The usefulness of near-infrared spectroscopy in the anesthetic management of endovascular aortic aneurysm repair.

Near-infrared spectroscopy (NIRS) may be a useful method for monitoring the regional oxygen saturation (rSO(2)) of the lower extremity during endovascular aortic repair. Eighteen patients with thoracic descending and/or abdominal aortic aneurysm were enrolled in this study. NIRS probes were placed bilaterally on the calves. Muscular rSO(2) (mrSO(2)) was monitored every 30 s throughout the operation. In the leg in which the femoral artery was clamped, mrSO(2) values were selected at 3 or 4 points-just before clamping (control value), 30 min after clamping, 10 min after the first declamping, and 10 min after the second declamping following repair of the femoral artery, if necessary. In all patients, mrSO(2) decreased significantly during clamping, from 64 ± 11 % (mean ± SD) of the control value to 32 ± 15 %. After declamping, mrSO(2) recovered to 69 ± 14 % of the control value in 16 patients. In the 2 other patients, however, mrSO(2) did not recover after the first declamping, because of femoral artery dissection. After additional repair, mrSO(2) recovered quickly to the control value. These data suggested NIRS may objectively and quantitatively reflect oxygenation of the lower extremities, and may indicate an ischemic event that needs additional repair during endovascular aortic repair.