Evaluation of different near-infrared spectroscopy technologies for assessment of tissue oxygen saturation during a vascular occlusion test

An increasing number of NIRS devices are used to provide measurements of peripheral tissue oxygen saturation (S_tO₂). The aim of the present study is to test the hypothesis that despite technological differences between devices, similar trend values will be obtained during a vascular occlusion test. The devices compared are NIRO-200NX, which measures S_tO₂ and oxyhemoglobin by spatially resolved spectroscopy and the Beer–Lambert law, respectively, and INVOS 5100C and Foresight Elite, which both measure S_tO₂ with the Beer–Lambert law, enhanced with the spatial resolution technique. Forty consenting adults scheduled for CABG surgery were recruited. The respective sensors of the three NIRS devices were applied over the brachioradial muscle. Before induction of anesthesia, 3 min of ischemia were induced by inflating a blood pressure cuff at the upper arm, whereafter cuff pressure was rapidly released. Tissue oxygenation measurements included baseline, minimum and maximum values, desaturation and resaturation slopes, and rise time. Comparisons between devices were performed with the Kruskal–Wallis test with post hoc Mann–Whitney pairwise comparisons. Agreement was evaluated using Bland–Altman plots. Oxyhemoglobin measured with NIRO responded faster than the other NIRS technologies to changes in peripheral tissue oxygenation (20 vs. 27–40 s, p ≤ 0.01). When comparing INVOS with Foresight, oxygenation changes were prompter (upslope 311 [92–523]%/min vs. 114[65–199]%/min, p ≤ 0.01) and more pronounced (minimum value 36 [21–48] vs. 45 [40–51]%, p ≤ 0.01) with INVOS. Significant differences in tissue oxygen saturation measurements were observed, both within the same device as between different devices using the same measurement technology.