Krajewski W, Kucharska M, Pilacik B, Fobker M, Stetkiewicz J, Nofer J-R, Wronska-Nofer T
Department of Anaesthesia and Intensive Care Medicine, The Polish Mother Memorial Hospital, Lodz, Poland.
Br J Anaesth. 2007 Dec;99(6):812-8. doi: 10.1093/bja/aem280. Epub 2007 Oct 20.
Previous studies demonstrated inactivation of vitamin B12 by nitrous oxide (N(2)O). The intraoperative exposure to N(2)O was shown to induce megaloblastic anaemia and myelopathy in subjects with subclinical vitamin B12 deficiency. In contrast, no data concerning the influence of occupational exposure to N(2)O on vitamin B12 metabolic status are available to date. In the present study, the vitamin B12 status in operating theatre personnel was assessed in relation to the extent of exposure.
Ninety-five operating theatre nurses with the history of exposure to N(2)O and 90 unexposed counterparts were examined. Vitamin B12 and folic acid were measured by immunoassay. Total homocysteine (tHcy), an indicator of impaired vitamin B12 metabolism, was determined by high performance liquid chromatography. N(2)O concentration was monitored by adsorption gas chromatography and mass spectrometry.
No significant differences were found between both groups with respect to haematological parameters and folic acid. However, subjects exposed to N(2)O presented with lower vitamin B12 [372.8 (12.1) vs 436.8 (13.2) pmol litre(-1), P<0.001] and higher tHcy [11.2 (0.5) vs 8.9 (0.5) micromol litre(-1), P=0.006]. The changes in vitamin B12 status were aggravated in subjects exposed to N(2)O in concentrations substantially exceeding occupational exposure limit (180 mg m(-3)) [vitamin B12: 341.9 (17.7) vs 436.8 (13.2) pmol litre(-1), P=0.006; tHcy: 12.9 (0.7) vs 8.9 (0.5) micromol litre(-1), P=0.047].
Exposure to N(2)O in healthcare workers is associated with alterations of vitamin B12 metabolic status, the extent of which depends on the level of exposure.
先前的研究表明一氧化二氮（N₂O）可使维生素B₁₂失活。术中接触N₂O已被证明会在亚临床维生素B₁₂缺乏的受试者中诱发巨幼细胞贫血和脊髓病。相比之下，迄今为止尚无关于职业接触N₂O对维生素B₁₂代谢状态影响的数据。在本研究中，根据接触程度评估了手术室工作人员的维生素B₁₂状态。
对95名有接触N₂O史的手术室护士和90名未接触过的同行进行了检查。通过免疫测定法测量维生素B₁₂和叶酸。通过高效液相色谱法测定总同型半胱氨酸（tHcy），这是维生素B₁₂代谢受损的一个指标。通过吸附气相色谱法和质谱法监测N₂O浓度。
两组在血液学参数和叶酸方面未发现显著差异。然而，接触N₂O的受试者维生素B₁₂水平较低[372.8（12.1）对436.8（13.2）pmol/L，P<0.001]，tHcy水平较高[11.2（0.5）对8.9（0.5）μmol/L，P=0.006]。在接触N₂O浓度大幅超过职业接触限值（180mg/m³）的受试者中，维生素B₁₂状态的变化更为严重[维生素B₁₂：341.9（17.7）对436.8（13.2）pmol/L，P=0.006；tHcy：12.9（0.7）对8.9（0.5）μmol/L，P=0.047]。
医护人员接触N₂O与维生素B₁₂代谢状态的改变有关，其程度取决于接触水平。
