A QUANTITATIVE-ANALYSIS OF TRANSCAPILLARY REFILL IN SEVERE HEMORRHAGIC HYPOTENSION IN DOGS

In pressure-driven hemorrhage (PDH), where the rate of bleeding is a f unction of prevailing arterial pressure, survival time, arterial press ure, cardiac output, oxygen consumption, and base excess are functions of initial bleeding rate. The quantitative rate of transcapillary ref ill (TR) throughout PDH leading to death was determined in splenectomi zed dogs, through serial analysis of Cr-51-tagged red cell dilution. M ild, moderate, and severe levels of PDH were produced by varying initi al bleeding rate (10, 25, and 50 ml/min, respectively). The rate of TR is a function of the severity of PDH, but does not correlate with art erial pressure, cardiac output, or systemic resistance. The volume of transferred fluid represents an ever increasing fraction of total plas ma volume, and accounts for more than 75% of plasma volume in pretermi nal stages of shock. TR sustains a relatively fixed level of plasma vo lume, equivalent to two-third of the initial plasma volume, irrespecti ve of the rate of bleeding. Hypertonic NaCl (7.5%) enhances TR, while isotonic NaCl reverses it.