Table of Contents

Reasons for IV Tubing Discoloration

IV Tubing Discoloration

The function of the IV tubing

The IV tubing, or the IV set connects the IV fluid bag to the patient’s IV access site. Thus, the whole set, also known as the infusion line, acts as a passageway of the fluid from the bag into the patient. The fluid flow restores the blood volume, transfers medications, and provides electrolytes needed by the patients. This process of infusing substances into the patient is called intravenous therapy.

The integrity of the IV tubing

The IV tubing must be clean and sanitized before medical staff use it for intravenous therapy. If not, medical personnel may introduce infections into the patient, and some unwarranted drug reactions may take place. Medical employees must avoid breaching the integrity of IV tubing at all times, and medical staff need to know when they can no longer use the IV tubing because of signs of damage and loss of integrity. Replace IV tubing as routinely and frequently as needed.

Signs of the breach in the integrity of IV tubing

IV tubing discoloration

Possible causes for IV tubing discoloration include:

Failing to follow performance specifications

Other performance specifications for the production of IV tubing are the following:

  • Pressure rating specifies the minimum or maximum pressures the tube can withstand, measured in pounds per square inch (psi).
  • Maximum vacuum sets the maximum pressure allowed in the tube, measured in inches or millimeters of mercury.
  • Temperature range defines the extent of ambient temperatures within which the tubing can operate.   

If the production group fails to follow one or more of the performance specifications as required in the actual operations, the IV tubing may change color or be discolored.

Depending on the specific application, medical tubing, specifically IV tubing, may require different features. One is opacity, which defines the ability to see through the tube. Clear tubing is essential for tubes that handle fluid delivery to track fluid movement and account for possible air bubbles in the system. If the production people do not follow the required opacity, then the IV tubing discoloration may take place.

Other features include sterilizability, the ability to coil the tubing for storage or transport and spark or static resistance.

Migration of amine catalyst

Polyvinyl chloride (PVC) is the primary material for the production of IV tubing. In one of the companies producing fabrics, the management hired a group of plastic expert to do extensive analysis and explain the discoloration of their fabrics. The experts discovered that the migration of the amine catalyst from the polyurethane foam backing underneath the PVC was the cause of the discoloration. The migration can happen in IV tubing.

PVC resin’s low resistance to heat, light, and oxygen 

PVC resin has a unique molecular chain structure with low heat, light, and oxygen resistance. This property makes the resin quickly decompose and change color. Theoretically, material scientists believed that the de-He1 reaction of the PVC molecular chain under the action of heat, light, oxygen, and other elements to form a long conjugated polyene structure is the principal reason for the degradation and discoloration (yellowing) of the PVC. Thus, the degradation mechanism and stabilization technology of PVC resin in the processing and application have always been the focus of research in the polymer materials industry.


During processing, storage, and utilization, the PVC degrades as it is exposed to high temperatures, high mechanical stresses, or ultraviolet light, all in the presence of oxygen. Degradation of the polymer happens because of successive elimination of hydrogen chloride (HCl), known in chemistry as dehydrochlorination, producing long polyenes, which subsequently cause discoloration, deterioration of the mechanical properties, and lowering chemical resistance.

PVC degradation

PVC is the principal material component of IV tubing. In addition, other products used in different industries contain PVC as well. As the application of PVC expanded, the processing conditions became more demanding, and PVC stability at higher temperatures became a problem. When subjected to different forms of energy, such as heat, light, and ionizing radiation, PVC liberates hydrogen chloride, with accompanying discoloration and a general deterioration of its mechanical and electrical properties.

With the finding that PVC is adversely affected by elevated temperatures, ways and means to combat its degradation must be developed and thus started. Mixing PVCs with stabilizers could be the way. However, the search and development for such stabilizer(s) could be taxing and challenging because the material researchers need to evaluate the resulting product’s efficiency, cost, and toxicity. Scientists need to establish the basic knowledge of the stabilization mechanism to achieve a thorough evaluation.

Understanding the stabilization mechanism requires detailed and adequate information on the degradation mechanism. In other words, the first logical step towards improving stabilizing PVC is to determine the fundamental mechanism of degradation. Some scientists believe that thermal degradation and atmospheric aging share the exact mechanism and only differ in the form of stimulating energy.

Kinking of the IV tubing

IV set manufacturers follow performance specifications in the production of tubes, such as IV tubing. They consider the minimum bend radius (MBR) to determine the tube flexibility. The smaller the MBR, the higher the tube flexibility will be. If the MBR is high, flexing the tube too far can cause kinking or permanent deformation.

The presence of moisture inside the IV tubing

The moisture inside the IV tubing could be a sign that there has been an existing leakage along the tube and in its other parts. More often than not, the tube’s kinking caused leakage to be generated. Discard this item and never use it.

Final words on the IV tubing discoloration

The principal material component of the IV tubing is the PVC. Thus, physical changes in the IV tubing, such as discoloration, kinking, and generation of leakage, can be traced to the properties of PVC. For many years, PVC stood out as one of the best materials ever produced and used in different industries, such as construction and medical supply. Its limitation occurred some years ago when heat, light, ionizing radiation, and other elements could seemingly lead to its degradation, thus affecting its material properties and operational competence. To solve the problem, the search for a cost-effective stabilizer started, and prospective beneficiaries have been hoping for its final development. 

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