Also known as peel-apart tubing, paratubing entails a set of tubes bonded to remain bundled together until device assembly, patient care, or other pre-determined point of separation.
For medical devices, among the more sensitive risks is loss of suction during a procedure. Proper and consistent vacuum levels for fluid or mass removal are a critical factor in many application areas.
The other application factor of high importance is adequate and constant anaesthetic or medicinal delivery. Disruption of an anaesthetic agent can be painful and even dangerous for a patient, while insufficient medicinal supply caused by a tubing line leak could render a procedure ineffective or even harmful.
Considering all this, it is paramount that a paratubing assembly-based solution have a validated, consistent manufacturing process behind a well-designed and robust product solution. Let’s explore.
Mixing and Matching
Many medical devices must incorporate multiple single-use tube lines, each of which supplies or removes a different fluid or gas. In addition, some of these devices also require a separate power line to provide a light source. A paratube makes it possible to combine these tubes into a single structure that is significantly easier for clinicians to manage.
To minimise risk during medical procedures requiring multiple lines to deliver fluids, gases, suction and power to the same application space, a custom design may be recommended or even necessary to best ensure proper line connections.
Tubes can be composed of differing compounds engineered to accommodate the fluid, gas or suction it provides, and tube ends can be separated to ensure efficient and secure bonding into connecting ports. Some advanced tubing manufacturers, such as TekniPlex Healthcare, can even produce configurations of up to eight tubes in eight distinct colours, bonded together in a single device solution.
But of course, matching the right tubes to the right ports isn’t the only challenge associated with paratubes. Several other pitfalls may arise far upstream from patient care, in the production and inspection processes.
Separation Anxiety
Paratube production is far from simple, presenting opportunities for several unacceptable issues to arise.
“Peel strength Goldilocks Zone” – a sweet spot that must be maintained throughout the manufacturing process to best ensure paratubing efficacy. On one end of the spectrum, to avoid premature separation it is crucial that tubes maintain a consistent bond, which typically requires a minimum 0.22 pounds of peel strength. On the other end, bond strength must not surpass 1.5 pounds of peel strength at any spot; otherwise, mission-critical damage can occur to one or multiple tube lines.
There are two distinct bonding methods – thermal and chemical – and various die configurations utilised to manufacture paratubes. All setups have their own subsets of challenges that often come to light only when the application moves to full-scale production – a result of inadequate steps toward ensuring product consistency at higher production line speeds.
Fortunately, some of the resulting product problems are instantly obvious. Among the more catastrophic issues with paratubing design occurs when the bond strength between two tubes goes beyond 1.5 pounds of pull force. In this scenario, significant portions of adjacent tube walls can stick to one another upon separation, causing improper mating connection. This insufficient fitting attachment adds to the risk of a fluid path leak or loss of suction in the application.
A more subtle failure can occur if non-uniform bonding between tubes leads to smaller markings (chatter marks) or void spaces on an individual tube. While large portions of a tube wall sticking are more recognisable and therefore likelier to be caught during inspection, smaller chatter marks are more difficult to identify but can lead to process leaks all the same.
This outlines the importance of maintaining proper process controls and inline testing to ensure uniform, repeatable, and consistent peel strength, as well as inner and outer diameter tolerancing on individual tubing lines. Such rigorous process controls significantly improve the likelihood that products received during design stages will be representative of those produced at high-speed, full-scale manufacturing.