Expansion of air bubbles in aqueous solutions of nitrous oxide or xenon

Anaesthesia using xenon may be contraindicated in some situations because of its diffusion into intravascular bubbles. The expansion of air bubbles in water equilibrated with either nitrous oxide or xenon was studied.

Equilibrated water was transferred to a stirred vial, closed except for a long, narrow-bore tube. Injection of an air bubble caused displacement of water along the tube, allowing expansion of the bubble to be charted on a linear scale.

At 20 degrees C, bubbles expanded from 10 microliters to a median volume of 23 microliters (range 20-23 microliters) and 30 microliters (range 27-34 microliters) in water equilibrated with xenon and nitrous oxide, respectively. Half of the expansion took place in the first 20 s (15-45 s) for xenon and in the first 5 s (5-10 s) for nitrous oxide. At 37 degrees C the expansion was less with both gases, but the relative differences were maintained between them.

Xenon anaesthesia may be less likely to aggravate injury from intravascular bubbles than anaesthesia with nitrous oxide.