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

Three malignant hyperthermia susceptible (MHS) and three normal Danish landrace pigs were heated using a water-heated mattress, warm blankets and warm intravenous saline during anaesthesia with barbiturate and 50% nitrous oxide in oxygen. The MHS pigs developed typical malignant hyperthermia (MH) at a rectal temperature of 41.0 +/- 0.7 degrees C, whereas the normal pigs tolerated heating to the same temperature without any ill effects. Haemodynamic and metabolic findings during MH were similar to those previously reported for anaesthetic-induced MH in pigs. Heat intolerance may thus be one factor in the genesis of MH.
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PMID:Malignant hyperthermia triggered by heating in anaesthetized pigs. 393 14

Malignant hyperthermia (MH) is a genetic disease of man, swine, dogs, cats, and horses. The syndrome is normally triggered by inhalational anesthetics or the administration of depolarizing muscle relaxants such as succinylcholine or various environmental stress factors. We have used the MH-susceptible pig as an animal model to study the hormonal changes developing during this highly lethal syndrome. High-performance liquid chromatography with electrochemical detection was used for the quantitation of the plasma levels of norepinephrine and epinephrine during MH. This research presents evidence that the rapid release of massive quantities of norepinephrine (up to 108 ng/ml) into the blood stream occurs simultaneously with the initiation of tachycardia which is the herald signal of the onset of MH. Norepinephrine levels exceed epinephrine by a 4:1 ratio early in the syndrome. Even pigs with MH which do not develop the muscle rigor phase have high levels of circulating norepinephrine. Tachycardia, pulmonary hypertension, increased venous oxygen desaturation, and increasing core temperature develop as the syndrome progresses.
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PMID:Plasma levels of norepinephrine and epinephrine during malignant hyperthermia in susceptible pigs. 408 71

Three cases of postoperative malignant hyperthermia (MH) episodes, after what was considered to be a "safe" anaesthetic, are described. In each case the temperature rose in a delayed fashion after an uneventful anaesthetic. Treatment included intravenous dantrolene, surface cooling and ventilation with 100 per cent oxygen. Stress in the postoperative period may have been the triggering factor responsible for these reactions. Patients should be monitored well into the postoperative period as MH episodes may occur long after surgery is completed. If stress represents a significant triggering mechanism then no anaesthetic technique can be considered entirely safe.
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PMID:Postoperative malignant hyperthermia episodes in patients who received "safe" anaesthetics. 633 48

Malignant hyperthermia (MH) is a rare syndrome seen when susceptible individuals are exposed to one or more of various triggering agents, most commonly a depolarizing muscle relaxant or an inhalational anaesthetic agent. There is a dramatic rise in metabolic rate and oxygen consumption which if not treated promptly and effectively results, in the majority of cases, in the patient's death. Fatal responses to physical stress associated with the familial muscular disease known as MH are being increasingly reported in situations not related to anaesthesia or drugs. Moreover, cases of MH were recognized to be "induced" in the postoperative period when obviously the major effects of anaesthesia were no longer of important consideration. Therefore a more expanded concept of MH seems to develop, including the assumption that one of the other factors in MH is stress. The implication of this extends far beyond the scope of anaesthesiology. The acute hypermetabolic state in MH, resulting in acidosis, heat production and muscular activity is probably due to an inability to control calcium concentration within the skeletal muscle fiber, and may involve a generalized alteration in cellular or subcellular membrane permeability. The susceptibility to develop MH is controlled by several genetic factors. Evaluation of affected families is guided by in vitro analysis of drug-induced contractures in muscle biopsy specimens; a practical and reliable non-invasive test to predict the susceptibility is still being sought. At the present time there is incontrovertible evidence that the hydantoin derivate dantrolene sodium is the only known specific drug in treatment and prophylaxis of MH. A concept for the treatment of MH and guidelines for the management of a patient at risk are presented; medico legal aspects of the complication are stressed.
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PMID:[Malignant hyperthermia]. 634 13

Purebred Pietrain malignant hyperthermia (MH)-susceptible pigs (n = 102) were subjected to halothane (0%, 1%, 2%, 3%, 4%, and 5%) in oxygen. The number of pigs in each group exhibiting muscle rigidity (MH(+) reaction) and the reaction times were recorded, as were the number of deaths resulting from MH. Mortality was not affected by the halothane concentration. However, halothane concentration did markedly affect the number of MH(+) reactions and the reaction times. False-negative reactions were apparent in the pigs at halothane concentrations less than 3%. Increasing the halothane concentration incrementally to 5% (from 0%) significantly (P less than 0.05) decreased reaction times between treatment groups. The reductions in reaction times which occurred in the pigs given the 3%, 4%, and 5% halothane concentrations (62.1, 56.2, and 50.05)--although significant (P less than 0.05)--would indicate that 3% halothane would generally be sufficient for MH testing.
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PMID:Halothane testing for malignant hyperthermia in swine: dose-response effects. 649 30

To study the haemodynamic, cellular and humoral changes seen during septicemia-endotoxinemia a relatively large animal is needed. Pigs are satisfactory in size but have a tendency to develop malignant hyperthermia reaction to stress situations and certain anaesthetic agents. This problem was solved using a screening test of halothane exposure. When later used for experiments, the nonresponding pigs developed the typical hypokinetic low-flow state after endotoxin challenge seen in the advanced stage of septicemia in man. Decreased number of circulating leucocytes and platelets, increased tissue thromboplastin production in monocytes, and a significant coagulation disorder (DIC) were observed. Release of oxygen radicals and lysosomal enzymes from leucocytes could be estimated. Endotoxin levels in plasma were easily measured. This pig model of controlled endotoxinemia correlates well with some important haemodynamic, cellular and humoral reactions observed during human in vivo observations and in vitro studies. This model may thus be a valuable tool in clinical research of endotoxinemia and septicemia.
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PMID:Controlled endotoxinemia in pigs. A suitable model for in vivo studies of some haemodynamic, humoral and cellular reactions. 653 28

The biochemical characteristics of skeletal muscle mitochondria of malignant hyperthermia (MH) susceptible Dutch Landrace pigs have been investigated before and during an MH attack, induced in vivo by halothane plus succinylcholine. The muscle homogenates have a decreased capacity to synthesize ATP and creatine phosphate during the MH period. Muscle mitochondria prepared from susceptible pigs in an MH period consume less oxygen than do mitochondria isolated before the attack, or mitochondria from control pigs during the challenge. The oxidative phosphorylation is not uncoupled during the critical period. The production of CO2 indicates that the in vitro measured capacity of the MH muscle mitochondria correctly reflects the in vivo condition during the MH attack. The restricted synthesis may be caused by a factor, finding expression in the mitochondria themselves, and obtained or activated during the MH attack.
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PMID:In vivo induced malignant hyperthermia in pigs. II. Metabolism of skeletal muscle mitochondria. 671 Dec 68

Hepatic metabolism during porcine malignant hyperthermia (MH) was investigated in seven Pietrain pigs. The estimated hepatic blood flow decreased during MH, but an increase in oxygen extraction enabled the splanchnic oxygen uptake to be maintained. There was a large release of glucose and potassium from the liver in MH which made an important contribution to the hyperglycaemia and hyperkalaemia. Measurement of hepatic uptake of the precursors of gluconeogenesis, lactate, glycerol and alanine, showed that glucose efflux from liver was derived mainly from glycogenolysis. Lactate uptake by the liver increased during MH, and there was no evidence of hepatic lactate production during the profound acidosis as suggested by in vitro studies with the isolated liver. There was no evidence of major abnormality of hepatic function during porcine MH.
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PMID:Porcine malignant hyperthermia. VII: Hepatic metabolism. 699 Sep 47

The effect of the intravenous administration of dantrolene 3.5 mg/kg body weight on leg metabolism during porcine malignant hyperthermia (MH) was investigated in six Pietrain pigs. Arterial pH improved only slowly after dantrolene and was associated with the continuing efflux of lactate from the leg. Oxygen uptake by the leg had returned to control values 30 minutes after dantrolene. Glucose production by the leg was observed during malignant hyperthermia but this was rapidly abolished by dantrolene. It is concluded that the most useful indices for assessing the adequacy of the treatment of MH are those which reflect changes in oxidative muscle metabolism.
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PMID:Effect of dantrolene on leg metabolism in porcine malignant hyperthermia. 718 Oct 63

Malignant hyperthermia is a pharmacogenetic disease involving uninhibited flow of calcium ion into the muscle substance. This leads to a combined metabolic and respiratory acidosis and the liberation of heat. If not immediately controlled, cellular death results. We treated a 4-year-old girl who suffered a malignant hyperthermia crisis during strabismus surgery. Hyperventilation with 100% oxygen and intravenously administered dantrolene sodium, furosemide, and fluids controlled the attack and the child recovered completely.
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PMID:Malignant hyperthermia syndrome. 729 8


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