Westmead Hospital, Department of Neonatology, Westmead, New South Wales, Australia.
The University of Sydney, Sydney, New South Wales, Australia.
Transfusion. 2019 Oct;59(10):3093-3101. doi: 10.1111/trf.15452. Epub 2019 Jul 16.
Red blood cell (RBC) transfusion is a standard treatment for anemia of prematurity. Cerebral tissue oxygenation and blood flow velocities improve when a restrictive transfusion threshold is followed, but little is known about the effect of practicing a liberal transfusion threshold on cerebral tissue oxygenation, cerebral blood flow velocities, and cardiac output measurements.
A prospective observational study of preterm infants under 32 weeks' gestation who received RBC transfusion. Monitoring was performed immediately before, immediately after, and 24 hours after transfusion. Data obtained included physiologic parameters, cerebral tissue oxygenation index (TOI), anterior and middle cerebral artery pulsed Doppler ultrasound measurements, and cardiac output measurements. Data were analyzed using analysis of variance for repeated measures.
Fifty RBC transfusion episodes in 40 preterm infants were monitored. The mean gestational age was 26.72 weeks (±1.6 weeks), and the mean birth weight was 855.25 g (±190.7 g). We did not observe significant changes in cerebral TOI (pretransfusion mean TOI = 70.5 [11.54], immediately after transfusion = 71.38 [12.51], [p = 0.924; 95% confidence interval (CI), -4.64 to 6.39], and 24 hours after transfusion = 75.64 [14.4]; [p = 0.07; 95% CI, -0.37 to 10.65]), cerebral fractional tissue oxygen extraction (pretransfusion = 0.25 [0.12], immediately after transfusion = 0.24 [0.13], and 24 hours after transfusion = 0.20 [0.15]), cerebral resistive index, cerebral pulsatility index, or right ventricular output. Statistically significant changes were observed immediately after transfusion in peak systolic velocity, end-diastolic velocity and time-averaged maximum velocity in the cerebral arterial circulation. Left ventricular output (pretransfusion = 374.32 mL/kg/min, immediately after transfusion = 346.67 mL/kg/min [p = 0.000; 95% CI, -39.61 to -15.68], and 24 hours after transfusion = 361.17 mL/kg/min [p = 0.027; 95% CI, -25.11 to -1.18]) and heart rate (pretransfusion = 163.37 [9.49], immediately after transfusion = 157.29 [10.2] [p = 0.000; 95% CI, -8.96 to -3.20], and 24 hours after transfusion = 160.40 [10.4] [p = 0.041; 95% CI, -5.85 to -0.09]) showed statistically significant changes throughout the monitoring period.
Our findings show that practicing liberal transfusion thresholds did not improve cerebral TOI in preterm infants who have mild anemia, but it did improve the compensatory response in cerebral arterial blood flow and cardiac output.
红细胞（RBC）输血是治疗早产儿贫血的标准治疗方法。遵循限制性输血阈值可改善脑组织氧合和脑血流速度，但对于实践宽松输血阈值对脑组织氧合、脑血流速度和心输出量测量的影响知之甚少。
对接受 RBC 输血的妊娠 32 周以下的早产儿进行前瞻性观察性研究。输血前、输血后立即和输血后 24 小时进行监测。获得的数据包括生理参数、脑组织氧指数（TOI）、前中脑动脉脉冲多普勒超声测量值和心输出量测量值。使用重复测量方差分析对数据进行分析。
40 名早产儿的 50 次 RBC 输血事件进行了监测。平均胎龄为 26.72 周（±1.6 周），平均出生体重为 855.25 克（±190.7 克）。我们没有观察到脑 TOI 明显变化（输血前平均 TOI = 70.5 [11.54]，输血后立即 = 71.38 [12.51]，[p = 0.924；95%置信区间（CI），-4.64 至 6.39]，输血后 24 小时 = 75.64 [14.4]；[p = 0.07；95% CI，-0.37 至 10.65]），脑分氧摄取率（输血前 = 0.25 [0.12]，输血后立即 = 0.24 [0.13]，输血后 24 小时 = 0.20 [0.15]），脑阻力指数，脑搏动指数或右心室输出。输血后立即观察到大脑动脉循环的收缩期峰值速度、舒张末期速度和平均最大速度有统计学显著变化。左心室输出（输血前 = 374.32 毫升/千克/分钟，输血后立即 = 346.67 毫升/千克/分钟 [p = 0.000；95% CI，-39.61 至 -15.68]，输血后 24 小时 = 361.17 毫升/千克/分钟 [p = 0.027；95% CI，-25.11 至 -1.18]）和心率（输血前 = 163.37 [9.49]，输血后立即 = 157.29 [10.2] [p = 0.000；95% CI，-8.96 至 -3.20]，输血后 24 小时 = 160.40 [10.4] [p = 0.041；95% CI，-5.85 至 -0.09]）在整个监测期间均显示出统计学显著变化。
我们的研究结果表明，在患有轻度贫血的早产儿中，实践宽松的输血阈值并不能改善脑 TOI，但确实改善了脑动脉血流和心输出量的代偿反应。
