CAPILLARY PROTEIN LEAKAGE AND PLASMA VOLUME IN THE EARLY POST-BURN PERIOD

Abstract

S131 Indocyanine green (ICG) has been used for evaluation of plasma volume (PVICG). However, Obvious capillary protein leakage has potential to modify PVICG within 24 post-burn hours, since ICG binds to plasma proteins. Recent radioisotopic studies demonstrated that extracellular glucose distribution is not affected by its metabolism [1,2]. Assuming that the initial distribution volume of glucose (IDVG) consistently indicates the extracellular fluid volume of the highly perfused organs including plasma volume (PV) [3], the PVICG/IDVG ratio (normal range: 0.30 - 0.40) would provide the magnitude of overestimation of PVICG. The purpose of the study is to evaluate PVICG by comparing with the IDVG and other routine clinical variables. METHODS: With IRB approval 10 severely burned patients admitted to the ICU within 24 hours post-burn were studied. Fluid resuscitation with crystalloids alone were performed by 24 hours post-burn. ICG 25mg and glucose 5 g were simultaneously infused over 30 sec throughout the first 3 post-burn days. Daily two estimates were calculated using a one compartment model utilizing increased plasma values 3-11 min and 3-7 min postinfusion, for PVICG and the IDVG. RESULTS: Each variable tended to indicate an increase in PV day by day, even though statistically significant change was observed only in hematocrit (Table 1). Apparent overestimation of PVICG occurred in 4 patients within 24 hours post-burn judged by clinical variables other than the IDVG, whose ratio ranged between 0.45 and 0.74. No correlation was found between two estimates on that day (r=0.15).Table 1CONCLUSIONS: In addition to capillary protein leakage in the burned tissues, obvious generalized leakage may occur in some severely burned patients within 24 hours post-burn, resulting in an overestimation of PVICG. The simultaneous determination of PVICG and IDVG is useful to evaluate the presence of the leakage.