Badner N H, Freeman D, Spence J D
Department of Anesthesiology, Clinical Pharmacology, University of Western Ontario, London, Ontario, Canada.
Anesth Analg. 2001 Dec;93(6):1507-10, table of contents. doi: 10.1097/00000539-200112000-00034.
Nitrous oxide increases total homocysteine (tHcy) plasma levels, which are associated with an increase in perioperative myocardial ischemia. We designed this study to determine whether oral B vitamins, which are cofactors in homocysteine metabolism, can prevent nitrous oxide anesthesia-induced tHcy increases in patients undergoing elective surgery scheduled to last longer than 3 h. Fifty-three patients presenting for elective revision knee or hip arthroplasty received in random, double-blinded fashion oral vitamin B complex (folate 2.5 mg, B(6) 25 mg, and B(12) 500 microg) or placebo daily for 1 wk before surgery. Anesthesia was induced with propofol and maintained with an opioid, isoflurane, and nitrous oxide/oxygen (inspired nitrous oxide >50%). Blood samples for measurement of tHcy concentration were obtained at study enrollment, before induction, on arrival in the postanesthesia care unit, and on Day 5. Fourteen patients had their surgery rescheduled after taking their vitamins and were removed from the study. The Placebo group had a mean increase in tHcy concentration from baseline of 15% +/- 31% compared with the Vitamin group, which had an initial decrease of 9.1% +/- 11% (P = 0.035). This was maintained throughout the 5-day study period. The use of an oral B vitamin complex prevented the increase in postoperative tHcy by nitrous oxide.
The use of nitrous oxide anesthesia increases postoperative homocysteine concentrations and associated myocardial ischemia. This study indicates that a 1-wk course of oral B vitamins can prevent the increase in homocysteine from nitrous oxide, and, by implication, myocardial ischemia as well.
氧化亚氮会使血浆总同型半胱氨酸（tHcy）水平升高，这与围手术期心肌缺血增加有关。我们设计本研究以确定作为同型半胱氨酸代谢辅助因子的口服B族维生素是否能预防在计划持续时间超过3小时的择期手术患者中氧化亚氮麻醉引起的tHcy升高。五十三名接受择期膝关节或髋关节翻修置换术的患者在手术前1周以随机、双盲方式每日接受口服复合维生素B（叶酸2.5毫克、维生素B6 25毫克和维生素B12 500微克）或安慰剂。麻醉诱导采用丙泊酚，维持采用阿片类药物、异氟烷和氧化亚氮/氧气（吸入氧化亚氮>50%）。在研究入组时、诱导前、到达麻醉后护理单元时以及第5天采集血样以测定tHcy浓度。十四名患者在服用维生素后手术被重新安排并退出研究。安慰剂组tHcy浓度较基线平均升高15%±31%，而维生素组最初下降9.1%±11%（P = 0.035）。在整个5天研究期间均维持这一差异。口服复合维生素B可预防氧化亚氮引起的术后tHcy升高。
使用氧化亚氮麻醉会增加术后同型半胱氨酸浓度及相关的心肌缺血。本研究表明，为期1周的口服B族维生素疗程可预防氧化亚氮引起的同型半胱氨酸升高，由此也可预防心肌缺血。
