title: Pre-operative vitamin B infusion and prevention of nitrous oxide-induced homocysteine increase.
abstract: Nitrous oxide inactivates vitamin B(12) with detrimental consequences for folate and methionine metabolism, detectable by an increase in total plasma homocysteine. We hypothesised that a pre-operative vitamin B(12) and folate infusion prevents nitrous oxide-induced homocysteine increase. Sixty-three healthy patients having elective surgery were randomly allocated to receive either B-vitamin plus nitrous oxide; placebo plus nitrous oxide or placebo plus air. Fifty-nine patients completed the study. After intravenous B-vitamin infusion, plasma vitamin B(12) and folate concentrations increased 35-fold and 12-fold, respectively, on the first postoperative measurement. Patients who received B-vitamins developed a similar increase (18%) in homocysteine after nitrous oxide (1.9 micromolxl(-1); 95% CI 0.2-3.6 micromolxl(-1)) as those who did not (22%; 2.7 micromolxl(-1); 95% CI 0.6-4.8 micromolxl(-1)). Patients not receiving nitrous oxide had no homocysteine change (0.5 micromolxl(-1); 95% CI -0.8-1.9 micromolxl(-1)), indicating that pre-operative intravenous B-vitamins may not prevent nitrous oxide-induced hyperhomocysteinaemia.
authors.affiliation: Department of Anesthesiology, Washington University, St Louis, MO, USA.
authors.forename: L K
authors.initials: LK
authors.lastname: Rao
authors.forename: A M
authors.initials: AM
authors.lastname: Francis
authors.forename: U
authors.initials: U
authors.lastname: Wilcox
authors.forename: J P
authors.initials: JP
authors.lastname: Miller
authors.forename: P
authors.initials: P
authors.lastname: Nagele
mesh_terms: D000328:Adult; D018685:Anesthetics, Inhalation / Q000009:adverse effects*; D004311:Double-Blind Method; D005260:Female; D005492:Folic Acid / Q000008:administration & dosage / Q000097:blood / Q000627:therapeutic use; D006710:Homocysteine / Q000097:blood; D006801:Humans; D020138:Hyperhomocysteinemia / Q000097:blood / Q000139:chemically induced / Q000517:prevention & control*; D008297:Male; D008875:Middle Aged; D009609:Nitrous Oxide / Q000009:adverse effects*; D011229:Preanesthetic Medication; D011446:Prospective Studies; D014805:Vitamin B 12 / Q000008:administration & dosage*; D014803:Vitamin B Complex / Q000008:administration & dosage*
chemical_list: D018685:Anesthetics, Inhalation; D006710:Homocysteine; D014803:Vitamin B Complex; D005492:Folic Acid; D009609:Nitrous Oxide; D014805:Vitamin B 12