A nurse is caring for a patient who has a peripheral IV saline lock in place but is not currently receiving a continuous infusion. Which action best maintains the patency of the saline lock?

A. Flush the IV with heparin instead of saline is incorrect because most modern peripheral IV saline locks are maintained with normal saline, not heparin. Heparin flushes are typically reserved for certain central lines (e.g., implanted ports) and are not recommended for routine use in peripheral IVs due to the risk of heparin-induced complications such as HIT (heparin-induced thrombocytopenia). Evidence-based practice supports saline-only maintenance for peripheral locks. B. Leave the IV catheter open to air when not in use to prevent pressure build-up is incorrect and unsafe. Leaving a catheter open to air increases the risk of air embolism, infection, and contamination. IV lines must always remain capped, clamped, or connected to a sterile device to protect the patient from serious complications. C. Flush the IV catheter with saline before and after medication administration and every 8 to 12 hours when not in use is correct because this follows evidence-based guidelines for maintaining the patency of a peripheral saline lock. Flushing removes residual medication, prevents clot formation, and maintains catheter patency. The recommended frequency (typically every 8–12 hours for an unused peripheral line) ensures proper maintenance and reduces the risk of occlusion. Using the correct amount of saline, following the push-pause technique, and assessing for resistance are key components of safe IV care. D. Clamp the IV tubing after each medication administration without flushing is incorrect because clamping without flushing leaves medication and blood residue inside the catheter. This significantly increases the risk of clot formation, catheter occlusion, and infiltration upon next use. Proper flushing is essential to maintain line function and ensure safe future medication delivery.