TRANSLATIONAL PHYSIOLOGY In vivo assessment of human vaginal oxygen and carbon dioxide levels during and post menses

Hill, Donna R., Marianne E. Brunner, Deborah C. Schmitz, Catherine C. Davis, Janine A. Flood, Patrick M. Schlievert, Sherry Z. Wang-Weigand, and Thomas W. Osborn. In vivo assessment of human vaginal oxygen and carbon dioxide levels during and post menses. J Appl Physiol 99: 1582–1591, 2005. First published June 2, 2005; doi:10.1152/japplphysiol.01422.2004.—Previous in vitro and in vivo animal studies showed that O2 and CO2 concentrations can affect virulence of pathogenic bacteria such as Staphylococcus aureus. The objective of this work was to measure O2 and CO2 levels in the vaginal environment during tampon wear using newly available sensor technology. Measurements by two vaginal sensors showed a decrease in vaginal O2 levels after tampon insertion. These decreases were independent of the type of tampons used and the time of measurement (mid-cycle or during menstruation). These results are not in agreement with a previous study that concluded that oxygenation of the vaginal environment during tampon use occurred via delivery of a bolus of O2 during the insertion process. Our measurements of gas levels in menses showed the presence of both O2 and CO2 in menses. The tampons inserted into the vagina contained O2 and CO2 levels consistent with atmospheric conditions. Over time during tampon use, levels of O2 in the tampon decreased and levels of CO2 increased. Tampon absorbent capacity, menses loading, and wear time influenced the kinetics of these changes. Colonization with S. aureus had no effect on the gas profiles during menstruation. Taken collectively, these findings have important implications on the current understanding of gaseous changes in the vaginal environment during menstruation and the potential role(s) they may play in affecting bacterial virulence factor production.