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的发生机制，建立预测ALD的有用指标，我们在心脏手术患者中引入肝静脉血氧饱和度(ShVO2)监测。37例患者，其中先天性心脏病17例，获得性心脏病20例。将最低点(m-ShVO2)前后24小时的ShVO2平均值与术后肝功能、肝乳酸代谢及血流动力学结果进行比较。结果表明：1.m-ShVO_2含量在5%~79%之间，平均为44%。14例m-ShVO2+30%患者中，11例ALD患者血清丙氨酸氨基转移酶(ALT)+GT；100U/L(最高值：4,050U/L)或总胆红素(TB)+GT；3.0 mg/dl(最高值：11.5 mg/dl)，且m-ShVO2与血生化最高值(ALT、GLDH、T-Bil)呈显著负相关。23例m-ShVO_2和GT；40%的患者，肝功能指标基本在正常范围内，与m-ShVO_2无显著相关性。在14例m-ShVO_2+30%的患者中，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与混合静脉血氧饱和度(SvO_2)、中心静脉压(CVP)显著相关。多因素分析显示，在术前、围手术期和术后，m-ShVO2对ALD评分的影响最为显著，ShVO2在30%以下时显著降低，提示肝组织缺氧是肝脏低灌流引起的，是全身低灌流和高CVP的结果。ShVO2监测可能有助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.