I read with interest the recent report by Dr. Yang describing two cases of cerebral arterial air embolism (AGE) occurring during cerebral angiography in which the emboli appeared to be spontaneously absorbed into the bloodstream.
Another explanation for the bubble disappearance is distal progression and passage via the capillaries into the cerebral veins. In anesthetized rabbits it has been shown that arterial air bubbles often do not remain trapped in the arterial circulation, but rather progress distally and can be recovered on the venous side.
As Dr. Yang and colleagues point out, hyperbaric oxygen (HBO2) does result in rapid resolution of intravascular bubbles. However it has other pharmacological properties that are beneficial in AGE. HBO2 tends to inhibit the endothelial binding of leukocytes that occurs after tissue ischemia, and thus reduces mechanical obstruction in the microvasculature caused by adherent leukocytes.
In summary, spontaneous resolution of cerebral AGE reported by Dr. Yang is supported by other clinical observations. However, in managing these patients it is important to realize that AGE can initiate secondary phenomena such as regional hypoperfusion, which can sustain neurological injury. HBO2 not only can facilitate bubble resolution but also ameliorate some of these secondary phenomena and facilitate clinical improvement even when bubbles have resolved. It is therefore important not to withhold HBO2 merely on the basis of the absence of bubbles.