Center for Women's Reproductive Health and the Departments of Obstetrics and Gynecology and Biostatistics, the University of Alabama at Birmingham, Birmingham, Alabama.
Obstet Gynecol. 2014 Nov;124(5):926-932. doi: 10.1097/AOG.0000000000000517.
To assess the utility of umbilical cord venous blood gas measures for prediction of umbilical artery pH and base deficit acidemia.
A retrospective cohort study was conducted of all singletons with valid paired arterial and venous cord gas samples delivered at our institution from January 2006 to March 2012. Fetal acidemia was defined primarily as cord arterial blood gas pH less than 7.0. We also evaluated prediction of acidemia, defined as an arterial base deficit 12 mmol/L or greater. Logistic regression was performed to estimate probabilities of fetal arterial pH and base deficit acidemia given venous blood gas pH or base deficit. Receiver operating characteristic curves were derived to determine predictive ability. Venous blood gas pH and base deficit cutoffs associated with 1% or less, 5%, 10%, and 50% probability of fetal acidemia were identified.
Of 23,506 births, 11,455 (49%) met criteria for inclusion. The frequency of arterial blood gas pH less than 7.0 was 127 (1.1%); arterial blood gas base deficit 12 mmol/L or greater was 245 (2.1%). Venous blood gas pH (area under the curve [AUC] 0.949, 95% confidence interval [CI] 0.920-0.979; P<.001) and base deficit (AUC 0.969, 95% CI 0.954-0.983; P<.001) were predictors of acidemia based on arterial blood gas pH and base deficit, respectively. Venous blood gas pH cutoffs associated with 1% or less, 5%, or 10% probabilities of arterial blood gas pH less than 7.0 were 7.23, 7.17, and 7.14, respectively. Venous blood gas base deficit values associated with similar probabilities for base deficit 12 mmol/L or greater were 6.3 or less, 8.2 or less, and 9.0 mmol/L or less. For prediction of arterial blood gas pH, adjusting venous blood gas pH for base deficit increased the AUC (0.961, 95% CI 0.938-0.984). Prediction of arterial blood gas base deficit by venous blood gas base deficit was unchanged by adjustment for pH (AUC 0.969, 95% CI 0.955-0.984).
We demonstrate that venous blood gas parameters are powerful predictors of arterial blood gas pH and base deficit and can be used to predict the likelihood of fetal acidemia when the cord arterial blood gas is not available.
评估脐静脉血气指标对预测脐动脉 pH 值和碱缺失性酸中毒的效用。
本回顾性队列研究纳入了 2006 年 1 月至 2012 年 3 月在我院分娩且具有有效配对动静脉脐带血气样本的所有单胎妊娠。胎儿酸中毒主要定义为脐带动脉血气 pH 值小于 7.0。我们还评估了酸血症的预测，定义为动脉碱缺失大于 12 mmol/L。采用逻辑回归估计静脉血气 pH 值或碱缺失与胎儿动脉 pH 值和碱缺失性酸中毒的概率。绘制受试者工作特征曲线以确定预测能力。确定与胎儿酸中毒 1%或更低、5%、10%和 50%概率相关的静脉血气 pH 值和碱缺失截断值。
在 23506 例分娩中，有 11455 例（49%）符合纳入标准。动脉血气 pH 值小于 7.0 的发生率为 127 例（1.1%）；动脉血气碱缺失大于 12 mmol/L 的发生率为 245 例（2.1%）。静脉血气 pH 值（曲线下面积[AUC] 0.949，95%置信区间[CI] 0.920-0.979；P<.001）和碱缺失（AUC 0.969，95%CI 0.954-0.983；P<.001）分别是基于动脉血气 pH 值和碱缺失的酸血症的预测因素。与动脉血气 pH 值小于 7.0 的 1%或更低、5%或 10%概率相关的静脉血气 pH 值截断值分别为 7.23、7.17 和 7.14。与类似概率的动脉血气碱缺失大于 12 mmol/L 相关的静脉血气碱缺失值分别为 6.3 或更低、8.2 或更低和 9.0 mmol/L 或更低。对于动脉血气 pH 值的预测，静脉血气 pH 值校正碱缺失后 AUC 增加（0.961，95%CI 0.938-0.984）。静脉血气碱缺失预测动脉血气碱缺失不受 pH 值校正的影响（AUC 0.969，95%CI 0.955-0.984）。
我们证明了静脉血气参数是动脉血气 pH 值和碱缺失的有力预测指标，当脐带动脉血气不可用时，可用于预测胎儿酸中毒的可能性。
