心脏直视手术患儿主动脉开放前低钙血症对心肌缺血再灌注损伤的影响

目的 探讨心脏直视手术患儿主动脉开放前低钙血症对心肌缺血再灌注损伤的影响.方法 选择拟在体外循环下行房缺或室缺修补术患儿50例,年龄6月～4.5岁,体重5～15 kg,根据主动脉开放前血浆离子钙浓度,将患儿分为低钙组(＜1.0 mmol/L)和常钙组(≥I.0 mmol/L),观察2组患儿心脏复跳情况.分别于CPB前、停CPB后即刻、停CPB后12 h时抽取桡动脉血1.5 ml,测定血浆离子钙浓度和动脉血气;于上述时点同时抽取中心静脉血3 ml,测定血浆肌钙蛋白I(cTnI)浓度.结果 在主动脉开放前患儿低钙血症发生率为72%,低钙组较常钙组患儿年龄小,体重轻(P＜0.05),而心脏复跳时间、室颤率、辅助循环时间、拔除气管导管时间、ICU监护时间和血浆cTnI浓度两组间差异无统计学意义(P＞0.05).结论 体外循环心脏直视手术患儿主动脉开放前低钙血症对心肌缺血再灌注损伤无影响.

Effects of low plasma ionized calcium concentration before aortic unclamping on myocardial reperfusion injury during cardiopulmonary bypass in children undergoing open heart surgery

Objective To investigate the effects of low plasma ionized calcium concentration before aortic unclamping on myocardial reperfusion injury during cardiopulmonary bypass (CPB) in children undergoing open heart surgery.Methods Fifty children of both sexes (30 male,20 female) aged 6 months-4.5 yr weighing 5-15 kg undergoing repair of atrial or ventricular septal defect under CPB were divided into 2 groups based on the plasma ionized calcium concentration before aortic unclamping:group I low ionized calcium(<1.0 retool/L)(L) and groupⅡ normal ionized calcium(≥1.0mmol/L)(N).Cardiac performance after aortic unclamping was recorded.Blood samples were taken simultaneously from radial artery and central vein for blood gas analysis,and determination of blood electrolytes,plasma concentrations of ionized calcium and troponin I(cTnl)before CPB(To,baseline),immediately (TI) and 12 h after termination of CPB(T2).Results The plasma concentration of ionized calcium was low before aortic unclamping in 72% patients.The patients were younger and their body weights lower in group L than in group N.but there was no significant difference in the recovery time of spontaneous heart beat,rate of ventricular fibrination,time of assisted cireulafion,extubation time,duration of ICU stay and plasma concentration of cTnl between the two groups.Conclusion Decrease in plasma concentration of ionized calcium to some extent.before aortic unelamping during CPB does not attenuate myocardial reperfusion injury in children undergoing open heart surgery.