肝移植期间终末期肝病的奢侈性肺灌注

Stenqvist O, Olausson M, Karlsen K L

Department of Anaesthesia, Sahlgrenska University Hospital, Göteborg, Sweden.

Acta Anaesthesiol Scand. 1999 Apr;43(4):447-51. doi: 10.1034/j.1399-6576.1999.430413.x.

BACKGROUND

End-stage liver disease is accompanied by a hyperkinetic circulation sometimes combined with hypoxaemia. Nitric oxide overproduction has been described as a possible cause by dilating the vasculature and decreasing cardiac afterload. The aim of this study was to evaluate haemodynamics, ventilation/perfusion matching, alveolar and alveolar dead space ventilation and resistance of systemic and pulmonary vasculature during liver transplantation.

METHODS

Ten liver transplantation patients were studied. Cardiac output, CO, was measured with thermodilution technique. Pulmonary shuntflow was calculated from standard formulas. Effective cardiac output, COeff, was defined as the CO in contact with alveolar ventilation, VA. Effective alveolar ventilation, VAeff, was defined as VA in contact with pulmonary circulation. Measurements were performed during dissection, anhepatic and reperfusion phases.

RESULTS

During the dissection phase the shunt was 23 +/- 3%, COeff was 7.9 +/- 0.6 l/min, SVR was 620 +/- 67 dyn.s/cm5, VAeff was 3.4 +/- 0.5 l/min, SaO2 was 98 +/- 1% and SvO2 was 86 +/- 2%. Corresponding values during the anhepatic phase were 16 +/- 2%, 5.6 +/- 0.4 l/min, 931 +/- 78 dyn.s/cm5, 3.1 +/- 0.2 l/min, 99 +/- 1% and 88 +/- 1%. During the reperfusion phase the values returned to levels close to that of the dissection phase. The reduction of COeff between the dissection and the anhepatic phase was significant (P < 0.01).

CONCLUSIONS

The low vascular resistance is accompanied by a high cardiac output. In spite of the high shunt fraction, these patients were not hypoxaemic. This is explained by the fact that the increased cardiac output leads to a decrease in arterio-mixed venous oxygen content difference and an increase in mixed venous oxygenation level, SvO2 86-88%, normal value approximately 70%. The VAeff/COeff in this study was approximately 0.5, i.e. the effective cardiac output, COeff is 235, 180 and 197% of the effective alveolar ventilation, VAeff during the three phases. Thus, about twice the amount blood is oxygenated as compared to a normodynamic situation, which compensates for the effect of the shunt flow on oxygenation.

背景

终末期肝病伴有高动力循环，有时合并低氧血症。一氧化氮生成过多被认为是血管扩张和降低心脏后负荷的可能原因。本研究旨在评估肝移植过程中的血流动力学、通气/灌注匹配、肺泡及肺泡无效腔通气以及体循环和肺循环阻力。

方法

对10例肝移植患者进行研究。采用热稀释技术测量心输出量（CO）。根据标准公式计算肺分流。有效心输出量（COeff）定义为与肺泡通气（VA）接触的CO。有效肺泡通气（VAeff）定义为与肺循环接触的VA。在解剖、无肝和再灌注阶段进行测量。

结果

解剖阶段分流率为23±3%，COeff为7.9±0.6升/分钟，体循环血管阻力（SVR）为620±67达因·秒/厘米⁵，VAeff为3.4±0.5升/分钟，动脉血氧饱和度（SaO₂）为98±1%，混合静脉血氧饱和度（SvO₂）为86±2%。无肝阶段相应值分别为16±2%，5.6±0.4升/分钟，931±78达因·秒/厘米⁵，3.1±0.2升/分钟，99±1%和88±1%。再灌注阶段各项值恢复至接近解剖阶段的水平。解剖阶段与无肝阶段之间COeff的降低具有显著性（P<0.01）。

结论

低血管阻力伴有高心输出量。尽管分流分数较高，但这些患者并未出现低氧血症。这是因为心输出量增加导致动脉-混合静脉血氧含量差减小，混合静脉氧合水平升高，SvO₂为86 - 88%，正常值约为70%。本研究中VAeff/COeff约为0.5，即在三个阶段中，有效心输出量COeff分别是有效肺泡通气VAeff的235%、180%和197%。因此，与正常血流动力学情况相比，氧合的血量约为两倍，这补偿了分流对氧合的影响。