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

Islander, Gunilla LU ; Ording, H; Bendixen, D and Ranklev Twetman, Eva LU (2002) In Acta Anaesthesiologica Scandinavica 46(9). p.1144-1149
Abstract
BACKGROUND: 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... (More)
BACKGROUND: 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-1 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 < 5 mN (0.5 g) were reproducible in less than half of the tests. There was no difference in reproducibility or size of contractures between tests fulfillling all quality criteria and those not fulfillling these criteria. CONCLUSIONS: IVCT responses close to cut off limits, i.e. <5 mN (0.5 g) in the EMHG protocol, are less reproducible and must scientifically be considered as less reliable. The clinical cut off limits must remain unchanged for reasons of clinical safety. The outcome of quality measurements does not influence the test results. (Less)
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Contribution to journal
publication status
published
subject
in
Acta Anaesthesiologica Scandinavica
volume
46
issue
9
pages
1144 - 1149
publisher
Wiley-Blackwell
external identifiers
  • wos:000178337800014
  • pmid:12366511
  • scopus:0036785262
ISSN
0001-5172
DOI
10.1034/j.1399-6576.2002.460914.x
language
English
LU publication?
yes
id
b9763962-62d9-4106-8e07-3b1e9c45f629 (old id 110753)
alternative location
http://www.ncbi.nlm.nih.gov/sites/entrez?Db=pubmed&Cmd=ShowDetailView&TermToSearch=12366511&ordinalpos=5&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum
date added to LUP
2007-06-28 09:48:03
date last changed
2017-11-12 03:18:47
@article{b9763962-62d9-4106-8e07-3b1e9c45f629,
  abstract     = {BACKGROUND: 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-1 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 &lt; 5 mN (0.5 g) were reproducible in less than half of the tests. There was no difference in reproducibility or size of contractures between tests fulfillling all quality criteria and those not fulfillling these criteria. CONCLUSIONS: IVCT responses close to cut off limits, i.e. &lt;5 mN (0.5 g) in the EMHG protocol, are less reproducible and must scientifically be considered as less reliable. The clinical cut off limits must remain unchanged for reasons of clinical safety. The outcome of quality measurements does not influence the test results.},
  author       = {Islander, Gunilla and Ording, H and Bendixen, D and Ranklev Twetman, Eva},
  issn         = {0001-5172},
  language     = {eng},
  number       = {9},
  pages        = {1144--1149},
  publisher    = {Wiley-Blackwell},
  series       = {Acta Anaesthesiologica Scandinavica},
  title        = {Reproducibility of in vitro contracture test results in patients tested for malignant hyperthermia susceptibility.},
  url          = {http://dx.doi.org/10.1034/j.1399-6576.2002.460914.x},
  volume       = {46},
  year         = {2002},
}