Differently from the manual count, the count of peaks of luminous intensity by Image J software seems to be promising to measure QBCF. The future is to create software allowing for real-time measure of the QBCF based on the peaks of luminous intensity inside the capillaries recorded by IVCM.

The venous-arterial difference in CO (ΔCO) has been proposed as an index of the adequacy of tissue perfusion in shock states. We hypothesized that the variation in PaCO (hyper- or hypocapnia) could impact ΔCO, partly through microcirculation adaptations. Fifteen healthy males volunteered to participate. For hypocapnia condition (hCO), the subjects were asked to hyperventilate, while they were asked to breathe a gas mixture containing 8 % CO for hypercapnia condition (HCO). The 2 conditions were randomly assigned. Blood gases were measured at baseline before each condition, and after 5-7 min of either hCO or HCO condition. Microcirculation was assessed by the muscle reoxygenation slope measured with near infrared spectroscopy following a vascular occlusion test and by skin circulation with in vivo reflectance confocal microscopy. ΔCO was significantly increased with hCO while it tended to decrease with HCO (non-significant). HCO induced a moderate increase of the resaturation slope of NIRS oxygenation. Skin microcirculatory blood flow significantly dropped with hCO, while it remained unchanged with hypercapnia. Our results warrant cautious interpretation of ΔCO as an indicator of tissue perfusion during respiratory alkalosis.

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