Validation of a water-load protocol to define the pattern of bladder sensation.

INTRODUCTION AND HYPOTHESIS: The aim of this study was to confirm reliability of a water-load diuresis protocol and to assess the utility of bladder sensation curves. METHODS: For confirmation of fixed diuresis rate (phase 1), 12 volunteers consumed 250-300 ml of water every 15 min and recorded bladder sensation on a visual analogue scale (VAS) every 5 min to maximum sensation over two filling cycles: voids 1 and 2 (V1 and V2). The test was performed twice. For test-retest validation (phase 2), 24 participants underwent the same protocol drinking 300 ml of water every 15 min. Diuresis rates and voided volumes were compared between cycles and across tests. RESULTS: In phase 1, there was no difference in median void volume (V1 735 ml, V2 678 ml p = 0.433) or median diuresis rates (V2 12.1 ml/min, V3 14.4 ml/min p = 0.136) between cycles. When comparing those who drank 250-300 ml/15 min, there was less variability in those drinking 300-ml aliquots, so this was standardised for later experiments; 95% upper confidence limit of variability of the diuresis rate was calculated as 4.5 ml/min. Any test with a greater difference was rejected as invalid. In phase 2, only 16 participants were analysed. There was no difference in median void volumes between tests [V1 763 ml and 820 ml (p = 0.109) and V2 788 ml and 796 ml (p = 0.266)] or in diuresis rates between test 1 (12.33 ml/min) and 2 (14.40 ml/min) (p = 0.056). Median area under the curve was similar between test 1 404.96 and test 2 418.63. CONCLUSIONS: This refined protocol reliably produced stable diuresis with a water load of 300 ml/15 min, excluding those with a difference in diuresis rate > 4.5 ml/min.

Methods of assessing and recording bladder sensation: a review of the literature.

INTRODUCTION AND HYPOTHESIS: The objective was to review different methods that have been used to assess bladder sensation and to provide an overview of the accuracy and objectivity of the measurement of the subjective perception of the bladder. METHODS: The MEDLINE and PubMed databases were searched to identify articles. References from those articles were also searched. Terms used for the search were: urinary bladder, sensation, cystometry, urodynamics, urinary incontinence and focus group. Eight hundred and fifty abstracts were identified from databases, and 12 from other sources. Twenty-two duplicate articles were removed. Irrelevant articles were excluded after reading their titles. Fifty-four articles were eligible, but 17 were excluded after reading the full text, leaving 37 articles where assessment of bladder sensation was the main aim. RESULTS: Six different methods of measuring bladder sensation have been described in the literature. Although the most frequently used was cystometry, this is an invasive tool and does not reproduce bladder behaviour during daily life because it records bladder sensation as episodic events. The visual analogue scale using a forced diuresis protocol seemed to be an excellent tool. It was non-invasive and evaluated bladder sensation continuously, from an empty to a full bladder. CONCLUSIONS: In some of the studies, the samples were too small to draw any significant conclusions. There were also conflicting data on which tool was the most accurate, especially as each method of evaluating bladder sensation may influence the way it is described by participants.