A double-blind, randomized controlled trial of cystometry using saline versus 0.3 M potassium chloride infusion in...

To evaluate the effect of 0.3 M potassium chloride on cystometric parameters by comparing it with normal saline as a filling solution in women with overactive bladder (OAB).

Twenty-three women with significant OAB symptoms underwent consecutive cystometrograms (CMGs) using 0.9% normal saline (NS) and 0.3 M potassium chloride (KCl), the order of which was randomized for each patient. Individual CMGs were performed by separate investigators and both patients and investigators were blinded to the order in which each solution was given and to the results of the other CMG.

Regardless of the nature of the filling solution, the order in which the CMGs were performed had little influence on either first desire to void (FDV, mean 83.5 ml vs. 117.8 ml for first and second CMGs respectively, P = 0.10) or on maximum cystometric capacity (Cmax, mean 265.0 ml vs. 264.4 ml, P = 0.98). KCl produced a significant (24%) reduction in mean Cmax compared to NS (mean 228.6 ml vs. 300.8 ml, P = 0.001), irrespective of the order of infusion.

This comparative study using 0.3 M KCl versus NS as filling solutions suggests that intravesical potassium may not simply act on urothelial sensory nerve endings; it may also stimulate detrusor muscle contraction. These findings may influence the interpretation of the potassium sensitivity test in patients with OAB symptoms, particularly in those suspected of having interstitial cystitis.