Heterogeneity of splanchnic vascular transit times in man

A new method of quantifying the heterogeneity of transit times through vascular beds, free from corrections for effects of recirculation, is applied to data of splanchnic transit times in eight normal subjects and three patients with cirrhosis and end-to-side portocaval shunts, as obtained by Bradley's method. There is proportionality between the heterogeneity, expressed as standard deviation and the mean transit time in the eight normal subjects. The heterogeneity of plasma transit times is not appreciably larger than that of red blood cells, despite the larger volume of distribution of plasma. This may suggest that the large vessels contribute substantially to the dispersions of vascular transits in the entire splanchnic system. Pearson Type III distribution is proposed for the frequency function of the splanchnic transit times, and the power of the pre-exponential factor is deduced for plasma and for red blood cells. It is found that the initial splanchnic transits are dominated by plasma, this may be due to sequestration of red cells in the spleen. The heterogeneity of transit times in normals is not appreciably different from that in patients with cirrhosis and portocaval shunt, which suggests that the extra heterogeneity of the cirrhotic liver is of the same order as the heterogeneity of the normal extrahepatic splanchnic organs. The method may be a useful tool to describe heterogeneity of vascular transits in other organs.