Intravenous (IV) medication delivery is a common procedure for administering therapies directly into a patient’s bloodstream. The effectiveness of these treatments depends on both the medication and the infusion equipment. Selecting the correct IV tubing is necessary to ensure the prescribed dose is accurately delivered, safeguarding patient safety and treatment outcomes.
Understanding Medication Sorption in IV Tubing
The need for specialized IV tubing stems from sorption, a process where medication is lost from a solution. This can happen through adsorption, where drug molecules stick to the tubing’s inner surface, or absorption, where the drug soaks into the plastic material itself.
This phenomenon is common with standard IV tubing made from polyvinyl chloride (PVC). To make PVC flexible, manufacturers add plasticizers like diethylhexyl phthalate (DEHP). While DEHP provides flexibility, it can facilitate the sorption of certain medications, causing the active drug to bind to the tubing.
The consequence of sorption is a reduced drug concentration, which can lead to underdosing. The extent of this loss depends on factors like the drug’s properties, tubing length, and infusion rate. For some medications, this loss can be substantial enough to compromise treatment.
Common Medications Requiring Low-Sorbing Tubing
A wide array of medications, particularly those that are hydrophobic (repel water), are susceptible to sorption in standard PVC tubing. These medications require tubing made from alternative materials that do not interact with the drug molecules, ensuring the full prescribed dose is delivered. Key examples include:
- Nitroglycerin, a medication used to treat chest pain (angina), is highly prone to sorption. When infused through PVC tubing, a significant percentage can be lost, reducing its ability to relieve symptoms.
- Insulin, a hormone used to manage blood sugar in patients with diabetes, also demonstrates notable sorption. The loss of insulin to PVC tubing can affect glycemic control, especially with low-concentration infusions.
- Amiodarone, a medication for heart rhythm disorders, exhibits significant binding to PVC. This can prevent patients from achieving the necessary blood concentration to control dangerous arrhythmias.
- Benzodiazepines, such as diazepam and lorazepam, are known to be highly sorbed by PVC materials. This can lead to a reduced sedative or anti-seizure effect, requiring dose adjustments.
- Chemotherapy agents like paclitaxel and docetaxel can be significantly lost to sorption in PVC tubing. Using non-PVC or low-sorbing sets is standard practice for these drugs.
- Immunosuppressant drugs, such as tacrolimus and cyclosporine, are given to prevent organ rejection. Sorption can lower their concentration in the blood to subtherapeutic levels.
Clinical Consequences of Improper Tubing Selection
The use of incorrect IV tubing can have direct clinical consequences. When a drug is lost to sorption, the patient receives a lower dose than intended. This can lead to treatment failure or a worsening of their condition.
For a patient receiving nitroglycerin for acute chest pain, insufficient dosage can mean the difference between relief and continued cardiac ischemia. This failure to achieve a therapeutic drug level might be misinterpreted as the patient not responding to the medication, possibly leading to more invasive interventions.
In organ transplantation, a patient receiving tacrolimus or cyclosporine relies on maintaining a consistent drug level. If sorption causes this level to drop, the patient’s immune system may begin to reject the new organ, which can cause irreversible damage.
With infections, delivering a reduced dose of an antimicrobial agent can contribute to drug-resistant pathogens. For chemotherapy, a subtherapeutic dose could lead to a reduced tumor response, allowing the cancer to progress. In these scenarios, the problem originates with the delivery system.
Identifying and Using Appropriate IV Tubing
Healthcare providers can ensure proper medication delivery by using the correct IV tubing. The drug’s package insert provides specific instructions from the manufacturer regarding administration requirements. Consulting a clinical pharmacist is also standard practice for clarifying compatibility.
Low-sorbing tubing is made from materials other than standard PVC, such as polyethylene (PE) or polypropylene (PP). Some tubing features a polyethylene lining inside a PVC tube, combining inertness with flexibility. These sets are often labeled by the manufacturer as “low-sorbing” or “non-PVC.”
It is important to distinguish between “DEHP-free” and “low-sorbing” tubing, as a DEHP-free PVC tube may still sorb certain drugs. For medications with significant sorption issues, selecting a set made from a material like polyethylene is the safest approach. Following hospital protocols prevents treatment errors.