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Neurourol Urodyn. 2018 Apr;37(4):1434-1440. doi: 10.1002/nau.23466. Epub 2018 Jan 24.

Comparison of water and air charged transducer catheter pressures in the evaluation of cystometrogram and voiding pressure studies.

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Drexel Unversity School of Medicine, Philadelphia, Pennsylvania.
Laborie Medical Co., Missasagga, Canada.
St George's University School of Medicine, Genada.



Air-charged (AC) and water-perfused (WP) catheters have been evaluated for differences in measuring pressures for voiding dysfunction. Typically, a two-catheter system was used. We believe that simultaneous pressure measurements with AC and WP in a single catheter will provide analogous pressures for coughs, Valsalvas, and maximum pressures in voiding pressure studies (VPS).


This IRB approved prospective study included 50 women over age 21. AC dual TDOC catheters were utilized. The water-filling channel served as the bladder filler and the water pressure readings. Patients were evaluated with empty bladders and at volumes of 50-100 mL, 200 mL, and maximum capacity with cough and Valsalva maneuvers. Comparative analysis was performed on maximum stress peak pressures. At maximum bladder capacity, VPS was done and maximum voiding pressure was recorded.


Comparing coughs and Valsalva maneuvers pressures, there was significant increase in variability between AC and WP measurements with less than 50 mL volume (P < 0.001). Significant correlations were observed between AC and WP measurements for coughs and Valsalvas with bladder volume over 50 mL. Visual impression showed virtually identical tracings. Cough measurements had an average difference of 0.25 cmH2 O (±8.81) and Valsalva measurements had an average difference of 3.15 cmH2 O (±4.72). Thirty-eight women had usable maximum voiding pressure measurements and had a strong correlation.


Cystometrogram and maximum voiding pressure measurements done with either water or air charged catheters will yield similarly accurate results and are comparable. Results suggest more variability at low bladder volumes <50 mL.


TDOC; air-charged catheters; air-filled catheters; cystometrogram; pressure measurements; urodynamic; voiding pressure studies; water-filled catheters


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