Nitrous oxide anesthesia may double the balloon gas volume of Swan-Ganz catheters

The authors studied the overdistension of Swan-Ganz catheter balloons that may result from exposure of N₂O. They surrounded balloons with saline equilibrated with 50% or 75% N₂O at 37° for ten-minute periods. When the inflating gas was air, the original balloon volume (1.5 ml) rapidly expanded by 65% and 96%, respectively, for the two levels of N₂O in the surrounding medium. Volume decreased 18% and 29% when the inflating gas was 50% or 75% N₂O, respectively. Volume decreased the most (49% and 38%, respectively, for the two levels of N₂O in the surrounding medium) when the inflating gas was 100% CO₂. Volume decreased only slightly when the balloon was inflated with air and exposed to saline equilibrated with air. It is concluded that complications associated with overdistension of Swan-Ganz catheter balloons may be minimized by avoiding prolonged inflation of the balloon during N₂O anesthesia or by using CO₂ or N₂O as the inflating gas.