Comparison of tissue oxygenation achieved breathing oxygen using different delivery devices and flow rates

Divers with suspected decompression illness require high concentration oxygen (O₂). There are many different O₂ delivery devices, with few data comparing their performance. This study evaluated O₂ delivery, using tissue O₂ partial pressure (P_tcO₂), in healthy divers breathing O₂ via three different delivery devices.

Twelve divers had P_tcO₂ measured at six limb sites. Participants breathed O₂ from: a demand valve using an intraoral mask with a nose clip (NC); a medical O₂ rebreathing system (MORS) with an oronasal mask and with an intraoral mask; and a non-rebreather mask (NRB) at 15 or 10 L·min⁻¹ O₂ flow. In-line inspired O₂ F_IO₂) and nasopharyngeal F_IO₂ were measured. Participants provided subjective ratings of device comfort, ease of breathing, and overall ease of use.

P_tcO₂ values and nasopharyngeal FIO₂ were similar with the demand valve with intraoral mask, MORS with both masks and the NRB at 15 L·min⁻¹. P_tcO₂ and nasopharyngeal F_IO₂ values were significantly lower with the NRB at 10 L·min⁻¹. The NRB was rated as the most comfortable to wear, easiest to breathe with, and overall the easiest to use.

Of the commonly available devices promoted for O₂ delivery to injured divers, similar PtcO₂ and nasopharyngeal F_IO₂ values were obtained with the three devices tested: MORS with an oronasal or intraoral mask, demand valve with an intraoral mask and NRB at a flow rate of 15 L·min⁻¹. P_tcO₂ and nasopharyngeal F_IO₂ values were significantly lower when the flow rate using the NRB was decreased to 10 L·min⁻¹.