Back priming an intravenous (IV) line is a technique used when administering a secondary medication, often called a “piggyback” infusion, into an existing primary IV line. This method uses the solution already flowing in the primary line to clear the air from the secondary tubing before the medication infuses. This technique prevents the waste of expensive medication that would be lost if the secondary tubing were primed directly with the drug itself. Back priming also ensures that air bubbles are removed from the secondary line, supporting the safe delivery of the medication.
Necessary Equipment and Initial Setup
The back priming procedure requires the primary IV bag and its administration set, the secondary medication bag, and its shorter secondary administration set. You will also need an IV pole and an antiseptic wipe, typically an alcohol swab, to ensure the connection point remains clean. The secondary tubing set usually includes a plastic hook designed to facilitate the necessary height adjustment of the bags.
A crucial initial step is preparing the bags on the IV pole, which allows back priming to work through gravity. The primary IV bag must be temporarily lowered so that it hangs below the secondary medication bag. This height difference is essential because the primary fluid will flow upward into the secondary tubing when the clamp is opened, displacing the air and priming the line. Before connecting the secondary line, the primary IV fluid should already be infusing correctly to ensure the line is patent and ready.
Detailed Steps for Back Priming
The back priming process begins by preparing the connection point on the primary IV line. The upper Y-port (the access port closest to the primary bag) must be cleaned with an antiseptic swab for the recommended duration, often 10 to 15 seconds, and then allowed to fully air dry. This step maintains aseptic technique before the secondary line is connected.
With the secondary tubing roller clamp completely closed, the spike end of the line is securely attached to the cleaned Y-port of the primary line. The secondary medication bag is then lowered to a position below the primary bag, reversing the standard infusion hierarchy. Fluid from the primary line, driven by the pressure head of the higher primary bag, is now ready to flow backward.
The roller clamp on the secondary tubing is then slowly and carefully opened. Fluid from the primary line will flow up the secondary tubing, pushing the air out and filling the line until it reaches the drip chamber of the secondary bag. This controlled opening prevents overly rapid flow, which could cause turbulence or force air into the primary line. The drip chamber should be filled to about one-half to two-thirds capacity with the primary fluid to ensure the entire line is cleared of air.
Once the desired fluid level is reached in the drip chamber, the roller clamp on the secondary tubing must be immediately and completely closed. The tubing is now primed, and all the air has been safely removed. The final action is to reposition the bags back to their proper infusion height. The primary IV bag is raised using the provided hook so that the secondary medication bag now hangs higher, allowing the medication to infuse via gravity when the dose begins.
Connecting the Medication and Final Checks
After back priming is complete, the secondary medication bag is correctly positioned on the IV pole, hanging above the primary bag. With the secondary line primed and its clamp closed, the infusion is ready to begin. If an infusion pump is being used, it must be programmed with the correct volume and rate for the medication, typically delivering the drug over 30 to 60 minutes for intermittent infusions.
The secondary line’s roller clamp is then opened to start the infusion, and the flow is verified. Safety checks involve observing the drip chambers to confirm that drops are falling only in the secondary line’s chamber, indicating the primary flow has temporarily stopped due to the height difference. The patient’s IV access site should also be monitored for any signs of infiltration or adverse reaction to the medication. When the secondary infusion is complete, the pump will automatically revert to the primary line flow, or the primary bag will resume dripping as the secondary bag empties.