早产儿脐血维生素K依赖因子水平及产前补充维生素K1对其影响的研究

目的了解早产儿是否存在维生素(Vit)K依赖因子水平低下及其与早产儿脑室周围-脑室内出血的关系,探讨产前补充维生素(Vit)K1对早产儿血浆VitK依赖因子水平的影响及对脑室周围-脑室内出血的预防作用.方法将有早产可能且至分娩时孕周不足35周的孕妇分为两组对照组133例,在产前给予地塞米松注射;对照组44例,产前给予地塞米松+VitK1.两组早产儿各30例留取脐动脉血离心零下20℃以下保存用凝固法检测Ⅱ、Ⅶ、Ⅸ、Ⅹ等凝血因子活性水平,同时留取同期出生的健康足月新生儿30例脐血标本作对照.两组早产儿生后1周内常规作头颅超声检查以明确有无脑室周围-脑室内出血及其程度.结果早产儿与足月新生儿脐血VitK依赖因子活性水平分别为Ⅱ(25.6±9.5)%对(36.7±4.9)%,Ⅶ(59.0±17.7)%对(64.5±10.6)%,Ⅸ(24.7±8.9)%对(30.2±5.7)%,Ⅹ(30.2±5.0)%对(34.3±12.6)(P<0.05).母亲产前补充VitK1后其婴儿脐血VitK依赖因子水平分别为Ⅱ(36.4±6.9)%,Ⅶ(69.6±16.6)%,Ⅸ(25.7±10.9)%和Ⅹ(39.3±8.0)%,除Ⅸ因子外,Ⅱ、Ⅶ和Ⅹ因子活性均显著升高(P<0.05).脑室周围-脑室内出血发生率在对照组为52.6%,观察组为31.8%(χ2=5.744,P=0.017);重度出血对照组为12.0%,观察组为2.3%(χ2=3.626,P=0.057).结论早产儿存在VitK依赖因子水平低下,可能为其易于发生脑室周围-脑室内出血的原因之一.分娩前母亲补充VitK1可显著提高其血浆Ⅱ、Ⅶ和Ⅹ因子水平,并对脑室周围-脑室内出血有一定的预防作用.

Level of vitamin K-dependent coagulation factors in premature infants and the influence of maternal antenatal administration of vitamin K1 on their activity

OBJECTIVE: Infants less than 35 weeks of gestational age are susceptible to peri-/intraventricular hemorrhage (PIVH). This may be due in part to low concentrations of vitamin K-dependent coagulation factors. This study was conducted to determine the umbilical cord blood activities of vitamin K-dependent coagulation factors II, VII, IX and X in premature infants to understand whether preterm infants have absence status of these factors the changes of theses factors' activities in premature infants' umbilical blood after vitamin K(1) was given to mothers antenatally and the preventing effectiveness of PIVH after maternal antenatal supplement of vitamin K(1). METHODS: Pregnant women in preterm labor at less than 35 weeks of gestational age were randomly selected to receive antenatal vitamin K(1) intramuscular or intravenous injections 10 mg per day for 2 to 7 days (vitamin K(1) group), or no vitamin K(1) treatment (control group). Dexamethone was antenatally given to both groups of pregnant women routinely. Vitamin K(1) group had 44 infants and the control group had 133 infants. During the same period, thirty full-term neonates' cord blood samples were obtained to determine theses factors to compare with those from the premature infants. The cranial ultrasound was performed by a same physician to understand whether the neonates were complicated with PIVH and its severity. RESULTS: The levels of vitamin K-dependent coagulation factors in umbilical blood in control group were significantly lower than those in full-term infants' cord blood (P < 0.05). However, in vitamin K(1) group, supplement of vitamin K(1) antenatally could significantly increase activities of factors II, VII and X in preterm infants' cord blood (P < 0.05). The total occurrence rates of PIVH in vitamin K(1) group and control group were 31.8% and 52.6%, respectively, (P = 0.017), and the frequency of severe PIVH in vitamin K(1) group and control group was 2.3% and 12.0%, respectively (P = 0.057). CONCLUSION: Preterm infants have absence status of vitamin K-dependent coagulation factors. Administration of vitamin K(1) to pregnant women at less than 35 weeks of gestational age resulted in significantly improved activities of vitamin K-dependent coagulation factors II, VII, and X, and a significantly decreased frequency of PIVH and less severe hemorrhage in preterm infants.