Reproducibility of in vitro contracture test results in patients tested for malignant hyperthermia susceptibility

Abstract

Reproducibility of in vitro contracture test results in patients tested for malignant hyperthermia susceptibility.Islander, Gunilla; Ording, H; Bendixen, D; Ranklev Twetman, EvaPublished in: Acta Anaesthesiologica Scandinavica DOI: 10.1034/j.1399-6576.2002.460914.x Published: 2002 Link to publication Citation for published version (APA): Islander, G., Ording, H., Bendixen, D., & Ranklev Twetman, E. (2002). Reproducibility of in vitro contracture test results in patients tested for malignant hyperthermia susceptibility. Acta Anaesthesiologica Scandinavica, 46(9), 1144 -1149 . DOI: 10.1034 /j.1399 -6576.2002 General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal Department of Anaesthesiology, Herlev Hospital, University of Copenhagen, DenmarkBackground: The in vitro contracture test (IVCT) is the golden standard to diagnose malignant hyperthermia susceptibility (MHS). A high reproducibility is important for a high validity of a test. Methods: We have therefore analyzed IVCT in 838 patients, investigated in two laboratories. Each halothane and caffeine test was performed in two muscle strips. The test results were analyzed with respect to reproducibility of abnormal outcomes within pairs of tested muscle strips and size of contractures, thresholds and quality criteria. The patients were tested according to the European Malignant Hyperthermia Group protocol (EMHG). To fulfill quality criteria in the EMHG protocol the twitch height should be 10 mN (1 g) or more. For the caffeine test a minimum contracture of 50 mN (5 g) or more at 32 mmol l ª1 caffeine could be used as an alternative quality criterion Results: There was better reproducibility with larger contractures. The correlation between size of contractures and fraction of muscle strips with abnormal contractures was 0.77 or larger. Contractures Ͻ 5 mN (0.5 g) were reproducible in less than half

Use of the caffeine-halothane contracture test for the diagnosis of malignant hyperthermia in Brazil

“…MH susceptibility was found in 46.4% of the patients (90/194), in agreement with rates from laboratories from Denmark and Toronto, 51.8 and 31.8% (22), respectively, where 1082/2214 patients were found to be susceptible to MH (48.9%) (23). MH susceptibility was lower (21.1%) in 10 laboratories from the North American MH Association (19).…”

Sevoflurane is less sensitive than halothane for in vitro detection of malignant hyperthermia susceptibility

“…According to a study on a larger patient database, the reproducibility of caffeine‐ and halothane‐induced contractures was higher with increasing absolute size of contractures compared with contractures close to the diagnostic threshold . In our investigation, comparison of contracture sizes was of limited value: contracture sizes in different muscle strips of the same patient after incubation with sevoflurane, halothane, or caffeine as well as after repeated tests with only one of these agents did not show any correlation in our group of patients.…”

Cystathionine β-synthase-derived hydrogen sulfide is involved in human malignant hyperthermia

“…The concentration response of H 2 S was performed using a concentration range similar to that used for caffeine in the IVCT. These concentrations are required for the IVCT procedure to achieve better reproducibility of the response for fulfilment of the quality criteria, with consequent patient safety [38], and worldwide they are accepted and applied by both European and North American MH groups. It must be noted that, at the concentration of H 2 S used for MHN biopsies, incubation in the organ bath in itself modified neither the skeletal muscle tension nor the tissue viability, within the timeframe of the IVCT and for up to 60 min.…”