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Query: UMLS:C0024591 (malignant hyperthermia)
 2,353 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Metabolic, hemodynamic and neuroendocrine responses to the combined use of halothane and succinylcholine (SCh) were measured in five normal swine and five swine susceptible to malignant hyperthermia (MH). Constant-volume ventilation was used, and no therapy was instituted. The overall response in susceptible swine was fulminant, in that it involved the rapid onset of SCh-induced MH combined with the more severe metabolic, endocrine, and cardiovascular effects of halothane-induced MH. Maximal changes in VO2 were equivalent with either drug or both combined, while changes in lactate, potassium (K+), pH, and catecholamines were perhaps synergistic. Utilizing similar measurements, procaine or procainamide was used in 20 susceptible swine in attempts to prevent MH initiated by halothane, SCh, or both. Recommended therapeutic doses of either drug did not prevent characteristic MH changes in oxygen consumption, cardiac output, lactate, K+, pH, catecholamines, or temperature.
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PMID:Porcine malignant hyperthermia induced by halothane and succinylcholine: failure of treatment with procaine or procainamide. 0 27

Although consideral information is available concerning the structural and biochemical changes in the skeletal muscles of patients with malignant hyperthermia, little is known of the cardiac changes in this disease. However, ventricular fibrillation and cardiac arrest are frequent in these patients. In 3 patients with malignant hyperthermia, contraction bands and foci of myofiberlysis were found in the heart at necropsy. Ultrastructurally, areas of myofiber overstretching adjacent to contraction bands and foci of extensive myofiberlysis were associated with disruptions of the sarcolemma. Similar ultrastructural findings have been reported in the skeletal muscles of these patients and are thought responsible for the hyperkalemia which is a constant feature of malignant hyperthermia. Our findings suggest that the ventricular arrhythmias, frequent in this disease, are the result of direct damage to cardiac muscle rather then secondary to elevated plasma levels of potassium.
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PMID:Myocardial changes in malignant hyperthermia. 33 38

In vitro muscle contracture responses in swine susceptible to malignant hyperpyrexia (MH) were similar to those found in muscle from humans susceptible to this anaesthetic complication, confirming the suitability of the pig as an animal model for studying MH. The results suggest that there are different degrees of susceptibility to MH. Whichever drug was used, there was some overlap in the contracture responses between susceptible animals and controls, suggesting that the most accurate way of identifying susceptibility to MH is to use a variety of chemical agents, the best of which seem to be halothane, caffeine, suxamethonium and potassium chloride. Thymol, which is used as a preservative in commercial preparations of halothane, potentiates halothane contractures, but it is not known if this is significant clinically.
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PMID:Identification of susceptibility to malignant hyperpyrexia in swine. 43 38

Lactic acid, glucose, creatine phosphokinase (CPK) and some mineral components were determined in the blood of piglets before and after a halothane test of five minutes (only before for CPK). Two different experimental groups were studied: 222 Pietrain piglets from an INRA experimental herd, and 325 piglets from the Large White, French Landrace and Belgian Landrace breeds entering performance testing stations. Animals reacting positively to halothane ("MHS" piglets) have significantly higher blood levels of lactic acid and potassium before anesthesia than normal animals. CPK is also higher, except for the Belgian Landrace: in this breed CPK shows the same average value and distribution in the two groups of piglets (normal and MHS). There are also breed differences in blood magnesium, independently of the reaction to halothane. But the breed differences observed in lactic acid and CPK are related to the proportion of MHS piglets in each breed. Anesthesia by means of halothane lowers the measured blood characteristics--except for glucose--in normal animals, and rises them--except for potassium--in MHS piglets. The results are discussed in view of the incomplete discrimination between the two types of pigs, with a 5 minutes test, and, particularly, considering possible breed differences in that respect.
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PMID:[Blood characteristics of some french pig populations. Relationships with the malignant hyperthermia syndrome (author's transl)]. 54 25

Malignant hyperpyrexia is a dangerous complication of general anesthesia occurring in individuals with an underlying disease of muscle. The essential clinical features of the syndrome are a drastic and sustained rise in body temperature, metabolic acidosis, and widespread muscular rigidity. The results of experiments on susceptible pigs and in vitro studies of human muscle have shown that all the clinical features of the syndrome can be explained by a raised level of calcium ions in the myoplasm. This is caused by a massive and sudden release of calcium into the myoplasm from the calcium-storing membranes in the muscle cell when exposed to general anesthetic agents. Two myopathies predisposing to malignant hyperpyrexia have been identified. One is usually subclinical, dominantly inherited, and manifested only by raised serum CPK levels. The other occurs in young boys with a number of physical abnormalities, whose relatives are unaffected. The serum CPK is a useful screening test in families in which malignant hyperpyrexia has occurred. Unfortunately, though, the serum CPK is not a specific test, and in doubtful cases the only unequivocal method of establishing susceptibility to malignant hyperpyrexia is to carry out an in vitro muscle test in which the muscle is exposed to caffeine, halothane, succinylcholine, and potassium chloride. Susceptible individuals should be given local, regional, or spinal anesthesia if an operation is needed. If this form of anesthesia is unsuitable, barbiturates such as thiopentone, tranquilizers such as diazepam, narcotics such as Pantopon, and neuroanaleptics such as fentanyl, nitrous oxide, d-tubocurarine, and althesin appear to be safe. By far the most important aspect of treatment is prophylaxis. Early diagnosis and immediate cessation of the offending anesthetic agents are the most important factors in trying to reduce the very high mortality of the syndrome.
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PMID:Malignant hyperpyrexia. 77 64

Skeletal muscle from normal human subjects produced linear contracture responses in vitro to caffeine at concentrations of between 4 and 32 mmol/litre. In the presence of 0.4% halothane, caffeine contractures were greater but the magnitude of halothane potentiation decreased as the caffeine concentration was increased. The contractures produced by caffeine 4 and 8 mmol/litre at 37 degrees C were significantly reduced by decreasing the temperature of the incubation solution to 25 degrees C. Among 57 normal subjects, 18% had fibres which responded to halothane treatment with contracture. On the basis of these findings, it is suggested that screening for malignant hyperpyrexia by in vitro pharmacological testing of skeletal muscle should be carried out at 37 degrees C, and should include exposure of the sample to halothane, caffeine, suxamethonium and potassium rather than to halothane alone.
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PMID:Screening for malignant hyperpyrexia. 83 48

1. The effects of dantrolene on pharmacologically-induced contractures and potentiated isometric twitches in normal human skeletal muscle have been studied in vitro. 2. Dantrolene sodium, at concentrations of 3 mumol/l or less, attenuates basal twitch, inhibits halothane potentiation of basal twitch and inhibits halothane-potentiated potassium contractures, but has less effect on twitch potentiation by 2 mmol/l caffeine. 3. Caffeine contractures are attenuated by dantrolene concentrations of 12 mumol/l or greater. The effect of dantrolene on caffeine contracture is characterized by decreased contracture tension and by prolonged time to peak contracture. 4. The results indicate that halothane and 2 mmol/l caffeine have agonistic effects on the excitation-contraction (E-C) coupling mechanism, and suggest that they may act at separate E-C coupling sites. The relationships of these findings to the pathopharmacology of malignant hyperpyrexia are discussed.
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PMID:Studies on normal human skeletal muscle in relation to the pathopharmacology of malignant hyperpyrexia. 89 Oct 45

Metabolic, haemodynamic and neuroendocrine responses to suxamethonium (SCh) were measured in five normal swine and five swine susceptible to malignant hyperthermia (MH), to compare the responses with those previously reported for halothane. Following SCh, the onset of MH was sooner and more abrupt than following halothane. The maximal changes in aerobic metabolism and body temperature sere similar, while the changes in lactate, potassium, hydrogen ion and catecholamine concentrations were smaller than those observed following halothane. These results are discussed in terms of the action of chemical depolarizing drugs such as suxamethonium and acetylcholine. The propagated muscle action potentials produce an increase in the free intracellular calcium concentration which may be self-regenerative, but which may become uncontrollable because of the peculiarities of MH that effect the calcium pump or storage areas.
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PMID:Suxamethonium-induced porcine malignant hyperthermia. 95 85

The effectiveness of intravenous administration of dantrolene in prevention and treatment of fulminant malignant hyperthermia (MH) initiated by halothene and succinylcholine (SCh) in genetically susceptible swine was assessed. In six animals, prior administration of dantrolene in doses of 5 mg/kg or more prevented MH, while 1 or 3 mg/kg attenuated MH, and 0.1 mg/kg had no effect. In ten additional swine, therapy was not started until MH was fulminant. Five of these were then given supportive therapy only (discontinuation of anesthesia, hyperventilation with oxygen, surface cooling, and NaHCO3). The remaining five received the same supportive therapy, plus dantrolene (7.5 mg/kg). With supportive therapy only, arterial blood pH, Po2 and Pco2 returned toward normal, but oxygen consumption (Vo2), blood lactate, potassium (K+), catecholamines, and temperature continued to increase and the course of MH was unaltered. When dantrolene was added to supportive therapy, Vo2, lactate, K+, catecholamines, and temperature decreased, and the course of MH was dramatically slowed and, apparently, reversed.
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PMID:Dantrolene in porcine malignant hyperthermia. 127 16

A moderate malignant hyperthermia developed in a Labrador Retriever anaesthetized with isoflurane for a femoral shaft fracture repair. Signs of malignant hyperthermia included progressive increases in PETCO2 and rectal temperature up to 39.8 degrees C, tachycardia, cyanosis, and elevated serum levels of potassium, inorganic phosphorus, AST, CK and alkaline phosphatase. Treatment initiated in the early recovery period consisted of hyperventilation with 100% oxygen, stomach lavage with iced water, body surface cooling, and intravenous administration of cold isotonic saline solution. Cooling was continued until the rectal temperature had dropped to 37.3 degrees C. After treatment the dog recovered uneventfully. Clinical signs, pathophysiology, therapy, prevention of malignant hyperthermia and its association with other disorders are discussed.
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PMID:[Malignant hyperthermia as a complication of anesthesia in the dog]. 144 May 99


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