Transorally obtained oxygen tension as an indicator of arterial oxygen tension

Transcutaneous oxygen electrodes have been used with success in neonates as indicators of arterial oxygenation, but with less success in adults because of differences in skin thickness and vascularity. In this study a prototype transoral oxygen electrode was evaluated to determine if a heated mucous membrane would yield arterialized values of oxygen tension in adults. Using a miniaturized Clark electrode, we measured transoral oxygen tension (PtoO₂) in 29 subjects at steady-state conditions. Simultaneously a sample was anaerobically obtained from a radial artery for measurement of arterial oxygen tension (PaO₂). Data were analyzed using linear regression analysis, Student'st test, and analysis of variance. There was no statistically significant difference between non-white and white subjects or male and female subjects. There was a highly significant difference (P<0.001) between the pooled, matched values for PtoO₂ versus PaO₂, and the regression between the PtoO₂ and the PaO₂ was linear (slope 0.92, y-intercept ?8.37,r=0.62,P<0.003). The calculated ratio of PtoO₂ to PaO₂ was 0.83±0.03 (standard error). We concluded that the PtoO₂ was linearly related to the PaO₂, although its accuracy in reflecting PaO₂ was low. This finding correlates with previously published data that suggested that the PtoO₂ reflects tissue oxygen tension rather than arterialized oxygen tension. Gender and race appeared not to affect the function of the electrode in our study.