Prognostic value of intraoperative measurements of renal tissue oxygenation and microcirculation on renal function in partial nephrectomy.

BACKGROUND: Partial nephrectomy (PNx) can be associated with macrocirculatory and microcirculatory alterations, ultimately leading to acute kidney injury (AKI). Measuring kidney tissue oxygenation (μHbO2) and microcirculation during open PNx might be feasible to early detect these alterations and prevent postoperative AKI.

METHODS: μHbO2 and microcirculation were measured in 45 patients undergoing PNx by reflectance spectrophotometry and laser Doppler flowmetry (O2C™, Lea, Germany), related to ischemia time and tumour size. Pre- and postoperative creatinine levels were determined.

RESULTS: μHbO2 was lower after reperfusion than before clamping (72 vs. 75%), while microcirculation and regional haemoglobin did not differ. Ischemia time was 15.7 min on average. μHbO2 was higher without ischemia (80 vs. 70%, p = 0.109) and in T1a- than T1b-tumours, independent of ischemia time and reperfusion. The renal collecting system (RCS) was opened in 19/45 patients with μHbO2 of 68% after reperfusion compared to 74% with intact RCS. Postoperative complications occurred in 6/45 patients (13%). μHbO2 was 68% before clamping vs. 75% without complications. Serum creatinine of patients with T1b was higher compared to T1a (103 vs. 87 µmol/L). Patients with larger tumours had higher postoperative creatinine levels (173 vs. 124 µmol/L; p = 0.052).

CONCLUSION: We showed for the first time that the method is feasible to monitor renal tissue oxygenation at the level of microcirculation non-invasively and reproducibly during PNx. Tumour size seems to have a decisive influence on oxygenation and postoperative renal function. Our results imply that postoperative complications may be predicted by low intraoperative renal oxygenation and microcirculatory flow measurements.