Analysis of all possible combinations of four measurements determining true propagation in arteries

All possible combinations of four measurements of blood pressure, blood flow and vascular diameter are examined by transmission-line theory. It is found that only nine measurement combinations can give the attenuation coefficient gamma, reflection coefficient R and characteristic impedance Z0 simultaneously. At least one pressure measurement must be included. Their general expressions with arbitrary measuring locations are presented, together with some simplified forms which cover all the previous methods. A greater choice of method is thereby made available for use in practice. The results show that, regardless of the measurement locations, all combinations can be solved in the order gamma first, R second and Z0 last.