Regional Differences of Hemodynamics and Oxygenation in the Human Calf Muscle Detected with Near-Infrared Spectrophotometry

Abstract

Measurements in muscle tissue are often performed at a selected single location over the muscle of interest. The hypothesis is that the values obtained reflect the status within the entire muscle or muscle group. This, however, may not be the case. The study was performed to investigate whether this hypothesis is true for hemodynamics and oxygenation in the healthy human calf muscle at rest. Hemoglobin flow, blood flow, oxygen consumption, and venous hemoglobin oxygen saturation were mapped at 22 locations in 30 legs of 15 healthy subjects (nine women, six men aged 26-37 years) simultaneously by using frequency-domain near-infrared spectrophotometry with a specially designed probe during venous occlusion. For all parameters, spatial heterogeneity was found between subjects and within individual legs. All parameters were highly significantly different when comparing proximal and distal regions. Differences were also found between medial and lateral regions. The global mean values (+/-standard deviation) over all measurements were as follows: hemoglobin flow, 1.27 micromol per 100 mL/min +/- 0.88; blood flow, 0.56 mL per 100 g/min +/- 0.38; oxygen consumption, 0.016 mL per 100 g/min +/- 0.011; and venous oxygen saturation, 77.6% +/- 5.9. The thickness of the overlying adipose tissue had an influence on the measurements and must be considered. Highly significant spatial heterogeneity of hemodynamics and oxygenation was found in the healthy human calf muscle.