Background. Oxygen administration is currently used in dinical medicine to improve peripheral oxygen delivery to tissues threatened by ischemia. However, conflicting results have been reported on the effects of oxygen in ischemic areas. This study was aimed at investigating the effects of 40% oxygen inhalation on the skin microcirculation in the feet of patients with peripheral arterial occlusive disease (PAOD). Methods and Results. Transcutaneous oxygen tension (tc PO2) was measured on the dorsal skin of the foot, and the nailfold microcirculation was investigated by a combination of laser Doppler flowmetry (LDF) and dynamic capillaroscopy (CBV) in the great toes of 17 legs of 11 patients, with 13 legs of eight normal subjects as a control group. Inhalation of oxygen induced a significant decrease of both the total (DELTA-LDF, -307%,p<0.02) and nutritional (DELTA-CBV, -17%,p<0.002) skin microcirculation in normal legs compared with baseline values. A similar response was observed in 10 legs of patients who showed a significant increase of the tc P(O2) (greater-than-or-equal-to 10 mm Hg) (DELTA-LDF, - 14%, NS; DELTA-CBV, - 13%, p<0.005). By contrast, both the total (+21%, p<0.03) and nutritional (+52%, p<0.05) circulation significantly increased in the seven legs without significant tc PO2 increase. In addition, the flow motion, which was impaired in the patients, was significantly (p<0.05) improved by oxygen inhalation. Conclusions. Inhalation of 40% oxygen induces a vasoconstriction in the skin microcirculation of toes of the normal subjects and patients with moderate PAOD but induces an increase of the skin microcirculation in patients with severe PAOD.
