Sevoflurane
When ATH:
N01AB08
Pharmacological action
Means for inhalation anesthesia. Inhaler use of sevoflurane for induction of anesthesia causes rapid loss of consciousness, which quickly restored after the cessation of anesthesia.
Induction is accompanied by minimal signs of excitement and irritation of the upper respiratory tract and causes excess secretion in the tracheobronchial tree, and stimulation of the central nervous system. Sevoflurane (like other powerful tools for inhalation anesthesia) causes dose-dependent suppression of the respiratory function and the reduction of blood pressure. In humans, the threshold level of sevoflurane, causes the development of arrhythmias by the action of epinephrine (adrenaline), was comparable to that of isoflurane and halothane exceeds the threshold level.
Sevoflurane has minimal effects on the intracranial pressure and does not reduce the response to CO 2. It does not have a clinically significant effect on the function of the liver or kidneys and causes growth of kidney or liver failure. It does not affect the concentration of renal function even after prolonged anesthesia (about 9 no).
The minimum alveolar concentration (MAK) – the concentration, where y 50% patients observed motor response in response to a single stimulation (skin incision). MAC sevoflurane in oxygen is 2.05% adult person aged 40 years. MAC sevoflurane, as well as other halogenated agents, decreases with age and by the addition of nitric oxide.
Pharmacokinetics
The low solubility of sevoflurane in blood provides a rapid increase in alveolar concentration upon administration of anesthesia and rapid decrease following termination of inhalation. The ratio of the alveolar concentration and concentration in the inspired mixture through a phase of accumulation 30 minutes after inhalation of sevoflurane 0.85. The launch phase of the alveolar concentration ratio through 5 minutes after inhalation of sevoflurane 0.15.
Rapid elimination of sevoflurane minimizes the lung metabolism of sevoflurane. A person less than 5% sucked dose of sevoflurane is metabolized with the participation of isoenzyme CYP2E1 to form hexafluoroisopropanol, release of inorganic fluoride and carbon dioxide (or one carbon dioxide). The resulting hexafluoroisopropanol quickly conjugated with glucuronic acid and excreted in the urine. Other metabolic routes are not installed sevoflurane. Sevoflurane is the only fluorinated volatile anesthetics, is not metabolized to trifluoroacetic acid.
The concentration of fluoride ions depends on the duration of anesthesia, the concentration of sevoflurane administered, and the composition of the mixture for anesthesia.
Barbiturates not cause defluorination of sevoflurane.
Testimony
Background and supporting general anesthesia in adults and children during surgery in hospital and outpatient.
Dosage regimen
Means for premedication should be selected individually anesthesiologist.
When administered in a dose of anesthesia and picked individually titrated to achieve the desired effect, taking into account the age and condition of the patient. For administration in general anesthesia may be used sevoflurane in oxygen or a mixture of oxygen and nitrous oxide.
Before surgery in adults and children in the concentration of sevoflurane inhalation to 8% generally provides an introduction to general anesthesia in less than 2 m.
The required level of general anesthesia can be maintained by inhalation of sevoflurane concentration 0.5-3% in combination with nitric oxide or without.
With age, the MAC is reduced. The average concentration of sevoflurane, IAC provides patients aged 80 years, is approximately 50% from that of the patient's age 20 years.
Side effect
From the central and peripheral nervous system: ažitaciâ, drowsiness after general anesthesia of, dizziness; in a few cases were noted after administration of sevoflurane intermittent seizures. Although after the outage sevoflurane usually recover consciousness in a few minutes, Nonetheless, state intellectual capacity for 2-3 days after anesthesia has not been studied. Within a few days after the application of sevoflurane (as well as other means to narcosis) may experience minor mood changes.
The respiratory system: dose-dependent respiratory depression, increased cough, respiratory disorders (Apnea after intubation, laringospazm).
Cardio-vascular system: dose-dependent inhibition of cardiac activity, reduction or increase in blood pressure, bradycardia, tachycardia.
From the digestive system: nausea, vomiting, increased salivation; in some cases – transient disturbances in liver function tests.
Allergic reactions: in some cases – rash, hives, itch, bronchospasm, anaphylactic or anaphylactoid reactions.
From the laboratory parameters: may be a transient increase in glucose and white blood cell count.
Other: chills, fever.
In predisposed patients powerful tools for inhalation anesthesia, including sevoflurane, may induce a state of hypermetabolism of skeletal muscle, which leads to an increase of the oxygen demand and the development of clinical syndrome, known as malignant hyperthermia. The first sign of this syndrome is hypercapnia, and clinical signs may include muscle rigidity, taxikardiju, tachypnea, cyanosis, arrhythmias and / or instability BP. Some of these nonspecific signs may also appear during light anesthesia, acute hypoxia, hypercapnia and hypovolemia. Later, can develop kidney failure (should be monitored and, where possible to maintain urine output).
The majority of adverse reactions were mild or moderate and transient.
Contraindications
Confirmed or suspected genetic susceptibility to the development of malignant hyperthermia; increased sensitivity to sevoflurane or other halogenated drugs.
Pregnancy and lactation
There are no adequate and well-controlled studies safety of sevoflurane during pregnancy was conducted. Application of pregnancy is possible only in cases of extreme necessity.
Unknown, Do sevoflurane allocated with breast milk. To use caution during lactation (breast-feeding).
Cautions
Use caution when kidney function, in neurosurgical interventions, If the patient has a threat of increased intracranial pressure (in combination with the measures, aimed at reducing intracranial pressure, such as hyperventilation).
Sevoflurane may be used only doctors, have experience of general anesthesia. It is necessary to have ready the equipment for airway management, ventilator, oxygen therapy and resuscitation.
The level of general anesthesia can be easily and quickly changed, so the supply of sevoflurane should be used only by specially calibrated vaporizers. With the deepening of general anesthesia point increase in hypotension and respiratory function suppression.
When anesthesia supports increasing the concentration of sevoflurane causes dose-dependent blood pressure reduction. Excessive drop in blood pressure may be associated with deep general anesthesia; in such cases, it can be increased by reducing the concentration of sevoflurane feed.
As with any funds for general anesthesia in patients with coronary artery disease is necessary to maintain stable hemodynamics, to prevent myocardial ischemia.
Patients, emerging from general anesthesia, before transport to the police should be carefully monitored.
In the treatment of malignant hyperthermia is a cancellation of drugs, caused its development, / in the introduction of dantrolene sodium and supportive symptomatic therapy.
Effects on ability to drive vehicles and management mechanisms
Patients should be informed, that for some time after anesthesia may deteriorate the ability to perform work, requiring a rapid response, such as driving a car or the use of potentially hazardous machinery.
Drug Interactions
Expected, benzodiazepines and opioid analgesics reduce sevoflurane MAC.
MAC sevoflurane is reduced, while the use of nitric oxide.
Sevoflurane has an effect on the intensity and duration of neuromuscular blockade, caused by non-depolarizing muscle relaxants. With the introduction of sevoflurane as an adjunct to anesthesia alfentanil / N2O increases the effect of pancuronium, vecuronium and atracurium. By designating these relaxants combined with sevoflurane their dose should be adjusted so as, in the case of use with isoflurane. Influence of sevoflurane on succinylcholine and the effect of the duration of depolarizing neuromuscular blocking agents has not been studied.
Unnecessarily. potentiation of muscle relaxants observed a few minutes after the beginning of sevoflurane inhalation, reduction in the dose of muscle relaxants during induction of anesthesia may delay intubation or inadequate muscle relaxation
Among non-depolarizing drugs studied the interaction of sevoflurane with vecuronium, pancuronium and atracurium. Although specific recommendations for their application no, Nonetheless, when endotracheal intubation should not reduce the dose of non-depolarizing muscle relaxants; while maintaining the dose of non-depolarizing muscle relaxant anesthesia, probably, should be below, than for anesthesia N2O / opioid analgesics. Additional doses of muscle relaxants are administered with the response to nerve stimulation.
