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Effects of bladder volume on detrusor contractility during sacral nerve stimulation
Author(s) -
Walter James S.,
Tang Pei C.,
Wheeler John S.
Publication year - 1991
Publication title -
neurourology and urodynamics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.918
H-Index - 90
eISSN - 1520-6777
pISSN - 0733-2467
DOI - 10.1002/nau.1930100107
Subject(s) - medicine , contractility , urinary bladder , stimulation , detrusor muscle , anatomy , volume (thermodynamics) , anesthesia , urology , physics , quantum mechanics
In spinalized dogs under Nembutal anesthesia, electrical stimulation of sacral nerves with electrodes inserted into the sacral canal induced maximal urinary bladder contractions. The amplitude of the peak vesical pressure varied with the bladder volume. Active peak pressures were highest when the bladder volume was 25 to 50 ml. Pressure declined to less than 50% of its maximum value at a bladder volume of 400 ml. In order to further describe the contractile properties of the detrusor muscle, wall tension was calculated using Laplace's law, wall stress was determined as tension per unit wall thickness, and the circumference of the vesical volume was calculated as a measure of muscle length. Active detrusor wall tension during stimulation tended to be highest at the midrange of volumes, whereas the wall stress increased linearly with increasing bladder volume. This increase in wall stress was secondary to the wall becoming thin at large volumes.