Recently Air charge catheter (ACC) system has been used for pressure measurement in urodynamic study especially in USA. However, the usage of ACC has not been admitted as ICS standard like water filling catheter (WFC) system.  We investigated to compare the data of pressure flow study using water filling catheter (WFC) and air charged catheter (ACC) systems and examine the agreement for the degree of detrusor contractility and BOO.

From the UDS database between 2018 and 2019, the female patients who underwent a pair of consecutive pressure flow studies (WFC and ACC systems) were selected for this study. Pdet used in this study was a change in pressure from baseline rather their raw value. Detrusor contractility was examined with PIP1(1). Weak detrusor contractility wad defined as PIP1 < 30. BOO was evaluated with cut-off value of PFS for Female BOO as follows ;Pdet@Qmax>20cmH2O when the Qmax is ≤ 12ml/s or Pdet@Qmax> 30cmH2O when the Qmax is 13 and 15ml/s(2).  The agreements of Qmax and Pdet@Qmax between two catheter systems were assessed using the Bland and Altman analysis. Cohen’s kappa was used for the agreements of category of detrusor contractility and BOO between two catheter systems.

Thirty-eight patients had paired sets for analysis. After the exclusion of 18 patients (unacceptable normal range of initial resting pressure 12, no urination 3, poor quality 3), 20 patients were selected for analysis. The mean age of these patients was 69.1 ± 10.4 years. The presenting lower urinary tract symptoms of these patients were as follows: difficulty on urination 7; urgency urinary incontinence 7; stress urinary incontinence 4; mixed urinary incontinence 2. Applying the Bland and Altman method, the values of Qmax were similar (mean differences 0.3ml/s), however, the values of PdetQmax in the ACC systems were higher than that in the WFC (mean differences -1.1cmH2O) (Fig1). There were wide 95% limits for agreement for difference in both Qmax and PdetQmax (-3.9 to 4.5 mL/s and -18.0 to 15.9 cmH2O, respectively). To examine BOO using King and Goldman cut-off criteria and detrusor contractility using PIP1, Cohen’s kappa for obstruction and detrusor contractility were 0.6250 and 0.5288 respectively (Table 1).

Difference of average of Pdet@Qmax  between ACC and WFC systems was only 1.1 cmH2O(Bland and Altoman analysis). The agreements of female BOO and detrusor contractility categories between them  werem oderate by Cohen kappa analysis. These agreements might be acceptable for clinical use because the pressure flow study commonly have some noises and bias in same procedure  in the same patient.

The pressure flow study using ACCs systems may be a possible alternative to that using WFC system if their data is high-quality with cares to avoid pitfalls and obey the rules strictly with caution for moderate agreement of ACC and WFC system. This is a small-scale study; therefore, a greater number of cases is needed to generalize this concept.

Neurourology and Urodynamics 2004;23:184
Cur Urol Rep 2014;15:436