[The approach to patients susceptible to malignant hyperthermia].
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Genetic Predisposition to Disease↗
Biomedical subjects
V Glauber
Publications and source records attributed to V Glauber.
Malignant hyperthermia.
Malignant hyperthermia is a rare autosomal dominant trait that predisposes affected individuals to great danger when exposed to certain anaesthetic triggering agents (such as potent volatile anaesthetics and succinylcholine). A sudden hypermetabolic reaction in skeletal muscle leading to hyperthermia and massive rhabdomyolysis can occur. The ultimate treatment is dantrolene sodium a nonspecific muscle relaxant. Certain precautions should be taken before anaesthesia of patients known to be susceptible to malignant hyperthermia. These include the prohibition of the use of triggering agents, monitoring of central body temperature and expired CO2, and immediate availability of dantrolene. In addition, careful cleansing of the anaesthesia machine of vapours of halogenated agents is recommended. If these measures are taken, the chances of an MH episode are greatly reduced. When malignant hyperthermia-does occur in the operating room, prompt recognition and treatment usually prevent a potentially fatal outcome. The most reliable test to establish susceptibility to malignant hyperthermia is currently the in vitro caffeine-halothane contracture test. It is hoped that in the future a genetic test will be available.
Anesthesia↗
In vitro contracture test for diagnosis of malignant hyperthermia following the protocol of the European MH Group: results of testing patients surviving fulminant MH and unrelated low-risk subjects. The European Malignant Hyperthermia Group.
BACKGROUND: Determination of sensitivity and specificity of the in vitro contracture test (IVCT) for malignant hyperthermia (MH) susceptibility using the European MH Group (EMHG) protocol has been performed in some laboratories but only on a small sample from the combined EMHG. Thus, the purpose of the present study was to determine combined EMHG sensitivity and specificity of the test. METHODS: Results of IVCT of patients with previous fulminant MH and normal, low-risk subjects (controls) were collected from 22 centres of the EMHG. IVCT was performed according to the EMHG protocol. Patients were included in the study if the clinical crisis had a score of at least 50 points with the Clinical Grading Scale. Low-risk subjects were included provided they did not belong to a family with known MH susceptibility, they had not developed any signs of MH at previous anaesthetics, and they did not suffer from any neuromuscular disease. For inclusion of both MH patients and low-risk subjects, at least 1 muscle bundle in the IVCT should have twitches of 10 mN (1 g) or more. For evaluation of individual tests, only muscle bundles with twitch heights of 10 mN (1 g) or more were used. RESULTS: A total of 1502 probands had undergone IVCT because of a previous anaesthesia with symptoms and signs suggestive of MH. Of these, 119 had clinical scores of 50 and above. From these 119 MH-suspected patients and from 202 low-risk subjects, IVCT data were collected. Subsequently, 14 MH-suspected patients were excluded from further analysis for the following reasons: In 3 patients, the suspected MH episode could be fully explained by diseases other than MH; in 11 MHS patients, IVCT was incomplete (n = 1), data were lost (n = 3), or none of the muscle bundles fulfilled twitch criteria (n = 7). Of the remaining 105 MH-suspected patients, 89 were MHS, 10 MHEh, 5 MHEc, and one MHN. Thus, we observed a diagnostic sensitivity of the IVCT of 99.0% if the MHE group is considered susceptible (95% confidence interval 94.8-100.0%). Of the 202 low-risk subjects, 3 were MHS, 5 MHEh, 5 MHEc, and 189 MHN. This gives a specificity of the IVCT of 93.6% (95% confidence interval 89.2-96.5%). CONCLUSION: The IVCT for diagnosis of MH susceptibility in Europe has a high sensitivity and a satisfactory specificity.
Adolescent↗
The Israeli Diagnostic Center for Malignant Hyperthermia: 7-years' accumulated experience.
Malignant hyperthermia (MH), a rare pharmacogenetic trait, can be lethal when susceptible individuals are exposed to triggering agents during general anesthesia. We present our experience with the caffeine-halothane in vitro contracture test (IVCT) for the diagnosis of malignant hyperthermia susceptibility. Out of 75 patients that were referred for consultation to the MH diagnostic center over a period of 7 years, we performed muscle biopsies and IVCT in 21 patients. A total of 6 patients were found to be MH-positive. Appropriate recommendations for future anesthetic management, and additionally, for testing the immediate family were made following a positive diagnosis. Improved familiarity with the syndrome of MH, and performance of IVCT when family or clinical history suggest malignant hyperthermia susceptibility, are imperative measures to prevent the potential fatality associated with this syndrome.
Academies and Institutes↗
End-tidal CO2 levels are a reliable indicator of band tightness in pulmonary artery banding.
BACKGROUND: Monitoring of end-tidal CO2 levels, performed routinely nowadays in most operating rooms, is obligatory in our hospital for all anesthesia patients. Levels are dependent on pulmonary blood flow, ventilation, and CO2 content of blood. When ventilation is kept constant, the end-tidal CO2 closely follows pulmonary blood flow. METHODS: Reduction of end-tidal CO2 in the expired air was used to adjust tightness of the pulmonary band in 10 patients with complex cardiac anomalies, all including ventricular septal defect, who underwent pulmonary artery banding. Other parameters were systemic blood pressures and distal pulmonary artery pressures. RESULTS: There were no operative deaths. Average reduction was 3.8 mm Hg (range, 2 to 10 mm Hg; p < 0.001 by paired t test), average increase in systolic blood pressure was 14 mm Hg (range, 4 to 20 mm Hg; p < 0.03 by Wilcoxon sign rank test), distal pulmonary artery pressure was reduced from 56 mm Hg (range, 37 to 79 mm Hg) to 29 mm Hg (range, 20 to 38 mm Hg; p < 0.03 by t test), and postoperative pulmonary artery to systemic pressure ratio averaged 0.36 mm Hg (range, 0.24 to 0.49 mm Hg, difference from preoperative value, p < 0.06). CONCLUSIONS: End-tidal CO2 tension is a simple and convenient, yet highly reliable parameter for adjusting pulmonary artery band tightness.
Carbon Dioxide↗
[Masseter muscle spasm--approach to patient].
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Anesthetics↗
[In vitro diagnosis of malignant hyperpyrexia syndrome].
Malignant hyperthermia syndrome (MHS) is rare, inherited, and triggered by volatile anesthetics and depolarizing muscle relaxants. While potentially fatal, if recognized and treated early recovery is usual. However, the condition is often not recognized until an extreme increase in temperature develops with profound circulatory depression. In this stage the syndrome is irreversible, despite specific treatment with dantrolene. At present, the only reliable diagnostic test for susceptibility to malignant hyperthermia requires sampling of viable muscle for in vitro contracture tests with caffeine and halothane. Until our malignant hyperthermia diagnostic center was opened, such tests could not be performed in Israel. Since then we encountered a 22-year-old man who developed the partial picture of malignant hyperthermia syndrome during anesthesia for inguinal herniorrhaphy. He received dantrolene and recovered. 4 months later in vitro contracture tests with caffeine and halothane performed on biopsied muscle confirmed the diagnosis.
Adult↗