Relationship between early gastric mucosal pH and cardiac function in infants with congenital heart disease undergoing cardiopulmonary bypass

Abstract

Objective To explore the relationship between early gastric mucosal pH and cardiac function in infants with congenital heart disease undergoing cardiopulmonary bypass. Methods 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. Results 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). Conclusion The gastric mucosal pH, SvO2 and blood lactic acid are associated with cardiac index, and can reflect the changes of cardiac function. Key words: Extracorporeal circulation; Heart defects, congenital; Gastric mucosal pH; Infants