Table of Contents

Air Bubble in IV Line

Air Bubbles in IV Line

Limits of admixed air in the IV line

The air bubbles in the IV line may not pose a danger if the threshold value is not reached. A patient may tolerate up to 1 cc of air per kilogram body weight of the patient. If this threshold value is reached and surpassed, complications may set in. Other medical practitioners contend that accidentally admixing five ml of air per kilogram of body weight in the IV line will cause significant complications. Following this contention, it means that accidentally injecting 350 ml of air into a 70-kg patient will cause significant problems.

In the paper titled “Accidental Intravenous Infusion of Air: A Concise Review,” authored and published by Robert G. Wilkins and Martin Unverdorben in The Journal of Nursing in 2012, in human adults, the acutely lethal volume of air from bubbles is about 3 to 5 cc or ml/kg body weight of the patient. At this level of air bubbles, the authors contended, the patient may die from the accidental entry of air into the bloodstream.

Complications from air bubbles in IV line

Air embolism

An air embolism occurs when air enters the bloodstream through the peripheral IV line and forms a blockage within the blood vessels. This complication is infrequent, but it can be fatal. The presence of air bubbles in the bloodstream can disrupt the normal flow of the blood and potentially lead to severe complications. However, this danger can be prevented, first and foremost, by properly priming the IV line. Priming means that the medical worker removes all the air bubbles in the IV line before inserting the cannula of the IV tube into the patient’s vein.
Several factors can cause air embolism in IV therapy. Some common causes include the following

  • Improper and inadequate priming: Failing to remove air from the IV tubing before inserting the cannula into the patient can introduce air into the bloodstream.
  • Detachment of IV tubing: An unexpected detachment of IV tubing while the catheter and part of it are still attached to the patient’s vein permits air to enter the patient’s bloodstream.
  • Non-functioning equipment: IV administration sets, or infusion pumps needing repairs can introduce air into the bloodstream.
  • Rapid changes in pressure: Sudden changes in pressure, such as during bag changes or adjustments to infusion rates, can form air bubbles.

End-organ damage

If a significant amount of air from bubbles reaches the brain or muscles of the heart, the said organs will be damaged. R. G. Wilkins and M. Unverdorben stated that in intravenous tubing with an internal diameter of 3-4 mm, the air bubbles could reach a total volume of approximately 15 microliter (uL). This air volume will easily pass through the lungs and reach the arterial circulation. Still, it is large enough to cause a decrease in the blood supply of the brain’s cerebrum, resulting in damage.

Wilkins and Unverdorben emphasized the volume of air bubbles that matter and the rate at which said air is infused into the bloodstream. One cc of air infused over 15 minutes is very close to the 1.4 cc dose that would potentially harm the heart circulation of an adult.

Prevention of air bubbles

  • Remember to prime the IV line. Before inserting the cannula attached to the IV tube into the patient’s vein, let the fluid flow into a pan until all the air bubbles in the IV line are removed.
  • When replacing an old IV bag on an existing line with a new one, inspect to ensure the previous fluid was not consumed, leaving significant airspace in the IV line. If a large airspace is visible, you can insert the spike into the new IV fluid bottle but let the IV line flow into the outside pan until the new fluid totally obliterates the airspace. With no airspace in the IV line, you can start inserting the cannula into the patient’s vein. 
  • Do not lay IV fluids on the bed when transferring patients. Laying the drip chamber down on its side only encourages air to enter the tubing. Raise the IV fluid bottle higher than the patient’s height while transferring him. 
  • Expel any air from syringes of IV antibiotics, analgesics, etc., you are about to administer. Before injecting the syringe into the injection port of the IV line, ensure that no air bubbles or airspace are in the syringe barrel.
  • Stabilize connections: Inspect and stabilize all connections in the IV line to avert unforeseen detachments. 
  • Regular monitoring: Regularly monitor the IV infusion site and tubing for signs of air infiltration.
  • Refresher course: Conduct a refresher course on air embolism among healthcare workers, covering preventive measures, diagnosis, and initial treatment.
  • Equipment maintenance: Regularly inspect and maintain IV administration sets and infusion pumps to ensure their proper functioning.

Final words on air bubbles 

Table 1 shows that air bubbles, whether small or large in diameter, can possibly harm the patient. A bubble with a diameter of 0.2 mm could harm the patient just as a bubble with a diameter of 1.8-2.1 cm does. 

The International Electrotechnical Commission (IEC) has developed guidelines on when the volume of air bubbles in the IV line can be considered harmful. Wilkins and Unverdorben, however, stated in their paper that visible bubbles may raise concern for the staff and the patient. Patients of different ages and sizes and with pre-existing medical conditions may vary in their susceptibility to harm from air injection or infusion, making a single recommendation inappropriate.

Based on the preceding, the entry of air into the bloodstream, regardless of size and volume, through the peripheral IV line should not be taken for granted. Medical workers must take air bubbles seriously, and they should always be avoided and prevented. Based on the aforecited paper, Wilkins and Unverdorben strongly recommend using an air elimination filter to prevent air bubbles in the IV line, thus averting its adverse health consequences. They cited the role of an air elimination filter in removing air in the IV line and eliminating bacteria and particulates in the infusion fluid.


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