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

INTRODUCTION: 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 (PtcO2), in healthy divers breathing O2 via three different delivery devices. METHODS: Twelve divers had PtcO2 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 FIO2) and nasopharyngeal FIO2 were measured. Participants provided subjective ratings of device comfort, ease of breathing, and overall ease of use. RESULTS: PtcO2 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. PtcO2 and nasopharyngeal FIO2 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. CONCLUSION: Of the commonly available devices promoted for O2 delivery to injured divers, similar PtcO2 and nasopharyngeal FIO2 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. PtcO2 and nasopharyngeal FIO2 values were significantly lower when the flow rate using the NRB was decreased to 10 L·min⁻¹.