目的:胎儿心率的减速面积(DA)和容量(DC)可以帮助预测产时胎儿受损的风险。然而,其在高危妊娠中的预测价值尚不清楚.我们调查了他们是否可以预测在短暂的低氧血症重复期间低血压的发作,其发生率与先前存在低氧血症的胎羊的早期分娩一致。
方法:前瞻性,对照研究设置:实验室样本:慢性仪器,未麻醉的近期胎羊研究设计:在基线paO2<17mmHg(低氧血症,n=8)和>17mmHg(常氧,n=11)持续4h或直到动脉压下降<20mmHg。
方法:DA,DC和动脉压结果:常氧胎儿显示出有效的心血管适应,而没有低血压和轻度酸血症(最低动脉压40.7±2.8mmHg,pH7.35±0.03)。低血胎儿出现低血压(最低动脉压20.8±1.9mmHg,p<0.001)和酸血症(最终pH7.07±0.05)。在低氧血症胎儿中,减速显示FHR在前40s的UCOs中下降更快,但最终减速深度与常氧胎儿没有差异.在UCOs的倒数第二个(p=0.04)和最后一个(p=0.012)20分钟期间,低氧血症胎儿的DC略有升高。组间DA没有差异。
结论:慢性低氧血症胎儿在类似分娩的短暂重复UCOs中早期出现心血管损害。DA无法确定在这种情况下会出现低血压,而DC仅显示组间的适度差异。这些发现强调,DA和DC阈值需要根据产前风险因素进行调整,有可能限制其临床应用。
Deceleration area (DA) and capacity (DC) of the fetal heart rate can help predict risk of intrapartum fetal compromise. However, their predictive value in higher risk pregnancies is unclear. We investigated whether they can predict the onset of hypotension during brief hypoxaemia repeated at a rate consistent with early labour in fetal sheep with pre-existing hypoxaemia.
Prospective, controlled study.
Laboratory.
Chronically instrumented, unanaesthetised near-term fetal sheep.
One-minute complete umbilical cord occlusions (UCOs) were performed every 5 minutes in fetal sheep with baseline pa O2 <17 mmHg (hypoxaemic, n = 8) and >17 mmHg (normoxic, n = 11) for 4 hours or until arterial pressure fell <20 mmHg.
DA, DC and arterial pressure.
Normoxic fetuses showed effective cardiovascular adaptation without hypotension and mild acidaemia (lowest arterial pressure 40.7 ± 2.8 mmHg, pH 7.35 ± 0.03). Hypoxaemic fetuses developed hypotension (lowest arterial pressure 20.8 ± 1.9 mmHg, P < 0.001) and acidaemia (final pH 7.07 ± 0.05). In hypoxaemic fetuses, decelerations showed faster falls in FHR over the first 40 seconds of UCOs but the final deceleration depth was not different to normoxic fetuses. DC was modestly higher in hypoxaemic fetuses during the penultimate (P = 0.04) and final (P = 0.012) 20 minutes of UCOs. DA was not different between groups.
Chronically hypoxaemic fetuses had early onset of cardiovascular compromise during labour-like brief repeated UCOs. DA was unable to identify developing hypotension in this setting, while DC only showed modest differences between groups. These findings highlight that DA and DC thresholds need to be adjusted for antenatal risk factors, potentially limiting their clinical utility.