ESPU Congress 2018 - Abstract Book

47 11–14 APRIL, 2018, HELSINKI, FINLAND 16:32–16:35 S3-13 (PP) FLOW CHARACTERISTICS OF URETHRAL CATHETERS FOR CIC IN CHILDREN Joseph ORTENBERG  1 , Carrie STEWART  1 and Eiichiro YAMAGUCHI  2 1) Children's Hospital - New Orleans, Louisiana State / Tulane University School of Medicine, Urology, New Olreans, USA - 2) Tulane University, Biomedical Engineering, New Orleans, USA PURPOSE For CIC, little information exists regarding catheter flow rates, to guide catheter selection. MATERIAL AND METHODS 3 sizes – 8, 10, and 12 french, of 10 male catheters were selected. Using microscopic imaging and a precision caliper, we determined inner diameter (I.D.) and tip/inlet hole size. With a hydraulic sys- tem modified from ASTM specifications, we measured flow rate (Q) at 20 cmH2O and 40 cmH2O. RESULTS Average Q for 8, 10, 12 Fr. sizes respectively were 15 %, 33 %, 55 % lower than the laminar flow predictions. Since the flow regime of an 8 Fr. catheter was laminar (Reynolds number, Re<1100), the correlation between Q and I.D. matched well with predictions from the Hagan-Poiseuille equa- tion, with minor impact of the inlet dimensions. All catheters had an opening area ratio (A.R. = area of inlet holes / lumen) larger than 1.0 – ranging from 1.1 < A.R. < 4.0, without size dependency. With 10 Fr. at 40 cmH2O and 12 Fr. at 20 and 40 cmH2O, we identified deviation from the laminar flow prediction. The impact of A.R. became significant as the flow transitioned to turbulence (Re>2000). Our results also show that the reversed, non-physiologic flow direction for Q measurement sug- gested by ASTM, overestimates Q at high Re conditions. CONCLUSIONS Though I.D. is the dominant parameter to characterize Q, there is a significant impact of A.R. on larger catheters with higher hydraulic pressure conditions. Proper configuration of inlet holes at the tip, could improve Q about 20 % for 12 Fr. catheters. Better design of catheters could lessen time for CIC.