Is muscle StO2 an appropiate variable for investigating early compensatory tissue mechanisms under physiological and pathological conditions ?

Because StO2 measured during ischemia actually measures oxygen extraction and, therefore, reflects the tissue metabolic rate, the desaturation slope serves only as a comparative measurement. Nevertheless, some authors describe contrasting results on the effects of desaturation rates measured with various NIRS devices in two forearm muscles in subjects undergoing volemic subtraction. We have mentioned only some reasons why, provided that studies are designed to give a wider range of information, NIRS can offer a useful insight into the early compensatory tissue mechanisms under various physiological or pathological conditions. Instead of focusing on a single variable, StO2, future clinical studies should aim to investigate several other variables that are highly sensitive and specific and provide more meaningful findings.