逐级增氧体外循环防止再氧合损伤的作用与安全性评价

The role of graded reoxygenation with cardiopulmonary bypass in prevention of reoxygenation injury and its safety.

目的研究逐级增氧体外循环方法防止紫绀型先天性心脏病患儿再氧合损伤的作用,并对其安全性进行评价。方法选择20例紫绀型先天性心脏病患儿,按照体外循环给氧方法随机分成2组,第一组常规高分压氧体外循环组(10例),体外循环均采用100%氧气预充和转流;第二组逐级增氧体外循环组(10例),体外循环采用正常氧浓度(21%)预充转流,5～10min逐渐提高至30%～60%氧气进行体外循环全程灌注。在体外循环开始前,开始后1、5和10min,分别测定血液中心肌肌钙蛋白(TnI)、脑S100β蛋白(S100)、丙二醛含量,同时采用近红外光谱分析仪观察逐级增氧过程中脑组织氧合血红蛋白(HbO2)和氧化细胞色素aa3(CytOx)变化,并测定颈内静脉乳酸含量,同时观察临床指标。结果体外循环前,两组TnI、S100β和MDA含量均在正常水平,差异无统计学意义;体外循环开始后三者均上升。血清TnI含量在体外循环开始1、5min时逐级增氧组升高水平低于高分压氧组,差异有统计学意义(均P<0.01);血清S100β含量在体外循环开始1、5和10min时,逐级增氧组均低于高分压氧组,5min和10min时差异有统计学意义(均P<0.05);血清MDA含量在体外循环开始1、5和10min时,逐级增氧组均低于高分压氧组,差异均有统计学意义(均P<0.05)。

Objective To investigate the role of graded reoxygenation with cardiopulmonary bypass(CPB) in prevention of reoxygenation injury in children with cyanotic congenital heart defects, and to evaluate its safety. Methods Twenty pediatric patients with cyanotic congenital heart defect were randomly divided into 2 equal groups according to CPB methodology: group1, undergoing routine hyperoxic CPB with CPB primed and initiated at FiO_2 of 1.0, and group 2 undergoing modified CPB with graded reoxygenation (CPB was primed and initiated at FiO_2 of 0.21 and the FiO_2 was increased slowly to 30% to 60% over the next 5 to 10 minutes). Serum troponin 1 (TnI), S100β protein, and malondialdehyde(MDA) were measured before CPB, and 1 minute,5 minutes, and 10 minutes after CPB. Near infrared spectroscopy (NIRS) was applied to evaluate the cerebral oxygenated hemoglobin (HbO_2) and oxidized cytochrome aa3 (CytOx) and jugular venous lactate was measured during the reoxygenation period. Clinical indexes were observed. Results Before CPB the TnI,S100β, and MDA levels in these 2 groups were all normal without significant differences between them. After initiation of CPB the TnI,S100β, and MDA levels in the two groups began to increase. The serum Tn1 levels 1 minute and 5 minutes after the initiation of CPB of the group 1 were significant lower than those of the group 2 (both P<0.01). The serum S100β levels 1, 5, and 10 minutes after the initiation of CPB in the group 2 were all lower than those of the group 1 and there were significant differences between these 2 group 5 and 10 minutes after (both P<0.05). The serum MDA levels 1, 5, and 10 minutes of the group 1 were significantly higher than those of the group 2 (all P<0.05). NIRS showed that HbO_2 decreased slightly because of hemodilution when CPB was begun, and then increased rapidly 2 minutes after the initiation of CPB; and CytOx decreased progressively during the reoxygenation period, however, without significant difference between these 2 groups. The serum lactate level was markedly increased 1 minute after the initiation of CPB and then gradually decreased through the reoxygenation period, however, without significant differences between these 2 groups. There was no significant difference between the two groups in clinical observation. Conclusion Not damaging the cerebral aerobic metabolism, graded reoxygenation with CPB can reduce the extent of reoxygenation injury of routine hyperoxic CPB and is an easy, effective, and safe CPB strategy.