Catheter-associated bladder mucosal trauma during intermittent voiding: An experimental study in pigs.

Objective: The objective of this study is to characterize bladder mucosal trauma associated with intermittent catheterization with conventional eyelet catheters (CECs) and to assess if a microhole zone catheter (MHZC) design concept reduces this adverse effect. Materials and Methods: A porcine model was developed to reflect human catheterization and bladder drainage. Nine pigs were randomized for catheterization with CEC (n = 6) or MHZC (n = 3). The bladder was drained repeatedly 20 times through the catheter. Cystoscopy was performed before and after the procedure, and bladders were analysed by histopathology. Two additional pigs were used for cystoscopy visualization of suction events in vivo. Cystoscopy, gross pathology, histopathological score, leucocyte infiltration, and intracatheter pressure at flow stops during voiding were compared for each group. Results: A significant higher pressure gradient was measured inside the CECs compared with MHZCs during flow stop. Consequently, CECs resulted in suction events inflicting bladder trauma characterized by loss of epithelium, oedema, haemorrhage, and neutrophil tissue infiltration. No significant trauma was identified when using MHZC. Conclusions: Considerable mucosal bladder trauma is inflicted by CECs which may be an overlooked risk factor for urinary tract infection. Catheters can be designed to minimize mucosal suction and reduce associated trauma. This may be a solution to reduce infection frequency and increase user comfort. Furthermore, the study demonstrates the potential of pigs as an attractive animal model for investigating urinary catheter performances.

New micro-hole zone catheter reduces residual urine and mucosal microtrauma in a lower urinary tract model.

Urinary tract infections (UTIs) are the main complication associated with clean intermittent catheterization (CIC) and are facilitated by post-void residual urine and trauma to the mucosa during voiding. The risk of UTI may be diminished by reducing the residual volumes and preventing microtrauma caused by mucosal suction through the eyelets of conventional eyelet catheters (CEC). A new micro-hole zone catheter (MHZC) was developed and tested in an ex vivo porcine lower urinary tract model and in vivo, in pigs, against a CEC. It was shown that, irrespective of the micro-hole diameter, the new catheter ensured increased flowrates and significantly lower residual volumes at the first flow-stop. Furthermore, with a micro-hole diameter of 0.4 mm, mucosal suction was virtually eliminated, regardless of the insertion depth or simulated intra-abdominal pressure mimicking sitting or standing humans. Pressure profile experiments and endoscopy studies indicated that the bladder gradually folds against the drainage tip of the new catheter, without blocking the flow, and, unlike with the CEC, sharp pressure variations and flow-stops did not occur during voiding. The MHZC outperformed the CEC in all tested scenarios and decreased residual volumes, thus potentially decreasing the risk of UTIs.

Development of an ex-vivo porcine lower urinary tract model to evaluate the performance of urinary catheters.

Intermittent catheterization is the gold standard method for bladder management in individuals with urinary retention and/or incontinence. It is therefore important to understand the performance of urinary catheters, especially on parameters associated to risks of developing urinary tract infections, and that may impact the quality of life for urinary catheter users. Examples of such parameters include, urine flowrate, occurrence of flow-stops, and residual urine left in the bladder after flow-stop. Reliable in-vitro and/or ex-vivo laboratory models represent a strong asset to assess the performance of urinary catheters, preceding and guiding in-vivo animal studies and/or human clinical studies. Existing laboratory models are generally simplified, covering only portions of the catheterization process, or poorly reflect clinical procedures. In this work, we developed an ex-vivo porcine lower urinary tract model that better reflects the catheterization procedure in humans and allows to investigate the performance of standard of care catheters. The performance of three standard of care catheters was investigated in the developed model showing significant differences in terms of flowrate. No differences were detected in terms of residual volume in the bladder at first flow-stop also when tuning the abdominal pressure to mimic a sitting down and standing up position. A newly discovered phenomenon named hammering was detected and measured. Lastly, mucosal suction was observed and measured in all standard of care catheters, raising the concern for microtrauma during catheterization and a need for new and improved urinary catheter designs. Results obtained with the ex-vivo model were compared to in-vivo studies, highlighting similar concerns.