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

New compact micro-hole zone catheter enables women to achieve effective bladder emptying without flow-stops

BACKGROUND

Clean intermittent self-catheterisation (CISC) with conventional eyelet catheters (CECs) is associated with urine flow-stops, which require the catheter to be repositioned so flow can resume. Flow-stops often occur because bladder mucosa is sucked into the eyelets.

AIMS

This investigation aimed to compare the bladder-emptying performance of the micro-hole zone catheter (MHZC) with the CEC.

METHODS

This was a multi-centre, randomised, open-label, controlled cross-over study with 82 women comparing the MHZC to the CEC. The endpoints relating to bladder-emptying performance included the residual volume at first flow-stop, the number of flow-stops and the proportion of successful treatment responses. The women's perception of the catheters was assessed as well as device discomfort.

FINDINGS

Catheterisations with MHZC significantly reduced the risk of flow-stops, with relative risk results showing a 2.74 times lower risk of flow-stops with a health professional-led catheterisation and a 2.52 times lower risk during self-catheterisation. There was no statistical difference in residual urine volume at first flow-stop between the two catheters. Catheterisations with the MHZC were significantly more likely to achieve zero flow-stops and a residual urine volume of <10 ml at first flow-stop. The women had a significantly more positive perception of the MHZC than the CEC in areas including handling, confidence, sensation and satisfaction.

CONCLUSION

The MHZC enabled effective bladder emptying without catheters needing to be repositioned, supporting the women by simplifying the procedure and making them feel confident that their bladders were empty.

Reduction in lower urinary tract mucosal microtrauma as an effect of reducing eyelet sizes of intermittent urinary catheters

Intermittent catheterization (IC) utilizing conventional eyelets catheters (CECs) for bladder drainage has long been the standard of care. However, when the tissue of the lower urinary tract comes in close proximity to the eyelets, mucosal suction often occurs, resulting in microtrauma. This study investigates the impact of replacing conventional eyelets with a drainage zone featuring multiple micro-holes, distributing pressure over a larger area. Lower pressures limit the suction of surrounding tissue into these micro-holes, significantly reducing tissue microtrauma. Using an ex vivo model replicating the intra-abdominal pressure conditions of the bladder, the intra-catheter pressure was measured during drainage. When mucosal suction occurred, intra-catheter images were recorded. Subsequently affected tissue samples were investigated histologically. The negative pressure peaks caused by mucosal suction were found to be very high for the CECs, leading to exfoliation of the bladder urothelium and breakage of the urothelial barrier. However, a micro-hole zone catheter (MHZC) with a multi-eyelet drainage zone showed significantly lower pressure peaks, with over 4 times lower peak intensity, thus inducing far less extensive microtraumas. Limiting or even eliminating mucosal suction and resulting tissue microtrauma may contribute to safer catheterizations in vivo and increased patient comfort and compliance.

Understanding the properties of intermittent catheters to inform future development

Despite the extensive use of intermittent catheters (ICs) in healthcare, various issues persist for long-term IC users, such as pain, discomfort, infection, and tissue damage, including strictures, scarring and micro-abrasions. A lubricous IC surface is considered necessary to reduce patient pain and trauma, and therefore is a primary focus of IC development to improve patient comfort. While an important consideration, other factors should be routinely investigated to inform future IC development. An array of in vitro tests should be employed to assess IC's lubricity, biocompatibility and the risk of urinary tract infection development associated with their use. Herein, we highlight the importance of current in vitro characterisation techniques, the demand for optimisation and an unmet need to develop a universal 'toolkit' to assess IC properties.

Product evaluation of the Luja Micro-hole Zone Technology in clean intermittent self-catheterisation

Clean intermittent self-catheterisation is a common procedure undertaken by people with bladder dysfunction. However, it is not without its complications, the main one being urinary tract infection. The most common causes of urinary tract infections are poor hygiene, technique and adherence, excessive post-void residual urine and bladder trauma. A catheter with new Micro-hole Zone Technology has been developed, which can potentially improve bladder emptying and minimise these complications. A case study is used to illustrate its effects in practice.

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.

Improved emptying performance with a new micro-hole zone catheter in adult male intermittent catheter users: A comparative multi-center randomized controlled cross-over study

AIMS

To confirm the improved performance of the micro-hole zone catheter (MHZC) compared to a conventional eyelet catheter (CEC) in male users of clean intermittent catheterizations (CICs).

METHODS

Male self-catheterizing subjects, who used hydrophilic sleeved soft/flexible CIC as the only bladder emptying method, were enrolled into a multi-center, randomized, cross-over study performed across six European sites. Subjects tested the MHZC, featuring a drainage zone with 120 micro-holes and a CEC with two eyelets. The study consisted of four study visits (V0-V3), during which endpoints related to catheter performance (urinary flow-stops, bladder emptying, and intra-catheter pressure) were measured and two 4-week test periods at home (T1 and T2) where dipstick hematuria and user perception between catheters were evaluated.

RESULTS

Seventy-three male subjects with non-neurogenic and neurogenic bladder dysfunction (3:2) were enrolled. On average, catheterizations with the MHZC led to close to mean zero flow-stops compared to ≥1 flow-stops with the CEC, during both HCP- and self-led catheterizations (both p < 0.001). Residual urine at first flow-stop was significantly reduced for the MHZC compared to CEC (p = 0.001 and p = 0.004, for HCP- and self-led catheterizations, respectively). This was substantiated by a significantly smaller pressure peak at first flow-stop, a proxy for minimized mucosal suction (both HCP- and self-led catheterizations, p < 0.001). After home-use catheterizations, dipstick hematuria was comparable between catheters, whereas catheterizations were associated with significantly improved perception in favor of MHZC regarding bladder emptying, less blocking sensation, and improved hygienic catheterization compared to the CEC.

CONCLUSION

This study confirmed the evidence of improved bladder emptying with the MHZC compared to a CEC without the need to reposition the catheter. The MHZC therefore offers an enhanced benefit for the dependent CIC user securing complete bladder emptying in an uninterrupted free flow and reducing the need to reposition the catheter during emptying.

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.

New Intermittent Urinary Micro-Hole Zone Catheter Shows Enhanced Performance in Emptying the Bladder: A Randomised, Controlled Crossover Study

Urinary tract infections (UTIs) are common and troublesome complications of clean intermittent catheterisation (CIC) in individuals suffering from incomplete bladder emptying, which may exacerbate the underlying disease and lead to hospitalisation. Aside from the design of the intermittent catheter and its handling, a recent review highlighted residual urine as one of several UTI risk factors. A new urinary intermittent catheter with multiple micro-holes has been developed for improved bladder emptying. In a controlled crossover study, adult male CIC users were randomised for a health care professional-led catheterisation with the new micro-hole zone catheter (MHZC) and a conventional eyelet catheter (CEC) in two individual test visits to compare the number of flow-stops and the residual urine at the first flow-stop as co-primary endpoints. In 42 male CIC users, the MHZC resulted in significantly fewer flow-stop episodes compared to the CEC (mean 0.17, 95% CI [0.06, 0.45] vs. mean 1.09, 95% CI [0.75, 1.6], respectively; p < 0.001) and significantly less residual urine at the first flow-stop (mean 5.10 mL, SE [1.14] vs. mean 39.40 mL, SE [9.65], respectively; p < 0.001). No adverse events were observed in this study. The results confirm the enhanced performance of the MHZC compared to a CEC, ensuring an uninterrupted free urine flow with no need to reposition the catheter until the bladder is thoroughly empty.

Wound healing responses of urinary extravasation after urethral injury

The post-surgical fluid leakage from the tubular tissues is a critical symptom after gastrointestinal or urinary tract surgeries. Elucidating the mechanism for such abnormalities is vital in surgical and medical science. The exposure of the fluid such as peritonitis due to urinary or gastrointestinal perforation has been reported to induce severe inflammation to the surrounding tissue. However, there have been no reports for the tissue responses by fluid extravasation and assessment of post-surgical and injury complication processes is therefore vital. The current model mouse study aims to investigate the effect of the urinary extravasation of the urethral injuries. Analyses on the urinary extravasation affecting both urethral mesenchyme and epithelium and the resultant spongio-fibrosis/urethral stricture were performed. The urine was injected from the lumen of urethra exposing the surrounding mesenchyme after the injury. The wound healing responses with urinary extravasation were shown as severe edematous mesenchymal lesions with the narrow urethral lumen. The epithelial cell proliferation was significantly increased in the wide layers. The mesenchymal spongio-fibrosis was induced by urethral injury with subsequent extravasation. The current report thus offers a novel research tool for surgical sciences on the urinary tract.