Use of transcutaneous pressure of oxygen in the evaluation of edematous wounds.

Transcutaneous pressure of oxygen (Ptco2) was measured in edematous wounds before and after a regimen of hyperbaric oxygen (HBO2) therapy, in patients breathing normobaric air (AIR), 100% normobaric oxygen (O2), and 100% O2 at 239 kPa (2.36 atm abs; HBO). Wounds also were scored for severity, including three ratings for periwound edema. Only during AIR was pre Ptc O2 of markedly edematous wounds significantly lower than that of moderately edematous and non-edematous wounds (P < 0.001). After HBO2 therapy, wound severity score and periwound edema rating decreased significantly (P < 0.001), and periwound edema ratings could no longer be distinguished by PtcO2. Although pre periwound PtcO2 measured during both O2 and HBO evaluations was significantly greater than that measured during AIR (P < 0.0001) and was positively correlated with subsequent change in wound severity (P < 0.05), regression analyses failed to yield a significant prediction equation. The authors conclude: a) dramatically marked increases in PtcO2 of normally hypoxic (< 30 Torr O2) edematous wounds during O2 and HBO challenges demonstrate that periwound edema is an O2 diffusion barrier during normal conditions; b) HBO2 therapy significantly reduces periwound edema in markedly edematous wounds; c) despite significant correlations between pre-therapy periwound PtcO2 measured during O2 and HBO challenges and changes in wound severity, single PtcO2 measurements are not predictive of changes in periwound edema or overall wound severity.