The clinical significance of bladder speed.

By calculation of a notional maximum possible flow rate (Qm) from the pressure-flow parameters of clinical urodynamic studies, a variable is obtained which relates to the speed of shortening of the muscle fibres and hence to detrusor contractility. Bladder outlet obstruction causes a reduction in detrusor contractility. After the satisfactory relief of outflow obstruction, the clinical results are related to the degree of recovery of detrusor contractility.