Ulcerated edematous limbs: effect of edema removal on transcutaneous oxygen measurements

We studied the effect of edema removal on transcutaneous oxygen tension (TcPO2) in eight patients with leg ulcers. An external pneumatic compression device was effective in removing edema from the ulcerated limbs over a 5-day course of treatment, at which time all treated limbs were clinically free of edema. TcPO2 levels at room air at the ulcer site were markedly reduced when compared with the control chest site, both before and after external pneumatic compression device therapy (p less than 0.001). Edema removal, however, did not significantly alter TcPO2 values (p greater than 0.9). No significant positional effects on TcPO2 values were noted with patients supine, sitting, or with the affected limbs elevated. Five patients (63%) had increased TcPO2 values adjacent to the ulcer site when receiving supplemental oxygen. For these patients, TcPO2 values increased after oxygen inhalation, both before and after edema removal (p less than 0.05). We conclude that TcPO2 values are markedly reduced in ulcerated edematous limbs. Edema, however, may not constitute a barrier to oxygen diffusion through the skin and does not account for the low TcPO2 values in the ulcerated edematous limb. Therefore the positive therapeutic effect of removing edema is unlikely to be related to better oxygenation of the tissues.