Ngan Kee W D, Khaw K S, Ng F F
Department of Anaesthesia and Intensive Care, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong, China.
Br J Anaesth. 2004 Apr;92(4):469-74. doi: 10.1093/bja/aeh088. Epub 2004 Feb 20.
During spinal anaesthesia for Caesarean section, the optimal phenylephrine regimen and the optimal blood pressure (BP) to which it should be titrated are undetermined. The ideal regimen would balance efficacy for maintaining uteroplacental perfusion pressure against potential for uteroplacental vasoconstriction, both of which may affect fetal acid-base status. We compared phenylephrine infusion regimens based on three different BP thresholds.
After intrathecal injection, we infused phenylephrine 100 microg min(-1) for 2 min. Then, until delivery, we infused phenylephrine whenever systolic BP (SBP), measured every 1 min, was below a randomly assigned percentage of baseline: 100% (Group 100, n=25), 90% (Group 90, n=25) or 80% (Group 80, n=24). We compared umbilical blood gases, Apgar scores and maternal haemodynamics and symptoms.
Patients in Group 100 had fewer episodes [median 0 (range 0-8)] of hypotension (SBP <80% baseline) compared with Group 80 [5 (0-18)] and Group 90 [2 (0-7)] (P<0.001 in each instance). Total dose of phenylephrine was greater in Group 100 [median 1520 microg (interquartile range 1250-2130 microg)] compared with Group 90 [1070 (890-1360) microg] and Group 80 [790 (590-950) microg]. Umbilical arterial pH was greater in Group 100 [mean 7.32 (95% confidence interval 7.31-7.34)] than in Group 80 [7.30 (7.28-7.31)] (P=0.034). No patient had umbilical arterial pH <7.2. In Group 100, 1/24 (4%) patients had nausea or vomiting compared with 4/25 (16%) in Group 90 and 10/25 (40%) in Group 80 (P=0.006).
For optimal management, phenylephrine should be titrated to maintain maternal BP at near-baseline values.
剖宫产脊髓麻醉期间，去氧肾上腺素的最佳给药方案以及应将血压滴定至的最佳血压值尚未确定。理想的方案应在维持子宫胎盘灌注压的有效性与子宫胎盘血管收缩的可能性之间取得平衡，这两者均可能影响胎儿酸碱状态。我们比较了基于三种不同血压阈值的去氧肾上腺素输注方案。
鞘内注射后，我们以100μg·min⁻¹的速度输注去氧肾上腺素2分钟。然后，在分娩前，每当每1分钟测量一次的收缩压（SBP）低于随机分配的基线百分比时，我们就输注去氧肾上腺素：100%（100组，n = 25）、90%（90组，n = 25）或80%（80组，n = 24）。我们比较了脐血气、阿氏评分、产妇血流动力学和症状。
100组患者低血压（SBP<80%基线）发作次数较少[中位数0（范围0 - 8）]，与80组[5（0 - 18）]和90组[2（0 - 7）]相比（每次比较P<0.001）。100组去氧肾上腺素总剂量[中位数1520μg（四分位间距1250 - 2130μg）]大于90组[1070（890 - 1360）μg]和80组[790（590 - 950）μg]。100组脐动脉pH值[平均值7.32（95%置信区间7.31 - 7.34）]高于80组[7.30（7.28 - 7.31）]（P = 0.034）。没有患者脐动脉pH<7.2。100组中，1/24（4%）的患者出现恶心或呕吐，而90组为4/25（16%），80组为10/25（40%）（P = 0.006）。
为实现最佳管理，应滴定去氧肾上腺素以使产妇血压维持在接近基线值。
