Intravenous (IV) therapy involves delivering fluids, medications, or nutrients directly into a vein. Before connecting an IV line to a patient, the administration set (the tubing) must be filled with fluid from the IV bag in a process called “priming.” This step removes all air from the tubing, ensuring only the intended solution is administered. Priming creates a seamless column of liquid from the IV bag to the end of the line, preventing air from entering the patient’s circulatory system.
The Critical Importance of Removing Air
Completely removing air from the IV tubing is necessary to prevent air embolism. An air embolism occurs when an air bubble enters a vein or artery and blocks blood flow. In the venous system, air travels to the heart and lungs, where small amounts are usually filtered and absorbed. However, introducing a large volume of air can block pulmonary circulation, causing a sudden drop in blood pressure and potentially leading to cardiac arrest. Even small volumes have the potential to cause harm, particularly in patients with certain heart conditions.
Preparation and Setup
The process begins with meticulous preparation to establish an organized and sterile workspace. Thorough hand hygiene must be performed before handling any equipment to prevent microorganism transmission. Gather all necessary supplies, including the prescribed IV solution bag, the primary IV administration set, and a waste receptacle for the priming fluid. Inspect the IV solution bag by checking the expiration date and assessing the fluid for precipitates, cloudiness, or discoloration. After verifying the solution, remove the administration set from its packaging and immediately close all clamps on the tubing, including the roller clamp, to prevent premature fluid flow.
Step-by-Step Guide to Priming the Primary Set
With the clamps closed, “spike” the IV bag by inserting the tubing’s spike into the solution container port. Hang the bag on an IV pole above the tubing level so gravity assists the flow. Gently squeeze the drip chamber, located below the spike, until it is approximately one-third to one-half full of fluid. Filling the chamber prevents air from being sucked into the main tubing line as the fluid flows.
Priming the Line
Hold the distal end of the tubing over the waste receptacle and slowly open the roller clamp to start the fluid moving. The flow rate must be controlled and gradual, as opening the clamp too quickly creates turbulence that generates air bubbles. As the fluid progresses, momentarily invert and gently tap injection ports or backcheck valves along the line. This technique helps dislodge any air trapped in these side ports. The tubing is fully primed once the fluid reaches the distal end and drips out, confirming the entire line is filled with solution.
Identifying and Eliminating Residual Air
After the initial priming flush, inspect the entire length of the tubing for remaining air bubbles. Hold the transparent tubing against a dark background to make any trapped air columns clearly visible. Small, localized bubbles can often be eliminated by gently flicking or tapping the tubing near the bubble. This action moves the air pocket upward, allowing the continuous fluid flow to carry it out the distal end. For larger air columns, the line may need to be re-primed by momentarily opening the roller clamp to force the air out with a fresh flush of fluid.
Removing Air from Ports
If air is trapped near an injection port, a sterile syringe can be attached to the port, and the air can be aspirated directly out of the line. When using this technique, the tubing must be clamped just below the port to prevent the air from traveling further down the line. Once all residual air is removed and the line is a bubble-free column of fluid, the distal end is capped to maintain sterility until connection.