Drag-reducing polyethylene oxide improves microcirculation after hemorrhagic shock.

BACKGROUND: Despite resuscitation after trauma, microcirculatory abnormalities are known to persist in post-shock multiorgan dysfunction. The high-molecular weight polymer polyethylene oxide (PEO) (>10(6) Da), a classic drag-reducing polymer, can improve hemorrhagic shock (HS)-induced hemodynamic abnormalities in rats. MATERIALS AND METHODS: We examined the effects of PEO on microcirculation and on changes in multiple organs after shock. After the spinotrapezius muscle was prepared, HS was induced in Sprague-Dawley rats. Drug administration (normal saline or PEO) was performed 2 h after shock followed by infusion of shed blood. RESULTS: The velocity, blood flow, and functional capillary density in the shock + PEO group were significantly higher than those in the shock + normal saline group. Moreover, the kidney, liver, and lung function was improved, resulting in prolonged survival time. Our findings indicate that intravenous infusion of PEO can ameliorate shock-associated organ dysfunction and prolong survival time in severe HS, which may be a result of increased arteriolar blood velocity, blood flow, and functional capillary density. CONCLUSIONS: PEO could have potential clinical application in the treatment of shock-induced multiorgan dysfunction.

A new hydrodynamic approach by infusion of drag-reducing polymers to improve left ventricular function in rats with myocardial infarction.

BACKGROUND: Recent studies have shown that drag-reducing polymers (DRPs) prolonged survival time in rats with acute myocardial infarction (MI), but their effect on cardiac function post MI remains unknown. This study sought to test the hypothesis that intravenous infusion of DRPs may improve left ventricular (LV) function in rats following surgically induced MI. METHODS: MI was induced by ligation of the left anterior descending coronary artery in 36 Sprague-Dawley rats, and sham operations were performed in 12 animals. DRPs were then administered to 18 of the MI rats. Echocardiograpy was used to evaluate the changes of impaired LV function and global wall motion. Besides, the hydrodynamic effect of DRPs on microcirculation was also assessed. RESULTS: The survival rate at 24h following MI was significantly different among the sham, MI and DRP groups (p = 0.023). DRP-treated animals had marked smaller left ventricular end-systolic diameter and better anterior systolic wall thickness comparison with untreated rats. Significant improvement of fractional shortening and ejection fraction were detected in MI rats with DRP. Wall motion score index and contrast score index were both significantly reduced by DRP treatment. DRPs were shown to have beneficial effects on microvascular variables including red blood cell velocity, diameter, blood flow and calculated wall shear stress in third-order arteriole. CONCLUSIONS: Acute administration of DRPs improved LV function in a rat model of MI possibly by improving microvascular blood flow due to their unique hydrodynamic properties. DRPs may offer a new approach to the treatment of coronary artery ischemic diseases.