Progress toward resolving the controversy of positive Vs. negative interstitial fluid pressure.

PRIOR to 1960, interstitial fluid pressure was considered widely to be slightly above atmospheric pressure, averaging about +1 to +5 mm Hg.In 1963, Guyton reported that interstitial fluid pressure in dog subcutaneous tissue was negative relative to atmospheric pressure, averaging -6.4 mm Hg.Since 1963, there has been a continuing controversy as to whether the tissue fluid pressure is normally positive or negative relative to the ambient pressure.Although this difference of only a few mm Hg may appear insignificant, it is of major importance for several reasons which are discussed below.Consequently, a unified understanding of interstitial fluid pressure and its measurement is needed.In the last few years, considerable data have emerged which suggest that the existing controversy may be resolvable.This can be accomplished by first integrating the recent data with past information, and then suggesting additional studies which may more completely explore the arguments.The most pertinent articles and reviews that provide insights into the topic and into the development of the present controversy are the 1946 summary by McMaster, the 1963 article in which Guyton introduced the concept of negative interstitial fluid pressure, the discussions by Gauer (1972) and McDonald (1968), the 1971 and 1975 reviews by Guyton et al. which support the negative pressure concept, and the recent summary by Wiederhielm (1977) of the arguments against negative tissue pressure measurements.In this review, an attempt is made to cite data obtained with many methods and in different laboratories.In general, there are four main conclusions to be drawn.(1) Essentially all methods that