Saline lock and heparin lock refer to one method of intravenous medication administration. The purpose of intravenous administration is to induce a rapid response, as intravenous administration is the fastest way to deliver medication. There are several ways to administer intravenously, rapid injection (directly into the vein), intermittent administration through a secondary line or continuously mixed in the main IV solution. The most common is through a peripheral line, saline or heparin lock.
There are many reasons for using the intravenous method of drug administration, such as the saline lock or heparin lock. Each is the fastest way to deliver the drug and makes the drug available to the body instantly. Both controlling and maintaining drug levels is considerably easier with intravenous administration. Finally, this type of administration is also useful if the drug would be destroyed by digestive enzymes, poorly absorbed or painful to administer through intramuscular (into a muscle) or subcutaneous (directly under the skin) injection.
Saline and heparin locks are peripheral IV devices that are short IV lines. A peripheral line is when a needle attached to flexible catheter and tubing is inserted to the vein and left there in the event an IV needs to be started. They have been "locked" off to prevent venous fluid from leaking out. Each lock can be converted into a full-scale IV at any point.
Saline Lock and Heparin Lock Similarities
Both saline and heparin locks equally prevent the blockage of IV catheters. This is an important consideration, because keeping the vein open is necessary to properly administer medication. They both prevent phlebitis or inflammation of the vein and increase the amount of time the IV can be in the vein. Decreasing vein inflammation keeps the patient comfortable, which is important for long-term administration for therapeutic dosing.
Heparin Considerations and Risks
There are several risks relating to heparin locks. Because heparin is a blood thinner, there are several side effects associated with this drug, such as heparin-induced thrombocytopenia (abnormal drop in blood cells necessary for clotting), thrombosis (a clot of coagulated blood) and hemorrhage. Another consideration is negative drug interactions and medication incompatibility with antibiotics or other drugs.
Saline locks are the better choice (if possible) for cost and quality control reasons. The cost of saline vs. heparin is considerably less and when factoring the risks associated with heparin is the safer choice. Because they each function identically in preventing blockages, reducing inflammation and increasing duration, saline should also be the preferred choice. Heparin is an anticoagulant, so it prevents clotting around the catheter so access to the vein remains unblocked. However, heparin is only used if the catheter is deep in the body, in a large vessel or meant to stay in for a long duration. Saline is comparable in preventing clotting if blood is not aspirated into the lock or the pressure is maintain by the lock. If the pressure is maintained, then blood will not back up into the catheter and clot.