A MATHEMATICAL-MODEL FOR MEASURING BLOOD-FLOW IN SKELETAL-MUSCLE WITHTHE MICRODIALYSIS ETHANOL TECHNIQUE

A theoretical analysis of the microdialysis ethanol technique in skele tal muscle is presented, and a model governing the transport of ethano l from the microdialysis probe to the capillaries in the muscle tissue is proposed. The model is derived under the assumption of a steady-st ate situation, and an analytical solution is found for the outflow-to- inflow ratio of ethanol in the perfusate. Theoretically calculated res ults are compared with experiments, and for at least one of the two pr obe types used good agreement is achieved in a wide range of blood flo w and perfusate flow rates. The main uncertainty factor in the theoret ical calculations is the diffusivity of ethanol in muscle tissue, and the value for best agreement between theory and experiments has been u sed. Error estimates show that for a constant relative error in the ou tflow-to-inflow ratio of ethanol in the perfusate, low perfusate flow rates give better predictions of the blood flow.