Efeitos iniciais da reposição volêmica com solução salina hipertônica a 7,5% na perfusão e oxigenação esplâncnica após choque hemorrágico 1 Early effects of 7.5% hypertonic saline solution on splanchnic perfusion after hemorrhagic shock

Purpose: To evaluate the effects of SSH resuscitation on systemic and splanchnic hemodynamic variables in an experimental model of controlled hemorrhagic shock. Methods: 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 pCO 2 -gradients (D ap-a pCO 2 , D vp-a pCO 2 e D t-a pCO 2 , respectively) were assessed. Results: Hemorrhage (29.8±2.4ml/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 pCO 2 (5.3±0.8 to 19.9±1.6 mmHg) D vp-a pCO 2 (5.4±1.4 to 22.6±2.1 mmHg) and D t-a pCO 2 (6.1±1.1 to 43.8±7.5 mmHg). SSH infusion promoted only partial benefits in systemic and splanchnic blood flows. Reduced pCO 2 gradients but fewer effects in D t-a pCO 2 were observed. Conclusion: 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 pCO 2 . 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.