The calculation and comparison of the Detrusor Contractility Parameter and Watts Factor

Abstract

Aims: To test the significance of association between a validated index of detrusor contractility, v_CE , the Watts Factor, and the Detrusor Contractility Parameter, t_20-80 ; and to test whether t_20-80 depends on outflow tract resistance as indicated by Bladder Outlet Obstruction Index (BOOI).

Methods: Thirty-seven pressure-flow traces from 20 male and 17 female patients were analyzed and forms of the Watts Factor, t_20-80 and BOOI were compared with v_CE .

Results: The Detrusor Contractility Parameter, t_20-80 , is significantly associated with v_CE for both women and men without a high degree of bladder outlet obstruction. The Watts Factor only had a significant association with v_CE at the point of maximum flow in women.

Conclusions: The Detrusor Contractility Parameter (DCP) (t_20-80 ), can be measured easily from the pressure flow curves of a urodynamic test. The Watts Factor at maximum urine flow, WF_Qmax , can be readily calculated, but is only applicable to women. In both women and men without a high degree of bladder outlet obstruction, DCP is better associated with true detrusor contractility than any Watts Factor analysis.

Keywords: Wmax; bladder outlet obstruction; contractility.