Risk factors for acute kidney injury requiring continuous renal replacement therapy after off-pump coronary surgery

Abstract

Recently, off-pump coronary artery bypass grafting (OPCABG) without cardiopulmonary bypass has become less stressful surgery for coronary artery bypass grafting (CABG). There have been a lot of reports discussing risk factors involving in an association between on-pump coronary artery bypass grafting and acute kidney injury (AKI) requiring continuous renal replacement therapy (CRRT), however, there are few papers on OPCABG. The purpose of the present study was to assess the impact of OPCABG on the incidence of AKI requiring CRRT. An observational study of 237 consecutive non dialysis patients who underwent isolated CABG using OPCABG was conducted. Among them, 33 patients needed CRRT due to AKI. Variables with a P＜0.05 in bivariate analysis collected from pre-, intra- and postoperative data were entered in the multivariate and proportional hazards regression analysis as independent AKI requiring CRRT risk factors after OPCABG were carried out. The risk factors that were independently associated with AKI requiring CRRT were：pre-estimated glomerular filtration rate (GFR) (less than 60mL/min/1.73m²), pre-serum albumin level (less than 3.5g/dL), pre-hemoglobin level (less than 12g/dL), intra-urine volume(less than 600mL/hr), use of intra-aortic balloon pump, and post-PaO₂/FiO₂ (less than 300). In conclusion, the risk of developing AKI requiring CRRT depended on the levels of GFR, serum albumin and hemoglobin before surgery, on the levels of urine volume and use of intra-aortic balloon pump during surgery and the levels of PaO₂/FiO₂ after surgery.