Final answer:
Dextran 40 improves microcirculation by decreasing blood viscosity.
Step-by-step explanation:
Dextran 40 has been shown to improve microcirculation by decreasing blood viscosity. Dextran is a polysaccharide that absorbs water to form gels, which can help to increase blood flow by reducing the thickness and stickiness of blood. When blood viscosity is decreased, it allows for smoother and easier blood flow through the microcirculation.