Bojan Mirela, Gioia Enza, Di Corte Federica, Berkia Ilham, Tourneur Tiffany, Tourneur Laurent, De Somer Filip
Department of Anaesthesiology, Congenital Cardiac Unit, Marie Lannelongue Hospital, Le Plessis-Robinson, France.
Department of Anaesthesiology and Critical Care, Necker-Enfants Malades University Hospital; Paris, France.
Br J Anaesth. 2020 Apr;124(4):395-402. doi: 10.1016/j.bja.2019.12.034. Epub 2020 Feb 5.
The objective of cardiopulmonary bypass (CPB) is to maintain an adequate balance between oxygen delivery (Ḋo) and consumption. The critical Ḋo is that at which consumption becomes supply dependent. This study aimed to identify the critical Ḋo in neonates, who have higher metabolic rates than adults.
In a retrospective cohort of neonates, Ḋo was calculated from CPB parameters recorded during aortic cross-clamping. High lactate concentration measured after aortic unclamping (lactOFF) was used to identify anaerobic metabolism. Data were analysed using mixed linear and proportional odds regression models. The relationship between Ḋo and temperature was analysed in a subgroup of patients with lactOFF <2.5 mM, thought to have had balanced oxygen delivery and consumption. The estimated regression coefficient was further used to adjust hypothetical Ḋo thresholds, and Ḋo excursions below the threshold were quantified as magnitude-durations. The lowest threshold that provided magnitude-durations and linked with an increase in lactOFF was used as the lowest suitable (critical) Ḋo at 37°C.
Overall, 22 896 time points were analysed in 180 neonates. In 40 patients with lactOFF <2.5 mM, Ḋo varied by 22.87 (0.70) ml min m °C. When varying the Ḋo threshold between 340 and 380 ml min m, excursions below the threshold were linked with incremental lactOFF. A 100 ml m excursion below the 340 ml min mḊo threshold increased the risk of a 1 mM increment in lactOFF by 22% (odds ratio: 1.22; 95% confidence interval: 1.02-1.45).
It was found that 340 ml min m is likely to represent the lowest suitable Ḋo required in neonates to maintain aerobic metabolism during normothermic CPB.
体外循环（CPB）的目标是在氧输送（Ḋo）和消耗之间维持适当的平衡。临界Ḋo是指消耗变得依赖于供应时的Ḋo。本研究旨在确定新生儿的临界Ḋo，新生儿的代谢率高于成年人。
在一组新生儿回顾性队列中，根据主动脉交叉钳夹期间记录的CPB参数计算Ḋo。主动脉松开后测得的高乳酸浓度（lactOFF）用于识别无氧代谢。使用混合线性和比例优势回归模型分析数据。在lactOFF<2.5 mM的患者亚组中分析Ḋo与温度之间的关系，该亚组被认为氧输送和消耗平衡。估计的回归系数进一步用于调整假设的Ḋo阈值，低于阈值的Ḋo偏移量被量化为幅度-持续时间。在37°C时，提供幅度-持续时间并与lactOFF增加相关的最低阈值被用作最低合适（临界）Ḋo。
总体而言，对180例新生儿的22896个时间点进行了分析。在40例lactOFF<2.5 mM的患者中，Ḋo变化为22.87（0.70）ml·min·m²·°C。当Ḋo阈值在340至380 ml·min·m²之间变化时，低于阈值的偏移量与lactOFF增加相关。低于340 ml·min·m²Ḋo阈值100 ml·m²的偏移量使lactOFF增加1 mM的风险增加22%（优势比：1.22；95%置信区间：1.02 - 1.45）。
发现340 ml·min·m²可能代表新生儿在常温CPB期间维持有氧代谢所需的最低合适Ḋo。
