Simultaneous in vivo comparison of water‐filled and air‐filled pressure measurement catheters: Implications for good urodynamic practice

Abstract

This study shows that AFCs and WFCs cannot be assumed to register equal values of pressure. It has further shown that even when the p readings are compared with their value at the start of a test, a divergence of values of up to 10 cmH O remains. If AFCs are used, care must be taken to compensate for any p variations that occur during patient movement. Before AFCs are adopted, new normal values for resting pressures need to be developed to allow good quality AFC pressure readings to be made. Neurourol. Urodynam. 35:926-933, 2016. © 2015 Wiley Periodicals, Inc.

Performance analysis of the T‐DOC® air‐charged catheters: An alternate technology for urodynamics

“…Gammie et al indicated that frequency response should be at least 3 Hz for transducers, as most pressure signal changes in UDS occur under this frequency, including most coughs’ frequency spectrum . In a different study, Thind et al demonstrated that 88% of the frequency component of coughs are below 3 Hz . The results in this study established a cut‐off of 5 Hz, which should be adequate to capture most of the clinically relevant pressure events within a UDS study.…”

“…UDS has been widely used in the diagnostic and management of LUT dysfunction for several decades. Despite the multiple UDS catheters technologies currently available, there are not a sufficient number of studies assessing and comparing their performance . In this study, we aimed to assess important features to characterize high quality performance of the ACC.…”

The accuracy of static pressure measurement with water‐filled urodynamic systems

“…In a recent study comparing water‐filled with air‐filled systems, it was noted that the differences between the two in recorded p det could be up to 10 cmH 2 O. The study noted that the Bland‐Altman comparison used did not guide on absolute accuracy, but merely on differences between two measurements.…”

Re: McKinney TB et al: Comparison of water and air charged transducer catheter pressures in the evaluation of cystometrogram and voiding pressure studies. Neurourol Urodyn 2018 DOI: 10.1002/nau23466

“…See Figure modified from McKinney et al Having such huge differences in both directions shows that something is fundamentally wrong with this data. From basic biophysical considerations differences between air‐ and water‐filled measurement of cough spikes can be predicted and have been reported, but these differences are much smaller. Simple biophysics predicts that AC systems cannot record the full amplitude of fast pressure changes during coughs, that is, the peak AC pressure is lower than the WF pressure.…”