新生儿脐血pH和BE影响因素的研究

目的通过大样本收集新生儿脐血血气，研究脐血血气统计学参考值范围与不同影响因素的相关关系。方法选择2012年5～11月广东省妇幼保健院和新会妇幼保健院产科出生的新生儿进行前瞻性研究，选取其中1rainApgar评分〉7分者的脐血血气结果进行统计分析，了解正常新生儿脐血血气的统计学参考值范围；重点分析影响新生儿脐血pH和BE的因素。结果2000例新生儿中，1min Apgar评分≤7分11例，〉7分1989例，低Apgar评分组pH〈7．2的比例为45．5％，正常Apgar评分组pH〈7．2的比例为3．5％，差异有统计学意义（P〈0．001）；1800例足月单胎、体重适于或大于胎龄新生儿中，1794例1min Apgar评分〉7分者脐血pH和BE的统计学参考值范围分别是7．34±0．14（X±1．96S）和-3．53±6．57（X±1．96s）。单因素分析显示，宫内窘迫组、妊娠期并发症组pH值均低于对照组，剖宫产组pH和BE值均高于阴道分娩组，脐带绕颈组pH值降低，双胎组BE值高于单胎组；羊水性状对pH、BE值均无影响。多因素分析显示，宫内窘迫、分娩方式均对脐血血气有影响。结论足月单胎、体重适于或大于胎龄新生儿中，1min Apgar评分〉7分者脐血pH值和BE值的统计学参考值范围分别是7．34±0．14和-3．53±6．57；Apgar评分与脐血血气分析具有一致性，但单独使用Apgar评分诊断早产儿窒息可能会增加窒息的误诊率；宫内窘迫可能会增加新生儿酸中毒的发生率，不同分娩方式对脐血血气pH、BE值均有影响。

Factors affecting umbilical blood gas pH and BE values

Objective To study the normal value range of umbilical blood gas of newborns and its affecting factors. Methods Total of 2000 newborns delivered at Guangdong Women ＆ Children＇s Hospital and Xinhui Women and Children＇s Hospital from May 2012 to November 2012 were enrolled for this prospective study. 1794 term born singletons, with weight of appropriate or large for gestational age （AGA or LGA） , and lmin Apgar scores 〉 7 were chosen to establish the normal values of umbilical blood gas range and the relationships of umbilical blood gas values to the newborn＇s Apgar score, gestational age, pregnant complications and the mode of delivery . Results Of the 2000 newborns, abnormal umbilical blood pH values with pH 〈7.2 were found in 45.5% of the 11 newborns born with 1 min Apgar score ≤ 7, however, in 3.5% of the 1989 newborns with 1 rain Apgar score 〉 7 （P 〈 0. 001 ）. The statistical normal ranges （x ± 1.96 s） of umbilical blood pH was （7.34 ± 0. 14） , and BE was （ - 3.53 ±6.57） mmol/L. Single factor analysis revealed that umbilical blood pH values in newborns with fetal distress and the pregnancy related complications were lower when comparing to the normal control group （P 〈 0.05）. Both pH and BE values in infants delivered by cesarean section were higher when comparing to the infants delivered vaginally. Infants with umbilical cord around neck had lower umbilical pH values. The BE value of the twins group was higher comparing to the singleton group. The characteristic of the amniotic fluid had no impact on pH and BE valsue of the umbilical blood. Multiple-factor analysis revealed that fetal distress and mode of delivery both had impacts on umbilical blood gas. Conclusions 1. The statistical ranges of umbilical cord blood gas values in AGA or LGA term singletons born with I min Apgar score 〉 7 were pH =7.34 ± 0. 14 and BE = （ -3.53 ± 6.57） mmol/L. 2. Although Apgar Score coincides with the umbilical blood gas results in the current study, using Apgar score alone for diagnose of asphyxia in premature infants may have increased false positive rates, thus combining umbilical blood gas results may increase the specificity of diagnosis. 3. Fetal distress may increase the incidence of neonatal acidosis. 4. Different modes of delivery have impacts on both pH and BE values.