Objective:To assess whether air-charged urodynamic(ACC)can replace water-filled urodynamic(WFC)and the value of ACC for the diagnosis of benign prostatic hyperplasia(BPH)in these patients.Methods:In this prospective study, 27 male patients with BPH(aged 60-90 years)were randomly selected for WFC and ACC examinations during the same period to compare the values of urodynamic pressure parameters recorded for the two groups.Pressure values were compared using Bland-Altman plots and the paired sample t-test, and differences in abdominal pressure changes in the two groups were compared using the chi-square test. Results:Changes in WFC and ACC pressure values showed the same trends, but at the three points where data were recorded and compared, the mean abdominal pressure(Pabd), end of bladder filling pressure(Pves.fill)and maximum detrusor pressure(Pdet.void)were(25.3±8.5)cmH 2O(1 cmH 2O=0.098 kPa), (26.0±8.08.4)cmH 2O and(98.8±32.8)cmH 2O for WFC and(32.5, 5.5±5.3)cmH 2O, (32.6±5.0)cmH 2O and(95.3±36.3)cmH 2O for ACC, respectively, The pressure values of the two methods were significantly different( P<0.05). WFC pressure values were unstable, with 74.07%(20/27)showing a marked decrease during bladder filling, significantly different from those measured by ACC( P<0.001). Band-Altman plots illustrated high consistency between pressure values measured via WFC and ACC. Conclusions:The pressure measured by ACC does not represent that measured by WFC, suggesting a clinical need to establish standard reference data for ACC.The abdominal pressure instability measured by WFC may be one of the factors leading to different detrusor pressures from the two methods.The high consistency between pressure values from ACC and WFC indicates that the former can also be used to assess changes in bladder function in elderly BPH patients.