Comparative-fill urodynamics in individuals with and without detrusor overactivity supports a conceptual model for dynamic elasticity regulation.
AIMS
Dynamic elasticity was previously identified in individuals with overactive bladder (OAB) using comparative-fill urodynamics (UD) and is a biomechanical mechanism for acutely regulating detrusor wall tension. On the basis of this data, a conceptual model of dynamic elasticity regulation mediated through a balance of passive mechanisms and active contractions was constructed. The present study tested this model by determining whether individuals with detrusor overactivity (DO) exhibit less dynamic elasticity than individuals without DO.


METHODS
Individuals with and without urgency based on International Consultation on Incontinence Questionnaire-OAB surveys were prospectively enrolled in a comparative-fill UD study. An initial fill defined the presence or absence of DO and determined cystometric capacity. Three additional fills were employed with either passive emptying via a catheter or active voiding. To identify dynamic elasticity, average filling pressures (Pves ) were compared for fill 1 (before strain softening), fill 2 (after strain softening), and fill 3 (after active void). A dynamic elasticity index was defined.


RESULTS
From 28 participants, those without DO showed decreased Pves during filling after strain softening and restored Pves during filling following active voiding, revealing dynamic elasticity. Participants with DO did not show dynamic elasticity. A dynamic elasticity index less than 1.0 cmH2 O/40% capacity was identified in 2 out of 13 participants without DO and 9 out of 15 with DO, revealing a significant association between DO and reduced/absent dynamic elasticity (P = .024).


CONCLUSIONS
This study supports a conceptual model for dynamic elasticity, a mechanism to acutely regulate detrusor wall tension through a balance of competing active contractile and passive strain mechanisms. Improved understanding of this mechanistic model may help us to identify novel treatment strategies for OAB.
['Cullingsworth|Zachary E|ZE|0000-0002-4087-9764', 'Klausner|Adam P|AP|0000-0003-3849-7131', 'Li|Rui|R|0000-0003-0006-818X', 'Nagle|Anna S|AS|0000-0001-9960-4864', 'Carroll|Ashley W|AW|', 'Roseman|John T|JT|0000-0001-6031-4595', 'Speich|John E|JE|0000-0002-8824-4098']
D000328:Adult D001696:Biomechanical Phenomena D004548:Elasticity D005260:Female D006801:Humans D008297:Male D008875:Middle Aged D008954:Models, Biological D009119:Muscle Contraction D011446:Prospective Studies D011795:Surveys and Questionnaires D001743:Urinary Bladder D053201:Urinary Bladder, Overactive D014549:Urinary Incontinence D014563:Urodynamics
overactive bladder bladder biomechanics bladder compliance cystometry