Originally Published MPMN September 2007

ENGINEERING SOLUTIONS

Copolyester Toughens Up Portable Wound-Healing System

Designed to help patients minimize the number of dressing changes and nursing visits required for wound care, the vacuum-assisted closure (V.A.C.) Freedom therapy system is a lightweight, portable device that allows individuals to continue wound treatment while at work or performing normal daily activities. It is used to treat patients with pressure ulcers, partial-thickness burns, flaps, and grafts, as well as diabetic, abdominal, and trauma wounds.

The portable unit was designed to decrease the lengths of hospital stays, incidences of complications for patients in home-care settings, and healthcare costs. Having achieved those goals, the manufacturer, Kinetic Concepts Inc. (KCI; San Antonio, TX; www.kci-medical.com), shifted its focus to improving the system’s portability, functionality, and overall toughness.

KCI’s goal was to expand the benefits of wound treatment by improving patient and caregiver product interaction. The company also sought to improve ease of use and durability to provide overall peace of mind for the patient.

“Our plan to make the V.A.C. Freedom more robust required a medical plastics solution partner that could intimately understand the importance of our product's critical function,” says Michael Pollok, senior product engineer at KCI.

KCI turned to Eastman Chemical Co. (Kingsport, TN; www.eastman.com) and its Eastar copolyester to meet this challenge. “Eastar is the right material choice for our product due to its clarity, color, and property stability after sterilization,” says Pollok. “It has the shatter resistance needed to withstand the rigor of a hospital or patient-recovery environment.”

The Eastar copolyester polymer is the toughest of the Eastar family of plastics used for noninvasive medical devices. It incorporates a mold release agent and is resistant to various chemical cleaners, medical solvents, and lipids, ensuring it will meet the performance demands of the wound-drainage system.

Using the Eastar copolyester, KCI was able to improve the functionality of the system’s 300-ml canister, which facilitates wound drainage and is designed to reduce the risk of exposure to exudate fluids and infectious materials.

Over the course of a year, Eastman offered guidance to KCI in the areas of mold design, tooling, and troubleshooting to ensure optimal manufacturability. Eastman also was able to assist in identifying and then eliminating assembly challenges during processing. For example, when KCI was undergoing problems with its weld joints during manufacturing, Eastman assisted the company in redesigning the weld joint to eliminate processing challenges that might delay the product’s commercial availability.

Since implementing changes to the system, KCI has seen evidence of the benefits of incorporating Eastman’s material. The system was awarded Joint Airworthiness Certification status by the U.S. military after an extensive evaluation process testing the device’s safety for use on military medical evacuation aircraft. The V.A.C. system enables military caregivers to continue providing effective and uninterrupted treatment for injured military personnel being transported long distances from theater hospitals to continental U.S. hospitals.

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