Urodynamics

Hydrodynamics of the Ureter and Renal Pelvis

Saul Boyarsky, Carl W. Gottschalk, Emil A. Tanagho

• Publisher: Academic Press
• Year: 2014
• Print ISBN: 9780121212506
• eBook ISBN: 9781483216522
• Topic: Ciencias biológicas
• Subtopic: Fisiología

Urodynamics: Hydrodynamics of the Ureter and Renal Pelvis summarizes the present status of urodynamics in progression. The book presents papers on ureteral morphology as a basis for peristaltic activity; the concept of ureteral peristaltic function; and bioengineering aspects of ureteral function. The text also includes papers on factors controlling ureteral peristalsis; the clinical applications in urodynamics; and the theory and techniques of hydrodynamic measurements. Urologists, physiologists, and medical students taking related courses will find the book invaluable.

III

Bioengineering Aspects of Ureteral Function

Outline

Chapter 13: Ureteral Dimensions and Specifications for Bioengineering Modeling

Chapter 14: Basic Engineering Principles of Ureteral Flow

Chapter 15: Peristaltic Pumping: A Bioengineering Model

Chapter 16: The Ureter as a Peristaltic Pump

Chapter 17: Hydrodynamic Model of Ureteral Function

Chapter 18: A Systems Physiology Approach to Ureteral Modeling

Discussion

13

Ureteral Dimensions and Specifications for Bioengineering Modeling

SAUL BOYARSKY and PEREGRINA C. LABAY, DIVISION OF GENITOURINARY SURGERY, DEPARTMENT OF SURGERY, WASHINGTON UNIVERSITY SCHOOL OF MEDICINE, ST. LOUIS, MISSOURI

Publisher Summary

This chapter discusses ureteral dimensions and specifications for bioengineering modeling. Ureter is an adaptive organ, functioning as an adaptive system that alters one or more of its characteristics and dimensions to meet its functional requirements. A new ureter must be actively contractile so that it empties and sterilizes itself completely. It must carry no residual urine and should imitate normal rhythms, bolus volumes, and functional demands. A new ureter must be patent and offer low resistance to the elaboration of urine by the nephron. It should not absorb urinary constituents and should have a smooth lumen that provides no nidus for calculus formation, infection, or obstruction. It should allow only unidirectional flow with no retrograde peristalsis or reflux. The wall of the new ureter must be tolerated biologically and immunologically, and should not secrete substances into the urinary tract.

Although the ureter is in a continuous state of change and motion, its dimensions vary around fairly stable values. Whether the mean, the mode, or the media will turn out to be the most useful dimension for a particular purpose can only be determined by experience. Even the dimensions taken from postmortem, fixed, or immobilized tissues may not always be the best for our purpose.

There may be some objections to attributing static dimensions and measurements to the ureter, particularly from the physiologic approach. This tends to divert attention from the rhythm and cyclic variation in load or pressure, or to give a false impression in other respects. However, the engineer, the surgeon, and the morphologist must have a starting point and boundaries to work within. Neither can we expect ideally accurate measurements of the ureter to be recorded, since this would require every measurement to be recorded continuously with no disturbance of the system, conditions that are impossible.

Reasonable estimates have been made of ureteral length, peristaltic frequency, peristaltic pressure, conduction rate, flows, and capacities. Bolus length and diameter can be measured from X-rays and average bolus volume can be calculated. In the human, the adult ureter measures from 27 to 37 cm in length and lies retroperitoneally throughout its entire course along the posterior abdominal wall and bony pelvis. Its contour conforms to the shape of the wall of the pelvis. It enters the bladder wall at its base in the tigone at an angle. The intramural course is 1–1.5 cm in length. The uretervesical junction has a valvular function in preventing the reflux of urine from the bladder to the ureter or kidney.

Peristaltic contractions occur 1–5 times/min. The urinary output is usually 0.1–3.0 ml of urine per minute per ureter. Bolus volume would be calculated at 0.1–0.6 ml per bolus. In severe dehydration urine flow falls lower.

The peak peristaltic pressure amplitude has been measured to fall between 10 and 40 ml of mercury through indwelling catheters which are fluid-filled. The renal pelvic capacity is 4–8 ml of urine, but with distention, it can rise to 12 ml or more. In dis...

Table of contents

• Cover image
• Title page
• Table of Contents
• Contributors
• Copyright
• List of Contributors
• Preface
• I: Ureteral Morphology as a Basis for Peristaltic Activity: Basic Principles
• II: The Concept of Ureteral Peristaltic Function
• III: Bioengineering Aspects of Ureteral Function
• IV: Factors Controlling Ureteral Peristalsis
• V: Clinical Applications
• VI: Theory and Techniques of Hydrodynamic Measurements
• VII: Potential Adaptation of Available Instrumentation and Techniques Not Currently Used
• Subject Index