A clinical study on the mechamism and early diagnosis of acute liver dysfunction following cardiac surgery.

急性肝功能障碍（ALD）是心脏手术后的主要并发症之一。为了阐明心脏手术后ALD发生的机制，建立有效的ALD预测指标，我们对心脏手术患者引入肝静脉血氧饱和度（ShvO_2）监测。37例先天性心脏病17例，后天性心脏病20例，术后1 ~ 4天测量ShvO_2。术后24 h ShvO_2均值（m-ShvO_2）与肝功能、肝乳酸代谢及血流动力学结果进行比较。实验结果如下：1.实验结果表明：m-ShvO_2为5% ~ 79%，平均为44%。在14例m-ShvO_2 <30%的患者中，11例发生ALD，血清丙氨酸转氨酶(ALT) >100 U/l（最高4050 U/l）或血清总胆红素(TB)>3.0mg/dl（最高11.5 mg/dl），且m-ShvO_2与血化学（ALT、GLDH、T-Bil）最高值呈显著负相关。23例m-ShvO_2浓度为40%的患者肝功能指标基本在正常范围内，与m-ShvO_2浓度无显著相关性。在m-ShvO_2 <30%的14例患者中，m-ShvO_2与肝静脉乳酸丙酮酸比值呈显著负相关。多因素分析显示m-ShvO_2与混合静脉氧饱和度（SvO_2）和CVP有显著相关。多因素分析显示，在术前、围手术期和术后因素中，m-ShvO_2对ald评分的影响最为显著。综上所述，ShvO_2显著降低至30%以下，提示肝组织缺氧引起的ALD是由全身灌注不足和CVP升高引起的。ShvO_2监测可用于预测心脏手术后危重患者ALD的发展。

Acute liver dysfunction (ALD) is one of the major complications after cardiac surgery. To elucidate the mechanism of ALD following cardiac surgery and to establish useful predictor for ALD, we introduced hepatic venous oxygen saturation (ShvO_2) monitoring to the patients who underwent cardiac surgery.In 37 patients: 17 with congenital and 20 with acquired heart disease, ShvO_2 was measured for 1-4 days postoperatively. The mean ShvO_2 value for 24 hours around the lowest point (m-ShvO_2) was compared with the postoperative results of liver functions, hepatic lactate metabolism and hemodynamics. The results were as follows:1. m-ShvO_2 ranged from 5% to 79% with the average of 44%.2. In 14 patients with m-ShvO_2 <30%, 11 patients developed ALD with serum alanine aminotransferase (ALT) >100 U/l (the highest value: 4,050 U/l) or serum total bilirubin (TB)>3.0mg/dl (the highest: 11.5 mg/dl), and there were significant inverse correlations between m-ShvO_2 and the highest value of blood chemistry (ALT, GLDH, T-Bil). In 23 patients with m-ShvO_2>40%, the liver function indices stayed within almost normal ranges without significant correlations to m-ShvO_2.3. In 14 patients with m-ShvO_2 <30%, there was a significant inverse correlation between m-ShvO_2 and hepatic venous lactate pyruvate ratio.4. m-ShvO_2 showed significant relation to mixed venous oxygen saturation (SvO_2) and CVP in multivariate analysis.5. In pre, peri and postoperative factors, m-ShvO_2 most significantly contributed to ALD-score in multivariate analysis.In conclusion, significant decrease in ShvO_2 as below 30% appears to indicate hepatic tissue hypoxia causing ALD from hepatic hypoperfusion with resultant from systemic hypoperfusion and high CVP. And ShvO_2 monitoring may be useful to predict the development of ALD in critical patients after cardiac surgery.