Functional changes in microcirculation during hyperbaric and normobaric oxygen therapy

Objectives: Treatment of cutaneous Wounds is one of the many applications of hyperbaric oxygen therapy (HBO). However, the complex regulation of skin microcirculation during different phases of HBO is not completely understood. We therefore investigated skin microcirculation and oxygenation during HBO and normobaric oxygen (NBO) exposure. Methods: Seven healthy volunteers were investigated using measurements or transcutaneous oxygen pressure (PtcO2), tissue spectrophotometry and laser Doppler flowmetry recorded simultaneously in the hand and foot during HBO and NBO in 2- and 4-mm depths. We defined tissue hypoxia as a P1cO2 below 30 mmHg. Results: At the hand, in 2 mm depth, NBO induced a mild vasoconstriction (-37%, p=0.07), but a significant increase in PtcO2 (+380%, p<0.001). HBO induced a mild vasoconstriction (45%, p=0.08), significantly increasing PtcO2 (+1430%, p<0.001). Hand changes in 2 and 4 mm were comparable. Foot changes were smaller than at the hand and more pronounced in 4 mm than in 2 mm depth during NBO and compression. No episodes of tissue hypoxia occurred at any time. Conclusions: In healthy subjects, NBO and especially HBO significantly improve tissue oxygenation, despite vasoconstriction. Differences in vascular regulation between hand and foot and especially at the latter site between 2 and 4 mm depth exist.