The physical basis of some urodynamic measurements.

This report concerns certain principles of physics that are relevant to the clinical practice of Urology as well as the research urodynamicist. Supplemental material is available in previous publications for the physiologist, cardiovascular, dynamicist, anesthesiologist and the like. The material is fairly recent only in its application to the lower urinary tract. Pressure-volume relationships were applied to be cardiovascular system more than 20 years age. Indeed, for those interested in urodynamic methods, there is a vast fund of useful pertinent information in the literature on vascular dynamics. The problems of steady and unsteady flow in flexible structures are common to both specialties. It would be unfortunate if urodynamicists were required to learn of the phenomena and their implications by the drudgery of repeated measurements rather than taking guidance from previous work. This report is intended to serve as an introduction to the approach and, hopefully, will stimulate those who are interested in urodynamic methods to seek out this information and to interpret their measurements in the light of fundamental physical phenomena that have been described and analyzed.