Sustained gastric mucosal acidosis after hemorrhage in spite of rapid hemodynamic restoration with blood or hypertonic/hyperoncotic solution

Splanchnic hypoperfusion has been implicated as the motor of multiple organ dysfunction. Hypertonic saline has shown to benefit microcirculatory blood flow. In hemorrhaged animals, we tested the hypothesis that small-volume 3% NaCl/10% dextran 40 (3% HSD) promotes global and regional improvements, including gastric mucosal acidosis reversal. Seventeen dogs (18.8 +/- 1.2 kg) were bled (20 mL/min) to a mean arterial pressure of 40-45 mm Hg, which was maintained at these levels for 15 min. They were randomly assigned to two groups: Blood (n = 9), total shed blood retransfused at 40 mL/min; or a 4-min bolus injection of 3% HSD (n = 8), in a volume equivalent to 25% of total shed blood. All animals were followed for 30 min thereafter. Gastric mucosal PCO2 (gas tonometry), portal vein PCO2, superior mesenteric artery blood flow (SMA, ultrasonic flowprobes), and systemic and regional O-2-derived variables were evaluated throughout the protocol. Hemorrhage induced significant reductions of arterial pressure, cardiac output, and SMA blood flow, while portal-arterial and gastric-arterial PCO2 gradients increased. Total shed blood transfusion, as well as 3% HSD bolus injection, promptly restored all parameters, except for the increased gastric-arterial PCO2 gradient. We conclude that persistent gastric mucosal acidosis cannot be adequately predicted by global and splanchnic O-2 derived variables in following hemorrhage and resuscitation with total shed blood transfusion or small-volume hypertonic-hyperoncotic solution.