Saline Lock vs. Heparin Lock

Instructor: Courtney Dohse
In this lesson, we will learn the differences between a saline lock and a heparin lock in relation to peripheral intravenous catheters, as well as discuss the pros and cons of each.

A Case Study

Alice is a 28-year-old woman who is admitted to the Labor and Delivery Unit and is in labor with her first child. In her birth plan, she states that she wishes to have a natural, unmedicated birth with little intervention. The nurse explains to Alice that according to protocol, it is important for every patient that is admitted to have a peripheral intravenous catheter (IV). Alice agrees, but wishes to know more about the use and maintenance of the IV.

Definition and Uses

A peripheral intravenous catheter (IV) is a small tube-like catheter that is inserted into a vein for medical use. It is placed for easy medication or fluid administration and it is the route that allows medications to work the fastest because the catheter is placed directly into the bloodstream. Even though Alice has stated that she wants a natural, unmedicated birth, it is important for an IV to still be placed in the event of an emergency. If there are complications with Alice's delivery, such as a major loss of blood, or fetal distress, it is important to have quick access for fluid or life-saving medications to be given. Most hospital protocols require an IV to be inserted for emergent situations such as this, so that obtaining venous access in a crisis situation is not an issue. However, when an IV is started and not in use, regular maintenance is important to ensure patency and proper functioning of the line. This is where saline and heparin locks come into play. Let's take a look at the difference between the two.

Saline Locks

Saline locks are the most commonly used type of lock. When an IV is not in use, it can be 'capped off' with a short piece of tubing that has ports on the end. To prevent the backflow of blood into the line which may cause clotting, it is important to flush the line with normal saline, and allow the saline to remain in the tubing to ensure that the tube stays patent. In most adult patients, the line is flushed with 10 milliliters of normal saline, and then the line is clamped to allow the fluid to stay in the tubing. The use of saline locks is most common because it is cost effective and does not carry some of the risks that come with using heparin locks. It is also proven to be just as effective as heparin locks in maintaining patency in peripheral IV's.

Saline-locking of a Peripheral Intravenous Catheter

Heparin Locks

Heparin locks are similar to saline locks in that they are used to maintain patency of an IV. However, instead of the use of normal saline, a concentrated heparin solution is inserted into the tubing to prevent blood clots from forming. Heparin is an anticoagulant that keeps the blood thin and lowers the risk of the IV becoming occluded. It is an effective drug but it does come with some side effects. Heparin may cause heparin-induced thrombocytopenia which is a decrease of platelets in the blood. Platelets are the cells responsible for clotting. This can be dangerous and may cause bleeding in the patient. Because of this, any patient that has received heparin should be monitored for hemorrhage. There are also medication interactions that should be considered, as well as allergies that may occur as a result of heparin.

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