Malignant hyperthermia is a rare but life-threatening complication of general anesthesia in predisposed patients usually triggered by potent inhalation anesthetics and/or the depolarizing muscle relaxant succinylcholine. The authors present a case of delayed sevoflurane-induced malignant hyperthermia in a 21-year-old male patient that was sufficiently treated by discontinuation of trigger agent application and dantrolene infusion. After surviving an MH episode diagnostic procedures are indicated to increase patient safety. In the presented case, the use of a novel minimal-invasive metabolic test with intramuscular injection of halothane and caffeine successfully confirmed MH susceptibility and hence might be an alternative for invasive in vitro contracture testing in selected cases. 1. Introduction Malignant hyperthermia (MH) is a rare but potentially lethal pharmacological induced disease of skeletal muscle. Exposure to triggering agents such as volatile anesthetics and/or the depolarizing muscle relaxant succinylcholine may induce a hypermetabolic muscular syndrome characterized by hypoxemia, hypercapnia, tachycardia, muscular rigidity, acidosis, hyperkalemia, and hyperthermia, due to an uncontrolled sarcoplasmic calcium release via functionally altered ryanodine receptors subtype 1 or dihydropyridine receptors . Currently, the in vitro contracture test (IVCT) requiring an open muscle biopsy is the only reliable procedure to diagnose MH susceptibility in affected patients. However, due to its invasive characteristics this test is associated with severe risks to the patients, for example, wound infections, postoperative bleeding, or persistent dysesthesia. Important progress was made within the last years by screening for causative MH mutations, which allows a genetic diagnosis in 30% to 50% of MH families . Unfortunately, a negative genetic result does not sufficiently exclude MH susceptibility and hence must be confirmed by IVCT . Recently, a minimal-invasive metabolic test was proposed to analyze muscular alterations in MH patients under in vivo conditions. The local monitoring of interstitial lactate concentrations after pharmacological stimulation induced by MH trigger agents allowed a differentiation between MH susceptible (MHS) and MH nonsusceptible (MHN) patients . In the presented case report, we used this minimal-invasive test to screen for MH susceptibility in a patient who developed clinical sings of MH during general anesthesia with sevoflurane while undergoing an elective shoulder arthroscopy. 2. Case Presentation 2.1. Intra-
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