Comparison of air-filled and water-filled catheters for use in cystometric assessment
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Introduction and hypothesis
To determine whether pressure readings measured with air-filled catheter (AFC) and water-filled catheter (WFC) systems are equivalent during cystometric assessment, especially in case of pressure measurements at Valsalva manoeuvres and coughs.
Twenty-five subjects were recruited. The commercially available 7-Fr TDOC AFC, which simultaneously reads water and air pressures in the bladder and rectum, was used to compare filling and voiding data recordings. Data were compared using paired t-tests, Bland-Altman plots and linear correlation methods, respectively.
Pressure readings measured by the two systems showed a good correlation at Valsalva manoeuvres [R2 = 0.988, 0.968 for vesical pressure (Pves) and abdominal pressure (Pabd), respectively] and at coughs (R2 = 0.972, 0.943 for Pves and Pabd, respectively). There was a statistically significant difference between the two different measurement modalities at coughs (p < 0.01), initial resting pressure (p < 0.01) and the maximum pressure at detrusor overactivity (p < 0.01). This indicated that the difference between the two measurement modalities during Valsalva manoeuvres could reach up to 5.2 cmH2O and 8.1 cmH2O in Pves and Pabd measurements, respectively. During coughs, the difference could reach up to 20 cmH2O and 19.5 cmH2O in Pves and Pabd measurements, respectively.
Pressure recordings from AFC and WFC systems appear to be interchangeable for some urodynamics parameters such as Pves at Valsalva manoeuvres if the baseline pressure is compensated, but not for fast-changing pressure signals such as coughs. This has to be considered when pressures are being taken with the AFC.
KeywordsAir-filled catheter Water-filled catheter Urodynamics Comparison study
We thank Laborie Medical Technologies for funding of this study. Furthermore, the study was partly supported by a grant from the German charity fund “Association for continence research and continence education”, Karmeliterhöfe, Karmeliterstr. 10, 52064 Aachen, Germany. Some of the charity money was donated by reimbursement for urodynamic teaching from Laborie Medical Technologies. The corresponding author is grateful for the funding from the China Scholarship Council (201608080204).
Compliance with ethical standards
Ethical Commission, Faculty of Medicine, Rheinische Friedrich-Wilhelms-Universität Bonn, ethical vote number: 395/15.
Conflicts of interest
Ruth Kirschner-Hermanns received honoraria from Laborie Medical Technologies or Urodynamic Teaching and has been an invited speaker at Repha GmgH, Germany.
Wei Sheng has nothing to disclose.
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