Acute kidney injury in high-risk cardiac surgery patients: Roles of inflammation and coagulation

Aims Acute kidney injury (AKI) is a common complication following cardiac surgery. Cardiopulmonary bypass elicits coagulation and inflammation activation and oxidative stress, all involved in AKI but never simultaneously assessed. We aimed to evaluate relations between oxidative stress, inflammatory and coagulation systems activation and postoperative renal function in patients with normal preoperative renal function. Methods Forty-one high-risk patients (EuroSCORE >6 and preoperative haemoglobin <12 g/dl in women and <13g/dl in men) were prospectively enrolled. Prothrombin fragment 1.2 (coagulation marker), interleukin-6 and interleukin-10 (pro/anti-inflammatory markers) and 8-oxo-20-deoxyguanosine (oxidative stress marker) were evaluated until postoperative day 5. Results Patients were divided into two groups according to estimated glomerular filtration rate reduction observed postoperatively (reduction <25% in 26 patients: NO-AKI group; reduction >25% in 15 patients: AKI group). No differences were found for inflammatory markers. Oxidative stress slightly increased in the AKI group. Twenty-four hours after the operation prothrombin fragment 1.2 levels were significantly higher in the AKI group (506.6 W548 vs. 999 W 704.1 pmol/l; P =0.018), and they were independently associated with estimated glomerular filtration rate reduction, with an area under the receiving operating characteristic of 0.744. Conclusion Thrombin generation is higher in patients with renal function worsening, and it is an independent risk factor for AKI in patients with anaemia, possibly leading to microcirculation impairment and tubular cells damage.