Introduction: High-concentration normobaric oxygen (O₂) administration is the first-aid priority in treating divers with suspected decompression illness. The best O₂ delivery device and flow rate are yet to be determined.
Aim: To determine whether administering O₂ with a non-rebreather mask (NRB) at a flow rate of 10 or 15 L·min ⁻¹ or with a demand valve with oronasal mask significantly affects the tissue partial pressure of O₂ (PtcO₂) in healthy volunteer scuba divers.
Methods: Fifteen certified scuba divers had PtcO₂ measured at six positions on the arm and leg. Measurements were taken with subjects lying supine whilst breathing O₂ from a NRB at 10 or 15·L·min⁻¹, a demand valve with an adult Tru-Fit oronasal mask and, as a reference standard, an oxygen 'head hood'. End-tidal carbon dioxide was also measured.
Results: While none of the emergency delivery devices performed as well as the head hood, limb tissue oxygenation was greatest when O₂ was delivered via the NRB at 15 L·min⁻¹. There were no clinically significant differences in end-tidal carbon dioxide regardless of the delivery device or flow rate.
Conclusion: Based on transcutaneous oximetry values, of the commonly available emergency O₂ delivery devices, the NRB at 15 L·min ⁻¹ is the device and flow rate that deliver the most O₂ to body tissues and, therefore, should be considered as a first-line pre-hospital treatment in divers with suspected decompression illness.
Keywords: DAN (Divers Alert Network); Scuba diving; decompression illness; equipment; first aid; medical kits; oxygen; transcutaneous oximetry.