Enhanced objective quantitative cystometric analysis of compliance and contractility

OBJECTIVE To show, for pressure-time data from cystometrography (CMG), the potential practical clinical application of automatically identified, displayed, analysed and quantified compliance and contractility, as undesirable high-pressure detrusor storage may be caused by inefficient compliance or uninhibited contractions (UNC). MATERIAL AND METHODS Bladder contractility was measured by UNC and compliance by relaxed-state detrusor pressure (RSDP), i.e. the detrusor (bladder-abdominal) pressure with all UNC removed. Forty-one CMG examinations were used retrospectively to: (i) validate the separation and identification, by comparing the resulting separate graphs (data) of UNC and RSDP with an expanded time scale for raw vesical and rectal data; (ii) show that the separation is correct by examples; and (iii) show the potential practical utility by results for typical cases. RESULTS Separation into RSDP and UNC was correctly identified and plotted. The examples showed the utility and four types of UNC (‘high’, contractions of >25 cmH2O of long duration; ‘medium’, >25 cmH2O of short duration; ‘low’, 4–25 cmH2O of short duration; and ‘frequent’, of 2–6 cmH2O). CONCLUSIONS UNCs as small as 2 cmH2O can be detected and measured. The explicit enhanced estimate of compliance and contractility will be useful in the follow-up when comparing different patients and studies, and assist in more appropriate diagnosis and treatment. Because the treatment for bladders with poor contractility differs greatly from those with detrusor instability, the ability to reliably and accurately differentiate between these causes is important.