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Oxygen exposure and toxicity in recreational technical divers
Andrew Fock1, Richard Harris, Michael Slade
1The Alfred Hospital, Melbourne, Victoria, Australia. a.fock@alfred.org.au
Diving and Hyperbaric Medicine
|July 2, 2013
Summary
Divers on multi-day technical diving expeditions using closed-circuit rebreathers (CCRs) may exceed oxygen exposure limits. While lung function remains unaffected, some experience temporary vision changes (hyperoxic myopia).
Area of Science:
- Diving Medicine
- Hyperbaric Physiology
- Occupational Health
Background:
- Central nervous system oxygen toxicity is a known risk in recreational scuba diving with nitrox.
- Oxygen toxicity in other diving settings, particularly with closed-circuit rebreathers (CCRs), is less understood.
- Multi-day expeditions using CCRs may lead to cumulative oxygen exposures exceeding recommended limits.
Purpose of the Study:
- To assess cumulative oxygen exposures in technical recreational divers using CCRs.
- To evaluate the impact of these exposures on lung function and visual acuity.
- To determine if current oxygen exposure limits are adequate for extended CCR diving.
Main Methods:
- Monitoring cumulative oxygen exposure in divers during multi-day technical diving expeditions.
- Recording lung function and visual acuity at regular intervals throughout expeditions.
- Conducting formal visual acuity testing post-expedition for affected divers.
Main Results:
- Divers on 8- to 12-day expeditions frequently approached or exceeded recommended maximum repetition excursion oxygen exposure (REPEX) limits.
- No significant decrement in lung function was observed among divers.
- Several divers reported visual acuity changes, with one confirmed case of temporary myopic shift resolving within eight weeks.
Conclusions:
- Extended technical diving expeditions (8+ days) using CCRs can lead to exceeding REPEX oxygen limits.
- Significant pulmonary oxygen toxicity is a risk, especially if recompression therapy for decompression illness is required.
- While lung function appears unaffected, hyperoxic myopia can occur, though it typically resolves spontaneously.
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