Near-infrared spectroscopy monitoring in kidney transplantation: early detection of acute rejection—a case report

Abstract

Introduction: Acute rejection remains a major cause of morbidity and graft loss after kidney transplantation, despite advances in immunosuppressive therapy. Conventional monitoring methods, such as serum creatinine, urine output, and Doppler ultrasound, detect graft dysfunction only after significant injury has occurred. Near-infrared spectroscopy (NIRS) is a noninvasive technique that continuously measures regional tissue oxygen saturation (rSO2) and may allow earlier detection of perfusion abnormalities.
Case report: A 36-year-old male with end-stage kidney disease underwent living-donor kidney transplantation under general anesthesia with goal-directed fluid therapy. Postoperative NIRS monitoring was performed using a sensor placed over the graft site. The rSO2 was approximately 95% on postoperative day (POD) 1, decreased to 78% on POD 2, and reached a nadir of 66% on POD 3, followed by gradual recovery to 91% by POD 6. Despite the apparent improvement in NIRS values, the patient developed oliguria progressing to anuria on POD 6. A renal biopsy confirmed acute rejection, and immunosuppressive therapy was promptly intensified.
Discussion: The early decline in rSO2 likely reflected evolving hypoperfusion, while the subsequent increase may have resulted from impaired oxygen extraction due to microvascular injury. This paradoxical trend resembles shock states, in which poor oxygen utilization leads to deceptively normal saturation levels. NIRS enables continuous, real-time assessment of graft perfusion, complementing conventional monitoring tools. However, interpretation must consider confounding factors such as tissue characteristics, light interference, and hemodynamic variability.
Conclusion/take-home message: Near-infrared spectroscopy (NIRS) may serve as an early, noninvasive indicator of graft dysfunction and acute rejection after kidney transplantation.