The clinical incidence of central nervous system oxygen toxicity at 284kPa (2.8 ATA)

Abstract

Introduction: Central nervous system (CNS) oxygen toxicity is a recognised complication of hyperbaric oxygen treatment (HBOT), manifest most profoundly as a seizure. Reports have varied in the frequency of this complication. Methods: A retrospective review of the computerised database of the Hyperbaric Medicine Unit at the Royal Adelaide Hospital was performed from 1986 to 2003. Symptoms attributed to CNS oxygen toxicity and the occurrence of seizure were both recorded for all patient treatments at 284 kPa (2.8 ATA). Results: 1,395 patients received a total of 6,084 treatments at 284 kPa. Symptoms of CNS toxicity occurred in 64 treatments (1%) and seizure in 17 (0.3%). Incidence of seizure was significantly higher for emergency medical indications as compared with non-emergency medical indications. The highest incidence was found in the 1,493 treatments for decompression sickness (DCS) with symptoms in 32 (2%) and seizure in eight (0.5%). A gender disparity was observed, with an increased incidence of seizure in female divers that was not statistically significant. Of the eight seizures, seven occurred during the first treatment giving a risk of seizure during the first treatment for DCS of 1.80% or 1 in 55 patients. Conclusions: An incidence of CNS oxygen toxicity at 284 kPa has been described for one hyperbaric facility. There is an increased risk of seizure in emergency compared with non-emergency medical treatments. There appears to be an increased risk of seizure in female divers and during the first recompression treatment for DCS.