The Distensibility Characteristics of the Portal Vascular Bed

The distensibility of the splanchnic portion of the portal system has been evaluated by studying pressure and volume changes with or without any interruption of blood flow. The results of these determinations indicate two types of distensibility of the system: (1) a rapid elastic distension representing relatively small volumes, and (2) a secondary phase of slow distension, designated “delayed compliance,” which represents a significantly greater volume change. It is concluded that delayed compliance is of major importance in the pooling of blood in peripheral blood vessels under conditions of maintained elevation of venous pressure.