Near-infrared spectroscopy (NIRS) has been used to evaluate regional oxygen saturation (rSO2), a marker of tissue oxygenation, especially cerebral oxygenation in various clinical settings1,2,3 and has recently been applied to patients undergoing hemodialysis (HD)4,5,6,7,8,9,10,11. Cerebral rSO2 is reportedly associated with cognitive function in patients undergoing HD or those with non-dialyzed chronic kidney disease (CKD)11,12. However, thus far, the use of NIRS monitoring has been limited in patients with CKD.
As NIRS monitoring is real-time and noninvasive, we assessed its usefulness as a monitoring device in patients undergoing HD. Although NIRS is mainly used to measure cerebral rSO2, we also investigated rSO2 values in other organs during HD. Specifically, the rSO2 measurement sensors were attached to the forehead, the right hypochondrium and the lower legs to evaluate rSO2 in the brain, liver and lower muscles, respectively. The results showed that NIRS monitoring could be a new approach to clarify changes in organ oxygenation during HD or factors affecting tissue oxygenation in CKD patients.
To date, continuous monitoring was performed during HD, blood volume monitoring, central venous oxygen saturation, thoracic admittance and electronic stethoscope-guided estimated blood pressure (BP) in clinical settings13,14,15; however, there are limitations for the prediction of hypotension or the wide use of devices. In contrast, the new noninvasive approach here could provide real-time information on intradialytic oxygen dynamics in individual organs. Therefore, this monitoring method may allow the detection of transient organ ischemia in the early phases of intradialytic hypotension and may also permit the safe performance of HD. This article describes a protocol to measure tissue oxygenation represented by rSO2, as applied in patients undergoing HD.