Cerebral arterial air embolism: I. Is there benefit in beginning HBO treatment at 6 bar?

A method for studying treatment of cerebral arterial gas embolism in dogs is described. The model produces severe cortical dysfunction and cerebral blood flow deficits. The efficacy of treatment was assessed using median nerve somatosensory cortical evoked potentials (CEP), [14C]iodoantipyrene autoradiographic cerebral blood flow studies, brain water content, and various physiological parameters. A direct comparison of modified U.S. Navy Treatment Tables 6 and 6A is reported. Complete recovery of CEP was not seen after 90 min of treatment. The maximum rate of CEP recovery occurred in the first 15 min of treatment. Recovery continued out to 60 min. Thereafter, some dogs on treatment 6A showed signs of deterioration. The cerebral blood flow studies were the same in both groups and showed no sign of pathologically low levels of flow. It appeared that there was no advantage in preceding 2.8-bar (60-ft) oxygen treatments with compression to 6 bar (165 ft) on air for the treatment of arterial air embolism in this model.