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

The effects on whole body or cardiac metabolism of carbon dioxide, calcium, potassium, or digoxin were studied in 16 normal swine and 31 swine susceptible to malignant hyperthermia (MHS). Malignant hyperthermia (MH) was defined as an increase in metabolism that occurred in MHS but not in normal pigs. Whole body response: despite a sustained PaCO2 greater than 130 mmHg, MH did not develop in four intact MHS swine during thiopental-N2O anesthesia and controlled ventilation. Drugs given during total cardiopulmonary bypass: MH did not develop in five MHS pigs with blood ionized calcium to 15 mEq/l, in four MHS pigs with digoxin levels to 60 ng/ml, or in four normal pigs with potassium to 10 mEq/l. In six MHS pigs, oxygen consumption increased from 6.5 to 11.6 ml O2 X min-1 X kg-1 when potassium exceeded 6 mEq/l; lactate did not increase. Cardiac response (during extracorporeal right heart bypass): eight pigs (four normal, four MHS) with blood ionized calcium to 5 mEq/l and eight pigs (four normal, four MHS) with digoxin levels above 7.5 ng/ml had increased myocardial oxygen consumption. Cardiac potassium efflux or lactate production did not occur in normal or MHS pigs. Increased arterial potassium (7.4-8.5 mEq/l) did not alter myocardial oxygen consumption or lactate production in four MHS or four normal pigs. MH responses were initiated only by potassium and only in regard to whole body metabolism. Cardiac metabolism increased as a result of specific drugs (calcium, digoxin), unrelated to MH phenomena. Porcine inbreeding resulting in MH susceptibility of skeletal muscle does not imply abnormality in other tissues.
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PMID:Effect of CO2, calcium, digoxin, and potassium on cardiac and skeletal muscle metabolism in malignant hyperthermia susceptible swine. 307 72

Anesthesia in patients susceptible to malignant hyperthermia (MH) is generally considered to be very risky, although - with one notable exception - there are no prospective studies about anesthetic management in a large number of such patients. The prophylactic use of dantrolene has been recommended in MH patients, although there is no strong evidence supporting this - despite the fact that dantrolene may have serious side effects. We therefore decided to report the results of our own anesthetic technique for MH patients, as our technique does not include the prophylactic use of dantrolene. From 1981 to 1988, 19 operations on 16 MH-susceptible patients were performed. Patients 1-4 were pediatric survivors of an MH episode, where MH susceptibility was confirmed by muscle biopsy and in vitro contracture tests in at least one parent; patients 5-7 were survivors of an MH crisis, and they later underwent diagnostic muscle biopsies themselves; all other patients (nos. 8-16) were relatives of MH survivors with positive in vitro contracture tests. Diazepam, pentobarbital, pethidine, and chlorprothixene were used for premedication; no prophylactic dantrolene was given. Anesthesia was induced by thiopentone and was continued by nitrous oxide/oxygen, fentanyl, and droperidol; alcuronium, atracurium, and vecuronium were administered as necessary. Pyridostigmine, atropine, and naloxone were used if appropriate. New or disposable tubings were used for ventilation, and the vaporizers were removed from the anesthesia machines. ECG and body temperature were recorded in all patients; blood pressure was monitored invasively if indicated; end tidal CO2 was monitored whenever possible.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Malignant hyperthermia in Austria. III. Anesthesia in susceptible patients]. 317 78

In this methodological paper a quantitative blood flow measuring technique in porcine skin is described. The anatomy, technical preparation and surgical technique is emphasized. Baseline recordings yielded a total blood flow of 6.6 +/- 0.9 (S.E.) cc/100 g/min and an oxygen consumption of 0.16 +/- 0.02 cc/100 g/min at a dermal temperature of 35 degrees C. Approximately 75% of the experiments were successful and unsuccessful experiments were mainly due to malignant hyperthermia in the pig or inability to cannulate the vessels.
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PMID:Method for skin blood flow studies in the pig. 325 51

Malignant hyperthermia (MH) is a genetic syndrome usually initiated by exposure to volatile anesthetic agents or depolarizing neuromuscular blocking agents. We have used Ca2+-selective microelectrodes to measure in vivo the intracellular ionized calcium ([Ca2+]i) in skeletal muscle fibers of MH-susceptible swines before and during hyperthermic episodes and also after dantrolene administration. The animals were anesthetized with thiopental and fentanyl and maintained with a mixture of nitrous oxide (66%) and oxygen (34%). The malignant hyperthermic episode was triggered by exposure to halothane. Determinations of [Ca2+]i during the episode show an increase from 0.44 +/- 0.01 microM +/- SEM, n = 20) to 8.44 +/- 0.68 microM (mean +/- SEM, n = 10). Administration of dantrolene (2 mg/kg) during the hyperthermic episode reduces [Ca2+]i to 0.17 + 0.01 microM (mean +/- SEM, n = 10) and reverses the clinical symptoms. These results show that the MH episode is associated with an increase in the myoplasmic free Ca2+ concentration and that the therapeutic effect of dantrolene is related to a decrease in [Ca2+]i.
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PMID:Myoplasmic free [Ca2+] during a malignant hyperthermia episode in swine. 334 Jan 2

The use of dantrolene to reverse severe unexplained postanaesthetic muscle rigidity in a previously "healthy" 13-year-old male is described. Anaesthesia was induced with thiopentone. After intubation with pancuronium, the patient had an entirely uneventful nitrous oxide, oxygen and halothane anaesthetic. Immediately following reversal of the relaxant, the patient developed generalized muscle tightness and rigidity involving the trunk and extremities. This was prolonged and severe enough to interfere with adequate ventilation. The patient also had a prolonged recovery from the anaesthetic. After ruling out malignant hyperthermia and some other causes of rigidity, a tentative diagnosis of myotonia was made. The symptoms responded to IV dantrolene in a total dose of 2.0 mg.kg-1. Further testing failed to establish a definite diagnosis. Dantrolene could be a useful drug in treating such unexplained muscle rigidity.
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PMID:Reversal of prolonged postoperative muscle rigidity by dantrolene: a case report. 340 20

Many similarities in kidney-function abnormalities were found between hypertensive rats of the Milan strain (MHS) and young normotensive human subjects with hypertensive parents, compared with the appropriate controls. These similarities included an increased glomerular filtration rate, increased pressor effect of the kidney after transplantation, increased 24-h urinary output and lower plasma renin activity and urinary kallikrein. The isolated MHS kidney perfused in vitro with an artificial medium had a higher glomerular filtration rate, a higher urinary output, higher tubular sodium reabsorption and higher oxygen consumption than the kidney of control Milan normotensive rats (MNS). Further, reogenic sodium transport across brush border vesicles isolated from proximal tubular cells is faster in MHS than in MNS. Erythrocytes and proximal tubular cells of MHS have a lower volume and sodium content than those of MNS, while sodium transport is faster and the Ca2+-ATPase at Vmax is lower. This indicates that the 'genetic' cellular abnormality responsible for the renal-function abnormality and the hypertension is also present in erythrocytes. Thus these cells may be used to study the genetic cellular mechanisms of hypertension. Experiments with bone marrow transplantation and with F2 hybrids obtained by crossing the F1 (MHS X MNS) hybrids showed that the MHS erythrocyte abnormalities are genetically determined within the stem cells and are genetically associated with the hypertension. Since, in human hypertensives, there was a correlation between abnormal erythrocyte sodium transport and renal function, it is proposed that erythrocytes may be used in studying the cellular molecular mechanisms of hypertension.
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PMID:A renal abnormality in the Milan hypertensive strain of rats and in humans predisposed to essential hypertension. 353 35

Measurements of body temperature, respiratory gas exchange, sweat evaporation rate and circulating levels of catecholamines, lactate, pyruvate, free fatty acids and glucose were made in seven patients susceptible to malignant hyperpyrexia (MHS) and in seven control subjects during 2 h of treadmill walking at 40% of maximum oxygen consumption. These studies took place in an ambient temperature of 22 degrees C. The MHS patients displayed the same thermoregulatory, plasma catecholamine and metabolic responses as the control subjects. The results of the present study suggest that non-competitive, low-intensity, steady-state exercise need not be contraindicated for MHS patients.
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PMID:Thermoregulation, plasma catecholamine and metabolite levels during submaximal work in individuals susceptible to malignant hyperpyrexia. 356 67

It has been speculated that, in malignant hyperthermia-susceptible (MHS) individuals, an abnormality of sympathetic activity is seen during stressful situations, such as exercise. The authors investigated whether muscle metabolism in eight MHS subjects, at rest and during moderate and heavy short-term exercise, is different then that in normals. Leg exchange of energy substrates (glucose, lactate, and glycerol) was quantified by measuring leg blood flow and arterial-venous concentration differences. Muscle biopsies were also performed, and ATP, glycogen, and lactate were analyzed. Catecholamines and oxygen uptake were also measured. The study was performed at rest with subjects in the supine position and during two periods (40% and 80% of the subjects maximal oxygen uptake, respectively) on a bicycle ergometer. The principal finding of the study was that there was no major difference in oxygen uptake or leg exchange of glucose, lactate, and glycerol between MHS-subjects and previously standard normals during different grades of exercise. Furthermore, muscle metabolites and plasma catecholamines did not differ between the groups. This study indicates a normal sympathetic activity and muscle metabolism in MHS subjects during rest, as well as during moderate and severe exercise. The authors' results do not support the opinion that persons with positive in vitro tests for MH should restrict their physical activity.
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PMID:Effects of graded exercise on leg exchange of energy substrates in malignant hyperthermia susceptible subjects. 363 4

A healthy, 15-year-old male received a thiopental, nitrous oxide, oxygen, enflurane anesthetic for appendectomy. Cardiac arrest, following succinylcholine administration, was associated with marked hyperkalemia (potassium levels 8.7 to 11.6 meq), hemolysis (hematocrit fall from 41.7 to 26.6%, plasma hemoglobin 27 mg/dL), and creatine phosphokinase (CPK) elevation (8900 units). Vigorous resuscitative therapy including dantrolene was unsuccessful. The diagnosis of malignant hyperthermia was made by the marked CPK elevation on blood samples drawn during resuscitation and analyzed by the Medical Examiner's Office.
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PMID:Hemolysis and hyperkalemia complicate malignant hyperpyrexia during anesthetic death. 371 29

The case histories are presented including the anaesthetic and postoperative management, of two children, a two-year-old with undiagnosed Duchenne muscular dystrophy (DMD) and a three-year-old with known DMD. The child with undiagnosed DMD had no symptoms of DMD and had received halothane twice before, without succinylcholine, with no apparent difficulty. Following an uneventful induction of anaesthesia with halothane, nitrous oxide and O2, succinylcholine resulted in bilateral masseter muscle spasm and then, in rapid sequence, ventricular tachycardia and cardiac arrest. Resuscitation was difficult, prolonged and associated with hyperkalaemia (K+ = 12.57 mEq X L-1), severe metabolic and respiratory acidosis, high peripheral venous pressure and massive hepatosplenomegaly, but not hyperthermia. The patient was finally resuscitated but died two days later. Skeletal muscle biopsy results were consistent with malignant hyperthermia. The second patient was known to have DMD but did not receive prophylactic or intraoperative dantrolene nor have his anaesthetic machine flushed with oxygen for an extended period prior to induction of anaesthesia. This child was anaesthetized with fentanyl and N2O and, with the exception of a high intraoperative heart rate (155-160 beats X min-1), had an uncomplicated anaesthetic and operation (intraoperative axillary temperatures ranged between 36.8-37.9 degrees C). Postoperatively his temperature rapidly increased to 38.8 degrees C and then 40.3 degrees C and he became metabolically acidotic. Intravenous administration of dantrolene for 48 hours reduced the temperature and allowed normal recovery and discharge. A postoperative muscle biopsy was consistent with DMD.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Duchenne muscular dystrophy and malignant hyperthermia--two case reports. 374 23


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