探讨先天性心脏病患儿经体外循环心脏手术后早期胃黏膜pH值的变化及其与心功能的相关性。

选择18例行体外循环心脏手术的先天性心脏病患儿。采用空气张力计法对胃黏膜二氧化碳分压（PCO₂）进行动态监测，计算标准胃黏膜pH值。同时，于患儿入外科重症监护病房0 h（T₁）、4 h（T₂）、8 h（T₃）、12 h（T₄）、24 h（T₅）、48 h（T₆）及72 h（T₇）七个时间点记录并比较胃黏膜pH值、心指数、混合静脉血氧饱和度（SvO₂）及血乳酸水平。并采用Pearson相关分析胃黏膜pH值、SvO₂、血乳酸水平与心指数之间的相关性。

所有患儿不同时间点胃黏膜pH值、心指数、SvO₂、血乳酸指标的变化均有统计学意义（F = 5.702、8.225、3.164、13.051，P均< 0.05）。进一步两两比较发现，胃黏膜pH值T₂为7.33 ± 0.07，显著低于T₆、T₇（7.39 ± 0.06、7.40 ± 0.06，P均< 0.05）；心指数值T₆、T₇分别为（4.32 ± 0.75）L·min^-1·m^-2、（4.24 ± 0.78）L·min^-1·m^-2，均显著高于T₁、T₂、T₃、T₄[（3.61 ± 1.09）L·min^-1·m^-2、（3.60 ± 1.06）L·min^-1·m^-2、（3.42 ± 0.87）L·min^-1·m^-2、（3.33 ± 0.94）L·min^-1·m^-2，P均< 0.05]，SvO₂水平T₃、T₄分别为（71.7 ± 8.2）%、（72.3 ± 7.8）%，均显著低于T₅、T₆、T₇ [（79.9 ± 6.5）%、（78.5 ± 5.7）%、（78.1 ± 5.1）%，P均< 0.05]，而血乳酸水平T₁、T₂分别为（1.77 ± 0.79）mmol/L、（1.72 ± 0.83）mmol/L，均显著高于T₃、T₄、T₅、T₆、T₇[（1.52 ± 0.89）mmol/L、（1.31 ± 0.45）mmol/L、（0.99 ± 0.35）mmol/L、（0.77 ± 0.23）mmol/L、（0.73 ± 0.18）mmol/L，P均< 0.05]。Pearson相关分析发现，心指数与胃黏膜pH值、SvO₂呈正相关（r = 0.247、0.419，P均< 0.05），与血乳酸呈负相关（r = -0.318，P< 0.05）。

胃肠黏膜pH值、SvO₂与动脉血乳酸值与心指数相关，可以反映心功能的变化。

To explore the relationship between early gastric mucosal pH and cardiac function in infants with congenital heart disease undergoing cardiopulmonary bypass.

A total of 18 infants with congenital heart disease undergoing cardiopulmonary bypass were enrolled in this study. The air tension meter method was used to dynamically detect the arterial partial pressure of CO₂ of gastric mucosal, and gastric mucosal pH was calculated. The gastric mucosal pH, cardiac index, oxygen saturation of mixed venose blood (SvO₂) and blood lactic acid at 0 h (T₁), 4 h (T₂), 8 h (T₃), 12 h (T₄), 24 h (T₅), 48 h (T₆) and 72 h (T₇) after surgical intensive care unit were recorded and compared. The Pearson correlation analysis was used to analyze the relationship between early gastric mucosal pH, SvO₂, blood lactic acid and cardiac index.

The gastric mucosal pH, cardiac index, SvO₂ and blood lactic acid at different times all showed significant differences (F = 5.702, 8.225, 3.164, 13.051, all P< 0.05). The gastric mucosal pH at T₂ was 7.33 ± 0.07, lower than those at T₆ and T₇ (7.39 ± 0.06, 7.40 ± 0.06, all P < 0.05). The cardiac index at T₆ and T₇ were (4.32 ± 0.75) L·min^-1·m^-2, (4.24 ± 0.78) L·min^-1·m^-2 respectively, higher than those at T₁, T₂, T₃ and T₄ [(3.61 ± 1.09) L·min^-1·m^-2, (3.60 ± 1.06) L·min^-1·m^-2, (3.42 ± 0.87) L·min^-1·m^-2, (3.33 ± 0.94) L·min^-1·m^-2, all P < 0.05]. The level of SvO₂ at T₃ and T₄ were (71.7 ± 8.2)%, (72.3 ± 7.8)% respectively, lower than those at T₅, T₆ and T₇ [(79.9 ± 6.5)%, (78.5 ± 5.7)%, (78.1 ± 5.1)%, all P < 0.05]. And the levels of blood lactic acid at T₁ and T₂ were (1.77 ± 0.79) mmol/L, (1.72 ± 0.83) mmol/L, respectively, higher than those at T₃, T₄, T₅, T₆ and T₇ [(1.52 ± 0.89) mmol/L, (1.31 ± 0.45) mmol/L, (0.99 ± 0.35) mmol/L, (0.77 ± 0.23) mmol/L, (0.73 ± 0.18) mmol/L, all P < 0.05]. Meanwhile, the Pearson correlation analysis showed that the cardiac index was positively correlated with gastric mucosal pH and SvO₂ (r = 0.247, 0.419, all P< 0.05), and negative correlation with blood lactic acid (r = -0.318, P< 0.05).

The gastric mucosal pH, SvO₂ and blood lactic acid are associated with cardiac index, and can reflect the changes of cardiac function.