In Intagliettas study with hamsters in the Jacobs School of Engineerings Department of Bioengineering, 90 minutes after hypertonic saline was given to blood-depleted hamsters about 30 percent of normal flow was reconstituted through skin arterioles, tiny branches of arteries that lead to the even smaller capillaries. The bioengineering researchers quantified blood flow with special microscopic procedures.
In blood-depleted hamsters given both hypertonic saline and a small volume of a commercially available viscosity enhancer called Hextend, blood flow through arterioles improved to 40 percent of normal. When the hypertonic saline, Hextend, and a small volume of another viscosity enhancer called alginate were given, arteriole blood flow improved to 55 percent of normal. Hextend and alginate are plasma volume expanders, substances transfused to maintain the fluid volume of blood.
Our findings suggest that elevating the viscosity of blood after severe blood loss is beneficial in resuscitation, said Intaglietta. In fact, our studies indicate that Hextend and similar plasma extenders could produce even greater benefit if they were formulated with higher viscosities.
Arterioles regulate blood flow by constricting and dilating. A variety of factors in the body influence the process, including the viscosity of plasma, the fluid portion of blood. For example, higher viscosity plasma causes arterioles to dilate.
For centuries, dating back to the time of the early Greeks, the idea has always been that blood is thick, so the sick should be treated by bleeding in order to thin the blood, said Intaglietta. Even as late as World War II and the Vietnam Way, it was thought that adding isotonic fluids to replace blood
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University of California - San Diego