Critically ill patients often require frequent laboratory analysis for monitoring purposes but repeated venipuncture can lead to hematoma development, iatrogenic anemia, infection, and patient discomfort.1 A sampling catheter may be placed through a peripheral vein in hospitalized patients to facilitate repeated blood collection. In addition, access to the central (venous) circulation allows administration of hyperosmotic substances, parenteral nutrition, and measurement of central venous pressure.
If the catheter is used for repeated blood sample collection, this should be the catheter’s sole purpose. This is important to avoid sample errors that may result from administration of IV fluids and drugs through the same catheter lumen; some studies have shown that this may cause inaccurate diagnostic results, particularly with glucose, potassium, and venous blood gas analysis.2,3 A peripheral sampling catheter may be selected when frequent sampling is necessary, but a contraindication to true central venous catheterization via the jugular vein exists. Contraindications to jugular catheter placement include injury, infection, pain, or edema within the cervical region, coagulopathy, increased intracranial pressure, or cervical disk disease. Lateral or medial saphenous veins are most commonly used for sampling catheter placement in canine and feline patients. Through-the-needle catheters are typically used, as they are small enough to pass through a peripheral vein and are longer (8–12 in) than over-the-needle catheters; this allows more central placement into the vessel and, in smaller patients, access to the caudal vena cava.
Related Article: Intravenous Catheterization The catheters come in a variety of sizes and are appropriate for use in most patients (Table). As peripheral sampling catheters obtain closer proximity to the central circulation and are intended for longer term use, maintaining aseptic technique is important to decrease the risk of contamination, phlebitis, and catheter-associated infection or sepsis.