IMPACT OF DIFFERENT-SIZED CATHETERS ON PRESSURE-FLOW STUDIES IN PATIENTS WITH BENIGN PROSTATIC HYPERPLASIA

The importance of pressure-flow studies for the diagnostic work-up of patients suffering from benign prostatic hyperplasia (BPH) has recentl y been recognized more widely. For these studies, several different ty pes and sizes of catheters have been used. According to our experience , the degree of obstruction seems to be dependent on the catheter size applied. To evaluate the impact of catheter size on urodynamic result s, 64 male patients underwent pressure-flow studies; 41 had the clinic al diagnosis BPH; 23 were a nonobstructed control group. The 41 BPH-pa tients were randomized into two groups: group BPH 1 (n=20) had a 5F ca theter and group BPH 2 (n=21) had a 10F filling catheter in addition t o the 5F pressure transmission catheter in the urethra. All patients u nderwent three filling and pressure-flow studies. The filling catheter was removed for the third pressure-flow study. Peak flow rates (Qmax; ml/s), the corresponding detrusor pressure at maximum uroflow (pdetQm ax; cm H2O) and the degree of obstruction, rated according to the line ar passive urethral resistance relation (linear-PURR), were assessed. The removal of the 5F (group BPH 1) or 10F (group BPH 2) filling cathe ter resulted in a 21.1% and 55.7% increase of maximum uroflow rate res pectively. In parallel, we observed a 9.9% and 18.8% decrease of detru sor pressure at maximum flow. The degree of obstruction classified acc ording to linear-PURR decreased by 14.6% and 21.1% respectively. Furth ermore, it became evident that five patients (21.7%) of the unobstruct ed control group could have been wrongly interpreted as being obstruct ed if measured with the filling (10F) and the pressure measurement (5F ) catheter in situ. In conclusion, the degree of obstruction is depend ent on the cross-sectional diameter of the used catheters. Consequentl y, standardization with regard to catheter size is mandatory if data f rom different institutions are to be compared. (C) 1996 Wiley-Liss, In c.