• J G Kim, J Lee, J Roe, B J Tromberg, M Brenner, and T J Walters.
• Laser Microbeam and Medical Program, Beckman Laser Institute and Medical Clinic, University of California Irvine, Irvine, USA. jaegk@ici.edu
• Physiol Meas. 2009 Jul 1; 30 (7): 529-40.

AbstractIn this study, we hypothesized that non-invasive continuous wave near-infrared spectroscopy (CWNIRS) can determine the severity or reversibility of muscle damage due to ischemia/reperfusion (I/R), and the results will be highly correlated with those from physical examination and histological analysis. To test this hypothesis, we performed CWNIRS measurements on two groups of male Sprague-Dawley rats ( approximately 400 g) that underwent 2 h (n = 6) or 3 h (n = 7) of pneumatic tourniquet application (TKA). Tissue oxyhemoglobin [HbO(2)] and deoxyhemoglobin [Hb] concentration changes were monitored during the 2 h or 3 h of 250 mmHg TKA and for an additional 2 h post-TKA. Rats were euthanized 24 h post-TKA and examined for injury, edema and viability of muscles. Contralateral muscles served as controls for each animal. In both groups, [HbO(2)] dropped immediately, then gradually decreased further after TKA and then recovered once the tourniquet was released. However, releasing after 2 h of TKA caused [HbO(2)] to overshoot above the baseline during reperfusion while the 3 h group continued to have lower [HbO(2)] than baseline. We found a significant correlation between the elapsed time from tourniquet release to the first recovery peak of [HbO(2)] and the muscle weight ratio between tourniquet and contralateral limb muscles (R = 0.86). Hemodynamic patterns from non-invasive CWNIRS demonstrated significant differences between 2 h and 3 h I/R. The results demonstrate that CWNIRS may be useful as a non-invasive prognostic tool for conditions involving vascular compromise such as extremity compartment syndrome.

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