When air bubbles are in your IV line, do you feel lucky?

When was the last time you were in a hospital bed with an IV line attached to your arm and a bag of IV fluid hanging from a pole beside you?

Maybe when the bag of fluid began to empty, a health care worker entered the room to hang another bag, or maybe just attach a smaller bag to the IV line.You sat silently as she/he changed the bag and adjusted the drips on your IV line, thinking about what you had to do when you got out of the hospital.A large bubble of air slowly moved down your IV line towards your arm out of the corner of your eye.You were told by the clinician that there is nothing to worry about because a little bit of air will never hurt anyone.A short explanation about how it would take a lot of air to cause you harm and that there is nothing to worry about is followed by this explanation.

Unfortunately, this scenario is repeated thousands of times by health care workers who still consider air bubbles in the veins inconsequential, and then spend their careers ignoring small amounts of bubbles entering the circulation through an IV line.It is almost impossible to estimate how many times air bubbles enter a patient's blood stream in a health care setting.Iiatrogenic air comes from the activity of a health care provider.No harm is ever intended, assumed or imagined, but it is often just a part of the clinician's training, their routine practice of maintaining an IV, and their confusion and misinformation around the dangers of air bubbles entering the venous circulation.

There are consequences to small amounts of air bubbles entering a person's blood stream.There is no reason why air or air bubbles should be allowed to pass through an IV line in a patient.Every clinical protocol for setting up and maintaining an IV line stresses the importance of removing air from the line before it is attached to a patient's circulatory system.The majority of air bubbles can be removed from an IV line before entering the patient's circulation.Air bubbles have the potential to cause harm and are not in the best interest of the patient.

First of all, no matter the size of the bubble or its point of entry into our blood stream, it is alien to our circulation and our physiology.When a bubble enters the blood stream, it is immediately attacked and treated like any other foreign substance that enters our body's natural defense mechanisms.The bubbles are immediately covered by platelets, white blood cells and other cells as they travel to the right side of the heart.They can damage or degrade the blood vessels delicate lining, which can result in inflammation, swelling, and even obstruction in the tiny pulmonary capillary vessels.The latter has been found to cause low platelet counts.It is believed that bubbles will gradually break in the blood, but not before damaging the erythrocyte layer as they slip through the microcirculation.

The normal size of our capillaries is 4-9 microns in diameter, but the bubbles trying to pass through these capillaries can be hundreds or thousands of microns larger.If bubbles enter the blood going to the brain, they can cause a variety of problems.

All of us are born with an opening in the wall of our heart that separates the right and left sides.Our first few breaths at birth send blood to the lungs and arteries in the brain and the rest of the body.Patent Foramen Ovale are defects that do not close at birth and can be detected through auscultation.About 10% to 35% of adults have this PFO, and it has been reported to be an important risk factor for strokes, cerebrovascular accidents and TIA's.Most adults don't know they have a PFO until the doctor tells them.People with a PFO generally function well until they are diagnosed with symptoms.

Even in the absence of a PFO, microbubbles have the potential to pass from the venous circulation into the left side of the heart.The potential to increase in number in all adults during exercise is one of the reasons why the IPAVA shunts are known to exist in 30% of resting adults.A very small percentage of people have small openings in the ventricular walls of their hearts that can allow limited blood movement between the right side of the heart and the left side.

Regardless of the size of bubbles, they are called Venous Air Emboli.There is a chance that VAE can cross over to the left side of the heart.There are air bubbles that pass from the right side of the heart to the left side.PAE can be pumped towards the brain as the heart pumps blood from the left ventricle to the aortic valve.

The problem for the health care provider is that most of the patients they care for have no indication or warning signs that they may have a PFO.

A test called the bubble study is used to determine the presence of a PFO.This is a test where a fixed amount of saline solution is mixed with air and shaken in the syringes to create a lot of small microbubbles.The microbubble solution is injected into a vein in order to see if any of the bubbles can be seen through a hole in the heart wall.On the left side of the heart, paradoxical air will be detected if a PFO exists.In the case of a PFO, the microemboli should stay on the right side of the heart and be removed by the lungs.The investigators found that patients with a PFO who have some air on the left side of the heart can have strokes.

Air bubbles were found in the right side of the heart in all 21 patients that were studied for the incidence of PAE.Even after the bubbles in the right side of the heart dissipated, 3 of those 21 patients were still found to have air bubbles that passed through the atrial wall.

The statement that it would take a lot of air to cause you harm makes you wonder how much air it will take to create a life threatening problem after the air goes into the blood stream.After leaving the right side of the heart and entering the blood flow to the lungs, there can be a negative impact on the lung circulation.A single large injection of air into a vein can result in rapid breathing, heart rhythm changes and a decrease in blood pressure due to an air lock in the right side of the heart.In addition, this air can cause injury as a result of activation complement and other inflammatory mediators which can lead to fluid leaking in the lungs and the possibility of pulmonary edema.Venous air emboli is not always about how much air it would take to kill a person, the biggest concern around venous air should be the possibility of that air reaching the arterial circulation and causing strokes.

There are two areas of concern in healthcare.It would take large volumes of air to cause death, and small volumes are probably inconsequential.Microbubbles are frequently found in IV lines and can be difficult to remove, which is the second area of discussion.

There is technology that can be used to remove the air from an IV line.The technology is in the form of air filters.The smallest filters used in IV lines are 0.2 microns in size and they remove microbubbles from the fluids infused, as well as fragments of glass, plastic and rubber.IV filters can be used to prevent the entry of gram negativebacteria into the blood stream during IV fluid therapy.The filters are very effective if they are maintained at the same level as the patients heart.

In some cases, IV filters are only used when there is a suspicion of a PFO.If you asked why they are not used in adults, my answer would be, that is a very good question.Maybe it's based on the added cost of healthcare in your country.Maybe it is based on the fact that they require some deep change in a clinician's long held practice/belief, or even a lack of knowledge about their benefits within the medical community.They should be a part of IV fluid therapy because of their ability to reduce morbidity and mortality.The culture of "a little air won't hurt you" is outdated and should be stopped by future generations of health care workers.

The question comes back to you, that person who is noticing a large air bubble coming down the IV line.In the absence of an IV filter, should you accept the word of the person who tells you not to worry about that air in your IV line and just smile as you watch as the air bubble slowly enter your arm?How lucky do you feel on that given day, I guess the only way you can respond is to you.

If you find this information interesting, please share it with your network.Below is my editorial on this topic.

The Anaes Patient Safety Foundation Newsletter contains information about the dangers of in-line IV filters.

Chapter 3 (Common Features of Bacterial and Archaeal Cell Structure) pp50 is available at highered.mcgraw hill.com.

The potentially fatal Venous air embolism can be caused by air/fluid exchange.

The Case Reports Anesth article is about Venous air embolism leading to cardiac arrest in an infant with congenital heart disease.

The Pathophysiology of IV air embolism in dogs was written by Adornato and Gildenberg.

The Gas Embolism: Pathophysiology and treatment was written by Van Hulst and Klein.

There is a fatal air embolism during open eye surgery.

Cerebral ischemic events are associated withbubble study for identification of right to left shunts.

Exercise after scuba diving increases the incidence of arterial gas embolism.

Lovering AT, Riemer RK, and Thebaud B: arteriovenous anastomoses?The Ann Am THORac 2013; 10(5): 504-8 was published.

There are small- and moderate-size right-to- left shunts that are normal and unrelated to headaches.

Lynch, Schuchard, Gross, et al.There is a prevalence of right-to- left arrhythmia in a healthy population.Am J Cardiol was published in 1984.

Foster PP, Boriek AM, and others.There is a patent foramen ovale.The 74:B1–B64 is from the Aviat Space Environ Med.

Olmedilla L and Garutti I studied fatal air embolisms during liver transplantation.

There is Frequency and significance of right to left shunting in end stage hepatic disease.

In July of 1998, Mammoto T, Hayashi Y and their colleagues published an article about the incidence of air embolism in surgical patients in the sitting position.

My book entitled Gaseous Microemboli During Cardiopulmonary Bypass (revised Edition) was published by LivaNova Group, Mirandola, Italy, in the year 2017.The book is not for sale to the general public.