Near-infrared spectroscopy underestimates cerebral oxygenation in hemodialysis patients

Abstract

Regional cerebral oxygen saturation (rSO₂) measured using near-infrared spectroscopy has been reported to be significantly lower in hemodialysis (HD) patients than in non-HD ones, but the mechanisms are unknown. The aim of this prospective study was to assess the accuracy of near-infrared spectroscopy to estimate cerebral oxygenation in HD patients undergoing cardiovascular surgery. Our hypothesis was that rSO₂ values would underestimate cerebral oxygenation in HD patients. This study included 113 patients (7 HD patients and 106 non-HD ones) undergoing cardiac or major aortic surgery between December 2015 and November 2017. We evaluated the validity of rSO₂ by comparing it with ipsilateral jugular venous oxygen saturation (SjvO₂). In HD and non-HD patients, rSO₂ and SjvO₂ showed a weak correlation (R2: 0.46 and 0.28 in HD and non-HD patients, respectively). Bland–Altman analysis revealed that bias (95% limits of agreement) of rSO₂ compared to SjvO₂ was − 19.2% ( − 41.7–3.3%) in HD patients and − 1.9% (− 19.3–15.5%) in non-HD ones. The large negative bias suggests that the rSO₂ values measured using near-infrared spectroscopy substantially underestimate cerebral oxygenation in HD patients.