I am getting an increased amount of emails form specific groups with the question of validation on the discussion we have that MOXY. NIRS or e better SmO2 can be sued as a recovery indirect feedback on Cr.P.
SmO2 can be used a s a feedback on Cr.P recovery but we use often as well the tHb trend to increase the recovery feedback not just on metabolic or energy substrate but as well as a part of delivery feedback. It is fascinating for me to see with how much skepticism ( healthy skepticism ) NIRS./ MOXY is looked upon as we have finally a direct feedback on energy delivery and utilization. In contrast to the earlier used lactate, where we have in the best case scenario a trend with some speculation. LT was never under that much scrutiny and that's was good as it never woudl have been used for what it is used now in many centers.
Now here a fun article and how great the scientific back up is when using NIRS/ MOXY.
A cross-validation of near-infrared spectroscopy measurements of skeletal muscle oxidative capacity with phosphorus magnetic resonance spectroscopy
Terence E. Ryan, W. Michael Southern, Mary Ann Reynolds, and Kevin K. McCully
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The purpose of this study was to cross-validate measurements of skeletal muscle oxidative capacity made with near-infrared spectroscopy (NIRS) measurements to those made with phosphorus magnetic resonance spectroscopy (31P-MRS). Sixteen young (age = 22.5 ± 3.0 yr), healthy individuals were tested with both 31P-MRS and NIRS during a single testing session. The recovery rate of phosphocreatine was measured inside the bore of a 3-Tesla MRI scanner, after short-duration (∼10 s) plantar flexion exercise as an index of skeletal muscle oxidative capacity. Using NIRS, the recovery rate of muscle oxygen consumption was also measured using repeated, transient arterial occlusions outside the MRI scanner, after short-duration (∼10 s) plantar flexion exercise as another index of skeletal muscle oxidative capacity. The average recovery time constant was 31.5 ± 8.5 s for phosphocreatine and 31.5 ± 8.9 s for muscle oxygen consumption for all participants (P = 0.709). 31P-MRS time constants correlated well with NIRS time constants for both channel 1 (Pearson's r = 0.88, P < 0.0001) and channel 2 (Pearson's r = 0.95, P < 0.0001). Furthermore, both 31P-MRS and NIRS exhibit good repeatability between trials (coefficient of variation = 8.1, 6.9, and 7.9% for NIRS channel 1, NIRS channel 2, and 31P-MRS, respectively). The good agreement between NIRS and 31P-MRS indexes of skeletal muscle oxidative capacity suggest that NIRS is a valid method for assessing mitochondrial function, and that direct comparisons between NIRS and 31P-MRS measurements may be possible.
Keywords: mitochondrial capacity, 31P-MRS, oxidative metabolism, mitochondrial function