Medical Pharmacology: Physics in Anesthesiology


"Poiseuille's law gives insight into the complex task of regulating blood flow to different parts of the body. In response to demand, the body must direct more oxygen and nutrients to one region of the body, and if necessary temporarily curtail the supply to a less essential region. Since the flow resistance depends upon the fourth power to the interior radius of a vessel, the processes of vasodilation and vasoconstriction offer powerful control mechanisms." "If there is a need to increase the blood flow through a given vessel by percent, or to x its original value, then vasodilation by percent or to x its original radius will accomplish the increase. This assumes that the applied pressure remains the same." "The effect of vessel radius is just as dramatic in reduction. A reduction the the interior radius of a vessel by percent or to x its original radius will reduce the flow by percent, or to x its original value."