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What is an air embolism and how can it cause harm to patients?

Suzanne White, medical negligence partner, discusses the fatal dangers of air emboli and how the risk they pose can be reduced.

Posted on 15 August 2017

When air enters the circulation it can cause an air embolism, which can result in air bubbles that travel to the brain, heart or lungs. The air bubbles can cause a heart attack, stroke, or respiratory failure. These can occur in your arteries and veins.
There a number of ways in which air emboli can be caused, but in a clinical setting they are caused by injections, surgical procedures or by way of a catheter inserted or taken out of the vein or artery. 
I have recently settled a case where my client’s partner suffered what was likely to be an air embolus entering the blood stream after he was disconnected from a dialysis machine. He later collapsed and sadly suffered a stroke. An MRI taken of his brain showed that the likely cause of the stroke was an air embolism in the brain.
It is noted in the Oxford text book of clinical nephrology that:

“ …air embolism is one of the most serious complication of haemodialysis…if air embolism occurs, it is almost always due to human error.”
There should be safety precautions in place to make sure that it is impossible for an air bubble to enter the dialysis machine. Sadly, this did not happen in my client’s case. As a result of the air embolism entering the blood stream my client’s partner sustained cerebral damage. The NHS Trust responsible for his care made an admission of liability and wrote a letter of apology to my client.
Air emboli are very dangerous to patients and can occur when a central venous catheter or line is inserted or taken out. A central venous catheter (CVC), also called a central line, is a long, thin, flexible tube used to give medicines, fluids, nutrients, or blood products over a long period of time, usually several weeks or more. A catheter is often inserted in the arm or chest through the skin into a large vein.  
Later this week on 17 August an inquest will be heard into the death of Mr Neil Shestopal  whose CVC was removed whilst he was sitting in an armchair in the London Clinic. After removal it is claimed that he immediately suffered a cardiac arrest as a result of an air embolism entering his circulation.
There are basic guidelines to comply with when removing CVC lines to avoid an air embolism these are:
  • Inform the patient
  • Place the patient flat on their back, not sitting or upright.
  • Instruct the patient to hold their breath and do a Valsalva manoeuvre , which means to blow air into your closed mouth on breathing out while the  catheter is being taken out
  • If the patient is not conscious or able to understand the instructions make sure you remove the catheter following inspiration
  • Cover the insertion site straight away  with a sterile dressing, keep firm manual pressure until haemostasis is achieved. The insertion site must be covered with an air-occlusive dressing, and should stay on the site for  about 24-72 hours.
Patient safety is absolutely paramount and staff should, and must be, properly trained before they remove or insert CVC lines; without proper training, there is a real risk of stroke and death for the patient. These cases demonstrate how devastating this can be.