Spinal Near-Infrared Spectroscopy Measurements During and After Thoracoabdominal Aortic Aneurysm Repair: A Pilot Study

Background. Near-infrared spectroscopy (NIRS) is a noninvasive technique that allows continuous monitoring of regional hemoglobin oxygen saturation (rSO(2)). We evaluated its application to survey oxygenation of the spinal cord region during open thoracoabdominal aortic aneurysm (TAAA) repair and postoperatively in the intensive care unit (ICU). We also validated its association with motor-evoked potential (MEP) monitoring during the operation. Methods. The rSO(2) curves of 15 patients (8 men; mean age, 64.2 +/- 7.7 years) were measured continuously with NIRS at spinal cord levels of the thoracic vertebrae T3 (optode 1, reference spot) and T12 (optode 2) during open TAAA repair. T12/T3 ratios were calculated. NIRS measurements were continued in the intensive care unit and stopped 24 hours after the operation. MEP monitoring was performed in all patients during the procedure. Results. No clinical signs of spinal cord ischemia were documented in any of the patients. Continuous NIRS measurements were successfully performed in all patients during and after the operation. T12/T3 ratios were significantly lower in the MEP ratios that were less than 50% compared with theMEP ratios that were 50% or higher (p = 0.037). Conclusions. NIRS is an easily applicable noninvasive tool for continuous surveillance of oxygenation of the spinal cord region during TAAA repair and postoperatively in the intensive care unit. The rSO(2) curves provide useful information concerning hemodynamic changes in oxygenation of the spinal cord region and might contribute to early detection of spinal cord ischemia. Further investigation is needed before broad clinical implementation. (C) 2015 by The Society of Thoracic Surgeons