First aid normobaric oxygen for the treatment of recreational diving injuries.

INTRODUCTION: First aid oxygen (FAO2) has been widely used as an emergency treatment for diving injuries, but there are few studies supporting its efficacy.
METHODS: 2,231 sequential diving injury reports collected by the Divers Alert Network (DAN) Injury database from 1998 to 2003 were examined.
RESULTS: 47% (1,045) of cases received FAO2. The median time to FAO2 treatment after surfacing was four hours and after symptom onset was 2.2 hours. Persistent complete relief (14%) or improvement (51%) was seen with FAO2 alone (65% overall response; n = 330). After one recompression treatment 67% of FAO2 patients reported complete relief compared to 58% of the no FAO2 group (OR = 1.5, 95% CI = 1.2 -1.8). FAO2 given at any time after surfacing significantly reduced the odds of multiple recompression treatments (OR = 0.83, 0.70-0.98). When FAO2 was given within 4 hours of surfacing, the OR decreased to 0.50 (0.36-0.69) yielding a number needed to treat of 6. Case severity affected urgency of FAO2 treatment. Individuals with more prominent symptoms received prompt treatment. Cardiopulmonary, skin, and serious neurological symptoms had shorter delays to FAO2 (p < 0.001).
CONCLUSIONS: FAO2 increased recompression efficacy and decreased the number of recompression treatments required if given within four hours after surfacing.