Medical Polymers : Emerging Trends & Opportunities

Medical Tubings : Common Applications

 

Sr.	Materials	Common Applications
1	Polyvinyl Chloride PVC	Containers used for blood and blood components for urine or for ostomy products and tubing used for blood taking and blood giving sets, catheters, heart-lung bypass sets, haemodialysis set etc.
2	Polytetrafluoroethylene, PTFE	Catheter liner, Electrical Insulation, Fluid transfer, Telecommunication
3	Fluorinated Ethylene	IV catheter, Regional Anesthesia, Vascular access
4	Ethylene Tetrafluoro ethylene, ETFE	Fluid transfer, IV catheter, Electrical insulation
5	Perfluoroalkoxy, PFA	Fluid transfer, In Vitro diagnostics
6	NYLON, 6, 11, 12	Angiography, Choloecstectomy, Epidural catheter, Laparoscopic instruments, Radiology
7	Polyether Block Amide, PEBA	Angiography, Cholangeography, Epidural Catheter, Radiology
8	Polycarbonate PC	Laparoscopic instruments, IV therapy, Laparoscopic cannulae, Tube packaging, Microtubes
9	High Density Polyethylene LDPE	Embolectomy, Guidewire dispensers, Introducers, Protective tubes, Thrombectomy, Sheaths and dilators for introducers, Coextruded perfusion tubing, Aspirator tips
10	Low Density Polyethylene LDPE	Embolectomy, Guidewire dispensers, Introducers, Protective tubes, Throbectomy
11	Polyurethane PUR (Aliphatic)	Angiography, Cardiac catheters, Central Venous catheters, Dialysis, Epidural catheters, IV catheters, Epidural probes, Catheters, Highpressure lines
12	Polyurethane PUR (Aromatic)	Angiography, Cardiac catheters, Central Venous catheters, Dialysis, Epidural catheters, IV catheters
13	Polypropylene PP	Guidewire dispenser tubes and Protective tubes
14	Ethylene Vinyl Acetate EVA	Endotracheal, Embolectomy, IV therapy, Suction catheter
15	ACETAL	Laparoscopy, Guiding catheter

About Catheter Tubing :

Number of variables affect the performance of a finished catheter – the most paramount being the properties of the raw material and the extrusion process. Careful consideration of the extrusion process is essential to ensure consistency and repeatability.

Single- or dual-screw extrusion is used to manufacture catheter tubing.

During the extrusion process, air at a specific pressure is used to obtain the intended tubing shape. A heat-transfer process begins as the polymer exits the die. Air is used as the initial cooling medium, followed by water in a cooling bath. A belt or wheel hauloff (puller) pulls the tube from the die and through the cooling bath at a controlled speed.

Because of the complexity of catheter tube manufacturing, several parameters associated with the extrusion process may affect the properties of the finished product.

1 These parameters include:

• Temperature profile.
• Initial method of drying the polymer granules.
• Temperature of the cooling bath.
• Tubing dimensions.
• Screw geometry.
• Rotational speed of the screw.
• The distance between the die head and the cooling bath.
• Polymer choice can also affect the finished product's properties.

Critical Applications - Medical Tubing Configurations - Material & Process Requirements For High-Quality Extruded Tubing - Economics Of Extrusion

Enhancing performance and design

Following are the various features incorporated in the catheter tubings to enhance performance depending on the applications :

• Braid/coil reinforcement for strength, rigidity and torque control along the length of the catheter to balance the need for flexibility and kink resistance to navigate tortuous pathways.
• Use of hydrophilic coatings delivers high lubricity to achieve low insertion force or a reduction in friction for a specific delivery application.
• Soft tip and multi-durometer segments along the length of the catheter provide atraumatic entry and maneuverability.
• Radiopaque contrast at the tip and key segments offer better visibility for the physician to visualize accurate anatomical placement.
• Steerability and deflection help attain optimal navigation.

Methods To Assess Tubing Properties :

Briefly. methods used to measure the effects of extrusion parameters on the final product and for comparison with the original polymer characteristics include : optical microscopy, tensile testing, rheometry testing, IR spectrophotometry, and enthalpy differential analysis.

Measuring Catheter Tubing Sizes

Problems can arise when the customer and catheter or tubing supplier are not using the same scale when discussing catheter tubing sizes.

French scale and gauge scale are the measures used to refer to the diameter of catheters and tubing. While each have certain advantages, misinterpreting these standards can lead to confusion. “OD” and “ID” are abbreviations for outer dia meter and inner diameter, respectively, and are generally measured in inches or millimeters.

The catheter sizing classification most commonly used in the medical industry is the French (Fr) scale, also known as the “Charrière’s system.” The French scale is an easy method to use to describe the basic size of a catheter, because it specifies the most obvious component, the outer diameter. The French size = 3 times the diameter in millimeters. The disadvantage of the French scale is that it does not specify the inner diameter of the catheter or tubing. Thus, the French sizing used alone, is not specific enough to adequately describe small catheters, where internal diameter is critical. This scale is much more useful to specify larger catheter sizes.

A second method of sizing catheters is the gauge measurement. Gauge is a descending scale, opposite the French scale of measurement which ascends with corresponding size. The higher the gauge size the smaller the tubing.

Another less common method for sizing catheter tubing is the “PE” scale. It is specific to polyethylene and is an ascending scale used by some manufacturers to represent the OD and ID of the tubing, similar to French sizing.

The most definitive method to describe a catheter’s dimension is simply to state the exact measurements of both the outer and inner diameters. While it may seem a little more difficult to communicate, this method will actually give all the details necessary to the researcher or catheter manufacturer to properly size your specific catheter and catheter connections.

The Economics Of Extrusion

• Important elements of Expenses in the medical tubing extrusions are : Materials, Equipment, Direct Labour, Others (includes : Power, Packaging, Insurance etc)
• In most of the cases , the largest cost is the material.
• Extrusion is usually a 24-hour continuous operation. Frequent starts and stops greatly increase production costs..