A peripherally inserted central catheter, commonly known as a PICC line, is a long, thin tube inserted into a peripheral vein in the arm. Its tip is positioned in one of the large central veins near the heart. This device provides safe, long-term intravenous access, often lasting for weeks or months, for administering medications, fluids, and liquid nutrition. Yes, blood can be drawn for laboratory tests directly from a PICC line. However, this procedure is not identical to a standard venipuncture and must be performed by trained healthcare professionals following a specific protocol. The process requires meticulous attention to technique to ensure the integrity of the blood sample and to protect the patient from potential complications.
Rationale for Drawing Blood from a PICC Line
The primary benefit of utilizing the PICC line for blood draws is improved patient comfort. For patients who require frequent laboratory work, using the catheter eliminates the need for repeated, painful needle sticks in the peripheral veins. This avoidance of trauma helps to preserve the smaller veins in the arms, which is particularly beneficial for individuals undergoing long-term treatment.
This method is also advantageous for patients who have difficult or limited peripheral venous access due to chronic illness or extensive prior treatments. A PICC line offers a reliable and consistent access point for necessary blood sampling. The catheter allows healthcare providers to gather the required specimens with greater efficiency, reducing the overall time spent on patient care tasks. Drawing blood this way also reduces the irritation that certain medications or concentrated solutions can cause to smaller veins, as the PICC line tip rests in a large vein where blood flow is rapid.
Technique Required for Accurate Blood Samples
The main challenge when drawing blood from a PICC line is preventing the sample from being contaminated or diluted by infusing solutions. To maintain the accuracy of the lab results, a strict aseptic technique is required throughout the entire process. Before the procedure begins, any continuous infusions, especially those containing substances like Total Parenteral Nutrition (TPN), must be paused for at least one minute.
The most critical step for sample integrity is the aspiration of a “waste” volume of blood before collecting the laboratory samples. This initial volume, which typically ranges from 3 to 5 milliliters, is discarded to clear the catheter’s internal lumen of any residual IV fluids, saline flushes, or heparin used to lock the line. Failing to remove this waste volume results in a diluted sample, leading to inaccurate results, such as falsely low potassium or hemoglobin values.
After the waste is discarded, the required volume of blood is collected using a syringe or a specialized vacuum collection system (Vacutainer with a Luer-lock adapter). Care must be taken to avoid drawing too forcefully, which can cause the catheter to collapse or damage the blood cells, leading to hemolysis. Following the successful blood collection, the catheter must be thoroughly flushed, often with 10 milliliters of normal saline, using a pulsing, push-pause technique. This flushing action is necessary to clear the catheter of all remaining blood, which is a common cause of line occlusion.
Potential Complications and Safety Measures
Drawing blood from a PICC line introduces risks that must be carefully managed. The primary concern is the potential for Catheter-Related Bloodstream Infections (CRBSIs), a risk inherent to any central line access. Meticulous adherence to aseptic technique, including scrubbing the access port (hub) for a specified duration, is a fundamental safety measure to prevent bacteria from entering the bloodstream.
Another significant risk is line occlusion, the partial or complete blockage of the catheter. Blood remaining in the catheter after a draw, or drawing too forcefully and causing trauma to the vessel wall, can lead to clot formation. The risk of occlusion must be mitigated by proper flushing and gentle aspiration during the draw.
Cautions and Contraindications
To ensure safety and accuracy, caution is warranted in certain situations. If the line is difficult to aspirate from, feels sluggish, or causes the patient pain upon use, an alternative access site, such as a peripheral venipuncture, should be utilized. Routine blood cultures are generally avoided from a PICC line due to the higher risk of sample contamination compared to a peripheral draw. If a catheter-related infection is suspected, paired blood cultures—one from the PICC line and one from a peripheral vein—are collected simultaneously to compare the results.