Visceral blood flow following thermal injury

To determine if visceral blood flow was altered by thermal injury, effective renal blood flow (ERBF) was measured by para-aminohippurate clearance in five control subjects and 13 nonbacteremic burn patients (mean burn size: 50% total body surface, range: 24.5-83.5) 6-25 days after burn injury. Splanchnic blood flow (SBF) and cardiac output were determined in a matched group of ten patients by indocyanine green clearance and dilution techniques, respectively. Renal and splanchnic oxygen consumptions (VO2) were calculated from regional arteriovenous O2 differences and blood flows. ERBF was not significantly elevated in these patients (780 +/- 68 ml/min x m2, mean +/- SE, versus 552 +/- 37 in controls). SBF, at 1463 +/- 96 ml/min x m2, was twice normal and 19% of the cardiac index (7764 +/- 393 ml/min x m2). Individual variations in ERBF and SBF were unrelated to burn size or the time after injury, but ERBF varied with 24-hour sodium excretion. Renal and splanchnic VO2 were twice normal levels at 33 +/- 6 and 66 +/- 4 ml/min, respectively. These results indicate that an increase in ERBF is not an obligatory response to burn injury, but is dependent on sodium load and/or vascular volume. Conversely, SBF is consistently increased by thermal injury and contributes to the rise in cardiac output after injury. While the increase of SBF is appropriate for the rise in local VO2, the cause of the apparent splanchnic vasodilation is unknown.