Holcroft Cynthia J, Graham Ernest M, Aina-Mumuney Abimbola, Rai Karishma K, Henderson Janice L, Penning Donald H
Department of Gyn-Ob, Division of Maternal-Fetal Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA.
J Perinatol. 2005 Apr;25(4):229-35. doi: 10.1038/sj.jp.7211245.
Our primary objective was to examine the relationship between umbilical arterial gas analysis and decision-to-delivery interval for emergency cesareans performed for nonreassuring fetal status to determine if this would validate the 30-minute rule.
For this retrospective cohort study, all cesarean deliveries performed for nonreassuring fetal status from September 2001 to January 2003 were reviewed. A synopsis of clinical information that would have been available to the clinician at the time of delivery and the last hour of the electronic fetal heart rate tracing prior to delivery were reviewed by three different maternal-fetal medicine specialists masked to outcome, who classified each delivery as either emergent (delivery as soon as possible) or urgent (willing to wait up to 30 minutes for delivery) since immediacy of the fetal condition is the key factor affecting the type of anesthesia used.
Of 145 cesareans performed for nonreassuring fetal status during this period, 117 patients met criteria for entry, of which 34 were classified as emergent and 83 as urgent. Kappa correlation was 0.35, showing only fair/moderate agreement between reviewers. In the emergent group, general anesthesia was more common (35.3%, 10.8%, p=0.003), and the decision-to-delivery interval was 14 minutes shorter (23.0+/-15.3, 36.7+/-14.9 minutes, p<0.001). Linear regression showed a statistically significant relationship between increasing decision-to-delivery interval and umbilical arterial pH (r=0.22, p=0.02) and base excess (r=0.33, p<0.001) showing that delivery proceeded sooner for most of those with the worst cord gases, with a gradual improvement over time. For the 13 (11%) neonates with cord gases placing them at increased risk for long-term neurologic sequelae, the decision-to-delivery interval was 24.7+/-14.6 minutes (range 6 to 50 minutes), and 3/13 (23%) were classified as urgent rather than emergent.
Electronic fetal monitoring shows considerable variation in interpretation among maternal-fetal medicine specialists and is not a sensitive predictor of the fetus developing metabolic acidosis. There is no deterioration in cord gas results after 30 minutes, and most neonates delivered emergently or urgently for nonreassuring fetal status even when born after 30 minutes have normal cord gases. The 30-minute rule is a compromise that reflects the time it takes the fetus to develop severe metabolic acidosis, our imprecision in its identification, and its rarity in the presence of nonreassuring fetal monitoring.
我们的主要目的是研究脐动脉血气分析与因胎儿状况不佳而行急诊剖宫产时的决定分娩间隔之间的关系，以确定这是否能验证30分钟规则。
在这项回顾性队列研究中，对2001年9月至2003年1月期间因胎儿状况不佳而行的所有剖宫产进行了回顾。三位不同的母胎医学专家在不知道结果的情况下，回顾了分娩时临床医生可获得的临床信息概要以及分娩前最后一小时的电子胎心监护图，他们根据胎儿状况的紧迫性将每次分娩分为紧急（尽快分娩）或紧急（愿意等待长达30分钟分娩），因为胎儿状况的紧迫性是影响所用麻醉类型的关键因素。
在此期间因胎儿状况不佳而行的145例剖宫产中，117例患者符合纳入标准，其中34例被分类为紧急，83例为紧急。kappa相关性为0.35，显示评审员之间只有中等程度的一致性。在紧急组中，全身麻醉更为常见（35.3%对10.8%，p = 0.003），决定分娩间隔缩短14分钟（23.0±15.3对36.7±14.9分钟，p < 0.001）。线性回归显示，决定分娩间隔增加与脐动脉pH值（r = 0.22，p = 0.02）和碱剩余（r = 0.33，p < 0.001）之间存在统计学上的显著关系，表明对于大多数脐带血气最差的患者，分娩进行得更快，且随着时间的推移逐渐改善。对于13例（11%）脐带血气使其有增加长期神经后遗症风险的新生儿，决定分娩间隔为24.7±14.6分钟（范围6至50分钟），13例中有3例（23%）被分类为紧急而非紧急。
电子胎儿监护在母胎医学专家之间的解读存在很大差异，不是胎儿发生代谢性酸中毒的敏感预测指标。30分钟后脐带血气结果没有恶化，即使在30分钟后出生，大多数因胎儿状况不佳而紧急或紧急分娩的新生儿脐带血气正常。30分钟规则是一种折衷，反映了胎儿发生严重代谢性酸中毒所需的时间、我们在识别方面的不精确性以及在胎儿监护不佳情况下的罕见性。
