Oxygen toxicity seizures: 20 years' experience from a single hyperbaric unit

Oxygen toxicity seizures (OTS) are a known complication of hyperbaric oxygen therapy (HBOT). The incidence of OTS has been variously reported and appears to be related to the duration and pressure of exposure in addition to individual susceptibility factors.

All OTS occurring in patients undergoing HBOT during the first 20 years of operation of the Fremantle Hospital Hyperbaric Medicine Unit were reviewed.

During 41,273 HBOT in 3,737 patients, 25 OTS occurred; a rate of 0.06% (1/1,650 or 6 per 10,000) HBOT exposures. For the initial treatment of dysbarism with United States Navy Treatment Table 6, the rate was 0.56%. (4/714) and for the treatment of carbon monoxide (CO) poisoning was 0.18% overall but 0.49% for the first HBOT. There was an increasing OTS rate with increasing pressure with a statistically significant difference (P < 0.001) in OTS rate at 203 kPa or less versus > 203 kPa (OR 8.5, 95% confidence intervals (CI) 2.0 to 36.1), and for comparison of two commonly used pressures of 203 kPa versus 243 kPa (P = 0.028, OR 5.1, 95% CI 1.1 to 22.8), but not with first versus follow-up HBOT at 284 kPa for dysbarism (P = 0.061) nor CO (P = 0.142).

This study reports all OTS in a single hyperbaric unit over a 20-year period, the longest observational study period yet reported for OTS during HBOT for all indications. The incidence of OTS in this study compares favourably to previously reported rates, and shows an increasing OTS rate with increasing pressure.