中国高原地区(拉萨)产妇产程吸氧对分娩的影响

Effect of oxygen inhalation during labor on delivery in parturients of Lhasa of China

目的探讨在高原地区,给予产妇产程吸氧对分娩的影响。方法选取2008年5月在西藏拉萨市妇幼保健院产科住院分娩的无产科合并症40名产妇为观察组,选取2007年同期5月曾在拉萨市妇幼保健院住院分娩、无产科合并症、产程未吸氧的59名产妇为对照组。观察组在确认其宫口开全、进入第二产程后给予双鼻导管持续管道氧气吸入,氧气流量为2～3 L/min,直至胎儿娩出。将吸氧观察组与不吸氧对照组进行比较,观察分析吸氧对分娩的影响。同时观察组记录吸氧前产妇的心率、血氧饱和度,及吸氧10 min后的心率及血氧饱和度的数值,对进行吸氧前后的自身比较,来观察吸氧对产妇生理指标的影响。结果①观察组与对照组产妇的一般情况即年龄、藏族构成比、孕次、产次、产检次数、分娩孕周比较差异无统计学意义;生理指标如心率、平均动脉压和血红蛋白含量差异也无统计学意义。②观察组第二产程时间(32.51±22.80)min,产后出血量为(211.25±95.06)mL,侧切率为55%(22/40),羊水污染率为20%(8/40);对照组第二产程时间为(32.27±25.98)min,产后出血量为(248.47±107.62)mL,侧切率为38.98%(23/59),羊水污染率为35.59%(21/59)。2组数据差异无统计学意义。观察组新生儿1分钟阿氏评分为8.200±0.687,5分钟阿氏评分为9.23±0.53,对照组新生儿1分钟阿氏评分为8.14±0.81,5分钟阿氏评分为9.20±0.61,差异无统计学意义。新生儿体质量、身长,胎儿附属物包括胎盘的体积、脐带的长度、脐带绕颈的比例等2组数据差异均无统计学意义。③观察组吸氧前血氧饱和度SO2为(93.40±3.23)%,吸氧后的SO2为(96.58±1.62)%,平均上升3.18%,差异有统计学意义。吸氧前心率(heart beat rate,HR)为(83.50±10.86)次/分,吸氧后的HR为(77.75±9.12)次/分,平均每分钟下降5.75次,差异有统计学意义。结论久居高原的妇女通过机体适应性改变,已经能够适应高原的缺氧环境。产妇即使在第二产程机体耗氧量最大时,通过机体的代偿反应,也能够保证机体的供氧,不至于由于缺氧影响子宫收缩造成产程延长以及引起产后出血量的增加。同时高原地区产妇子宫动脉及胎盘也发生了一系列适应性改变,以适应高原的缺氧环境保证胎儿的供应,在第二产程过程中不会出现因高原低氧分压引起新生儿窒息发生的可能增加。因此,对于正常的产妇产程过程没有缺氧表现,第二产程吸氧不改变产程的时间,也对新生儿的评分没有明显的影响,无需常规吸氧。但是,由于高原特有的低氧环境会对人体心脏产生普遍的负面影响,吸氧可以提高机体氧气的供给,减轻母体的代偿反应,这对高原地区的产妇的心脏具有一定的保护作用,尤其是那些心脏已经发生高原性病理改变的产妇。

Objective To investigate the effect of oxygen inhalation during labor on delivery in high altitude area（Lhasa of China）. Methods Forty parturients who had no obstetric complications and would have term delivery in May 2008 in Lhasa Maternal and Child Health Care Hospital were recruited as study group.Forty-nine parturients of term delivery in the same month in 2007 were taken as control group.When parturients in the study group entered the second stage of labor,they had oxygen inhalation via double nasal catheter at 2L-3L/min till fetal delivery.The data of delivery were recorded to compare with the control group.The heart rate and oxygen saturation（SO2） were also recorded before oxygen inhalation and after 10 minutes of inhalation to study the effect of oxygen inhalation on these data. Results ① There were no significant difference in general status including age,the proportion of the tibetan ethnicity,gravida,parity,antenatal care,age of gestation,mean arterial pressure（MAP）,heart beat rate（HR） and hemoglobin（Hb） between the two groups.② Time of the second stage was（32.51±22.8）min,the volume of postpartum hemorrhage was（211.25±95.06）mL,the ratio of lateral episiotomy was 55%（22/40）,the ratio of amniotic fluid contamination was 20%（8/40） in study group.In the control group,time of the second stage was（32.27±25.98）min,the volume of postpartum hemorrhage was（248.47±107.62）mL,the ratio of lateral episiotomy 38.98%（23/59）,the ratio of the amniotic fluid contamination was 35.59%（21/59）.There was no significant difference in each corresponding data between the two groups.At the same time,the data of newborns including the Apgar score at 1 minute and at 5 minutes after birth,weight,length and the data of placenta including volume,length of umbilical cord,the ratio of cord around neck had no significant difference,either.③ The HR was（77.75±9.12） beats per min after oxygen inhalation in the study group,that was significantly lower than HR before（84.29±2.3） beats per min（P=0.000）.SO2 after oxygen inhalation in the study group was（96.58±1.62）%,which was significantly higher than that（93.40±3.23）% before oxygen inhalation（P=0.000）. Conclusion Parturients who live in the highland for long time have already adapted to the low pressure of oxygen.Even in the second stage of labor,with the compensation of the parturient,parturient would fulfill the delivery successfully.Oxygen inhalation during the second stage of labor did not change the labor.So for normal parturient that have no sign of hypoxia,there is no need for oxygen inhalation.But it is generally believed that the lower oxygen pressure of highland give some negative influence on the heart.Oxygen inhalation can increase the supplement of oxygen for the body,and then reduce the reaction of compensation when the oxygen consumption increases.This action can protect the parturient heart in the high altitude area especially for those whose hearts have already shown some evidence of the negative influence of high altitude.