The relation between the blood pressure and the peripheral flow of blood is of interest in view of certain recent opinions on the mechanism of surgical shock (Freeman,1 Meek,2 Roome3). It has been suggested, and supported to various extents, by these authors that shock arises by the following mechanism: A marked reduction of the peripheral flow occurs as the result of a diminished blood volume and/or sympathicoadrenal activity; this ischemia produces capillary injury, with increased permeability, permitting a generalized loss of blood plasma, which finally progresses to peripheral circulatory failure.
Poiseuille and others4 have exhaustively studied the relation existing between the head of pressure (P) and the volume flow (F) of homogeneous fluids in small rigid tubes. Under these conditions F is proportional to P, the ratio P/F is a constant and the relation is graphically linear. These observations, however, cannot be directly applied to the