[Early effects of 7.5% hypertonic saline solution on splanchnic perfusion after hemorrhagic shock]

To evaluate the effects of SSH resuscitation on systemic and splanchnic hemodynamic variables in an experimental model of controlled hemorrhagic shock.

Ten mongrel dogs were bled (20 ml/min) to a target mean arterial pressure (MAP) of 40+/-5 mmHg. After 30 minutes of shock, animals received SSH infused in 5-minute and they were observed for 60 minutes thereafter. Systemic hemodynamics were evaluated through a Swan-Ganz and arterial catheters while gastrointestinal tract perfusion by a catheter inside the portal vein, an ultrasonic flowprobe around portal vein blood flow (PVBF) and a gastric tonometer. Splanchnic oxygen delivery and consumption, intramucosal pH and veno-arterial, portal-arterial and mucosal-arterial pCO2-gradients (D(ap-a)pCO2, D(vp-a)pCO2 e D(t-a)pCO2, respectively) were assessed.

Hemorrhage (29.8+/-2.4 ml/Kg) induced significant decreases in MAP (125+/-6 to 42+/-1 mmHg), in CO (1.9+/-0.2 to 0.6+/-0.1 L/min), and PVBF (504+/-73 to 126+/-12 ml/min) while significant increases were detected in D(ap-a)pCO2 (5.3+/-0.8 to 19.9+/-1.6 mmHg) D(vp-a)pCO2 (5.4+/-1.4 to 22.6+/-2.1 mmHg) and D(t-a)pCO2 (6.1+/-1.1 to 43.8+/-7.5 mmHg). SSH infusion promoted only partial benefits in systemic and splanchnic blood flows. Reduced pCO2 gradients but fewer effects in D(t-a)pCO2 were observed.

The SSH infusion promoted partial systemic and splanchnic hemodynamic benefits. Those benefits were especially poor at the splanchnic microcirculation, as evaluated by D(t-a)pCO2. In addition, systemic and regional oxygen-derived variables do not reflect the regional microcirculation disturbances. Gastrointestinal tonometry clearly represents a useful tool for monitoring splanchnic perfusion in patients in hemodynamic shock.