Division of Pediatric Cardiology, Stollery Children's Hospital, Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada.
J Thorac Cardiovasc Surg. 2012 Aug;144(2):474-9. doi: 10.1016/j.jtcvs.2011.12.023. Epub 2012 Jan 13.
We sought to determine the relationship between plasma calcium and magnesium concentrations with postoperative systemic hemodynamics and oxygen transport in neonates after the Norwood procedure.
Postoperative systemic oxygen consumption was continuously measured using respiratory mass spectrometry for 72 hours in 17 neonates. Arterial, superior vena caval and pulmonary venous blood gases and pressures, plasma calcium, and lactate levels were measured at 2- to 4-hour intervals to calculate cardiac output, rate pressure product, cardiac power output, systemic oxygen delivery, and oxygen extraction ratio. Plasma magnesium levels were measured at 2- to 8-hour intervals.
Plasma calcium levels decreased in the first 8 hours from 1.08±0.13 mmol/L to 0.98±0.08 mmol/L, followed by an increase to 1.10±0.26 mmol/L at 72 hours (P<.0001). Mg2þ change was significantly related to time after logarithmic transformation, rapidly decreasing from 1.62±0.25 mg/L to 0.90±0.15 mg/L in the first 40 hours and further decreasing slowly thereafter to 0.64±0.13 mg/L at 72 hours (P<.0001). Plasma magnesium levels had a significant positive correlation with cardiac output (P=.008) and cardiac power output (P=.01), and a negative correlation with heart rate (P=.05). Plasma magnesium levels correlated positively with systemic oxygen delivery and negatively with systemic oxygen consumption (P=.08 for both), resulting in significant negative correlations with oxygen extraction ratio (P=.04) and lactate levels (P=.05). For a given cardiac power output, plasma magnesium showed a significantly negative correlation with rate pressure product (P=.01). Plasma calcium levels showed the opposite trend, which was statistically insignificant except for lactate (P=.007).
Plasma magnesium may exert favorable effects on myocardial energetics and systemic oxygen transport in neonates after the Norwood procedure, whereas plasma calcium may be harmful. Maintaining a relatively high level of plasma magnesium and a low level of plasma calcium may improve myocardial work efficiency and the balance of systemic and myocardial oxygen transport.
我们旨在确定血浆钙镁浓度与新生儿 Norwood 术后全身血液动力学和氧转运之间的关系。
17 例新生儿连续 72 小时使用呼吸质谱法持续测量术后全身耗氧量。每 2-4 小时测量一次动脉、上腔静脉和肺静脉血气及压力、血浆钙和乳酸水平，以计算心输出量、心率血压乘积、心功率输出、全身氧输送和氧摄取率。每 2-8 小时测量一次血浆镁水平。
血浆钙水平在第 1 至 8 小时从 1.08±0.13mmol/L 降至 0.98±0.08mmol/L，72 小时时增至 1.10±0.26mmol/L（P<.0001）。Mg2+变化与对数转换后的时间显著相关，在最初的 40 小时内从 1.62±0.25mg/L 迅速降至 0.90±0.15mg/L，此后缓慢下降至 72 小时时的 0.64±0.13mg/L（P<.0001）。血浆镁水平与心输出量（P=.008）和心功率输出（P=.01）呈显著正相关，与心率呈负相关（P=.05）。血浆镁水平与全身氧输送呈正相关，与全身氧消耗呈负相关（两者均为 P=.08），与氧摄取率（P=.04）和乳酸水平（P=.05）呈显著负相关。对于给定的心功率输出，血浆镁与心率血压乘积呈显著负相关（P=.01）。血浆钙水平呈相反趋势，但除乳酸外均无统计学意义（P=.007）。
在 Norwood 手术后，血浆镁可能对新生儿心肌能量代谢和全身氧转运产生有利影响，而血浆钙可能有害。维持相对较高的血浆镁水平和较低的血浆钙水平可能会提高心肌工作效率和全身及心肌氧转运的平衡。
