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Malignant hyperthermia

Malignant hyperthermia – the state which is characterized by sharp hyper metabolism of skeletal muscles. Arises under the influence of medicines for an inhalation anesthesia, caffeine, a suktsinilkholin, stressful situations. It is shown in the form of metabolic, cardiovascular, muscular violations. Later the DVS-syndrome, polyorgan insufficiency develops. The diagnosis is made on the basis of a clinical picture, results of the analysis on KShchS and data obtained in the course test caffeine-galotanovogo. Treatment assumes elimination of all possible triggers, introduction of solution of sodium of a hydrocarbonate, dantrolen. For decrease in body temperature use physical methods.

Malignant hyperthermia

The Malignant Hyperthermia (MH) – a sharp pathological state which is characterized by considerable strengthening of the metabolic processes proceeding in cross-striped skeletal muscles. Has a pharmacogenetic origin. Occurrence frequency, according to different sources, varies within 1 case on 3-15 thousand general anesteziya. At adult patients this indicator makes 1 case on 50-100 thousand anesteziya. In reality of cases it is more, however it is not possible to trace all abortive forms. Besides, the practicing doctors not always provide information on similar complications. Pathology occurs at men by 4 times more often than at women.

Reasons of a malignant hyperthermia

The main reason for development of ZG – influence of the medicines and products possessing trigger action. To number of the drugs capable to provoke an attack, all inhalation anesthetics, kurarepodobny miorelaksant, caffeine carry. There are sketchy data on development of pathology in the people who underwent a strong mental shock or physical activity. It is considered that at the same time there is a production of simpatoadrenalovy substances (adrenaline, noradrenaline) which lead to development of crisis in the people predisposed to it.

The people having a prepotent mutation of a gene of a rianodinovy receptor of a chromosome 19 are considered more inclined to emergence of ZG. However cases when in the presence of obvious prerequisites to emergence of hyper metabolic muscular reactions, the gene responsible for a defective receptor, at the patient was absent are known. Predisposition to a disease is usually traced at all blood relatives.

Pathogenesis

Increase in duration of opening of muscular calcic channels is the cornerstone of pathogenesis. It leads to excess accumulation of ions of calcium in a sarkoplazma. Processes of polarization and depolarization are broken that becomes the reason of a generalized muscular contracture (rigidnost). ATP reserves which splitting leads to the strengthened consumption by cells of oxygen and to emission of thermal energy are exhausted. The fabric hypoxia develops, in muscles the lactate collects, there are phenomena of a rabdomioliz. In plasma of blood concentration of ions of potassium, calcium, magnesium, a myoglobin and kreatinfosfokinaza increases.

Primary defeat affects only skeletal muscles. However accumulation of toxic products of destruction of muscular tissue within an hour leads to formation of polyorgan insufficiency, violation of haemo dynamics, critical shifts of acid-base balance. Hypostasis of lungs and a brain can develop. There is a start of the cascade of inflammatory reactions of oxidizing type. There is a DVS-syndrome which leads to development of the latent internal and external bleedings.

Classification

The malignant hyperthermia can proceed in several clinical options which differ with the speed of development of pathological processes and time which passed from the beginning of influence of the trigger prior to a crisis demonstration. Besides, there are differences at expressiveness and a set of symptoms, weights of a current. Distinguish the following kinds of pathology:

  1. Classical. Meets in 20% of cases. Differs in the developed clinical picture, arises directly after introduction of the medicine having trigger activity. Pathology usually develops on the operating table in the face of the anesthesiologist having all necessary for knocking over of hyper thermal reaction. The lethality is rather low, death rate does not exceed 5%.
  2. Abortive. About 75% of all cases fall to its share. Differs in rather easy current, an incomplete set of clinical symptomatology. In many cases of substantial increase of body temperature does not occur. The easiest options of a current sometimes remain unnoticed or mistakenly belong to other pathological states. A lethality – 2-4%.
  3. Delayed. Meets in 5% of cases, develops in a day and more after contact with a provocative factor. Proceeds rather easily. Danger to the patient is that in 24 hours after operation control of physicians of it weakens. The malignant hyperthermia at the initial stage of development often remains unnoticed or is exposed to wrong diagnostics.

Symptoms of a malignant hyperthermia

Signs of ZG are divided on early and late. Early arise directly at development of crisis, late – in 20 and more minutes. The first symptom is the spasm of chewing muscles which is replaced by a generalized muscular contracture. Respiratory acidosis, CO2 at the end of an exhalation - more than 55 mm of mercury develops. Sweating amplifies, skin gets a marble shade. Oxygen consumption increases. In process of aggravation of metabolic violations there are changes in work of cardiovascular system: fluctuations of arterial pressure, takhiaritmiya.

The processes of a mioliz and splitting of ATP developing in spazmirovanny muscles lead to the sharp growth of body temperature. Usually this indicator does not exceed 40 °C. Cases of the fever reaching 43-45 °C that became a cause of death of the patient are known. Because of excess accumulation of potassium violations of a warm rhythm amplify. Urine becomes dark color, concentrated, the anury can be noted. The state is reversible if medical actions were begun in time. Otherwise at the patient complications develop.

Complications

The malignant hyperthermia can become the reason of a myocardial infarction, polyorgan insufficiency, disseminirovanny intra vascular folding. The heart attack develops as a result of electrolytic violations and a generalized muscular spasm. Volume sites of a necrosis of a myocardium lead to emergence of cardiogenic shock and asistoliya. Polyorgan insufficiency is characterized by malfunction of the vital structures that in 80% of cases leads to death of the patient. At the DVS-syndrome in the vascular course microblood clots which promote strengthening of polyorgan insufficiency are formed. Further the resource of the curtailing system is exhausted, there are heavy bleedings.

Diagnostics

Diagnostics of already developed ZG is carried out on the basis of the available symptoms, and also data of laboratory inspection. Predisposition to developing of crisis is determined by results of specific methods of testing. The algorithm of inspection of the patient includes:

  • Collecting anamnesis. It is possible to define existence of predisposition to a disease by preparation for operation. Careful survey of the patient and his family is for this purpose conducted. Speak about high risk if among blood relatives of the patient there are people who earlier had the hyper thermal crisis, sudden death during an anesthesia having episodes of inexplicable spasms in the anamnesis.
  • Laboratory diagnostics. At ZG in blood symptoms of metabolic acidosis (pH less than 7,25, deficiency of the bases more than 8 mmol/l), growth of concentration of KFK to 20 thousand are found. Piece/l and more, concentration of ions of potassium more than 6 mmol/l. Pathological changes in plasma accrue in process of process development. Normalization of indicators happens within a day from the moment of knocking over of crisis.
  • Kofein-galotanovy test. Is the specific analysis revealing tendency to emergence of a muscular contracture. During the test muscles place in the capacity filled with trigger solutions. With predisposition to ZG muscular tissue is reduced, there is a contracture. The test is carried out only to the patients entering into risk group as the procedure of an intake of biomaterial differs in injury.
  • Genetic inspection. The genetic research is shown to patients with the burdened anamnesis. It is directed to identification of the gene which is responsible for predisposition to development of generalized muscular contractures. The research during which mutations of genes of RYR1 and CACNA1S are found is considered positive. As the general screening method the genetic analysis is not used in view of the high cost and technical complexity of work.

Genetically caused attacks of a rigidnost of skeletal muscles have to be differentiated with anaphylactic reactions, signs of an insufficient analgeziya, cerebral ischemia, tireoidny crisis, a malignant antipsychotic syndrome, insufficiency of ventilation. An undoubted sign of ZG – decrease in expressiveness of symptoms soon after introduction of a dantrolen.

Treatment of a malignant hyperthermia

Efficiency of treatment directly depends on time which passed from the moment of development of an attack prior to the resuscitation actions. In the conditions of the operating room help to the patient is given on the place, having interrupted operation. If crisis developed in chamber, the patient is urgently transported in ORIT. Leaving of the patient in chamber of the general type is inadmissible. Treatment consists in use of unspecialized and etiotropny pharmacological methods, a hardware grant, application of physical ways of a hypothermia. The main actions include:

  • Termination of contact with the trigger. Giving of an inhalation anesthesia is stopped, contours of the narcotic and respiratory device blow pure respiratory mix. Replacement of the device, a contour, intubatsionny tube is not made. The method of a hyperventilation of 100% is used by oxygen. The minute volume of breath at the same time by 2-3 times exceeds norm. Duration of the procedure makes 10-15 minutes.
  • Etiotropny therapy. "a malignant hyperthermia" introduction of a dantrolen – the relaksant having ability to block rianodinovy receptors is shown to patients with the diagnosis. Means reduces intracellular concentration of Ca, slows down transfer of a neuromuscular impulse, leads to bystry elimination of symptoms of crisis. Drug is injected is dosed, before normalization of a condition of the patient.
  • Symptomatic therapy. Depends on the available clinical picture. For maintenance of haemo dynamics titrovanny supply of dopamine through can be used. Decrease in body temperature is carried out by imposing on area of a projection of large vessels of bubbles with ice, by introductions of cold infusion solutions. For correction of KShchS enter 4% hydrocarbonate sodium solution. Removal of surplus of electrolytes, toxins and maintenance of function of kidneys demands introduction of loopback diuretics.

Forecast and prevention

The forecast is favorable if the malignant hyperthermia was in due time noticed and stopped. At long stay of the patient in a condition of metabolic acidosis and hypoxia perhaps ischemic defeat of the central and peripheral nervous system, violation in operation of the cardiovascular device up to atrioventricular blockade, a myocardial infarction, fibrillation. At an abortive form chances of a happy end are much higher, than at classical.

Specific prevention consists in the careful preoperative inspection directed to establishment of the fact of predisposition of the patient to muscular contractures. The refusal of coffee and kofeinosoderzhashchy drinks, minimization of psychological stresses in everyday life is recommended to people with the confirmed genetic mutation.

Malignant hyperthermia - treatment

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