New instrument that uses near-infrared spectroscopy for the monitoring of human muscle oxygenation

Background: Early detection of vascular impairments after free tissue trans fers are essential to prevent flap failure. Near-infrared spectroscopy show ed good promise to monitor flaps at deep le, els successfully without being invasive. The purpose of this study was to test whether the INVOS 3100 cer ebral oxymeter is capable of detecting circulatory impairments. Methods: In 10 healthy adults, near-infrared spectroscopy was used to measu re regional saturation values during tourniquet ischemia and venous outflow restriction, in two test cycles. The probe, containing an infrared-light-e mitting source and two infrared-light sensors, was placed below the elbow a bove the brachioradialis muscle. Statistical comparison of the data nas per formed using the Friedman test and the Wilcoxon-Wilcox test, Results: Venous and arterial occlusions were characterized by an instantane ous fall of the regional saturation. Arterial occlusion showed a mean decre ase of the saturation values down to 28 +/- 9%, whereas venous occlusion sh owed a mean fall of saturation values down to 51 +/- 12%. These falls were significant after 3 minutes of occlusion compared with baseline values (74 +/- 6%). The differences between arterial and venous occlusions were statis tically significant, Conclusion: This study, designed to test less expensive equipment, was able to measure absolute values, and was not prone to interference caused by pr obe movement, providing information on the oxygenation profile accurately a nd noninvasively, and distinguishing between arterial and venous occlusion.