Comparison of tissue oxygenation achieved breathing oxygen from a demand valve with four different mask configurations

摘要

Introduction High concentration normobaric oxygen (Osub2/sub) is a priority in treating divers with suspected decompression illness. The effect of different Osub2/sub mask configurations on tissue oxygenation when breathing with a demand valve was evaluated. Methods Sixteen divers had tissue oxygen partial pressure (Psubtc/subOsub2/sub) measured at six limb sites. Participants breathed Osub2/sub from a demand valve using: an intraoral mask (IOM?) with and without a nose clip (NC), a pocket face mask and an oronasal mask. In-line inspired Osub2/sub (FsubI/subOsub2/sub) and nasopharyngeal FsubI/subOsub2/sub were measured. Participants provided subjective ratings of mask comfort, ease of breathing and holding in position. Results Psubtc/subOsub2/sub values and nasopharyngeal FsubI/subOsub2/sub (median and range) were greatest using the IOM? with NC and similar with the IOM? without NC. Osub2/sub measurements were lowest with the oronasal mask which also was rated as the most difficult to breathe from and to hold in position. The pocket face mask was reported as the most comfortable to wear. The NC was widely described as uncomfortable. The IOM? and pocket face mask were rated best for ease of breathing. The IOM? was rated as the easiest to hold in position. Conclusion Of the commonly available Osub2/sub masks for use with a demand valve, the IOM? with NC achieved the highest Psubtc/subOsub2/sub values. Psubtc/subOsub2/sub and nasopharyngeal FsubI/subOsub2/sub values were similar between the IOM? with and without NC. Given the reported discomfort of the NC, the IOM? without NC may be the best option.