Various hemodynamic disturbances and a rapidly changing circulatory blood volume necessitate the proper management of fluid administration. The causes of sudden hypotension can be anticipated with the usual monitoring devices. However, more accurate diagnosis of such event can only be made by actual measurement of cardiac output. And such an event may be related to cardiac depression due to autonomic disturbances. To elucidate the cause of sudden unexplainable hypotension during the preanhepatic stage, we analysed the hemodynamic data of patients undergoing liver transplantation prospectively.

Patients were divided into a normal and a hypotensive group, according to the presence of an episode of hypotension. The hypotensive group was further divided into an explainable and an unexplainable group, if causes were known or not. Preoperative echocardiograms and Child-Pugh scors were also analysed. The normal and unexplainable hypotensive groups were compared using Mann-Whitney non-parametric, Chi-square and Wilcoxon-signed rank tests. P<0.05 was considered statistically significant.

The incidence of hypotension was 25.2%. A severe unexplainable hypotensive episode occurred 9.3% of the the liver transplantations. Causes of hypotension were preload deficiency, vena caval compression, bleeding, and vagal reflex. Unexplainable hypotensive patients showed decreased ejection fraction (cardiac depression) and systemic vasodilatation.

These results suggest hepato-dyscirculatory syndrome is the main cause of unexplainable hypotension during the preanhepatic stage.