Agradecimentos: The authors thank the Biostatistical Consulting Core at Stony Brook University (Stony Brook, New York) for consulting with them on the statistical analysis. The authors also thank the veterinary technicians at the Division of Laboratory Animal Resources (DLAR) at Stony Brook University and Cecille Just, an electroencephalography (EEG) specialist, from the EEG Department at Stony Brook Hospital (Stony Brook, New York), for their assistance with their sheep experiments. This work has been supported by the Craig H. Neilsen Foundation (Encino, California); Stony Brook University Fusion Award (Stony Brook, New York); Stony Brook University’s Department of Anesthesiology; Office of the Vice President for Research; School of Medicine and University Hospital (Stony Brook, New York; to Drs. Floyd and Kogler); National Institutes of Health (Bethesda, Maryland; grant nos. R01-NS060653 and P41-EB015893 to Dr. Yodh); and the São Paulo Research Foundation through grant no. 2012/02500-8 (São Paulo, Brazil; to Dr. Galler) Ver menos

Abstract: Background: Spinal cord ischemia occurs frequently during thoracic aneurysm repair. Current methods based on electrophysiology techniques to detect ischemia are indirect, non-specific, and temporally slow. In this article, the authors report the testing of a spinal cord blood flow and oxygenation monitor, based on diffuse correlation and optical spectroscopies, during aortic occlusion in a sheep model. Methods: Testing was carried out in 16 Dorset sheep. Sensitivity in detecting spinal cord blood flow and oxygenation changes during aortic occlusion, pharmacologically induced hypotension and hypertension, and physiologically induced hypoxia/hypercarbia was assessed. Accuracy of the diffuse correlation spectroscopy measurements was determined via comparison with microsphere blood flow measurements. Precision was assessed through repeated measurements in response to pharmacologic interventions. Results: The fiber-optic probe can be placed percutaneously and is capable of continuously measuring spinal cord blood flow and oxygenation preoperatively, intraoperatively, and postoperatively. The device is sensitive to spinal cord blood flow and oxygenation changes associated with aortic occlusion, immediately detecting a decrease in blood flow (-65 32%; n = 32) and blood oxygenation (-17 +/- 13%, n = 11) in 100% of trials. Comparison of spinal cord blood flow measurements by the device with microsphere measurements led to a correlation of R-2 = 0.49, P < 0.01, and the within-sheep coefficient of variation was 9.69%. Finally, diffuse correlation spectroscopy is temporally more sensitive to ischemic interventions than motor-evoked potentials. Conclusion: The first-generation spinal fiber-optic monitoring device offers a novel and potentially important step forward in the monitoring of spinal cord ischemia Ver menos