THE EFFECT OF LOCAL COOLING ON THE FILTRATION AND ABSORPTION OF FLUID IN THE HUMAN FOREARM

Abstract

The effects of local cooling on fluid movement in the human forearm were studied using the pressure plethysmo-graph in 4 normal subjects. The accuracy of the method was improved allowing for quantitative measurements of minute changes in vol. of extravascular fluid. Cold produced filtration of fluid and increased the vol. of tissue fluid in the uncongested forearm. At 4.5[degree]C, the avg. rate of filtration was 0.017 ml./100 ml. of forearm tissue /minute. Smaller rates of filtration were observed at 14.5 [degree]C and 24.5 [degree]C, whereas at 34.5 [degree]C and 44.5 [degree]C extra vascular tissue fluid vol. did not change significantly. With venous congestion, the rate of filtration remained directly proportional to the venous pressure, but the unit rate of filtration (ml. fluid/100 ml. of forearm/min./cm. rise of venous pressure) was 30% less at 4.5[degree]C than at 34.5[degree]C. Cold reduced the rate of reabsorption of previously filtered fluid. The results indicate that local cooling increases the permeability of the human capillary wall to protein. The relation between these findings and the pathogenesis of "immersion foot" is discussed.