A double‐blind, randomized controlled trial of cystometry using saline versus 0.3 M potassium chloride infusion in women with overactive bladder syndrome

Abstract

Aim: To evaluate the e¡ect of 0.3 M potassium chloride on cystometric parameters by comparing it with normal saline as a ¢lling solution in women with overactive bladder (OAB). Patients and Methods: Twenty-three women with signi¢cant 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. Results: Regardless of the nature of the ¢lling solution, the order in which the CMGs were performed had little in£uence on either ¢rst desire to void (FDV, mean 83.5 ml vs. 117.8 ml for ¢rst and second CMGs respectively, P ¼ 0.10) or on maximum cystometric capacity (Cmax, mean 265.0 ml vs. 264.4 ml, P ¼ 0.98). KCl produced a signi¢cant (24%) reduction in mean Cmax compared to NS (mean 228.6 ml vs. 300.8 ml, P ¼ 0.001), irrespective of the order of infusion. Conclusion: This comparative study using 0.3 M KCl versus NS as ¢lling solutions suggests that intravesical potassium may not simply act on urothelial sensory nerve endings; it may also stimulate detrusor muscle contraction. These ¢ndings may in£uence the interpretation of the potassium sensitivity test in patients with OAB symptoms, particularly in those suspected of having interstitial cystitis.

The role of a leaky epithelium and potassium in the generation of bladder symptoms in interstitial cystitis/overactive bladder, urethral syndrome, prostatitis and gynaecological chronic pelvic pain

“…Subsequently, other investigators reported the same findings and it did not make any difference if the potassium infusion was given before or after the sodium. The results were the same; all patients with IC had reduced bladder capacities when exposed to potassium [20]. These same researchers tested both patients with OAB and those with IC and the potassium reactions were all positive in both groups [20,23].…”

“…Patients with IC were tested and compared with asymptomatic control subjects. To date, the international literature contains over 35 published reports on potassium testing in over 3000 patients with IC/painful bladder syndrome (PBS) and the data are very robust, with 80% of patients with IC testing positive [19–25]. Furthermore, several reports included data on about 200 normal subjects and the test was negative in 98.3%[14,18,26,27].…”

Interstitial Cystitis and the Overlap with Overactive Bladder

“…Multiple in vitro and in vivo models in humans and animals have demonstrated increased permeability across the urothelial barrier with bladder injury [18]. Leaky epithelium may be present in patients with irritative voiding symptoms, regardless of etiology [22]. In their study, Chung et al [4] found that 60% of patients with OAB symptoms had a positive PST.…”

“…Cystoscopy and/or urodynamics (UDS) should be considered in complex cases when the diagnosis is in question [ [37] performed a retrospective analysis of 118 women (40 patients with IC/ PBS, 78 with OAB) and discovered differences between OAB and IC/PBS, most notably decreased compliance and lower volume at first desire in the IC/PBS group. The PST also should be considered, but clinicians should be mindful that recent research suggests it may not be specific for IC/PBSrather that it indicates leaky epithelium that could be present in a variety of conditions that produce irritative voiding symptoms [22], as discussed previously in this review.…”

What’s new in the diagnosis and management of painful bladder syndrome/interstitial cystitis?

“…Newer versions of the test have emerged, using a potassium-based instillation in urodynamics, and seeing if the fi lling phase has lower capacity compared with water instillation [ 53 ]. Even this modifi ed version of potassium testing is controversial [ 54 ]. The potassium test and its modifi ed versions appear not to be performed commonly, in part, possibly due to physician reluctance to provoke pain in their patients.…”