Background: Venous air embolism is a rare but potentially fatal complication of arthroscopy. Fatal venous air embolism has been reported with as little as 100 mL of air entering the venous system. During liquid-only arthroscopy, avenues for air introduction into the joint are limited. Therefore, we hypothesized that commercially prepared 3-L saline-solution bags are a source of potentially fatal amounts of gas that can be introduced into the joint by arthroscopic pumps.
Methods: Eight 3-L arthroscopic saline-solution bags were obtained and visually inspected for air. The air was aspirated from four bags, and the volume of the air was recorded. A closed-system pump was prepared, and two 3-L bags were connected to it. The pump emptied into an inverted graduated cylinder immersed in a water bath. Both bags were allowed to run dry. Two more bags were then connected and also allowed to run dry. The air was quantified by the downward displacement of water. The experiment was then repeated with the four bags after the air had been aspirated from them. This experiment was performed at three institutions, with utilization of three pump systems and two brands of 3-L saline-solution bags.
Results: Air was visualized in all bags, and the bags contained between 34 and 85 mL of air. Arthroscopic pumps can pump air efficiently through the tubing. The total volumes of gas ejected from the tubing after the four 3-L bags had been emptied were 75, 80, and 235 mL. When bags from which the air had been evacuated were used, no air exited the system.
Conclusions: Because a saline-solution arthroscopic pump is theoretically a closed system, venous air embolism has not been a concern. However, this study shows that it is possible to pump a fatal amount of air from 3-L saline-solution bags into an environment susceptible to the creation of emboli. Evacuation of air from the 3-L bags prior to use may eliminate this risk.
Clinical Relevance: The importance of this study is indicated by the case reports documenting symptomatic and fatal venous air embolism despite the use of modern preventive arthroscopic equipment and techniques.
1Rothman Institute of Orthopaedics, Thomas Jefferson University Hospital, 925 Chestnut Street, Philadelphia, PA 19107. E-mail address for L. Austin: firstname.lastname@example.org