不同复苏氧浓度对宫内窘迫胎鼠脑细胞内外钙的影响

Cerebral intra and extra cellular calcium concentrations in asphyxiated rat fetuses resuscitated with oxygen of different concentrations

摘要:

目的：探讨窒息时复苏氧浓度与复苏效果的关系，找出较佳复苏氧浓度，改善窒息新生儿预后。方法：将56只胎龄为20 d的SD大鼠胎鼠随机分为5组，即假手术组(对照组)11只，空气复苏组(复苏组)10只，给予不同浓度氧和在不同时间内复苏的Ox1组14只，Ox2组11只和Ox3组10只。监测各组胎鼠脑细胞内外钙、钠、钾含量的变化。结果：复苏组与Ox1组(氧浓度92.8%)的脑细胞内游离钙离子浓度分别为(552.08±93.50) nmol/L和(520.61±79.08) nmol/L，两者相近(P>0.05)，但均明显高于对照组(315.27±86.88) nmol/L(P<0.01)。应用65%氧复苏时，在窒息缺氧前(Ox2组)和在窒息缺氧的同时(Ox3组)复苏者，其脑细胞内游离钙离子浓度分别为(441.46±47.93) nmol/L和(452.93±36.38) nmol/L，虽仍高于对照组，但明显低于空气复苏组(P<0.01)和Ox1组(P<0.05)。各组脑组织总钙、钠、钾含量基本上差异无显著性(P>0.05)。结论：不同氧浓度复苏，其效果不一样：应用 92.8% 氧或空气复苏，其复苏效果相似，提示临床上可考虑应用空气代替纯氧对窒息新生儿进行复苏；采用65% 氧复苏, 其复苏效果可能较纯氧或空气复苏更佳。

Abstract:

OBJECTIVE: To investigate the effects of resuscitation using oxygen of three concentrations on changes of cerebral intraand extracellular calcium, sodium and potassium in asphyxiated fetal rats. METHODS: Fifty-six fetal rats of twenty-day gestational age were randomly divided into five groups: sham operation (control, n=11), room-air resuscitation (n=10), and oxygen-resuscitated group Ｉ, Ⅱ, Ⅲ (n=14, 11, and 10 respectively) of different oxygen-inhaled concentrations and different oxygen timings. The fetal rats in the latter four groups suffered from ischemia and hypoxia in-uteri resulting from interruption of placental circulation. After recirculation, intra- and extra-cellular concentrations of calcium, sodium, and potassium in the brains were measured in each group. RESULTS: Intracellular free calcium concentrations of fetal rat brains in the room air resuscitation group and the oxygen-resuscitated group I (oxygen-inhaled concentration was 92.8%) were (552.08±93.50) nmol/L and (520.61±79.08) nmol/L respectively. They were similar and both significantly higher than those in the control (315.27±86.88) nmol/L (P<0.01). After resuscitation with 65% oxygen, no matter whether it started before (group Ⅱ) or at the beginning of hypoxia (group Ⅲ), their intracellular free calcium concentrations ［(441.46±47.93) nmol/L and (452.93±36.38) nmol/L respectively］ were significantly lower than those in the room-air resuscitation group (P<0.01) and group I (P<0.05), though still higher than those in the control. There was generally no difference in the total concentrations of calcium, sodium, or potassium among all groups. CONCLUSIONS: Resuscitation with oxygen of different concentrations produced different results: Resuscitation with 92.8% oxygen or room air had a similar effect on the parameters measured, indicating that resuscitation of asphyxiated neonates using pure oxygen might not be superior to that using room air; With lower cerebral intracellular calcium concentrations, resuscitation with 65% oxygen might produce a better outcome compared with that using pure oxygen or room air.