While multilumen and wire-reinforced tubes have been used both inside and outside of the medical device arena for many years, tubing that combines both of these technologies has not been available to medical device manufacturers--until now. Meeting the growing demands of minimally invasive surgeries, Putnam Plastics has begun to manufacture wire-reinforced multilumen tubing in both braided and coiled configurations.

Previously, both braided and coiled tubing was available primarily in single-lumen configurations, remarks Dan Lazas, Putnam Plastics' vice president of marketing and sales. But the increasing demand for tubes that feature multiple passageways to manage the flow of gases or fluids, provide access for surgical instruments, and deliver drugs has heightened the need for stronger, pressure-resistant tubing.

Tubing is always subjected to a certain amount of pressure or load, Lazas explains. "And while reinforcing a thin tubing structure is challenging, reinforcing a thin tubing structure with multiple lumens is even more challenging. Our tubing does that, and that's what's novel about it."

As the name suggests, braiding creates a cross-check pattern in the tubing, Lazas says. "It is formed by wrapping wire longitudinally around the circumference of the tube." Embedded inside the wall of the tubing, the wire braiding is customarily used to increase a tube's resistance to burst pressure. "For example, to expand a balloon, you have to apply pressure to the tube to get it to the balloon," Lazas comments. "And if the tube's inherent material properties cannot withstand that pressure, you have to reinforce it."

While braiding is a common reinforcement technique to resist burst pressure, it can also be used to improve pushability and torque, according to Lazas. Doctors require pushability to insert a tube into the body through a minimally invasive opening, while they rely on torqueability to turn the tube in a body cavity.

In contrast to braiding, coiling usually involves only one strand of wire. Resembling a spring, the coil wraps around the perimeter of the tube without overlapping. "Coiling is most commonly used to increase kink resistance," Lazas comments. "When you have to bend a tube around the tortuous corners inside the body, some materials can kink, much like a garden hose. If that occurs, you no longer have free passage."

Used in minimally invasive vascular and natural-orifice procedures, wire-reinforced multilumen tubing--both of the braided and coiled variety--is a complex working device with highly limited real estate, Lazas notes. "Thus, while braiding and coiling have been around for a while, we've been pulling them into a space in which the sizes are smaller, the complexities are more demanding, and the tubing is no longer just a pressure hose."

Putnam Plastics
Dayville, CT
www.putnamplastics.com