General recommendations
The drug Foran® can be used only by specialists who have experience in general anesthesia, in departments equipped with everything necessary to ensure airway patency, ventilation, oc-sygenotherapy and resuscitation.
Since the depth of anesthesia can be changed quickly and easily with isoflurane, only carefully calibrated evaporators and / orequipment that allows controlling the concentration of isoflurane in the inhaled and exhaled mixture. With deepening of general anesthesia, the increase in arterial hypotension and suppression of respiratory function is noted. The degree of reduction in blood pressure and respiratory depression can reflect the depth of anesthesia.
Due to irritation of the respiratory tract with the use of inhalation anesthetics, the following side effects were observed: bronchospasm and laryngospasm.
When using isoflurane, as well as other inhalation anesthetics, careful maintenance of normal hemodynamics is necessary to prevent myocardial ischemia in patients with coronary artery disease.
There were reports of lengthening of the QT interval associated with tachycardia such as "pirouette" (in very rare cases, a fatal outcome).
Isoflurane should be used with caution in patients exposed to these complications. When using isoflurane, as well as other inhalation anesthetics, the following side effects were observed: cardiac arrest, bradycardia, tachycardia.
Preparations for general inhalation anesthesia, including
isoflurane, should be used with caution in patients with mitochondrial diseases.
Isoflurane can potentiate neuromuscular depletion in patients with neuromuscular diseases, such as myasthenia gravis.
There have been reports of individual cases of an increase in the carboxyhemoglobin content in the use of fluoride-containing agents for anesthesia, such as
desflurane, enflurane and
isoflurane. In the presence of normally moistened CO2 sorbents, no increase in the concentration of carbon monoxide is observed. Care must be taken to follow the manufacturer's instructions for CO2 sinks.
Replacement of dried CO2 sorbents
When fluoride-containing agents are used for inhalation anesthesia with over-dried CO2 sorbents (especially those containing potassium hydroxide), rare cases of excessive overheating and / or spontaneous ignition in anesthesia apparatus are described.
If the anesthetist has reason to believe that the CO2 sorbent is over-dried, then it should be replaced before using isoflurane. When drying CO2 sorbent, the color of the indicator does not always change. Consequently, the absence of significant color changes in the indicator can not be considered a guaranteeadequate hydration. Sorbents CO2 must be regularly changed regardless of the color of the indicator.
Obstetric surgeries
Isoflurane, like other drugs for inhalation anesthesia, causes relaxation of the uterus musculature, so there is a potential risk of uterine bleeding. For anesthesia in obstetric operations
isoflurane should be used with caution and in the lowest possible concentrations.
Halogen-containing agents for inhalation anesthesia
There is information that
isoflurane can cause liver damage (from a small and transient increase in the activity of "liver" enzymes to liver necrosis with a fatal outcome in very rare cases).
There is evidence that the use of halogenated anesthetics in history, especially during the previous 3 months, may increase the risk of hepatotoxicity. Cirrhosis, viral hepatitis and other liver diseases in history can be grounds for refusing the use of a halogen-containing anesthetic.
Isoflurane significantly increases cerebral blood flow, depending on the depth of anesthesia.There may be a transient increase in cerebrospinal fluid pressure, which returns to the initial pressure during hyperventilation. Like other halogen-containing drugs for inhalation anesthesia,
isoflurane should be used with caution in patients with increased intracranial pressure. In these cases, controlled hyperventilation may be necessary.
Isoflurane can cause respiratory depression, which can be intensified when combined with narcotic analgesics used for premedication or other drugs that can cause respiratory depression. It is necessary to monitor the function of respiration and, if necessary, use artificial respiration.
Patients with a tendency to bronchoconstriction
Patients with a tendency to bronchoconstriction
isoflurane should be used with caution in connection with the risk of developing bronchospasm.
Caesarean section
Isoflurane at concentrations up to 0.75% demonstrated safety and efficacy in maintaining anesthesia during cesarean delivery.
Children up to 2 years old
Due to the limited experience of using isoflurane in newborns and children under 2 years of age, caution should be used in these patient groups.
Patients with hypovolemia, low blood pressure and weakened patients
The use of isoflurane in these patient groups has not been adequately studied. It is recommended to use minimum concentrations of isoflurane.
Malignant hyperthermia
In susceptible people, funds for inhalation anesthesia, including
isoflurane, can cause a state of skeletal muscle hypermetabolism, which leads to an increase in their oxygen demand and the development of a clinical syndrome known as malignant hyperthermia. The increase in total metabolism can be manifested by an increase in temperature (a rapid rise in both early and late terms, nevertheless, it can not be considered the first sign of increased metabolism) and an increase in the activity of the CO2 absorption system (hot storage). It is possible to reduce the pH and pH, as well as the development of hyperkalemia and deficiency of bases. The first sign of malignant hyperthermia is hypercapnia, and its clinical symptoms may include muscle stiffness, tachycardia, tachypnea, cyanosis, arrhythmias and / or unstable blood pressure. Some of these nonspecific symptoms may also occur with mild anesthesia, acute hypoxia, hypercapnia, and hypovolemia.
Treatment of malignant hyperthermia involves the abolition of the drugs that caused its development, intravenous dantrolene (detailed information on the use of dantrolene is given in its instructions for use) and supports symptomatic therapy, including maintenance of normal body temperature, respiratory and circulatory functions, control of water-electrolyte and acid- alkaline balance. Later, kidney failure may develop, so you should monitor and, if possible, maintain diuresis.
Hyperkalemia in the perioperative period
The use of funds for inhalation anesthesia in children caused in rare cases an increase in the concentration of potassium in the serum, which led to the development of cardiac arrhythmias and fatal outcomes in the postoperative period. The development of this condition is more susceptible to patients with latent or obvious neurological diseases, especially patients with Duchenne myodystrophy. In most of these cases, there was a link with simultaneous use of suxamethonium. These patients also had a significant increase in serum creatine-phosphokinase activity and, in some cases, a change in the urine composition indicating myoglobinuria.Unlike malignant hyperthermia, such patients never had muscle stiffness or symptoms associated with muscle hypermetabolism. If the development of such conditions threatens, especially if a patient has a latent current neuromuscular disease, intensive measures should be started immediately to stop hyperkalemia and stable arrhythmia. In the case of postoperative hyperkalemia after the use of funds for inhalation anesthesia, and if the patient has not previously been diagnosed with latent neuromuscular diseases, a follow-up examination is recommended to identify these diseases.
Increase in the concentration of fluorides
In the postoperative period and during anesthesia due to biotransformation of isoflurane, serum fluoride concentrations may be slightly increased (on average, up to 4.4 μmol / l). However, it is unlikely that such low concentrations of fluorides could cause toxic damage to the kidneys. they are well below the threshold toxic concentration.
Hypersensitivity reactions
There are reports of rare cases of hypersensitivity (including contact dermatitis, rash, dyspnea, wheezing, chest discomfort, facial edema), usually associated with prolonged use of inhalational anesthetics, including
isoflurane. These reactions were confirmed clinically (for example, methacholine test). However, the causes of anaphylactic reactions during inhalation anesthesia remain unexplained due to the simultaneous use of a variety of concomitant medications, many of which could cause similar reactions.
As with the use of other means for inhalation of general anesthesia, there was a transient increase in the number of white blood cells, even in the absence of surgical stress. When using the drug, there may be increased salivation and tracheobronchial secretion, which can lead to laryngealism, especially in children.