By: 25 October 2011

Luke Austin, MD, et al.
In The Journal of Bone and Joint Surgery. September 1, 2010. Vol. 92-A. No. 11. Pp. 2110-2114.

Ever hear the slogan, Air is our enemy? Take for example, arthroscopic surgery of the joint. Even a small bubble of air introduced into the joint can travel to the heart or brain and cause sudden death.

When performing arthroscopic surgery on the joint, it is necessary for the surgeon to put something inside the knee to distend or expand it. Over the years, different substances have been used — first nitrous oxide (laughing gas), then carbon dioxide. But studies showed that the use of any gas could result in a deadly embolism. Now surgeons use water or saline (salt solution).

But guess what? Cases of sudden death have occurred even when using an all-liquid arthroscopic system. It’s rare but it’s still fatal and therefore unacceptable. That’s what sent the authors of this study back to the lab to try and figure out what’s going on.

They started with the hypothesis (theory) that somehow even with an all-liquid arthroscopic procedure, air was getting into the joint. Where was it coming from? Was it an error in the way the procedure was being done? Was it the type of arthroscopic unit used? Maybe it was coming from a particular brand of saline solution bag.

So three surgeons from three separate institutions (a university hospital, a general hospital, and a surgery center) carried out this experiment. Each one tested three different types of arthroscopic pumps. Two different brands of saline solution were used.

They carefully inspected each bag for any signs of air. By turning the bags upside down and inserting a syringe, they were able to draw out of the bag any gas or air and measure it. The goal was to find out if it is possible for the arthroscopic pump to pull air from the bags of saline and then pump it through the system.

They were able to design the experiment in such a way as to be able to measure how much air was introduced into the system. They also devised a way to prevent air from entering the closed-system arthroscopic pump and tested it as well.

Sure enough (as suspected), they found that air in the saline-solution bags can be the source of venous air embolism in arthroscopic surgery. Not only that, but even a tiny amount of air is enough to cause a fatal result. And even though it seems like a rare event (there are only a few cases reported now and then), the authors suspect venous air embolism during shoulder arthroscopy happens more often than is realised or reported.

They concluded that by taking all of the gas out of the saline bags before connecting them to the arthroscopic pump takes care of the problem. It’s a simple thing to do before getting started. It can be done with a sterile technique. And best of all, it’s 100 per cent effective as proven by this experiment. With the two different brands of solution tested, there was a big difference in how much air was in the bags. Surgeons will want to pay attention to this important detail.

One other recommendation was made as a result of this experiment. The tubing attaching the bag of saline-solution to the pump must be free of air, too. This is an important step when one bag runs out and it’s time to use another bag. In some surgeries, two or three bags of saline-solution are used. Each time the bag is changed, not only must the bag be bled of any air but the tube must be primed to eliminate any air as well.