An engineering approach towards a more discrete and efficient urinary drainage system

Abstract

Modern urinary catheter-to-leg-bag systems suffer from a number of shortcomings. Drainage tubing of current urinary leg bags is perceived as unnecessarily bulky compared to the indwelling catheters to which it is connected, and catheter designs are prone to the formation of biofilms, leading ultimately to encrustation and blocking. We used analytical and experimental engineering methodologies, aligned with current international (International Standards Organisation) and European standards, to optimise drainage tube size and flow efficiency and characterise tube kinking behaviour. Using computational fluid dynamics, we studied the influence of modern Foley catheter design on urodynamics and explored its potential influence on biofilm formation and encrustation. Results indicate that tubing diameters could be reduced by 40%-50% and still satisfy current International Standards Organisation flow rate standards for leg bags; this might also reduce the likelihood of tube kinking. The computational study showed how current catheter design may promote the development of lower velocity recirculating flows and high shear in proximity of regions known to be affected by bacterial adhesion and biofilm formation. If confirmed, these findings will give manufacturers greater flexibility to develop less obtrusive and more encrustation-resistant products for end users.

The accumulation of particles in ureteric stents is mediated by flow dynamics: Full-scale computational and experimental modeling of the occluded and unoccluded ureter

“…The model could also be modified to enable investigation of the flow performance of other endourological devices, such as sphincter stents or urethral catheters, which are also known to suffer from encrustation, particularly upon long-term deployment. 42,43 Previous studies have demonstrated a qualitative dependence of encrustation on the flow field within a urethral catheter; 44 a more quantitative investigation could, thus, be performed in future research. Numerical models could also be further developed to include simulation of particle dynamics in urological devices.…”

Retained urethral catheter forming a closed loop secondary to excessive length in a cat: A non‐invasive technique to unwind and remove the loop

“…9,10 In human paediatric patients, catheters with a diameter smaller than 10 Fr and with an insertion length of more than 10 cm are at risk for spontaneous knotting. 11 Urethral catheters wider than 10 Fr are only used in large breed dogs; thus, smaller veterinary patients, such as paediatric patients, may be prone to urethral catheter knotting. 5 Interestingly, Singh and Sinha published a case series and literature review noting that most human patients presenting with a retained catheter are paediatric patients (97% were children, n = 31).…”

Therapy of Pyothorax in Cats via Small-Bore Thoracostomy Tube in Terms of Efficacy, Complications and Outcomes

“…Inadequate drainage effectiveness due to kinking of these tubes is described in 14% of cases (2/14 tubes) [ 8 ]. A possible cause could be the thin wall (0.4 mm) in relation to the large inner diameter (1.2 mm) [ 14 ].…”

“…The tube used in this study is constructed for wound drainage with suction, therefore it has a relatively thick wall (0.5 mm). The thick wall (0.5 mm) in relation to the small inner diameter (1 mm) could result in high kink resistance [ 14 ]. Nevertheless, due to its multiple fenestration (20 side holes), the tube has a very good drainage performance, which also reduces the risk of blockage.…”