Originally Published European Medical Device Manufacturer May/June 2002

Next-Generation Tubing: Good Things in Small Packages

Suppliers offer new medical-grade tubing products that pair a reduction in size with increased maneuverability and functionality for the end-user.

Offering small diameters and thin walls, microcatheters from TFX Medical OEM also increase product functionality by allowing customers to specify a number of performance characteristics that aid placement and use.

Offering small diameters and thin walls, microcatheters from TFX Medical OEM also increase product functionality by allowing customers to specify a number of performance characteristics that aid placement and use.

With the general trend toward device miniaturization, manufacturers are increasingly looking for tubing products that are smaller in diameter and have thinner walls. "The joke in the industry is that OEMs want tubing that has a bigger inner diameter than outer diameter, and no wall," quips Rich Riddle, vice president of sales and marketing for tubing company TFX Medical OEM (Limerick, Ireland). But the difficulties associated with reducing scale are not the only challenges tubing suppliers are being called upon to meet. Today, device manufacturers often require that these smaller tubes also offer increased strength and functionality to the end-user. In this article, two tubing suppliers offering products that meet this significant list of design requirements are examined. In addition, several new products are profiled in the accompanying company descriptions.

Tubing with Integrated Sensor Ensures Accurate Measurement, Minimizes Size

"Device manufacturers today are looking for more bang for their buck," says David Proctor, director of advanced technologies for MedSource Technologies Inc. (Minneapolis, MN, USA). "Not only do they want a smaller catheter that does the same job as their previous tube, they also want something that adds value to their product," he explains. To meet this demand, MedSource Technologies recently unveiled a thin-walled catheter that features an integrated thermocouple to accurately measure temperature without increasing product dimensions.

"In the past, if you wanted a tube that performed this function, you would have to take a multilumen tube and snake a sensor down the inside as a separate device," says Proctor. This often significantly increased tubing size, limiting the product's suitability for minimally invasive procedures. MedSource Technologies overcame this problem using a proprietary manufacturing process that places the thermocouple directly into the wall of the catheter without decreasing strength or increasing size. Suited for Type K or T sensors, this process allows sensor placement anywhere along the catheter shaft, and can even accommodate multiple sensors for thermal-gradient applications. According to Proctor, the size of the catheter shaft is limited only by the size of the wire that forms the electrical connection for the thermocouple.

In addition to decreasing scale, this unique product also offers cost benefits to device manufacturers. "Previously, a device manufacturer would have had to buy the tube, buy the sensor, and then pay for the labour required to glue it in place," says Proctor. "Our process is automated, so manufacturers just give us their specifications and receive a finished product in less time with greater positioning accuracy." Costs are further reduced as this manufacturing process minimizes the risk of device failure. "The sensor is incorporated within the tube wall, so it is more robust and less prone to breakage than traditional devices," says Proctor.

According to Proctor, the specialized tubing is suited for use "anywhere temperature needs to be measured." Common applications include devices used for the heat ablation of diseased tissue and products used to measure metabolic function.

Customizable Microcatheter Lets OEMs Specify Performance Characteristics

Catheters that incorporate secondary devices are an example of how the new generation of miniature tubing can increase functionality when properly positioned. But with smaller tubing, getting the product in place often presents a problem in itself. The relationship between a catheter's size and its maneuverability is often paradoxical, explains TFX Medical OEM's Riddle. Though theoretically a smaller tube will be able to reach further into the body, its diminutive size frequently does not lend it the strength needed to withstand the force to push it there. Microcatheters supplied by TFX Medical OEM are being designed to reverse this shortcoming, however, by allowing customization of a range of performance characteristics that increase maneuverability without increasing size.

"Manufacturers definitely want catheters that are smaller and thinner to access sites further into the vasculature," says Riddle. "But they're also looking for these products to provide kink resistance, torque transmission, variable flexibility, and a range of other features to help them get there and achieve specific tasks when they do," he adds. TFX Medical OEM microcatheters offer device manufacturers the best of both worlds: the products are supplied with outer diameters as small as 0.026 in. and can be specified in a range of configurations to achieve any of a number of desired tasks.

"We can modify these tubes to offer whatever traits the customer needs," says Riddle. "We offer PTFE lining for helping pass devices through the catheter, embeddable marker bands to aid visualization, and a variety of braid reinforcement configurations to increase pushability. The list just goes on," he adds. The catheters are supplied in a range of biocompatible materials, including polyamide, Pebax, polyurethane, and polyethylene. Products constructed with material mixtures and multiple layers are also available. Other options include flat embedded wires, radiopaque fillers, and variable shaft diameters and durometer hardnesses.

Applications for the microcatheters include the diagnostic and therapeutic neuroradiology and occlusive-therapy devices used to access small and difficult-to-reach vasculature.

Zachary Turke

Copyright ©2002 European Medical Device Manufacturer

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