Gender differences in human skeletal muscle and subcutaneous tissue gases under ambient and hyperbaric oxygen...

The purpose of this study is to ascertain if gender differences exist in human skeletal muscle (MM) and subcutaneous (SC) tissue gases using monoplace and multiplace hyperbaric oxygen (HBO2) treatment protocols.

Gas tensions in resting MM and SQ tissues were recorded at 4-minute intervals using two protocols: The 150 minute monoplace HBO2 chamber protocol utilized continuous oxygen (O2) breathing at 202.6 kPa, that is 2 atmospheres absolute (2 ATA). The multiplace HBO2 chamber protocol had four 5-minute air breaks between five 20 minute O2 breathing periods at 2 ATA and took 180 minutes to complete. Tissue gas samples were obtained by the vacuum technique through a low permeable Teflon membrane and analyzed using a mass spectrometer.

Over 40,000 individual step analyses showed gas tensions changed (repeated measures of variance, p = 0.00001) with time as the gas pressures and mixtures breathed were altered. Statistically significant differences between males and females in loading and unloading of SC nitrogen (N2) (P = 0.0001), SC O2 (P = 0.001) and MM O2 (P = 0.003) were observed in the multiplace protocol. Females release SC N2 more slowly; while increasing their MM and SC O2 tensions higher than males. Muscle and SC CO2 levels decrease in both males and females when exposed to HBO2 and increase when breathing air.

Three main gender differences are observed in tissue gas loading and unloading under hyperbaric oxygen exposures: Females release SC N2 more slowly and saturate MM O2 and SC O2 to greater extents. Finally, female MM and SC O2 rose to higher levels in the multiplace protocol than in the monoplace protocol, which was not observed in the male subjects. This information may help explain why males and females respond differently to diving decompression stresses and the clinical application of HBO2.