Fat Embolism *

As one might suppose, the patho-physiological aspects of this question are quite diversified and complex. Hoffheinz's approach to this phase of the subject has done much to integrate the symptomcomplex of fat embolism. One might well turn to physico-dynamics in an endeavor to explain the cause of impaction of fat particles. In his monograph Beneke states that the cohesive force of fat particles determines largely the viscosity of the blood. This cohesive force may be sufficiently pronounced to resist effectively the opposing force which is normally available. It is also generally believed that the walls of capillary vessels fail to yield to fat and so actually invite the state of impaction. Zangger laid much stress on the membrane of fat droplets which tends to limit their deformation or malleability. On the contrary, freshly introduced droplets of fatty acids are easily distorted and may, therefore, be readily propelled through capillary lumina. While studying the influence of fat on the viscosity of the blood, Bissell noted that the addition of 10 per cent fat to the blood increased its viscosity 200 per cent. Gauss added olive-oil' to citrated blood and arrived at much the same result. Schade has advanced a somewhat more plausible explanation for the tendency for impaction. His ingenious method of approach is worthy of comment. First of all, certain premises must be established in order to appreciate his work. It is generally recognized that the surface tension between the limiting membranes of two non-miscible substances is such that each respective membrane tends to diminish in circumference. In so doing the affected particles take on a globular form, and thus the greatest volume with the smallest possible surface is obtained. And so, when two non-miscible substances are mixed to form an emulsion they assume small globular contours. Each attempt at deformation results in an increase of surface area, to which end energy must be expended. The surface tension in-