Changes of dermal haemoglobin oxygenation and concentration in healthy subjects and in patients with peripheral arterial occlusive disease during and after acute ischemia

Abstract

Background: Oxygen saturation (SHB) and concentration (CHB) of dermal haemoglobin play an important role in the nutrition of the skin. In patients with severe peripheral arterial occlusive disease (PAOD) they are reduced at the forefoot. We investigated the changes of the named parameters during an acute ischemia and during reactive hyperemia using an occlusion test.

Patients and methods: Dermal reflection spectra were conducted from the forefoot of 11 healthy subjects and 39 patients with peripheral arterial occlusive disease of various stages at rest, during, and after an arterial occlusion at the thigh. Using a multicomponent analysis SHB and CHB were calculated iteratively. The halftime of the post-occlusive increase of SHB (post-occlusive recovery halftime PORHT) and the relation of post- to pre-occlusive CHB (post-occlusive reactive hyperemia PORH) were calculated to estimate the dynamic of the post-occlusive inflow of blood. TcPO2 (37 degrees C) was additionally determined at the forefoot.

Results: In patients from stage III and IV all resting values were lower compared to controls. TcPO2 decreased in all persons to 0 mm Hg during the occlusion, SHB was between 0 and 10%, while CHB remained unchanged. In healthy subjects and in patients with claudication the post-occlusive values exceeded the preocclusive ones, while in some patients with higher stages of the disease this could not be found. There was a marked, on the stage of the disease depending difference in the post-occlusive course between controls and patients: in healthy subjects it took only 5.5 +/- 4.8 s until SHB reached half of the maximum value, in patients from the stage IIa group 26.8 +/- 16.9 s (p < 0.001) was measured while in stage III and IV the value was 132 +/- 75 s (p < 0.001).

Conclusions: During ischemia a decrease of the haemoglobin oxygen saturation (SHB) and tcPO2 was found. Haemoglobin concentration (CHB) remained constant, hence a significant shift of blood from skin to muscle did not take place. PORHT was selectively dependent on the stage of the disease. The occlusion manoeuvre enhances the significance of reflection photometry in PAOD.