The effect of bladder filling rate on the voiding behaviour of patients with overactive bladder.

Many self-help guides advise patients that spreading fluid intake throughout the day can reduce symptoms of overactive bladder (OAB).1,2 However, although animal studies suggest a link between faster filling rates and increased afferent nerve firing, the relationship between filling rate and bladder sensation has not been examined in humans. The aim of this study is to investigate the effect of bladder volume and rate of bladder filling on the bladder sensation and voiding patterns of patients with OAB.

Forty female volunteers (control group) were recruited by open advertisement. A further 24 female patients with OAB were recruited from the urology outpatients department. Each participant completed a UDI-6, IIQ-7 and 3-day sensation-related bladder diary.

The proportion of urgent voids in the control group increased with increasing voided volumes (p=<0.001) and bladder filling rates (p=<0.001). The proportion of urgent voids in patients with OAB also increased with increasing voided volumes (p=0.004) and bladder filling rates (p=0.013). On regression analysis the rate of bladder filling was an independent predictor of urgent voids in patients with OAB but not in the control group. Patients with OAB were less tolerant of higher bladder filling rates and experienced most grades of bladder sensation at lower voided volumes and filling rates than the control group.

The rate of bladder filling appears to influence the intervoiding interval and sensation associated with each void in patients with OAB. Advising patients to lower their bladder filling rate should help reduce urinary frequency, urgency and urge incontinence.

The Journal of urology. 2019 Feb 28 [Epub ahead of print]

E J Redmond, T O'Kelly, H D Flood

University Hospital of Limerick, Dooradoyle , Limerick , Ireland., University College Hospital Galway , Galway , Ireland.

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