dose-dependent inhibition of consciousness comes on (from sedation to a deep anesthesia).They have no analgetic effect, sometimes, exert even antianalgetic effect (lowering a pain threshold). Being administered and absorbed from the intestine or muscles into the blood, 80% of them are bound with albumin, and only a remained fraction acts as a narcotic. Therefore, in hypoproteinemia a conventional dose causes a deeper anesthesia. Alkalosis contributes to binding with proteins, acidosis — on the contrary. Biotransformation of barbiturates occurs in the liver down to inactive water-soluble metabolites excreted by the kidneys. Barbiturates are applied, primarily, for initial narcosis in short-term operations. They are administered slowly as 1% solution (do not use a solution prepared more than 24 hrs ago) in the dose of approximately 3-7 mg/kg for initial narcosis, but the final dosage depends on gaining a desired effect (a
It is transparent, colorless 5% solution in ampules or bottles. It stimulates a functioning of some structures of the brain (limbic system taking part in awareness of sensations) and inhibits the others (thalamus switching sensitive impulses from the reticular formation to the cortex, some areas of neocortex et al.). It is subject to biotransformation in the liver. In its repeated application a tolerance (resistance) may develop to it in patients, due to the induction of hepatic enzymes as in the action of barbiturates. Metabolites are excreted through the kidneys. For initial narcosis it is introduced slowly intravenously 0.5-1.5 mg/kg or intramuscularly 3-8 mg/kg. To maintain anesthesia it is administered once again as 0.3-1.0 mg/kg. Duration of action is 5-15 min following intravenous and 12-25 min after intramuscular injection. The last dose is introduced 30-40 min before the end of operation. In the postanesthetic period for 2-3 hrs the patient has no need in analgetics. It is suitable for anesthesia of deliveries and cesarean section (does not penetrate placental barrier), in hypovolemia, shock, blood loss. Side effects: it has an inhibiting effect on respiration only in case of fast administration. Unlike all other anesthetics it increases AP, HR, cerebral blood flow, ICP and the pressure of cerebrospinal fluid through stimulation of sympathic centers. It increases salivation and bronchorrhea (atropine premedication is compulsory). Laryngeal and pharyngeal reflexes, hypertonus of crossstriated, smooth and cardiac muscles are preserved during deep anesthesia (antagonist — magnesium). It elevates the uterine tonus and causes a depression of immunogenesis. A recovery from anesthesia may be accompanied by psychomotor excitement, delirium, hallucinations, particularly in adults. Side effects, especially psychomotor ones, are diminished in combination of ketamine with benzodiazepins (diazepam, midazolam, rohypnol), barbiturates, neuroleptics (droperidol). ETOMIDATE (hypnomidate, radenarcon)
2% solution inlO-ml ampules. It inhibits, as barbiturates, the reticular formation, but, in contrast to them, disinhibits an extrapyramidal motor activity causing a myoclonic effect. It acts like y-aminobutyric acid (GABA). A significant portion of this agent is being bound with proteins in the vessels. It is hydrolyzed in the liver and plasma down to inactive metabolites 5 times faster than thiopental. Products of hydrolysis are excreted through the kidneys. It is applied for initial narcosis — 0.2-0.3 mg/kg, to maintain anesthesia for 5-10 — min 0.1mg/kg/min., then — 0.01 mg/kg/min. It has no analgetic activity, therefore, it is not permitted to intubate trachea and to do other painful manipulations under etomidate monoanesthesia. Side effects — muscular clonus, increase of pain sensation (premedication with opioids, except fentanyl, decreases a myoclonus incidence). A moderate decrease of TPVR and AP is observed. It diminishes energy demands of the brain, cerebral blood flow and ICP. Postoperative nausea and vomiting may occur to exclude which a premedication is recommended with anesthetics. It inhibits synthesis of corticosteroids up to a cortical insufficiency. PROPOFOL (diprivan, recofol). 1% miljc -white ej mdsi^njnjO^mLaxnpules.. 50 and 100-ml bottles, it needs to snake before use. It does not contain any antimicrobic preservatives and is a good nutrient medium for microorganisms, therefore, after opening the ampule it is to be stored no more than 6 hrs, at the room temperature. It causes a hypnotic effect by facilitating inhibitory action of GABA on the nerve impulse transmission.
It is being intensively bound with proteins in the vessels, however, its high liposolubility ensures the induction of anesthesia, as rapid as thiopental, and still more rapid recovery. It is metabolized in the liver and outside of it, inactive metabolites are excreted through the kidneys. This agent is used for initial narcosis in the dose of 2-2.5mg/kg in adults, decreasing this dose down to 1-1.5 mg/kg in the elderly and weakened patients. In children under three years of age propofol is not applied, for more senior children the following formula is used: Dose = 5.2-(0.152 x age), where: dose — in mg/kg, age — in years. A final dose for induction depends on clinical picture of anesthesia development. Maintenance of anesthesia is supported, according to the clinical picture, by repeated administration of propofol for adults — 25-50 mg/kg in the undiluted form or diluted in 5% glucose solution. It has no analgetic effect and requires an addition of analgetics or other anesthetics with such effect. A new step in the development of anesthesiology is the method of intravenous infusion of propofol according to the target concentration established at the moment of loss of consciousness (see page 65). Side effects — inhibition of respiration and blood circulation, bronchospasm, nausea, vomiting, allergic reactions. It decreases cerebral blood flow and ICP, protects the brain from local ischemia and hypoxia, and causes decrease of the intraocular pressure. It is painful when administered into small veins. SODIUM OXIBUTIRATE (GOBA, Gamma-OH, butyric acid) — sodium salt of y-hydroxybutiric acid. Manufactured as 10-ml ampules with 20% solution. It is chemically close to GABA — the main inhibitor mediator of CNS. Evidently, it is associated with sedative, anesthetic and weak analgetic action of GOBA. It is absorbed from the vascular bed in intravenous and from the gastrointestinal tract in peroral administration. A great portion of administered GOBA is utilized in the organism as a metabolic substrate, increasing, in so doing, the brain resistance to hypoxia. 98% are excreted through the lungs in the form of carbon dioxide. For premedication it is administered intramuscularly 120-150 mg/kg or perorally in the form of 5% syrup 100-200 mg/kg. For initial narcosis — intravenously 100-120 mg/kg, for weakened patients — 50-70 mg/kg. In order to maintain anesthesia, it is injected intravenously 40-50 mg/kg every 30-40 min. A little controllability of anesthesia is being noted that is manifested by significant individual differences in the deepness of anesthesia and duration of recovery. Side effects: in rapid administration — respiratory rhythm disturbances (Cheyne-Stokes respiration), bradycardia, motor excitement, intensification of salivation, nausea, vomiting are noted. In the process of putting to sleep, cramps, muscular rigidity, trembling are not uncommon. It contributes to the development of hypopotassemia at the expense of transfer of potassium from the extracellular space into cells. Дата добавления: 2015-02-05 | Просмотры: 855 | Нарушение авторских прав |
