Low preoperative regional cerebral oxygen saturation in hemodialysis patients

[Background] Regional cerebral oxygen saturation (rSO2) monitoring by near-infrared spectroscopy provides valuable information regarding cerebral oxygen delivery, and it has been increasingly used in cardiovascular surgery. Although it has been shown that dialysis-dependent patients [hemodialysis (HD) patients] suffer from low cerebral perfusion, limited information is available on cerebral tissue oxygenation levels in HD patients. [Findings] In this retrospective study, the preoperative rSO2 values in 9 HD patients undergoing coronary artery bypass graft surgery were compared with those in 40 non-HD patients. HD patients had lower preoperative rSO2 values than non-HD patients (median: 46 vs. 68%, respectively, P < 0.001). Despite adjusting for age, hemoglobin concentration, and left ventricular ejection fraction using multivariable linear regression, HD showed a strong association with low rSO2 (estimated coefficient: −20.4, P < 0.001). [Conclusions] HD showed a strong association with low preoperative rSO2 values in patients undergoing coronary artery bypass graft surgery, even after adjusting for known factors that affect rSO2 values, including age, hemoglobin concentration, and cardiac systolic function. Further research is required to elucidate the mechanisms decreasing rSO2 values in HD patients