Hemodynamic Changes in Rat Leg Muscles during Tourniquet-induced Ischemia-reperfusion Injury Observed by Near-infrared Spectroscopy
ARMY INST OF SURGICAL RESEARCH FORT SAM HOUSTON TX
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In this study, we hypothesized that non-invasive continuous wave near-infrared spectroscopy CWNIRS can determine the severity or reversibility of muscle damage due to ischemiareperfusion IR, 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 IR. The results demonstrate that CWNIRS may be useful as a non-invasive prognostic tool for conditions involving vascular compromise such as extremity compartment syndrome.
- Anatomy and Physiology
- Medicine and Medical Research
- Atomic and Molecular Physics and Spectroscopy