Capillary filtration measurement by strain gauge. I. Analysis of methods.

The strain-gauge method for measuring changes in limb size, introduced by Whitney in 1953 has not received wide usage for measurement of capillary filtration coefficient (CFC). This method was compared for the dog hindlimb to simultaneous measurements by the classic gfavimetric technique and was found to give comparable results. The larger question of whether either method gives useful information about the true CFC of the limb was addressed by a mathematical analysis of the technique combined with analysis of data concerning methodologically induced alterations in the Starling forces in and around the capillaries. It was concluded that systematic error due to the method is probably less than -1% with an outside error of -14.6%. These findings demonstrate the strain gauge to be a useful tool in determining CFC.