Few companies make all the parts that go into IV devices. Special adhesives might come from one firm, filters and media from another, and secondary operations from a third. Here's a brief description of a few secondary operations that go into the manufacturing of IV components.

Secondary operations for IV components

Secondary operations often take a back seat in discussions on medical manufacturing. But they are important functions in the making of many devices including IV components, says Putnam Plastics Plus, Dayville, Conn. (putnamplus.com). The company, a unit of Putnam Plastics, focuses solely on providing services for secondary operations so other firms have the benefit of efficiency, traceability, and consolidated resources, says Putnam. Thus, for IV components such as tubing, needles, and molded inserts, secondary operations might include grinding profiles, CNC punching, printing depth marks on catheters, mating tubes with connectors, and bonding assemblies. The company has an in-house machine shop and in-house design and tooling capabilities. It also undergoes research and development and uses statistical control and controlled environments suitable for implantables.

Making medical membranes

Medical devices often require special filters called medical membranes that equalize pressure, block contaminates, or capture particles. W. L. Gore & Associates Inc., Newark, Del. (gore.com), says its venting and filtering products are made from polytetrafluoroethylene (PTFE) laminated to a membrane support. The configuration works well in medical-device designs. The company says the membranes are readily processed in automated equipment by clamping, heat sealing, ultrasonic welding, and high-frequency (radio frequency) welding. For heat sealing, heat, pressure, and time are important in creating a secure seal between the laminate and housing. Heat-sealing parameters are a function of the thickness of the membrane, type of membrane, membrane support material, and housing material. For ultrasonic welding, heat generated by high-frequency sound energy melts selected portions of the membrane support and housing material.

Pressure equalization and de-aeration are often important functions in medical devices. Effective pressure equalization can help liquids flow into or out of a vent-filter device, or regulate the pressure in a device. For example, medical liquids often contain gas bubbles, which would be hazardous to patients, or affect the proper operation of a medical device. Gore says its medical membranes dissipate gas bubbles while retaining liquids under pressure. A typical application, a urine-collection system, uses extended PTFE (ePTFE) membranes that deliver the high airflow needed to vent air during urine accumulation and disposal. The company says the special membrane design resists the adhesion of waste materials, eliminating blockage, and thereby promoting patient health. Other applications include suction filters, surgical-smoke filters, and ostomy bags.

The engineered membranes come in either roll form or die-cut custom parts to meet specific applications. Roll goods have slit-widths ranging from 0.25 to 13 in. and are typically provided on 3-in. internal-diameter roll cores. Custom die-cut parts come on a carrier roll, with or without pressure-sensitive adhesive. The membranes come in different pore sizes and can be steam, EtO, or radiation-sterilized. The company says its membrane manufacturing is quality-certified according to ISO9001 and ISO14001.

Skin-friendly adhesives

So it's critical that firms making medical products ensure high quality from development through manufacturing. This is particularly important for skin-contact medical adhesives used to hold IVs in place, says MACtac, Stow, Ohio (mactac.com) The company says complete control over manufacturing necessitates in-house mixing, reactive extrusion, and compounding capabilities — not just relying on off-the-shelf adhesives.

Skin-related applications have shaped how firms design and manufacture medical-grade adhesives, says the company. Many are now tested according to ISO 10993-5/-10 standards for cytotoxicity, skin irritation, and skin sensitization. Also, the adhesives target a wider range of patients.

Adhesives for IV-securement must comply with strict ISO regulations. The adhesives must also bond well to plastics used in the IV design as well as to acrylics and other materials used in the filaments, says MACtac. Also important, adhesives should bond well to skin, without adhering so strongly that they hurt or injure the patient when removed. Medical adhesives should also have excellent wear and shear properties, both of which are necessary to secure IVs for extended periods of time. Finally, adhesives must be tailored to standard as well as geriatric and pediatric applications, in which skin tends to be more sensitive.

Manufacturing medical-grade adhesives takes several steps. Companies such as MACtac, for example, first compound ingredients and then perform quality checks on the individual components. Ingredients are then mixed while QC personnel check mixing quality before the resulting adhesives are delivered to machines that coat special film or materials. During coating, the firm double-checks variables including coating weight, presence of gels, and visual defects, as well as inspects the adhesive tape after it is slit to size. Materials are visually inspected for issues or inaccuracies that might have slipped by during coating.

MACtac's Silk medical-grade adhesives use a different mixing process. In it, the company mixes adhesives by reactive extrusion to ensure a homogeneous blend. Reactive extrusion involves a chemical reaction of the feed polymer which can be modified by, for example, changing its molecular weight. The process makes adhesives that can be tailored to meet specifications for tack, peel, shear, and skin adhesion. Another form of the adhesive comes in film, single or double-coated foam, and nonwoven constructions that are EtO and gamma sterilizeable. The adhesive is said to feel cool on the skin, similar to a hydrogel.

Another line of transparent-dressing adhesives made from polyester and polyethylene casting sheets accommodate different slitting and dressing styles. Suitable for wound dressings as well as catheters and IVs, the adhesives have a good affinity for skin yet remove cleanly without hurting the patient, says MACtac. They also provide high breathability to keep a chronic wound moist for faster healing. The waterproof systems are impermeable to liquids, bacteria, and viruses.