Quarti A, Nardone S, Manfrini F, D'Orfeo F, Genova S, Silvano R, Pozzi M
Congenital and Paediatric Cardiac Surgery and Cardiology, Azienda Ospedaliera Ospedali Riuniti, Ancona, Italy.
Perfusion. 2013 Mar;28(2):152-5. doi: 10.1177/0267659112464382. Epub 2012 Oct 24.
Over the last few years, near-infrared spectroscopy (NIRS) has been introduced to study cerebral haemodynamics and oxygenation. This paper points out how the use of an external source of CO2 effects on the absolute value of cerebral NIRS during cardiac surgery on cardiopulmonary bypass.
Between January 2010 and September 2011, 368 patients underwent congenital heart disease correction on cardiopulmonary bypass (CPB). Nineteen patients, with a mean age of 26 days (range 6-120 days), required an external source of CO2 to correct hypocarbia during cardiopulmonary bypass. Different parameters were monitored: NIRS value, oxygen saturation, oxygen partial pressure, CO2 partial pressure, haematocrit, mean arterial pressure and pH. They were analyzed during different phases of the surgical procedure: before, during and after CO2 infusion.
There were no deaths during the hospital stay. The NIRS value increased significantly (p<0.05) after the addition of CO2, from a starting value of 52.9 to a final value of 63.4. PaCO2 was found to increase too: from 31.3 mmHg to 40.6 mmHg. On the other hand, both values decreased when the CO2 was removed, to respective final values of 55.8 and 34.4 mmHg. Mean arterial pressure, haematocrit and PaO2 didn't modify significantly during this period.
Nowadays, NIRS is usually used in cardiac surgery to reduce possible risks of neurological damage. The importance of the role of pCO2 in the cerebral vascular resistance and in cerebral blood flow has already been proven. This research demonstrates a relationship between pCO2 and the NIRS value. This paper could introduce an important correcting tool when an inadequate NIRS value occurs although the level of oxygenation, haematocrit and mean arterial pressure are acceptable and the arterial line is accurately positioned.
在过去几年中，近红外光谱技术（NIRS）已被用于研究脑血流动力学和氧合作用。本文指出在体外循环心脏手术期间，使用外部二氧化碳源对脑NIRS绝对值的影响。
2010年1月至2011年9月期间，368例患者接受了体外循环（CPB）下的先天性心脏病矫正手术。19例平均年龄26天（范围6 - 120天）的患者在体外循环期间需要外部二氧化碳源来纠正低碳酸血症。监测了不同参数：NIRS值、氧饱和度、氧分压、二氧化碳分压、血细胞比容、平均动脉压和pH值。在手术过程的不同阶段（二氧化碳输注前、期间和之后）对这些参数进行了分析。
住院期间无死亡病例。添加二氧化碳后，NIRS值显著增加（p<0.05），从初始值52.9增加到最终值63.4。发现动脉血二氧化碳分压（PaCO2）也增加：从31.3 mmHg增加到40.6 mmHg。另一方面，去除二氧化碳时，这两个值均下降，分别降至最终值55.8和34.4 mmHg。在此期间，平均动脉压、血细胞比容和动脉血氧分压（PaO2）无显著变化。
如今，NIRS通常用于心脏手术以降低可能的神经损伤风险。pCO2在脑血管阻力和脑血流中的作用的重要性已得到证实。本研究证明了pCO2与NIRS值之间的关系。当尽管氧合水平、血细胞比容和平均动脉压可接受且动脉管路位置准确，但NIRS值不足时，本文可引入一种重要的校正工具。
