PVC Tubing in Cardiopulmonary Bypass

Cardiopulmonary Bypass Tubing

• The predominant tubing material used in cardiopulmonary bypass is PVC (Polyvinyl Chloride).
• PVC has polar and non-polar bonds.

Properties of PVC

• The property of PVC that makes it a fairly strong material is its high degree of crystallinity.
• Plasticizers are added to PVC tubing to make it more flexible.
• Plasticizers work by reducing the glass transition temperature of the polymer, allowing it to be more flexible.

Safety of Plasticizers

• The FDA has determined that nearly all plasticizers are safe.
• The REACH organization has also determined that plasticizers are safe.
• Without plasticizers, PVC would be brittle and prone to cracking.

Manufacture of Plastic Tubing

• The two methods for manufacturing plastic tubing are extrusion and injection molding.
• The main ingredient in the extrusion process is polymer resin.
• Tubing is rated based on its pressure resistance, with a rating that defines the minimum or maximum pressure a tube can withstand.
• The rating is also based on the acceptable amount of deformation the tubing cross-section can undergo.

Tubing Connections

• The connectors used to make connections with tubing are called fittings.
• The method of connecting tubing by heating it and placing it on a specified connection site is called heat stake.

Sterilization

• The sterilization method best suited for polymer resin-based products and single-use medical devices is Ethylene Oxide sterilization.
• The four essential parameters that influence the effectiveness of Ethylene Oxide sterilization are temperature, humidity, gas concentration, and exposure time.
• The basic Ethylene Oxide sterilization cycle takes 12 hours.

Tubing Degradation

• The degradation of the walls of tubing and the release of plastic micro particles is called particulate generation.
• Biocompatible coatings are used on tubing to reduce particulate generation and prevent inflammation.

Circuit Coatings

• The sequelae from the inflammatory response to foreign surfaces are platelet activation, protein denaturation, and fibrin formation.
• A circuit coating that uses both hydrophobic and hydrophilic properties to reduce protein denaturation and platelet adhesion is called a phosphorylcholine coating.

Tubing Selection

• The most commonly used wall thickness in perfusion is 1/16 inch.
• When selecting the appropriate size of tubing, factors such as internal diameter, wall thickness, and material should be considered.
• A larger internal diameter of tubing can result in increased flow rates and decreased pressure drops.

Tubing Characteristics

• Tubing can be used to track fluid movement and account for possible air bubbles in the system by using a level sensor or ultrasound.
• The ability to coil the tubing for storage or transport is called flexibility.

Test your knowledge about the properties and uses of PVC tubing materials in cardiopulmonary bypass. Learn about the composition of PVC, its strength, and how it can be made more flexible.