Hyperbaric oxygen and cerebral infarction in the gerbil.

The effectiveness of hyperbaric oxygen in reducing the incidence of cerebral infarction during the first 36 hours after occlusion of the right common carotid artery was investigated in gerbils. After carotid ligation, the gerbils were divided into four groups: controls, which breathed air at ambient pressure; group 1, which received hyperbaric oxygen at 1.5 atmospheres absolute pressure (ATA) for 36 hours, with a 5-minute, 1.5-ATA air break each hour; group 2, which received hyperbaric oxygen at 1.5 ATA for 1 hour alternating with 1 hour air at 1 ATA, for 36 hours; and group 3, which received hyperbaric oxygen at 1.5 ATA with hourly 5-minute air breaks for 18 hours, and ambient air for the second 18 hours. Neurological evaluations and staining of the brain with tetrazolium revealed the following results at 36 hours after carotid ligation: 72% of the controls had cerebral infarcts; 26% of the gerbils in group 1 had infarcts, but all animals died at 24-36 hours after beginning hyperbaric oxygen exposure from oxygen toxicity; 44% of the gerbils in group 2 had infarcts; 11% of the gerbils in group 3 had infarcts during the first 18 hours after carotid ligation, and no infarcts developed in the 18 hours that followed. Hyperbaric oxygen reduces the incidence of cerebral infarction after carotid artery ligation, presumably by allowing time for collateral circulation to develop.