[abstract] TREATMENT OF DETERIORATION AFTER EXPERIMENTAL CEREBRAL AIR EMBOLISM IN DOGS: TABLE 6 VERSUS TABLE 6A.

Abstract

Victims of cerebral air embolism may initially recover when exposed to hyperbaric conditions, then later deteriorate; the deterioration can be resistant to further treatment. Initial recompression to 6 ATA (USN Table 6A) rather than 2.8 ATA (USN Table 6) is recommended in air embolism to hasten clearance of trapped air; it has been suggested that this results in improved outcome, with fewer cases of deterioration. We compared the effects of Table 6 and Table 6A treatment on somatosensory evoked potential (SSEP) recovery and intracranial pressure (ICP) in pentobarbital anesthetised dogs subjected to a combined insult of carotid air embolism and norepinephrine induced hypertension. This combined insult has previously been shown to result in poor SSEP outcome with deterioration. 7 animals were treated with Table 6A and 8 animals with Table 6; hyperbaric treatment in all animals began 8 minutes after air. Table 6 was extended for 30 minutes at 2.8 ATA to equalize the time under pressure in both groups. Table 6 treated animals recovered 39.7% +- 25% (mean +- SD) of their pre-air baseline SSEP amplitude and Table 6A treated animals recovered 33.6% +- 13.5%. ICP at the end of treatment was 12.7 +- 9.3 mmHg in the table 6A treated group and 9.3 +- 6.0 in the Table 6 group. We conclude that Table 6A is no better than Table 6 in promoting recovery of the SSEP after cerebral air embolism. (Supported by NMRDC Work Unit MR04101.001-1005)