Like all other potent general anesthetics, isoflurane should be used only if appropriate anesthesia equipment is available to qualified specialists who are familiar with the pharmacology of the drug, trained and experienced in managing patients under anesthesia. To accurately control the delivered concentration of anesthetic, anesthetic vaporizers, calibrated specifically for isoflurane, should be used.
Arterial hypotension and respiratory depression increase with deepening in anesthesia. Since the level of anesthesia can be quickly and easily changed by using isoflurane, only evaporators should be used,which provide a predictable yield with sufficient accuracy, or methods with monitoring of inhaled or exhaled concentrations.
The level of lowering blood pressure and respiratory depression can to some extent indicate the depth of anesthesia. Spontaneous respiratory activity should be carefully monitored and, if necessary, ancillary or controlled ventilation should be provided.
Lengthening of the interval has been reported QT, accompanied by polymorphic ventricular tachycardia (in exceptional cases with fatal outcome). Isoflurane should be administered with caution in patients at risk of lengthening the interval QT.
General anesthesia, including isoflurane, should also be used with caution in patients with mitochondrial disorders.
Isoflurane can cause liver dysfunction in the range from a mild transient increase in the concentration of hepatic enzymes to liver necrosis with a fatal outcome in very rare cases. It has also been reported that the previous exposure to halogenated hydrocarbon anesthetics, especially in the time interval of less than 3 months, may increase the likelihood of liver damage.Cirrhosis, viral hepatitis or other existing liver disease can be the reason for abandoning the halogenated anesthetic and choosing a drug from another group.
Isoflurane causes severe respiratory depression, and this effect can be exacerbated by narcotic premedication or the use of other drugs that cause respiratory depression. Respiratory activity should be carefully monitored and, if necessary, ancillary or controlled ventilation should be used (see section "Side effect"). All patients receiving isoflurane anesthesia should be under constant supervision, including ECG monitoring, blood pressure, oxygen saturation and partial pressure of CO2 in the exhaled air at the end of exhalation. It is necessary to have a full set of equipment for resuscitation, and staff should be trained in the implementation of resuscitation.
Other available risk factors should also be considered (see the "Side effect" section).
The use of isoflurane in patients with hypovolemia, arterial hypotension and in weakened patients has not been studied in detail.Such patients are recommended to reduce the concentration of isoflurane. The level of lowering blood pressure and respiratory depression can to some extent indicate the depth of anesthesia.
In humans, a relatively small fraction of the absorbed isoflurane is metabolized. In the postoperative period, only 0.17% of the absorbed isoflurane can be excreted as metabolites with urine. The average concentration of organic fluoride in the serum is usually less than 5 μmol / L and occurs about 4 hours after anesthesia, returning to normal levels within 24 hours. There was no reported kidney damage after using isoflurane.
There is insufficient data on the re-use of anesthesia in order to provide some guidance on how to use it in this mode. As with all halogenated anesthetics, repeated anesthesia should be used with caution for a short period of time.
Patients with severe pseudo-paralytic myasthenia gravis (myasthenia gravis) are extremely sensitive to drugs that depress the breath. Some means for general anesthesia enhance this effect. Isoflurane should be used with caution in such patients.
In patients with such neuromuscular diseases as severe pseudo-paralytic myasthenia gravis, there may be an increase in neuromuscular fatigue. Isoflurane should be used with caution in such patients.
It is recommended to carry out controlled ventilation in patients with neurosurgical operations: the cerebral blood flow remains unchanged at an early stage of general anesthesia, whereas with deeper anesthesia it tends to increase. Increased intracranial pressure can be reduced to normal values or reduced by hyperventilation of the patient before or during anesthesia.
AERRAN should be administered with caution to patients who may develop bronchial narrowing due to bronchospasm (see section "Side effect"). When neurosurgical operations should be monitored properly. Like other halogenated anesthetics, AERRAN increases cerebral blood flow, which is accompanied by a transient increase in cerebrospinal fluid pressure.In most cases, hyperventilation can be used to prevent this increase in pressure.
Regardless of the anesthetics used, maintenance of normal hemodynamics is important for the exclusion of myocardial ischemia in patients with ischemic heart disease.
Due to the fact that AERRAN acts as an irritant of the mucous membranes, the drug is difficult to use when performing an inhalation anesthesia with a mask. During the introduction of anesthesia salivation and tracheobronchial secretion can be intensified and cause laryngospasm, especially in children (see section "Side effect").
As with the use of other inhalation anesthetics, patients experienced severe blood loss when using isoflurane with the artificial termination of pregnancy.
There is insufficient information about the use of the drug in pregnancy or in obstetric practice, except for caesarean section. Isoflurane relaxes the muscles of the uterus, and in operations in obstetric practice, the minimum possible concentrations of isoflurane should be used (see the section on "Application during pregnancy and during breastfeeding").
In predisposed patients anesthesia with isoflurane can cause a state of hypermetabolism in skeletal muscles, leading to an increase in the need for oxygen and the development of a clinical syndrome known as perioperative malignant hyperthermia. This syndrome includes such nonspecific signs as muscle rigidity, tachycardia, tachypnea, cyanosis, arrhythmia and unstable blood pressure. It should also be noted that many of these non-specific signs may appear at an early stage of general anesthesia, with acute hypoxia and other conditions. The increase in total metabolism can be manifested as a rise in temperature (which may increase earlier or later, but is not the first sign of increased metabolism) and increased use of the CO adsorbent system2 (hot absorption box). The partial pressure of O2 and pH, as well as hyperkalaemia and a deficiency of bases. There have been reports of fatal cases following malignant hyperthermia with isoflurane. Treatment of malignant hyperthermia includes the withdrawal of the drug that caused it (eg, isoflurane),intravenous administration of dantrolene sodium (additional information on the treatment of patients is provided in the instructions for the use of dantrolene sodium drugs) and the appointment of maintenance therapy. Such therapy includes active measures to restore normal body temperature, support breathing and vascular function according to indications, as well as elimination of electrolyte and acid-base disorders. Later, kidney failure may develop.
Individual cases of increased concentrations of carboxyhemoglobin have been reported with the use of halogenated inhalation anesthetics with α-CF2H group (i.e. desflurane, enflurane and isoflurane). In the presence of normally hydrated adsorbents, clinically significant concentrations of carbon monoxide are not formed. It is necessary to follow the instructions of manufacturers of adsorbents CO2.
There have been reports of rare cases of excessive heating, smoke formation and / or spontaneous ignition in the anesthesia apparatus when using general anesthetics from this class with dried CO absorbents2, especially those containing potassium hydroxide (for example, Baralaim).If the doctor suspects adsorbent2can be over-dried, it should be replaced before using isoflurane. The color of the indicator found in most CO adsorbents2, does not necessarily change due to drying of the adsorbent. Therefore, the absence of a change in the color of the indicator can not be considered a confirmation of an adequate degree of hydration. Adsorbents CO2 It is necessary to change regularly irrespective of color of the indicator.
The use of funds for inhalation anesthesia was rarely accompanied by an increase in potassium concentration in the serum, which caused arrhythmias and deaths in children in the postoperative period. Patients with latent, as well as with obvious neuromuscular diseases, in particular Duchenne's myodystrophy, appear to be most prone to these disorders.
In most, but not in all of the cases mentioned above, concomitant use of succinylcholine was noted. In these patients, a significant increase in the serum creatin kinase concentration and, in some cases, changes in urine corresponding to myoglobinuria were also determined. Despite the similarity with manifestations of malignant hyperthermia,none of these patients had symptoms or signs of muscle rigidity or hypermetabolic state. Early and active intervention is recommended for the treatment of hyperkalemia and resistant arrhythmia followed by examination for latent neuromuscular disease.
Isoflurane can cause a slight decrease in mental function within 2-4 days after anesthesia. A slight change in mood and symptoms can persist up to 6 days after the appointment. This should be taken into account when the patient resumes normal daily activities, including transport management or working with dangerous mechanisms (see "Impact on the ability to drive vehicles and work with machinery").
Complementary appointment with muscle relaxants: isoflurane enhances effects muscle relaxants and, in particular, nondepolarizing muscle relaxants. Therefore, it is recommended to use reduced doses of these drugs.
Isoflurane should be given with caution in patients with diabetes mellitus, as it can increase blood glucose and the number of white blood cells during the operation.
Children under two years of age
Isoflurane should be given with caution in young children due to limited experience with the drug in patients in this group.