Malignant hyperthermia in susceptible individuals powerful inhalation anesthetic isoflurane including, hypermetabolic state may cause skeletal muscle, leading to increased oxygen demand of the development and the clinical syndrome known as malignant hyperthermia. The first sign of this syndrome is hypercapnia, and its clinical symptoms may include muscle rigidity, tachycardia, tachypnea, cyanosis, arrhythmias, and / or unstable blood pressure. Some of these nonspecific signs may also appear during light anesthesia, acute hypoxia, hypercapnia, and hypovolemia. Treatment of malignant hyperthermia involves the abolition of the drugs that caused its development, intravenous dantrolene and supportive symptomatic therapy. Later trenbolone acetate it may develop renal failure, and therefore should be controlled as much as possible to maintain diuresis. The use of inhalation anesthesia in children rarely caused increase in serum potassium levels, leading to the development of cardiac arrhythmias and death in the postoperative period. This condition can occur especially in patients with latent or explicitly occurring neurological diseases, especially in patients with Duchenne muscular dystrophy. In some cases, there was a connection with the simultaneous use of succinylcholine. These patients also experienced a significant increase in serum creatine kinase levels, changes in the composition of urine and contrast to malignant hyperthermia and in the manifestation of a certain similarity in these patients never marked muscle rigidity or symptoms associated with muscle hypermetabolism. With the threat of such states, especially to patients with current latent neuromuscular disease, should immediately initiate action to relief of hyperkalemia and resistant arrhythmias.