Chang Kyung-ho, Bougaki Masahiko, Kubota Ryou, Tsubaki Kumiko, Matsuo Hideki, Hanaoka Kazuo
Department of Anesthesia, Showa General Hospital, Tokyo 187-8510.
Masui. 2003 Apr;52(4):356-62.
Although there is growing evidence to suggest that magnesium supplementation to patients undergoing cardiac surgery is beneficial, the way to administer magnesium is not established. Moreover in Japan St Thomas' cardioplegic solution, containing a high level of magnesium is widely used and the effect of such magnesium-rich cardioplegic solutions on blood magnesium concentration has not been well defined.
We measured ionized magnesium concentrations (iMg) during cardiac surgery employing St Thomas' solution. Patients were divided into four groups. Group 1 patients were adults and group 2 were children, both of whom received St. Thomas' solution. Group 3 patients underwent cardiopulmonary bypass but did not receive any cardioplegic solution. Group 4 patients underwent off-pump coronary artery bypass grafting.
In cardioplegia group (group 1 and 2) iMg was higher than the normal reference range at periods of rewarming, immediately postbypass, and at the end of the operation. iMg at immediately postbypass was related to the total amount of cardioplegic solution. In non-cardioplegia group (group 3 and 4) progressive decrease of iMg was observed throughout the operation.
Because magnesium in cardioplegic solutions has substantial effect on perioperative iMg, it is crucial to measure iMg to avoid overdose of magnesium when magnesium-rich cardioplegic solutions are employed.
尽管越来越多的证据表明，对接受心脏手术的患者补充镁有益，但镁的给药方式尚未确定。此外，在日本，含有高浓度镁的圣托马斯心脏停搏液被广泛使用，而这种富含镁的心脏停搏液对血镁浓度的影响尚未明确界定。
我们在使用圣托马斯溶液进行心脏手术期间测量了离子镁浓度（iMg）。患者分为四组。第1组患者为成年人，第2组为儿童，两组均接受圣托马斯溶液。第3组患者接受体外循环，但未接受任何心脏停搏液。第4组患者接受非体外循环冠状动脉搭桥术。
在心脏停搏组（第1组和第2组）中，复温期、体外循环后即刻及手术结束时的iMg高于正常参考范围。体外循环后即刻的iMg与心脏停搏液总量相关。在非心脏停搏组（第3组和第4组）中，整个手术过程中iMg呈逐渐下降趋势。
由于心脏停搏液中的镁对围手术期iMg有显著影响，因此在使用富含镁的心脏停搏液时，测量iMg以避免镁过量至关重要。
