An accurate and simple method for measurement of paw edema

Several methods for measuring inflammation are available that rely on the p arameters changing during inflammation. The most commonly used methods esti mate the volume of edema formed. In this study, we present a novel method f or measuring the volume of pathologically or artificially induced edema. In this model, a liquid column is placed on a balance. When an object is imme rsed, the liquid applies a force F to attempt its expulsion. Physically, F is the weight (W) of the volume of liquid displaced by that part of the obj ect inserted into the liquid. A balance is used to measure this force (F = W). Therefore, the partial or entire volume of any object, for example, the inflamed hind paw of a rat, can be calculated thus, using the specific gra vity of the immersion liquid, at equilibrium mass/specific gravity = volume (V). The extent of edema at time t (measured as V) will be V-t - V-o. This method is easy to use, materials are of low cost and readily available. It is important that the rat paw (or any object whose volume is being measure d) is kept from contacting the wall of the column containing the fluid whil st the value on the balance is read. (C) 2000 Elsevier Science Inc. All rig hts reserved.