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Homocysteine After Nitrous Oxide Anesthesia

This study has been completed.
ClinicalTrials.gov Identifier:
First Posted: June 5, 2007
Last Update Posted: June 5, 2007
The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details.
Information provided by:
Medical University of Vienna

Our study looks at the interaction of a common mutation in the MTHFR gene and the risk of developing higher homocysteine levels after nitrous oxide (N2O) anesthesia.

Specifically, we want to test the hypothesis that healthy patients carrying the MTHFR 677C>T haplotype develop abnormal homocysteine levels after nitrous oxide anesthesia.

Condition Intervention Phase
Anesthesia, General Adverse Effects Nitrous Oxide Drug: Nitrous oxide Phase 4

Study Type: Interventional
Study Design: Intervention Model: Single Group Assignment
Masking: None (Open Label)
Primary Purpose: Basic Science
Official Title: Influence of the MTHFR 677C>T Mutation on Homocysteine Levels After Nitrous Oxide Anesthesia.

Resource links provided by NLM:

Further study details as provided by Medical University of Vienna:

Primary Outcome Measures:
  • Homocysteine levels dependent on MTHFR genotype [ Time Frame: 2 years ]

Enrollment: 140
Study Start Date: January 2005
Study Completion Date: March 2007
Detailed Description:

Nitrous oxide – laughing gas – is a widely used anaesthetic gas with many favourable but also some dangerous properties. Among the latter is the increase in homocysteine levels after nitrous oxide (N2O) exposure by inhibition of enzymes in the vitamin B12 pathway. Elevated homocysteine levels have been found to be an independent risk factor for ischemic events and are associated with an increased risk for perioperative myocardial ischemia. If a patient carries one or more loss-of-function mutations in enzymes of the methionine/homocysteine/folate pathway he is at an increased risk for hyperhomocysteinemia and if exposed to N2O might suffer severe, sometimes disastrous neurological damage. Recently, a case report in the New England Journal of Medicine reported the death of a child with an enzyme defect in the MTHFR gene after anaesthesia with nitrous oxide (NEJM 2003;349:45-50).

Thus, we are convinced that if we can determine the risk of patients who carry mutations in the MTHFR gene and undergo anaesthesia with N2O for developing pathological levels of homocysteine, we can add an important piece of information to the safety profile of N2O.

Our study tests the hypothesis that patients who carry the 677C<T mutation in the MTHFR gene (the most common mutation) have a higher risk of developing hyperhomocysteinemia after N2O anaesthesia.


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Ages Eligible for Study:   18 Years and older   (Adult, Senior)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No

Inclusion Criteria:

  • Patient scheduled for general anaesthesia (> 2 hours)
  • Age > 18 years
  • ASA status I-II

Exclusion Criteria:

  • Pregnancy
  • Age < 18 years
  • contraindication against N2O: pneumothorax, mechanical bowel obstruction, middle ear occlusion, laparoscopic surgery
  • recent use of vitamin preps (B12, B6, folate)
  Contacts and Locations
Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT00482456

Dept of Anesthesiology, Medical University of Vienna
Vienna, Austria, A-1090
Sponsors and Collaborators
Medical University of Vienna
Principal Investigator: Peter Nagele, M.D. Medical University of Vienna
  More Information

Publications automatically indexed to this study by ClinicalTrials.gov Identifier (NCT Number):
ClinicalTrials.gov Identifier: NCT00482456     History of Changes
Other Study ID Numbers: EK 286/2004
First Submitted: June 1, 2007
First Posted: June 5, 2007
Last Update Posted: June 5, 2007
Last Verified: May 2007

Keywords provided by Medical University of Vienna:
Nitrous oxide
vitamin B12

Additional relevant MeSH terms:
Nitrous Oxide
Anesthetics, Inhalation
Anesthetics, General
Central Nervous System Depressants
Physiological Effects of Drugs
Analgesics, Non-Narcotic
Sensory System Agents
Peripheral Nervous System Agents