Estimation of bladder contractility from intravesical pressure-volume measurements.
To describe parameters from urodynamic pressure recordings that describe urinary bladder contractility through the use of principles of muscle mechanics.



Subtracted detrusor pressure and voided flow were recorded from patients undergoing filling cystometry. The isovolumetric increase of detrusor pressure, P, of a voluntary bladder contraction before voiding was used to generate a plot of (dP/dt)/P versus P. Extrapolation of the plot to the y-axis and the x-axis generated a contractility parameter, vCE(the maximum rate of pressure development) and the maximum isovolumetric pressure, P0, respectively. Similar curves were obtained in ex vivo pig bladders with different concentrations of the inotropic agent carbachol and shown in a supplement.



Values of vCE, but not P0, diminished with age in female subjects. vCEwas most significantly associated with the 20-80% duration of isovolumetric contraction t20-80; and a weaker association with maximum flow rate and BCI in women. P0was not associated with any urodynamic variable in women, but in men was with t20-80and isovolumetric pressure indices.



The rate of isovolumetric subtracted detrusor pressure (t20-80) increase shows a very significant association with indices of bladder contractility as derived from a derived force-velocity curve. We propose that t20-80is a detrusor contractility parameter (DCP). Neurourol. Urodynam. 36:1009-1014, 2017. © 2016 Wiley Periodicals, Inc.
School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, United Kingdom.
Christopher H
CH
Fry
Bristol Urological Institute, Southmead Hospital, Bristol, United Kingdom.
Andrew
A
Gammie
Bristol Urological Institute, Southmead Hospital, Bristol, United Kingdom.|School of Clinical Sciences, University of Bristol, Bristol, United Kingdom.
Marcus John
MJ
Drake
Bristol Urological Institute, Southmead Hospital, Bristol, United Kingdom.
Paul
P
Abrams
School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, United Kingdom.
Darryl Graham
DG
Kitney
Bristol Urological Institute, Southmead Hospital, Bristol, United Kingdom.|Department of Biological, Biomedical and Analytical Sciences, University of the West of England, Bristol, United Kingdom.
Bahareh
B
Vahabi
D000328:Adult; D000368:Aged; D001696:Biomechanical Phenomena; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction / Q000502:physiology*; D009130:Muscle, Smooth / Q000502:physiology*; D011312:Pressure; D001743:Urinary Bladder / Q000502:physiology*; D014554:Urination / Q000502:physiology*; D014563:Urodynamics
bladder; contractility; force-velocity relationship; urodynamics